import OAI.Computability.BinPacking.Computation.MachineOverlayRows
import OAI.Computability.BinPacking.Computation.MachineVertexPadding

namespace OAI

namespace BinPackingGames.Foundations.Complexity.MachineOverlayTable

open Turing MachineComposition
open PCP PCP.GraphTables PCP.PreprocessingOverlayWords
open MachineCloudPadding

variable {A : Type}

abbrev Tape := Fin 5 ⊕ Fin 12
abbrev Ambient (A : Type) (d e : Nat) := ((A × Fin e) × MachineLazyRows.Buffer) × Fin d
abbrev State (A : Type) (d e : Nat) := Ambient A d e × Option Bool

def graphArchive : Tape := .inl 0
def graphStream : Tape := .inl 1
def scratch : Tape := .inl 2
def vertexCount : Tape := .inl 3
def dartCount : Tape := .inl 4
def expanderArchive : Tape := .inr 0
def expanderStream : Tape := .inr 1
def fuel : Tape := .inr 2
def vertex : Tape := .inr 3
def tail : Tape := .inr 4
def oldReverse : Tape := .inr 5
def relation : Tape := .inr 6
def dividedCopy : Tape := .inr 7
def quotient : Tape := .inr 8
def newReverse : Tape := .inr 9
def rowBuffer : Tape := .inr 10
def output : Tape := .inr 11

def oldTapes : Fin 10 → Tape :=
  ![tail, oldReverse, relation, scratch, dividedCopy, quotient, newReverse,
    output, rowBuffer, graphStream]

def expanderTapes : Fin 10 → Tape :=
  ![tail, oldReverse, relation, scratch, dividedCopy, quotient, newReverse,
    output, rowBuffer, expanderStream]

theorem oldTapes_injective : Function.Injective oldTapes := by
  intro i j h
  fin_cases i <;> fin_cases j <;>
    simp_all [oldTapes, tail, oldReverse, relation, scratch, dividedCopy, quotient,
      newReverse, output, rowBuffer, graphStream]

theorem expanderTapes_injective : Function.Injective expanderTapes := by
  intro i j h
  fin_cases i <;> fin_cases j <;>
    simp_all [expanderTapes, tail, oldReverse, relation, scratch, dividedCopy, quotient,
      newReverse, output, rowBuffer, expanderStream]

def clean (d e : Nat) (hd : 0 < d) (he : 0 < e) (a : A) : State A d e :=
  MachineLazyRows.streamClean d hd (a, MachineFixedDivMod.residue e he 0)

def expanderState (A : Type) (d e : Nat) :
    MachineOverlayRows.State ((A × MachineLazyRows.Buffer) × Fin d) e ≃ State A d e where
  toFun
    | ((((a, buffer), rd), re), bit) => ((((a, re), buffer), rd), bit)
  invFun
    | ((((a, re), buffer), rd), bit) => ((((a, buffer), rd), re), bit)
  left_inv := by rintro ⟨⟨⟨⟨a, buffer⟩, rd⟩, re⟩, bit⟩; rfl
  right_inv := by rintro ⟨⟨⟨⟨a, re⟩, buffer⟩, rd⟩, bit⟩; rfl

theorem expanderState_clean (d e : Nat) (hd : 0 < d) (he : 0 < e) (a : A) :
    expanderState A d e (MachinePortReindex.clean e he
      ((a, MachineRegularOriginalRow.zeroBuffer), MachineFixedDivMod.residue d hd 0)) =
      clean d e hd he a := rfl

inductive MainLabel (d e : Nat)
  | copyHFirst | copyHSecond
  | countSeed | countScan | countRestore
  | headerSeed | headerScan | headerRestore
  | fuelSeed | fuelScan | fuelRestore | vertexSeed | guard
  | old (stage : MachineLazyRows.VertexLabel d)
  | tailSeed | tailScan | tailRestore
  | expander (stage : MachineOverlayRows.VertexLabel e)
  | drainTail | increment
  | drainFuel | drainVertex | drainVertexCount | drainDartCount
  deriving DecidableEq, Fintype

abbrev Label (d e : Nat) := MachineTableSplit.Label ⊕ MainLabel d e

def next {d e : Nat} (l : MainLabel d e) : Option (Label d e) := some (.inr l)

def mainInstruction (d e : Nat) (hd : 0 < d) (he : 0 < e) :
    MainLabel d e → TM2.Stmt (fun _ : Tape => Bool) (Label d e) (State A d e)
  | .copyHFirst => Reduction.MachineTransfer.loopAt expanderArchive scratch id false
      (.inr .copyHFirst) (next .copyHSecond)
  | .copyHSecond => MachineCopy.forkLoop scratch expanderArchive expanderStream false
      (.inr .copyHSecond) (next .countSeed)
  | .countSeed => MachineUnaryAffineAt.seed output 0 (.inr .countScan)
  | .countScan => MachineUnaryAffineAt.scan vertexCount scratch output (d + e)
      (.inr .countScan) (.inr .countRestore)
  | .countRestore => Reduction.MachineTransfer.loopAt scratch vertexCount id false
      (.inr .countRestore) (next .headerSeed)
  | .headerSeed => MachineUnaryAffineAt.seed output 0 (.inr .headerScan)
  | .headerScan => MachineUnaryAffineAt.scan vertexCount scratch output 1
      (.inr .headerScan) (.inr .headerRestore)
  | .headerRestore => Reduction.MachineTransfer.loopAt scratch vertexCount id false
      (.inr .headerRestore) (next .fuelSeed)
  | .fuelSeed => MachineUnaryAffineAt.seed fuel 0 (.inr .fuelScan)
  | .fuelScan => MachineUnaryAffineAt.scan vertexCount scratch fuel 1
      (.inr .fuelScan) (.inr .fuelRestore)
  | .fuelRestore => Reduction.MachineTransfer.loopAt scratch vertexCount id false
      (.inr .fuelRestore) (next .vertexSeed)
  | .vertexSeed => .push vertex (fun _ => false) (.goto fun _ => .inr .guard)
  | .guard => MachineUnaryCounter.guard fuel (.inr (.old (0, none))) (.inr .drainFuel)
  | .old stage => MachineLazyRows.vertexInstruction d hd (d + e) 0 oldTapes
      (fun stage => .inr (.old stage)) (next .tailSeed) stage
  | .tailSeed => MachineUnaryAffineAt.seed tail 0 (.inr .tailScan)
  | .tailScan => MachineUnaryAffineAt.scan vertex scratch tail 1
      (.inr .tailScan) (.inr .tailRestore)
  | .tailRestore => Reduction.MachineTransfer.loopAt scratch vertex id false
      (.inr .tailRestore) (next (.expander (0, none)))
  | .expander stage => MachineStateEquiv.statement (expanderState A d e)
      (MachineOverlayRows.vertexInstruction d e he expanderTapes
        (fun stage => .inr (.expander stage)) (next .drainTail) stage)
  | .drainTail => MachineDrain.drain tail (.inr .drainTail) (next .increment)
  | .increment => .push vertex (fun _ => true) (.goto fun _ => .inr .guard)
  | .drainFuel => MachineDrain.drain fuel (.inr .drainFuel) (next .drainVertex)
  | .drainVertex => MachineDrain.drain vertex (.inr .drainVertex) (next .drainVertexCount)
  | .drainVertexCount => MachineDrain.drain vertexCount (.inr .drainVertexCount) (next .drainDartCount)
  | .drainDartCount => MachineDrain.drain dartCount (.inr .drainDartCount) none

def program (d e : Nat) (hd : 0 < d) (he : 0 < e) :
    Label d e → TM2.Stmt (fun _ : Tape => Bool) (Label d e) (State A d e)
  | .inl l => Placement.statement Sum.inl Sum.inl (next .copyHFirst)
      (MachineTableSplit.program l)
  | .inr l => mainInstruction d e hd he l

