import Mathlib
import OAI.Computability.MinUncut.Machines.MachineExpanderRowFrames
import OAI.Computability.MinUncut.PCP.ExpanderTableEnumeration

namespace OAI

namespace MinUncutGames.Foundations.Complexity.MachineExpanderTable

open Turing
open PCP.ExpanderTables PCP.ExpanderRowControl PCP.ExpanderTableWords
open PCP.ExpanderTableEnumeration

private def singleStep {α : Type*} (step : α → Option α) (a b : α)
    (h : step a = some b) : StateTransition.EvalsToInTime step a (some b) 1 where
  steps := 1
  evals_in_steps := by change step a = some b; exact h
  steps_le_m := Nat.le_refl _

private def sequence {α : Type*} {step : α → Option α} {a b c : α} {m n : Nat}
    (first : StateTransition.EvalsToInTime step a (some b) m)
    (second : StateTransition.EvalsToInTime step b (some c) n) :
    StateTransition.EvalsToInTime step a (some c) (m + n) := by
  simpa only [Nat.add_comm n m] using
    StateTransition.EvalsToInTime.trans step m n a b (some c) first second

private def widen {α : Type*} {step : α → Option α} {a : α} {b : Option α} {m n : Nat}
    (run : StateTransition.EvalsToInTime step a b m) (bound : m ≤ n) :
    StateTransition.EvalsToInTime step a b n where
  toEvalsTo := run.toEvalsTo
  steps_le_m := run.steps_le_m.trans bound

def tableRowData {v d : Nat} (G : Table v (degree d)) (H : Table (cloudSize d) d)
    (vertex : Fin v) (position : Position d) : MachineExpanderRow.RowData v d :=
  MachineExpanderRow.rowData G H vertex (positionPair position).1 (positionPair position).2

theorem tableRowData_finalValue {v d : Nat} (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (position : Position d) :
    (tableRowData G H vertex position).finalValue = rowValue G H vertex position := rfl

theorem tableRowData_frame0 {v d : Nat} (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (position : Position d) (output : List Bool) :
    MachineExpanderRow.frame0 (tableRowData G H vertex position) output =
      rowTapes vertex.val (encodeWords (rotationWords G)) output := by
  funext tape
  cases tape <;> rfl

theorem tableRowData_finalFrame {v d : Nat} (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (position : Position d) (output : List Bool) :
    MachineExpanderRow.emittedWord .output
      (MachineExpanderRow.frame0 (tableRowData G H vertex position) output)
      (tableRowData G H vertex position).finalValue =
      rowTapes vertex.val (encodeWords (rotationWords G))
        ((encodeWord (rowValue G H vertex position)).reverse ++ output) := by
  rw [tableRowData_frame0, tableRowData_finalValue]
  funext tape
  cases tape <;> simp [MachineExpanderRow.emittedWord, rowTapes]

variable {ρ : Type} [Fintype ρ] {v d : Nat}

def rowAfterState (positive : 0 < d) (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (state : State ρ d) : State ρ d :=
  (MachineExpanderRow.divisionState positive (caller state)
    (tableRowData G H vertex state.2).control2 none, state.2)

omit [Fintype ρ] in
@[simp] theorem rowAfterState_position (positive : 0 < d) (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (state : State ρ d) :
    (rowAfterState positive G H vertex state).2 = state.2 := rfl

omit [Fintype ρ] in
@[simp] theorem caller_rowAfterState (positive : 0 < d) (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (state : State ρ d) :
    caller (rowAfterState positive G H vertex state) = caller state := rfl