theorem program_main (d e : Nat) (hd : 0 < d) (he : 0 < e) (l : MainLabel d e) :
    program (A := A) d e hd he (.inr l) = mainInstruction d e hd he l := rfl

def extraTapes (rawH : List Bool) : Fin 12 → List Bool :=
  fun i => if i = 0 then rawH else []

def splitView : Tape → Option (Fin 5)
  | .inl i => some i
  | .inr _ => none

def combine (left : Fin 5 → List Bool) (rawH : List Bool) : Tape → List Bool
  | .inl i => left i
  | .inr i => extraTapes rawH i

def initialTapes (graph rawH : List Bool) : Tape → List Bool :=
  combine (MachineTableSplit.initialTapes graph) rawH

def splitTapes (n m : Nat) (rows rawH : List Bool) : Tape → List Bool :=
  combine (MachineTableSplit.resultTapes n m rows) rawH

theorem placedTapes (left : Fin 5 → List Bool) (rawH : List Bool) :
    Placement.tapes splitView left (initialTapes [] rawH) = combine left rawH := by
  funext k
  cases k <;> rfl

theorem splitTrace (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (table : GraphTables.Table) (rawH : List Bool) (a : A) :
    (advance (TM2.step (program d e hd he)))^[MachineTableSplit.exactSteps
      table.vertices table.darts (MachineTableSplit.rowsBits table)]
      (some ⟨some (.inl .copyFirst), clean d e hd he a,
        initialTapes (GraphTables.tableBits table) rawH⟩) =
      some ⟨next .copyHFirst, clean d e hd he a,
        splitTapes table.vertices table.darts (MachineTableSplit.rowsBits table) rawH⟩ := by
  let ambient := (clean d e hd he a).1
  have source := MachineTableSplit.tableTrace table ambient none
  have placed := Placement.trace (Sum.inl : Fin 5 → Tape) splitView (fun _ => rfl)
    (by intro j k h; cases j <;> simp_all [splitView])
    (Sum.inl : MachineTableSplit.Label → Label d e) (next .copyHFirst)
    (initialTapes [] rawH) MachineTableSplit.program (program d e hd he) (fun _ => rfl)
    _ _ _ source
  simp only [Placement.configuration, Placement.label] at placed
  rw [placedTapes, placedTapes] at placed
  simpa only [initialTapes,
    splitTapes, ambient, clean, MachineLazyRows.streamClean, MachinePortReindex.clean] using placed

def memory (g h gs hs n m f v t out : List Bool) : Tape → List Bool
  | .inl i => ![g, gs, [], n, m] i
  | .inr i => ![h, hs, f, v, t, [], [], [], [], [], [], out] i

@[simp] theorem memory_graphArchive (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out graphArchive = g := rfl
@[simp] theorem memory_graphStream (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out graphStream = gs := rfl
@[simp] theorem memory_scratch (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out scratch = [] := rfl
@[simp] theorem memory_vertexCount (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out vertexCount = n := rfl
@[simp] theorem memory_dartCount (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out dartCount = m := rfl
@[simp] theorem memory_expanderArchive (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out expanderArchive = h := rfl
@[simp] theorem memory_expanderStream (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out expanderStream = hs := rfl
@[simp] theorem memory_fuel (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out fuel = f := rfl
@[simp] theorem memory_vertex (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out vertex = v := rfl
@[simp] theorem memory_tail (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out tail = t := rfl
@[simp] theorem memory_oldReverse (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out oldReverse = [] := rfl
@[simp] theorem memory_relation (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out relation = [] := rfl
@[simp] theorem memory_dividedCopy (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out dividedCopy = [] := rfl
@[simp] theorem memory_quotient (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out quotient = [] := rfl
@[simp] theorem memory_newReverse (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out newReverse = [] := rfl
@[simp] theorem memory_rowBuffer (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out rowBuffer = [] := rfl
@[simp] theorem memory_output (g h gs hs n m f v t out : List Bool) :
    memory g h gs hs n m f v t out output = out := rfl

@[simp] theorem update_output (g h gs hs n m f v t out x : List Bool) :
    Function.update (memory g h gs hs n m f v t out) output x = memory g h gs hs n m f v t x := by
  funext k; rcases k with i | i <;> fin_cases i <;> rfl
@[simp] theorem update_expanderStream (g h gs hs n m f v t out x : List Bool) :
    Function.update (memory g h gs hs n m f v t out) expanderStream x =
      memory g h gs x n m f v t out := by
  funext k; rcases k with i | i <;> fin_cases i <;> rfl
@[simp] theorem update_graphStream (g h gs hs n m f v t out x : List Bool) :
    Function.update (memory g h gs hs n m f v t out) graphStream x =
      memory g h x hs n m f v t out := by
  funext k; rcases k with i | i <;> fin_cases i <;> rfl
@[simp] theorem update_fuel (g h gs hs n m f v t out x : List Bool) :
    Function.update (memory g h gs hs n m f v t out) fuel x = memory g h gs hs n m x v t out := by
  funext k; rcases k with i | i <;> fin_cases i <;> rfl
@[simp] theorem update_vertex (g h gs hs n m f v t out x : List Bool) :
    Function.update (memory g h gs hs n m f v t out) vertex x = memory g h gs hs n m f x t out := by
  funext k; rcases k with i | i <;> fin_cases i <;> rfl
@[simp] theorem update_tail (g h gs hs n m f v t out x : List Bool) :
    Function.update (memory g h gs hs n m f v t out) tail x = memory g h gs hs n m f v x out := by
  funext k; rcases k with i | i <;> fin_cases i <;> rfl
@[simp] theorem update_vertexCount (g h gs hs n m f v t out x : List Bool) :
    Function.update (memory g h gs hs n m f v t out) vertexCount x = memory g h gs hs x m f v t out := by
  funext k; rcases k with i | i <;> fin_cases i <;> rfl
@[simp] theorem update_dartCount (g h gs hs n m f v t out x : List Bool) :
    Function.update (memory g h gs hs n m f v t out) dartCount x = memory g h gs hs n x f v t out := by
  funext k; rcases k with i | i <;> fin_cases i <;> rfl

private theorem joinTrace {X : Type*} {f : X → X} {a b c : X} {n m : Nat}
    (first : f^[n] a = b) (second : f^[m] b = c) : f^[n + m] a = c := by
  rw [Nat.add_comm, Function.iterate_add_apply, first, second]

theorem initialTapes_memory (g h : List Bool) :
    initialTapes g h = memory g h [] [] [] [] [] [] [] [] := by
  funext k
  rcases k with i | i <;> fin_cases i <;>
    simp [initialTapes, combine, extraTapes, MachineTableSplit.initialTapes,
      MachineTableSplit.tapes, memory]

theorem splitTapes_memory (n m : Nat) (rows rawH : List Bool) :
    splitTapes n m rows rawH = memory (encodeWords [n, m] ++ rows) rawH rows []
      (encodeWord n) (encodeWord m) [] [] [] [] := by
  funext k
  rcases k with i | i <;> fin_cases i <;>
    simp [splitTapes, combine, extraTapes, MachineTableSplit.resultTapes,
      MachineTableSplit.tapes, memory]

def preparationSteps (n : Nat) (h : List Bool) : Nat := 2 * (h.length + 1) + 6 * (n + 1) + 4

theorem preparationTrace (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (g h gs : List Bool) (n m : Nat) (a : A) :
    (advance (TM2.step (program d e hd he)))^[preparationSteps n h]
      (some ⟨next .copyHFirst, clean d e hd he a,
        memory g h gs [] (encodeWord n) (encodeWord m) [] [] [] []⟩) =
      some ⟨next .guard, clean d e hd he a,
        memory g h gs h (encodeWord n) (encodeWord m) (encodeWord n) (encodeWord 0) []
          (encodeWords [n, n * (d + e)])⟩ := by
  let b0 := memory g h gs [] (encodeWord n) (encodeWord m) [] [] [] []
  let b1 := memory g h gs h (encodeWord n) (encodeWord m) [] [] [] []
  let b2 := memory g h gs h (encodeWord n) (encodeWord m) [] [] [] (encodeWord ((d + e) * n))
  let b3 := memory g h gs h (encodeWord n) (encodeWord m) [] [] []
    (encodeWords [n, n * (d + e)])
  let b4 := memory g h gs h (encodeWord n) (encodeWord m) (encodeWord n) [] []
    (encodeWords [n, n * (d + e)])
  let ambient := (clean d e hd he a).1
  have hcopy := MachineCopy.copyTrace expanderArchive expanderStream scratch
    (by decide) (by decide) (by decide) false (.inr .copyHFirst) (.inr .copyHSecond)
    (next .countSeed) (program d e hd he) rfl rfl b0 rfl ambient none
  have copyRun : (advance (TM2.step (program d e hd he)))^[2 * (h.length + 1)]
      (some ⟨next .copyHFirst, clean d e hd he a, b0⟩) =
      some ⟨next .countSeed, clean d e hd he a, b1⟩ := by
    simpa only [b0, b1, memory_expanderArchive, memory_expanderStream, next, List.append_nil,
      update_expanderStream, ambient, clean, MachineLazyRows.streamClean,
      MachinePortReindex.clean] using hcopy
  have hcount := MachineUnaryAffineAt.seededAffineTrace vertexCount scratch output
    (by decide) (by decide) (by decide) (d + e) 0
    (.inr .countSeed) (.inr .countScan) (.inr .countRestore) (next .headerSeed)
    (program d e hd he) rfl rfl rfl b1 n [] (by simp [b1, memory, vertexCount]) rfl ambient none
  have countRun : (advance (TM2.step (program d e hd he)))^[2 * (n + 1) + 1]
      (some ⟨next .countSeed, clean d e hd he a, b1⟩) =
      some ⟨next .headerSeed, clean d e hd he a, b2⟩ := by
    simpa only [b1, b2, memory_output, next, List.append_nil, Nat.add_zero, update_output,
      ambient, clean, MachineLazyRows.streamClean, MachinePortReindex.clean] using hcount
  have hheader := MachineUnaryAffineAt.seededAffineTrace vertexCount scratch output
    (by decide) (by decide) (by decide) 1 0
    (.inr .headerSeed) (.inr .headerScan) (.inr .headerRestore) (next .fuelSeed)
    (program d e hd he) rfl rfl rfl b2 n [] (by simp [b2, memory, vertexCount]) rfl ambient none
  have headerRun : (advance (TM2.step (program d e hd he)))^[2 * (n + 1) + 1]
      (some ⟨next .headerSeed, clean d e hd he a, b2⟩) =
      some ⟨next .fuelSeed, clean d e hd he a, b3⟩ := by
    simpa only [b2, b3, memory_output, next, Nat.one_mul, Nat.add_zero, update_output,
      Nat.mul_comm (d + e) n, encodeWords, List.append_nil,
      ambient, clean, MachineLazyRows.streamClean, MachinePortReindex.clean] using hheader
  have hfuel := MachineUnaryAffineAt.seededAffineTrace vertexCount scratch fuel
    (by decide) (by decide) (by decide) 1 0
    (.inr .fuelSeed) (.inr .fuelScan) (.inr .fuelRestore) (next .vertexSeed)
    (program d e hd he) rfl rfl rfl b3 n [] (by simp [b3, memory, vertexCount]) rfl ambient none
  have fuelRun : (advance (TM2.step (program d e hd he)))^[2 * (n + 1) + 1]
      (some ⟨next .fuelSeed, clean d e hd he a, b3⟩) =
      some ⟨next .vertexSeed, clean d e hd he a, b4⟩ := by
    simpa only [b3, b4, memory_fuel, next, List.append_nil, Nat.one_mul, Nat.add_zero,
      update_fuel, ambient, clean, MachineLazyRows.streamClean, MachinePortReindex.clean] using hfuel
  have seedRun : (advance (TM2.step (program d e hd he)))^[1]
      (some ⟨next .vertexSeed, clean d e hd he a, b4⟩) =
      some ⟨next .guard, clean d e hd he a,
        memory g h gs h (encodeWord n) (encodeWord m) (encodeWord n) (encodeWord 0) []
          (encodeWords [n, n * (d + e)])⟩ := by
    change some (TM2.stepAux (program d e hd he (.inr .vertexSeed)) _ _) = _
    simp only [program, mainInstruction, TM2.stepAux, b4, memory_vertex,
      update_vertex, next, encodeWord, List.replicate_zero, List.nil_append]
  have all := joinTrace (joinTrace (joinTrace (joinTrace copyRun countRun) headerRun) fuelRun) seedRun
  have count : preparationSteps n h =
      (((2 * (h.length + 1) + (2 * (n + 1) + 1)) + (2 * (n + 1) + 1)) +
        (2 * (n + 1) + 1)) + 1 := by unfold preparationSteps; omega
  rw [count]
  exact all

private theorem encodeWords_flatMap {α : Type*} (items : List α) (words : α → List Nat) :
    encodeWords (items.flatMap words) = items.flatMap (fun x => encodeWords (words x)) := by
  induction items with
  | nil => rfl
  | cons item items ih => simp only [List.flatMap_cons, encodeWords_append, ih]

private theorem encodeWords_flatten (items : List (List Nat)) :
    encodeWords items.flatten = (items.map encodeWords).flatten := by
  induction items with
  | nil => rfl
  | cons item items ih => simp only [List.flatten_cons, List.map_cons, encodeWords_append, ih]

private theorem encodeWords_flatten_flatMap {α : Type*} (items : List (List α))
    (words : α → List Nat) :
    encodeWords (items.flatten.flatMap words) =
      (items.map fun xs => encodeWords (xs.flatMap words)).flatten := by
  induction items with
  | nil => rfl
  | cons item items ih =>
      simp only [List.flatten_cons, List.flatMap_append, encodeWords_append, List.map_cons, ih]

def oldRows {n d : Nat} (G : PortTables.Table n d) (v : Fin n) := List.ofFn (row G v)
def expanderValues {n e : Nat} (H : ExpanderTables.Table n e) (v : Fin n) (p : Fin e) : Nat :=
  (ExpanderTables.reverseIndex H (ExpanderTables.rowIndex n e (v, p))).val

def oldBlock {n d : Nat} (G : PortTables.Table n d) (v : Fin n) : List Bool :=
  MachineLazyRows.recordsInput (oldRows G v)
def expanderBlock {n e : Nat} (H : ExpanderTables.Table n e) (v : Fin n) : List Bool :=
  encodeWords (List.ofFn (expanderValues H v))

def oldOutput {n d : Nat} (G : PortTables.Table n d) (e : Nat) (v : Fin n) : List Bool :=
  MachineLazyRows.recordsOutput d (d + e) 0 (oldRows G v)
def expanderOutput {n e : Nat} (d : Nat) (H : ExpanderTables.Table n e) (v : Fin n) : List Bool :=
  MachineOverlayRows.streamOutput d e v.val (List.ofFn (expanderValues H v))
def outputBlock {n d e : Nat} (G : PortTables.Table n d) (H : ExpanderTables.Table n e)
    (v : Fin n) : List Bool := oldOutput G e v ++ expanderOutput d H v