def preparedRowInTime (positive : 0 < d) (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (state : State ρ d)
    (remaining : Nat) (output countSuffix result : List Bool) :
    StateTransition.EvalsToInTime (TM2.step (program positive H))
      ⟨some (.inr .prepareRow), state,
        boundaryTapes vertex.val remaining (encodeWords (rotationWords G)) output countSuffix result⟩
      (some ⟨some (.inr .afterRow), rowAfterState positive G H vertex state,
        boundaryTapes vertex.val remaining (encodeWords (rotationWords G))
          ((encodeWord (rowValue G H vertex state.2)).reverse ++ output) countSuffix result⟩)
      (1 + 80 * ((encodeWords (rotationWords G)).length + 1)) := by
  have raw := rowExecution positive H state.2 (extraTapes remaining countSuffix result)
    (MachineExpanderRow.rowInTime positive (tableRowData G H vertex state.2) output (caller state))
  have run : StateTransition.EvalsToInTime (TM2.step (program positive H))
      ⟨some (.inl .initialize), prepareState positive H state,
        boundaryTapes vertex.val remaining (encodeWords (rotationWords G)) output countSuffix result⟩
      (some ⟨some (.inr .afterRow), rowAfterState positive G H vertex state,
        boundaryTapes vertex.val remaining (encodeWords (rotationWords G))
          ((encodeWord (rowValue G H vertex state.2)).reverse ++ output) countSuffix result⟩)
      (80 * ((encodeWords (rotationWords G)).length + 1)) := by
    rw [tableRowData_finalFrame, tableRowData_frame0] at raw
    simpa only [MachineEmbedding.configuration, MachineEmbedding.label, rowReturn,
      prepareState, boundaryState, rowAfterState, boundaryTapes,
      MachineExpanderRow.RowData.tableLength, MachineExpanderRow.RowData.control0,
      tableRowData, MachineExpanderRow.rowData] using raw
  exact sequence
    (singleStep _ _ _ (prepareRowStep positive H
      (boundaryTapes vertex.val remaining (encodeWords (rotationWords G)) output countSuffix result)
      state)) run

structure VertexSuffixRun (positive : 0 < d) (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (state : State ρ d)
    (remaining : Nat) (output countSuffix result : List Bool) where
  finalState : State ρ d
  caller_preserved : caller finalState = caller state
  position_zero : finalState.2 = zeroPosition positive
  execution : StateTransition.EvalsToInTime (TM2.step (program positive H))
    ⟨some (.inr .prepareRow), state,
      boundaryTapes vertex.val remaining (encodeWords (rotationWords G)) output countSuffix result⟩
    (some ⟨some (.inr .vertexGuard), finalState,
      boundaryTapes (vertex.val + 1) remaining (encodeWords (rotationWords G))
        (accumulate ((vertexWords G H vertex).drop state.2.val) output) countSuffix result⟩)
    ((rowFactor d - state.2.val) * (80 * ((encodeWords (rotationWords G)).length + 1) + 2))

private def suffixRun_aux (positive : 0 < d) (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (remaining : Nat)
    (countSuffix result : List Bool) (n : Nat) :
    (state : State ρ d) → state.2.val + n = rowFactor d → (output : List Bool) →
      VertexSuffixRun positive G H vertex state remaining output countSuffix result := by
  induction n with
  | zero =>
      intro state count output
      have hp := state.2.isLt
      exact False.elim (by omega)
  | succ n ih =>
      intro state count output
      let after := rowAfterState positive G H vertex state
      let nextOutput := (encodeWord (rowValue G H vertex state.2)).reverse ++ output
      have row := preparedRowInTime positive G H vertex state remaining output countSuffix result
      by_cases last : n = 0
      · have hp : state.2.val + 1 = rowFactor d := by omega
        have finish := singleStep _ _ _ (afterRow_last_boundaryStep positive H vertex.val remaining
          (encodeWords (rotationWords G)) nextOutput countSuffix result after (by
            change ¬ state.2.val + 1 < rowFactor d
            omega))
        refine ⟨resetPositionState positive after, ?_, rfl, ?_⟩
        · rfl
        · have all := sequence row finish
          have words : accumulate ((vertexWords G H vertex).drop state.2.val) output =
              nextOutput := by
            rw [vertexWords_drop_last G H vertex state.2 hp]
            rfl
          have budget : rowFactor d - state.2.val = 1 := by omega
          rw [words, budget, Nat.one_mul]
          exact widen all (by omega)
      · have more : state.2.val + 1 < rowFactor d := by omega
        let next := advancePositionState positive after
        have nextPositionValue : next.2.val = state.2.val + 1 :=
          nextPosition_val_of_lt positive state.2 more
        have nextCount : next.2.val + n = rowFactor d := by omega
        let tail := ih next nextCount nextOutput
        have advance := singleStep _ _ _ (afterRow_moreStep positive H
          (boundaryTapes vertex.val remaining (encodeWords (rotationWords G))
            nextOutput countSuffix result) after more)
        have all := sequence (sequence row advance) tail.execution
        refine ⟨tail.finalState, ?_, tail.position_zero, ?_⟩
        · exact tail.caller_preserved
        · have words : accumulate ((vertexWords G H vertex).drop state.2.val) output =
              accumulate ((vertexWords G H vertex).drop next.2.val) nextOutput := by
            rw [vertexWords_drop_succ G H vertex state.2, nextPositionValue]
            rfl
          rw [words]
          apply widen all
          have hcount : rowFactor d - state.2.val = n + 1 := by omega
          have hnext : rowFactor d - next.2.val = n := by omega
          rw [hcount, hnext, Nat.add_mul, Nat.one_mul]
          omega