theorem oldOutput_eq {n d : Nat} (G : PortTables.Table n d) (e : Nat) (v : Fin n) :
    oldOutput G e v = encodeWords ((List.ofFn (oldRow G e v)).flatMap rowWords) := by
  rw [encodeWords_flatMap]
  simp only [oldOutput, oldRows, MachineLazyRows.recordsOutput, List.flatMap_def, List.map_ofFn]
  apply congrArg List.flatten
  apply congrArg List.ofFn
  funext p
  change MachineLazyRows.reindexRowBits d (d + e) 0 (row G v p).tail.val
    (row G v p).reverseIndex.val (row G v p).relation = encodeWords (rowWords (oldRow G e v p))
  rw [oldRow_words]
  simp only [MachineLazyRows.reindexRowBits, MachinePortReindex.value, Nat.add_zero,
    oldReverseMap, row, PreprocessingLazyWords.row, List.cons_append, List.nil_append,
    encodeWords, List.append_assoc]

theorem expanderOutput_eq {n e : Nat} (d : Nat) (H : ExpanderTables.Table n e) (v : Fin n) :
    expanderOutput d H v = encodeWords ((List.ofFn (expanderRow d H v)).flatMap rowWords) :=
  MachineOverlayRows.streamOutput_expanderRows d H v

theorem outputBlock_eq {n d e : Nat} (G : PortTables.Table n d)
    (H : ExpanderTables.Table n e) (v : Fin n) :
    outputBlock G H v = encodeWords ((vertexRows G H v).flatMap rowWords) := by
  rw [outputBlock, oldOutput_eq, expanderOutput_eq]
  simp only [vertexRows, List.flatMap_append, encodeWords_append]

theorem graphRows_blocks {n d : Nat} (G : PortTables.Table n d) :
    MachineTableSplit.rowsBits (PortTables.graphTable G) = (List.ofFn (oldBlock G)).flatten := by
  change encodeWords ((PortTables.flatRows G).toList.flatMap rowWords) = _
  rw [PreprocessingLazyWords.flatRows_list, encodeWords_flatten_flatMap, List.map_ofFn]
  apply congrArg List.flatten
  apply congrArg List.ofFn
  funext v
  exact (MachineLazyRows.recordsInput_eq_codec (oldRows G v)).symm

theorem expanderRows_blocks {n e : Nat} (H : ExpanderTables.Table n e) :
    encodeWords (ExpanderTableWords.rotationWords H) = (List.ofFn (expanderBlock H)).flatten := by
  rw [rotationWords_vertices, encodeWords_flatten, List.map_ofFn]
  rfl

theorem tableBits_blocks {n d e : Nat} (G : PortTables.Table n d)
    (H : ExpanderTables.Table n e) :
    PortTables.tableBits (PreprocessingOverlayTables.overlay G H) =
      encodeWords [n, n * (d + e)] ++ (List.ofFn (outputBlock G H)).flatten := by
  rw [tableBits_overlay, encodeWords_append, encodeWords_flatten_flatMap, List.map_ofFn]
  congr 1
  apply congrArg List.flatten
  apply congrArg List.ofFn
  funext v
  exact (outputBlock_eq G H v).symm

def remaining {n : Nat} (block : Fin n → List Bool) (k : Nat) : List Bool :=
  ((List.ofFn block).drop k).flatten
def emittedPrefix {n : Nat} (block : Fin n → List Bool) (k : Nat) : List Bool :=
  ((List.ofFn block).take k).flatten

theorem remaining_step {n : Nat} (block : Fin n → List Bool) (v : Fin n) :
    remaining block v.val = block v ++ remaining block (v.val + 1) := by
  have hs := List.getElem_cons_drop (as := List.ofFn block) (i := v.val)
    (by simpa only [List.length_ofFn] using v.isLt)
  unfold remaining
  rw [← hs]
  simp only [List.flatten_cons, List.getElem_ofFn, Fin.eta]

theorem prefix_step {n : Nat} (block : Fin n → List Bool) (v : Fin n) :
    emittedPrefix block (v.val + 1) = emittedPrefix block v.val ++ block v := by
  unfold emittedPrefix
  rw [List.take_succ_eq_append_getElem (by simpa only [List.length_ofFn] using v.isLt)]
  simp only [List.flatten_append, List.flatten_cons, List.flatten_nil, List.append_nil,
    List.getElem_ofFn, Fin.eta]

@[simp] theorem remaining_zero {n : Nat} (block : Fin n → List Bool) :
    remaining block 0 = (List.ofFn block).flatten := by simp [remaining]
@[simp] theorem remaining_end {n : Nat} (block : Fin n → List Bool) :
    remaining block n = [] := by
  unfold remaining
  rw [List.drop_eq_nil_iff.mpr (by simpa only [List.length_ofFn] using (Nat.le_refl n)), List.flatten_nil]
@[simp] theorem prefix_zero {n : Nat} (block : Fin n → List Bool) : emittedPrefix block 0 = [] := by
  simp [emittedPrefix]
@[simp] theorem prefix_end {n : Nat} (block : Fin n → List Bool) :
    emittedPrefix block n = (List.ofFn block).flatten := by
  unfold emittedPrefix
  have ht : (List.ofFn block).take n = List.ofFn block :=
    List.take_of_length_le (by simpa only [List.length_ofFn] using (Nat.le_refl n))
  rw [ht]

theorem oldFrame {n m : Nat} (g h gs hs nv mv f v out : List Bool)
    (rows : List (DartRow n m)) :
    MachineLazyRows.streamFrame oldTapes (memory g h gs hs nv mv f v [] []) rows out =
      memory g h (MachineLazyRows.recordsInput rows ++ gs) hs nv mv f v [] out := by
  funext k
  rcases k with i | i <;> fin_cases i <;>
    simp [MachineLazyRows.streamFrame, oldTapes, memory, tail, oldReverse, relation,
      scratch, dividedCopy, quotient, newReverse, output, rowBuffer, graphStream]

theorem expanderFrame (g h gs hs nv mv f v t out : List Bool) (words : List Nat) :
    MachineOverlayRows.streamFrame expanderTapes (memory g h gs hs nv mv f v t []) words out =
      memory g h gs (encodeWords words ++ hs) nv mv f v t out := by
  funext k
  rcases k with i | i <;> fin_cases i <;>
    simp [MachineOverlayRows.streamFrame, expanderTapes, memory, tail, oldReverse,
      relation, scratch, dividedCopy, quotient, newReverse, output, rowBuffer, expanderStream]

theorem oldVertexTrace {n : Nat} (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (G : PortTables.Table n d) (v : Fin n) (g h gs hs nv mv f current out : List Bool) (a : A) :
    (advance (TM2.step (program d e hd he)))^[MachineLazyRows.vertexSteps d (d + e) 0 (oldRows G v) out]
      (some ⟨next (.old (0, none)), clean d e hd he a,
        memory g h (oldBlock G v ++ gs) hs nv mv f current [] out⟩) =
      some ⟨next .tailSeed, clean d e hd he a,
        memory g h gs hs nv mv f current [] (out ++ oldOutput G e v)⟩ := by
  have hrun := MachineLazyRows.vertexTrace d hd (d + e) 0 oldTapes oldTapes_injective
    (fun stage => .inr (.old stage)) (next .tailSeed) (program d e hd he) (fun _ => rfl)
    (memory g h gs hs nv mv f current [] []) (row G v)
    (by
      intro i hi7 hi9
      fin_cases i <;> simp_all [oldTapes, memory, tail, oldReverse, relation, scratch,
        dividedCopy, quotient, newReverse, output, rowBuffer, graphStream])
    (a, MachineFixedDivMod.residue e he 0) out
  simpa only [next, oldFrame, MachineLazyRows.recordsInput, List.flatMap_nil, List.nil_append,
    clean, oldBlock, oldRows, oldOutput] using hrun

theorem expanderVertexTrace {n : Nat} (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (H : ExpanderTables.Table n e) (v : Fin n) (g h gs hs nv mv f current out : List Bool) (a : A) :
    (advance (TM2.step (program d e hd he)))^[MachineOverlayRows.vertexSteps d e v.val
      (List.ofFn (expanderValues H v)) out]
      (some ⟨next (.expander (0, none)), clean d e hd he a,
        memory g h gs (expanderBlock H v ++ hs) nv mv f current (encodeWord v.val) out⟩) =
      some ⟨next .drainTail, clean d e hd he a,
        memory g h gs hs nv mv f current (encodeWord v.val) (out ++ expanderOutput d H v)⟩ := by
  let source := MachineStateEquiv.program (expanderState A d e).symm (program d e hd he)
  have code (stage : MachineOverlayRows.VertexLabel e) : source (.inr (.expander stage)) =
      MachineOverlayRows.vertexInstruction d e he expanderTapes
        (fun stage => .inr (.expander stage)) (next .drainTail) stage := by
    change MachineStateEquiv.statement (expanderState A d e).symm
      (MachineStateEquiv.statement (expanderState A d e) _) = _
    exact MachineStateEquiv.statement_symm_statement _ _
  have native := MachineOverlayRows.vertexTrace d e he expanderTapes expanderTapes_injective
    (fun stage => .inr (.expander stage)) (next .drainTail) source code
    (memory g h gs hs nv mv f current (encodeWord v.val) []) v.val (expanderValues H v)
    rfl
    (by
      intro i hi0 hi7 hi9
      fin_cases i <;> simp_all [expanderTapes, memory, tail, oldReverse, relation, scratch,
        dividedCopy, quotient, newReverse, output, rowBuffer, expanderStream])
    ((a, MachineRegularOriginalRow.zeroBuffer), MachineFixedDivMod.residue d hd 0) out
  have transported := MachineStateEquiv.trace (expanderState A d e) source _ _ _ native
  have back : MachineStateEquiv.program (expanderState A d e) source = program d e hd he :=
    MachineStateEquiv.program_symm_program (expanderState A d e).symm _
  rw [back] at transported
  simpa only [next, MachineStateEquiv.configuration, expanderState_clean, expanderFrame,
    encodeWords, List.nil_append, expanderBlock, expanderOutput] using transported

theorem tailCopyTrace (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (g h gs hs nv mv f out : List Bool) (k : Nat) (a : A) :
    (advance (TM2.step (program d e hd he)))^[2 * (k + 1) + 1]
      (some ⟨next .tailSeed, clean d e hd he a,
        memory g h gs hs nv mv f (encodeWord k) [] out⟩) =
      some ⟨next (.expander (0, none)), clean d e hd he a,
        memory g h gs hs nv mv f (encodeWord k) (encodeWord k) out⟩ := by
  let ambient := (clean d e hd he a).1
  have hrun := MachineUnaryAffineAt.seededAffineTrace vertex scratch tail
    (by decide) (by decide) (by decide) 1 0
    (.inr .tailSeed) (.inr .tailScan) (.inr .tailRestore) (next (.expander (0, none)))
    (program d e hd he) rfl rfl rfl
    (memory g h gs hs nv mv f (encodeWord k) [] out) k []
    (by simp [memory, vertex]) rfl ambient none
  simpa only [memory_tail, next, List.append_nil, Nat.one_mul, Nat.add_zero, update_tail,
    ambient, clean, MachineLazyRows.streamClean, MachinePortReindex.clean] using hrun

theorem tailFinishTrace (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (g h gs hs nv mv f out : List Bool) (k : Nat) (a : A) :
    (advance (TM2.step (program d e hd he)))^[k + 3]
      (some ⟨next .drainTail, clean d e hd he a,
        memory g h gs hs nv mv f (encodeWord k) (encodeWord k) out⟩) =
      some ⟨next .guard, clean d e hd he a,
        memory g h gs hs nv mv f (encodeWord (k + 1)) [] out⟩ := by
  let ambient := (clean d e hd he a).1
  have hd₀ := MachineDrain.drainTrace tail (.inr .drainTail) (next .increment)
    (program d e hd he) rfl (memory g h gs hs nv mv f (encodeWord k) [] out)
    (encodeWord k) ambient none
  have drain : (advance (TM2.step (program d e hd he)))^[k + 2]
      (some ⟨next .drainTail, clean d e hd he a,
        memory g h gs hs nv mv f (encodeWord k) (encodeWord k) out⟩) =
      some ⟨next .increment, clean d e hd he a,
        memory g h gs hs nv mv f (encodeWord k) [] out⟩ := by
    simpa only [next, encodeWord_length, Nat.add_assoc, update_tail, ambient, clean,
      MachineLazyRows.streamClean, MachinePortReindex.clean] using hd₀
  have increment : (advance (TM2.step (program d e hd he)))^[1]
      (some ⟨next .increment, clean d e hd he a,
        memory g h gs hs nv mv f (encodeWord k) [] out⟩) =
      some ⟨next .guard, clean d e hd he a,
        memory g h gs hs nv mv f (encodeWord (k + 1)) [] out⟩ := by
    change some (TM2.stepAux (program d e hd he (.inr .increment)) _ _) = _
    simp only [program, mainInstruction, TM2.stepAux, memory_vertex, next,
      update_vertex, encodeWord, List.replicate_succ, List.cons_append]
  have all := joinTrace drain increment
  simpa only [Nat.add_assoc] using all

def pairSteps {n d e : Nat} (G : PortTables.Table n d) (H : ExpanderTables.Table n e)
    (v : Fin n) (out : List Bool) : Nat :=
  MachineLazyRows.vertexSteps d (d + e) 0 (oldRows G v) out + (2 * (v.val + 1) + 1) +
    MachineOverlayRows.vertexSteps d e v.val (List.ofFn (expanderValues H v))
      (out ++ oldOutput G e v) + (v.val + 3)

theorem pairTrace {n : Nat} (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (G : PortTables.Table n d) (H : ExpanderTables.Table n e) (v : Fin n)
    (g h gs hs nv mv f out : List Bool) (a : A) :
    (advance (TM2.step (program d e hd he)))^[pairSteps G H v out]
      (some ⟨next (.old (0, none)), clean d e hd he a,
        memory g h (oldBlock G v ++ gs) (expanderBlock H v ++ hs)
          nv mv f (encodeWord v.val) [] out⟩) =
      some ⟨next .guard, clean d e hd he a,
        memory g h gs hs nv mv f (encodeWord (v.val + 1)) [] (out ++ outputBlock G H v)⟩ := by
  have h₁ := oldVertexTrace d e hd he G v g h gs (expanderBlock H v ++ hs)
    nv mv f (encodeWord v.val) out a
  have h₂ := tailCopyTrace d e hd he g h gs (expanderBlock H v ++ hs)
    nv mv f (out ++ oldOutput G e v) v.val a
  have h₃ := expanderVertexTrace d e hd he H v g h gs hs nv mv f
    (encodeWord v.val) (out ++ oldOutput G e v) a
  have h₄ := tailFinishTrace d e hd he g h gs hs nv mv f
    ((out ++ oldOutput G e v) ++ expanderOutput d H v) v.val a
  simpa only [pairSteps, outputBlock, List.append_assoc] using
    joinTrace (joinTrace (joinTrace h₁ h₂) h₃) h₄

def cleanupSteps (n m : Nat) : Nat := 2 * n + m + 8

theorem cleanupTrace (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (g h out : List Bool) (n m : Nat) (a : A) :
    (advance (TM2.step (program d e hd he)))^[cleanupSteps n m]
      (some ⟨next .drainFuel, clean d e hd he a,
        memory g h [] [] (encodeWord n) (encodeWord m) (encodeWord 0) (encodeWord n) [] out⟩) =
      some ⟨none, clean d e hd he a, memory g h [] [] [] [] [] [] [] out⟩ := by
  let ambient := (clean d e hd he a).1
  have h₁ := MachineDrain.drainTrace fuel (.inr .drainFuel) (next .drainVertex)
    (program d e hd he) rfl
    (memory g h [] [] (encodeWord n) (encodeWord m) [] (encodeWord n) [] out)
    (encodeWord 0) ambient none
  have h₂ := MachineDrain.drainTrace vertex (.inr .drainVertex) (next .drainVertexCount)
    (program d e hd he) rfl
    (memory g h [] [] (encodeWord n) (encodeWord m) [] [] [] out)
    (encodeWord n) ambient none
  have h₃ := MachineDrain.drainTrace vertexCount (.inr .drainVertexCount) (next .drainDartCount)
    (program d e hd he) rfl (memory g h [] [] [] (encodeWord m) [] [] [] out)
    (encodeWord n) ambient none
  have h₄ := MachineDrain.drainTrace dartCount (.inr .drainDartCount) none
    (program d e hd he) rfl (memory g h [] [] [] [] [] [] [] out)
    (encodeWord m) ambient none
  simp only [encodeWord_length, update_fuel, update_vertex, update_vertexCount, update_dartCount] at h₁ h₂ h₃ h₄
  have all := joinTrace (joinTrace (joinTrace h₁ h₂) h₃) h₄
  have hsteps : cleanupSteps n m = ((0 + 1 + 1 + (n + 1 + 1)) + (n + 1 + 1)) + (m + 1 + 1) := by
    unfold cleanupSteps
    omega
  rw [hsteps]
  exact all

def rawExpander {n e : Nat} (H : ExpanderTables.Table n e) : List Bool :=
  encodeWords (ExpanderTableWords.rotationWords H)

def outputPrefix {n d e : Nat} (G : PortTables.Table n d) (H : ExpanderTables.Table n e)
    (k : Nat) : List Bool := encodeWords [n, n * (d + e)] ++ emittedPrefix (outputBlock G H) k

theorem outputPrefix_step {n d e : Nat} (G : PortTables.Table n d)
    (H : ExpanderTables.Table n e) (v : Fin n) :
    outputPrefix G H (v.val + 1) = outputPrefix G H v.val ++ outputBlock G H v := by
  simp only [outputPrefix, prefix_step, List.append_assoc]

def loopBase {n d e : Nat} (G : PortTables.Table n d) (H : ExpanderTables.Table n e)
    (r : Nat) : Tape → List Bool :=
  memory (PortTables.tableBits G) (rawExpander H)
    (remaining (oldBlock G) (n - r)) (remaining (expanderBlock H) (n - r))
    (encodeWord n) (encodeWord (n * d)) [] (encodeWord (n - r)) [] (outputPrefix G H (n - r))

def loopCost {n d e : Nat} (G : PortTables.Table n d) (H : ExpanderTables.Table n e)
    (r : Nat) : Nat :=
  if hr : r < n then
    pairSteps G H ⟨n - (r + 1), by omega⟩ (outputPrefix G H (n - (r + 1)))
  else 0

theorem loopBodyTraces {n : Nat} (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (G : PortTables.Table n d) (H : ExpanderTables.Table n e) (a : A) :
    MachineCountedLoop.BodyTraces fuel (.inr .guard) (.inr (.old (0, none)))
      (program d e hd he) [] (fun _ => (clean d e hd he a).1) (fun _ => none)
      (loopBase G H) (loopCost G H) n := by
  intro r hr
  let v : Fin n := ⟨n - (r + 1), by omega⟩
  have hv : v.val + 1 = n - r := by dsimp [v]; omega
  have hinput : MachineUnaryCounter.counterTapes fuel (loopBase G H (r + 1)) r [] =
      memory (PortTables.tableBits G) (rawExpander H)
        (oldBlock G v ++ remaining (oldBlock G) (v.val + 1))
        (expanderBlock H v ++ remaining (expanderBlock H) (v.val + 1))
        (encodeWord n) (encodeWord (n * d)) (encodeWord r) (encodeWord v.val) []
        (outputPrefix G H v.val) := by
    simp only [MachineUnaryCounter.counterTapes, loopBase, List.append_nil, update_fuel]
    change memory _ _ (remaining (oldBlock G) v.val) (remaining (expanderBlock H) v.val)
      _ _ _ _ _ _ = _
    rw [remaining_step (oldBlock G) v, remaining_step (expanderBlock H) v]
  have houtput : MachineUnaryCounter.counterTapes fuel (loopBase G H r) r [] =
      memory (PortTables.tableBits G) (rawExpander H)
        (remaining (oldBlock G) (v.val + 1)) (remaining (expanderBlock H) (v.val + 1))
        (encodeWord n) (encodeWord (n * d)) (encodeWord r) (encodeWord (v.val + 1)) []
        (outputPrefix G H v.val ++ outputBlock G H v) := by
    simp only [MachineUnaryCounter.counterTapes, loopBase, List.append_nil, update_fuel]
    rw [← hv, outputPrefix_step]
  have run := pairTrace d e hd he G H v (PortTables.tableBits G) (rawExpander H)
    (remaining (oldBlock G) (v.val + 1)) (remaining (expanderBlock H) (v.val + 1))
    (encodeWord n) (encodeWord (n * d)) (encodeWord r) (outputPrefix G H v.val) a
  change (advance (TM2.step (program d e hd he)))^[loopCost G H r]
    (some ⟨next (.old (0, none)), clean d e hd he a,
      MachineUnaryCounter.counterTapes fuel (loopBase G H (r + 1)) r []⟩) =
    some ⟨next .guard, clean d e hd he a,
      MachineUnaryCounter.counterTapes fuel (loopBase G H r) r []⟩
  rw [hinput, houtput]
  simpa only [loopCost, dite_eq_left hr, v] using run

theorem loopTrace {n : Nat} (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (G : PortTables.Table n d) (H : ExpanderTables.Table n e) (a : A) :
    (advance (TM2.step (program d e hd he)))^[MachineCountedLoop.totalSteps (loopCost G H) n]
      (some ⟨next .guard, clean d e hd he a,
        memory (PortTables.tableBits G) (rawExpander H)
          (MachineTableSplit.rowsBits (PortTables.graphTable G)) (rawExpander H)
          (encodeWord n) (encodeWord (n * d)) (encodeWord n) (encodeWord 0) []
          (encodeWords [n, n * (d + e)])⟩) =
      some ⟨next .drainFuel, clean d e hd he a,
        memory (PortTables.tableBits G) (rawExpander H) [] []
          (encodeWord n) (encodeWord (n * d)) (encodeWord 0) (encodeWord n) []
          (PortTables.tableBits (PreprocessingOverlayTables.overlay G H))⟩ := by
  have run := MachineCountedLoop.loopTrace fuel (.inr .guard) (.inr (.old (0, none)))
    (.inr .drainFuel) (program d e hd he) rfl []
    (fun _ => (clean d e hd he a).1) (fun _ => none) (loopBase G H) (loopCost G H) n
    (loopBodyTraces d e hd he G H a)
  have startFrame : MachineUnaryCounter.counterTapes fuel (loopBase G H n) n [] =
      memory (PortTables.tableBits G) (rawExpander H)
        (MachineTableSplit.rowsBits (PortTables.graphTable G)) (rawExpander H)
        (encodeWord n) (encodeWord (n * d)) (encodeWord n) (encodeWord 0) []
        (encodeWords [n, n * (d + e)]) := by
    simp only [MachineUnaryCounter.counterTapes, loopBase, List.append_nil, update_fuel,
      Nat.sub_self, remaining_zero, outputPrefix, prefix_zero]
    simp only [graphRows_blocks, rawExpander, expanderRows_blocks]
  have endFrame : MachineUnaryCounter.counterTapes fuel (loopBase G H 0) 0 [] =
      memory (PortTables.tableBits G) (rawExpander H) [] []
        (encodeWord n) (encodeWord (n * d)) (encodeWord 0) (encodeWord n) []
        (PortTables.tableBits (PreprocessingOverlayTables.overlay G H)) := by
    simp only [MachineUnaryCounter.counterTapes, loopBase, List.append_nil, update_fuel,
      Nat.sub_zero, remaining_end, outputPrefix, prefix_end, tableBits_blocks]
  simp only [MachineCountedLoop.guardConfiguration, MachineCountedLoop.exitConfiguration] at run
  rw [startFrame, endFrame] at run
  simpa only [next, clean, MachineLazyRows.streamClean, MachinePortReindex.clean] using run

def tableSteps {n d e : Nat} (G : PortTables.Table n d) (H : ExpanderTables.Table n e) : Nat :=
  MachineTableSplit.exactSteps n (n * d) (MachineTableSplit.rowsBits (PortTables.graphTable G)) +
    preparationSteps n (rawExpander H) + MachineCountedLoop.totalSteps (loopCost G H) n +
    cleanupSteps n (n * d)

theorem tableTrace {n : Nat} (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (G : PortTables.Table n d) (H : ExpanderTables.Table n e) (a : A) :
    (advance (TM2.step (program d e hd he)))^[tableSteps G H]
      (some ⟨some (.inl .copyFirst), clean d e hd he a,
        initialTapes (PortTables.tableBits G) (rawExpander H)⟩) =
      some ⟨none, clean d e hd he a,
        memory (PortTables.tableBits G) (rawExpander H) [] [] [] [] [] [] []
          (PortTables.tableBits (PreprocessingOverlayTables.overlay G H))⟩ := by
  have h₁ := splitTrace d e hd he (PortTables.graphTable G) (rawExpander H) a
  rw [splitTapes_memory] at h₁
  have header : encodeWords [n, n * d] ++ MachineTableSplit.rowsBits (PortTables.graphTable G) =
      PortTables.tableBits G := (MachineTableSplit.tableBits_header_rows (PortTables.graphTable G)).symm
  change (advance (TM2.step (program d e hd he)))^[MachineTableSplit.exactSteps n (n * d)
      (MachineTableSplit.rowsBits (PortTables.graphTable G))]
    (some ⟨some (.inl .copyFirst), clean d e hd he a,
      initialTapes (PortTables.tableBits G) (rawExpander H)⟩) =
    some ⟨next .copyHFirst, clean d e hd he a,
      memory (encodeWords [n, n * d] ++ MachineTableSplit.rowsBits (PortTables.graphTable G))
        (rawExpander H) (MachineTableSplit.rowsBits (PortTables.graphTable G)) []
        (encodeWord n) (encodeWord (n * d)) [] [] [] []⟩ at h₁
  rw [header] at h₁
  have h₂ := preparationTrace d e hd he (PortTables.tableBits G) (rawExpander H)
    (MachineTableSplit.rowsBits (PortTables.graphTable G)) n (n * d) a
  have h₃ := loopTrace d e hd he G H a
  have h₄ := cleanupTrace d e hd he (PortTables.tableBits G) (rawExpander H)
    (PortTables.tableBits (PreprocessingOverlayTables.overlay G H)) n (n * d) a
  exact joinTrace (joinTrace (joinTrace h₁ h₂) h₃) h₄

private theorem flatMap_length_le {α : Type*} (items : List α) (f : α → List Bool)
    (B : Nat) (bounded : ∀ x ∈ items, (f x).length ≤ B) :
    (items.flatMap f).length ≤ items.length * B := by
  induction items with
  | nil => simp
  | cons x xs ih =>
      have hx := bounded x (by simp)
      have ht := ih (fun y hy => bounded y (by simp [hy]))
      simp only [List.flatMap_cons, List.length_append, List.length_cons]
      rw [Nat.add_mul, Nat.one_mul]
      omega

private theorem flatten_length_le (items : List (List Bool)) (B : Nat)
    (bounded : ∀ x ∈ items, x.length ≤ B) : items.flatten.length ≤ items.length * B := by
  simpa only [List.flatMap_id] using flatMap_length_le items id B bounded

def oldSize (d e n : Nat) : Nat := MachineLazyRows.rowSizeBound (d + e) 0 n (n * d)
def expanderSize (d e n : Nat) : Nat := MachineOverlayRows.rowSizeBound d e n (n * e)
def blockSize (d e n : Nat) : Nat := d * oldSize d e n + e * expanderSize d e n

theorem oldOutput_length_le {n d : Nat} (G : PortTables.Table n d) (e : Nat) (v : Fin n) :
    (oldOutput G e v).length ≤ d * oldSize d e n := by
  have bound := flatMap_length_le (oldRows G v)
    (fun r => MachineLazyRows.reindexRowBits d (d + e) 0 r.tail.val r.reverseIndex.val r.relation)
    (oldSize d e n) (fun r _ => MachineLazyRows.reindexRowBits_length_le d (d + e) 0 r)
  simpa only [oldOutput, MachineLazyRows.recordsOutput, oldRows, List.length_ofFn] using bound

theorem expanderOutput_length_le {n e : Nat} (d : Nat) (H : ExpanderTables.Table n e)
    (v : Fin n) : (expanderOutput d H v).length ≤ e * expanderSize d e n := by
  have bound := flatMap_length_le (List.ofFn (expanderValues H v))
    (MachineOverlayRows.rowBits d e v.val) (expanderSize d e n) (by
      intro j hj
      obtain ⟨p, rfl⟩ := List.mem_ofFn.mp hj
      have hrow := MachineOverlayRows.rowBits_length_le d e v.val (expanderValues H v p)
        (n * e) (MachineOverlayRows.expanderValues_bounded H v p)
      have hv := v.isLt.le
      unfold expanderSize MachineOverlayRows.rowSizeBound at *
      omega)
  simpa only [expanderOutput, MachineOverlayRows.streamOutput, List.length_ofFn] using bound

theorem outputBlock_length_le {n d e : Nat} (G : PortTables.Table n d)
    (H : ExpanderTables.Table n e) (v : Fin n) :
    (outputBlock G H v).length ≤ blockSize d e n := by
  have hg := oldOutput_length_le G e v
  have hh := expanderOutput_length_le d H v
  simp only [outputBlock, List.length_append, blockSize]
  omega

def outputCapacity (d e n : Nat) : Nat := n + n * (d + e) + 2 + n * blockSize d e n

theorem outputPrefix_length_le {n d e : Nat} (G : PortTables.Table n d)
    (H : ExpanderTables.Table n e) (k : Nat) :
    (outputPrefix G H k).length ≤ outputCapacity d e n := by
  have hblocks := flatten_length_le ((List.ofFn (outputBlock G H)).take k)
    (blockSize d e n) (by
      intro xs hx
      have hm := List.mem_of_mem_take hx
      obtain ⟨v, rfl⟩ := List.mem_ofFn.mp hm
      exact outputBlock_length_le G H v)
  have hlen : ((List.ofFn (outputBlock G H)).take k).length ≤ n := by
    simp only [List.length_take, List.length_ofFn]
    exact Nat.min_le_right _ _
  have hcap := Nat.mul_le_mul_right (blockSize d e n) hlen
  simp only [outputPrefix, emittedPrefix, List.length_append, encodeWords_length,
    List.sum_cons, List.sum_nil, List.length_cons, List.length_nil, Nat.add_zero, outputCapacity]
  omega

def pairBudget (d e n : Nat) : Nat :=
  (d * (MachineLazyRows.rowCostBound (d + e) 0 n (n * d) +
    2 * (outputCapacity d e n + d * oldSize d e n) + 1) + 1) +
  (e * (MachineOverlayRows.rowCostBound d e n (n * e) +
    2 * (outputCapacity d e n + d * oldSize d e n + e * expanderSize d e n) + 1) + 1) +
  (3 * n + 6)

theorem pairSteps_le {n d e : Nat} (G : PortTables.Table n d)
    (H : ExpanderTables.Table n e) (v : Fin n) (out : List Bool)
    (hout : out.length ≤ outputCapacity d e n) : pairSteps G H v out ≤ pairBudget d e n := by
  have hold := MachineLazyRows.vertexSteps_le d (d + e) 0 (oldRows G v) out
  simp only [oldRows, List.length_ofFn] at hold
  have hgsize := oldOutput_length_le G e v
  have hnew := MachineOverlayRows.vertexSteps_le d e v.val (n * e)
    (List.ofFn (expanderValues H v)) (by
      intro j hj
      obtain ⟨p, rfl⟩ := List.mem_ofFn.mp hj
      exact MachineOverlayRows.expanderValues_bounded H v p) (out ++ oldOutput G e v)
  simp only [List.length_ofFn, List.length_append] at hnew
  have hv := v.isLt.le
  have hsize : MachineOverlayRows.rowSizeBound d e v.val (n * e) ≤ expanderSize d e n := by
    unfold expanderSize MachineOverlayRows.rowSizeBound
    omega
  have hcost : MachineOverlayRows.rowCostBound d e v.val (n * e) ≤
      MachineOverlayRows.rowCostBound d e n (n * e) := by
    unfold MachineOverlayRows.rowCostBound
    change _ ≤ 8 * (n * e) + 4 * expanderSize d e n + _ + _ + 28
    omega
  have hsizeMul := Nat.mul_le_mul_left e hsize
  have holdBudget := Nat.mul_le_mul_left d
    (show MachineLazyRows.rowCostBound (d + e) 0 n (n * d) +
        2 * (out.length + d * MachineLazyRows.rowSizeBound (d + e) 0 n (n * d)) + 1 ≤
      MachineLazyRows.rowCostBound (d + e) 0 n (n * d) +
        2 * (outputCapacity d e n + d * oldSize d e n) + 1 by
      unfold oldSize
      omega)
  have hnewBudget := Nat.mul_le_mul_left e
    (show MachineOverlayRows.rowCostBound d e v.val (n * e) +
        2 * (out.length + (oldOutput G e v).length + e * MachineOverlayRows.rowSizeBound d e v.val (n * e)) + 1 ≤
      MachineOverlayRows.rowCostBound d e n (n * e) +
        2 * (outputCapacity d e n + d * oldSize d e n + e * expanderSize d e n) + 1 by omega)
  unfold pairSteps pairBudget oldRows
  omega

theorem loopSteps_le {n d e : Nat} (G : PortTables.Table n d) (H : ExpanderTables.Table n e) :
    MachineCountedLoop.totalSteps (loopCost G H) n ≤ n * (pairBudget d e n + 1) + 1 := by
  apply MachineCountedLoop.totalSteps_le
  intro r hr
  rw [loopCost, dite_eq_left hr]
  exact pairSteps_le G H _ _ (outputPrefix_length_le G H _)

noncomputable def phasePolynomial (d e : Nat) : Polynomial Nat :=
  let x := Polynomial.X
  let C := Polynomial.C (R := Nat)
  let oldValue := C (d + e) * (x * C d) + x * C d + C 0
  let os := x + oldValue + C 8194
  let newValue := C (d + e) * (x * C e) + x * C e + C d
  let es := x + newValue + C MachineOverlayRows.trueBits.length + C 2
  let block := C d * os + C e * es
  let cap := x + x * C (d + e) + C 2 + x * block
  let oldCost := C 2 * x + C 8 * (x * C d) + oldValue + C 4 * os + C 8224
  let newCost := C 8 * (x * C e) + C 4 * es + newValue + C MachineOverlayRows.trueBits.length + C 28
  let pair := (C d * (oldCost + C 2 * (cap + C d * os) + C 1) + C 1) +
    (C e * (newCost + C 2 * (cap + C d * os + C e * es) + C 1) + C 1) +
    (C 3 * x + C 6)
  x * (pair + C 1) + C 1 + (C 2 * x + x * C d + C 8)

@[simp] theorem phasePolynomial_eval (d e n : Nat) :
    (phasePolynomial d e).eval n = n * (pairBudget d e n + 1) + 1 + cleanupSteps n (n * d) := by
  simp only [phasePolynomial, Polynomial.eval_add, Polynomial.eval_mul, Polynomial.eval_C,
    Polynomial.eval_X, pairBudget, outputCapacity, blockSize, oldSize, expanderSize,
    MachineLazyRows.rowSizeBound, MachineLazyRows.rowCostBound, MachineLazyRows.valueBound,
    MachineOverlayRows.rowSizeBound, MachineOverlayRows.rowCostBound,
    MachineOverlayRows.valueBound, cleanupSteps]

noncomputable def timePolynomial (d e : Nat) : Polynomial Nat :=
  Polynomial.C 12 * Polynomial.X + Polynomial.C 18 + phasePolynomial d e

theorem tableSteps_le {n d e : Nat} (G : PortTables.Table n d) (H : ExpanderTables.Table n e) :
    tableSteps G H ≤ (timePolynomial d e).eval ((PortTables.tableBits G).length + (rawExpander H).length) := by
  have hsplit := MachineTableSplit.exactSteps_le n (n * d)
    (MachineTableSplit.rowsBits (PortTables.graphTable G))
  have header : encodeWords [n, n * d] ++ MachineTableSplit.rowsBits (PortTables.graphTable G) =
      PortTables.tableBits G := (MachineTableSplit.tableBits_header_rows (PortTables.graphTable G)).symm
  rw [header, MachineTableSplit.timePolynomial_eval] at hsplit
  have hn := PortTables.vertices_le_tableBits_length G
  have hloop := loopSteps_le G H
  have hmono := natPolynomial_eval_mono (phasePolynomial d e)
    (show n ≤ (PortTables.tableBits G).length + (rawExpander H).length by omega)
  rw [phasePolynomial_eval] at hmono
  simp only [timePolynomial, Polynomial.eval_add, Polynomial.eval_mul, Polynomial.eval_C,
    Polynomial.eval_X]
  unfold tableSteps preparationSteps
  omega

def tableInTime {n : Nat} (d e : Nat) (hd : 0 < d) (he : 0 < e)
    (G : PortTables.Table n d) (H : ExpanderTables.Table n e) (a : A) :
    StateTransition.EvalsToInTime (TM2.step (program d e hd he))
      ⟨some (.inl .copyFirst), clean d e hd he a,
        initialTapes (PortTables.tableBits G) (rawExpander H)⟩
      (some ⟨none, clean d e hd he a,
        memory (PortTables.tableBits G) (rawExpander H) [] [] [] [] [] [] []
          (PortTables.tableBits (PreprocessingOverlayTables.overlay G H))⟩)
      ((timePolynomial d e).eval ((PortTables.tableBits G).length + (rawExpander H).length)) where
  steps := tableSteps G H
  evals_in_steps := tableTrace d e hd he G H a
  steps_le_m := tableSteps_le G H

def machine (d e : Nat) (hd : 0 < d) (he : 0 < e) : FinTM2 where
  K := Tape
  k₀ := graphArchive
  k₁ := output
  Γ _ := Bool
  Λ := Label d e
  main := .inl .copyFirst
  σ := State Unit d e
  initialState := clean d e hd he ()
  m := program d e hd he

theorem machine_alphabet_finite (d e : Nat) (hd : 0 < d) (he : 0 < e) :
    ∀ k, Finite ((machine d e hd he).Γ k) := fun _ => inferInstanceAs (Finite Bool)

end BinPackingGames.Foundations.Complexity.MachineOverlayTable

end OAI