def suffixInTime (positive : 0 < d) (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (state : State ρ d)
    (remaining : Nat) (output countSuffix result : List Bool) :
    VertexSuffixRun positive G H vertex state remaining output countSuffix result :=
  suffixRun_aux positive G H vertex remaining countSuffix result
    (rowFactor d - state.2.val) state (by have h := state.2.isLt; omega) output

structure VertexRun (positive : 0 < d) (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (state : State ρ d)
    (remaining : Nat) (output countSuffix result : List Bool) where
  finalState : State ρ d
  caller_preserved : caller finalState = caller state
  position_zero : finalState.2 = zeroPosition positive
  execution : StateTransition.EvalsToInTime (TM2.step (program positive H))
    ⟨some (.inr .prepareRow), state,
      boundaryTapes vertex.val remaining (encodeWords (rotationWords G)) output countSuffix result⟩
    (some ⟨some (.inr .vertexGuard), finalState,
      boundaryTapes (vertex.val + 1) remaining (encodeWords (rotationWords G))
        (accumulate (vertexWords G H vertex) output) countSuffix result⟩)
    (rowFactor d * (80 * ((encodeWords (rotationWords G)).length + 1) + 2))

def vertexInTime (positive : 0 < d) (G : Table v (degree d))
    (H : Table (cloudSize d) d) (vertex : Fin v) (state : State ρ d)
    (position : state.2 = zeroPosition positive)
    (remaining : Nat) (output countSuffix result : List Bool) :
    VertexRun positive G H vertex state remaining output countSuffix result := by
  let run := suffixInTime positive G H vertex state remaining output countSuffix result
  refine ⟨run.finalState, run.caller_preserved, run.position_zero, ?_⟩
  have zero : state.2.val = 0 := congrArg Fin.val position
  simpa only [zero, List.drop_zero, Nat.sub_zero] using run.execution

open Turing MachineComposition
open PCP.ExpanderTables PCP.ExpanderRowControl PCP.ExpanderTableWords
open PCP.ExpanderTableEnumeration

def oldTableWord {v d : Nat} (G : Table v (degree d)) : List Bool :=
  encodeWords (rotationWords G)

def accumulatedVertices {v d : Nat} (G : Table v (degree d))
    (H : Table (cloudSize d) d) (current : Nat) : List Bool :=
  accumulate (priorVertices G H current) []

@[simp] theorem accumulatedVertices_zero {v d : Nat} (G : Table v (degree d))
    (H : Table (cloudSize d) d) : accumulatedVertices G H 0 = [] := by
  simp [accumulatedVertices, accumulate]

theorem accumulatedVertices_succ {v d : Nat} (G : Table v (degree d))
    (H : Table (cloudSize d) d) (current : Nat) (valid : current < v) :
    accumulatedVertices G H (current + 1) =
      accumulate (vertexWords G H ⟨current, valid⟩) (accumulatedVertices G H current) := by
  simp only [accumulatedVertices, priorVertices_succ G H current valid, accumulate_append]

theorem accumulatedVertices_full {v d : Nat} (G : Table v (degree d))
    (H : Table (cloudSize d) d) : accumulatedVertices G H v =
      (encodeWords (rotationWords (step G H))).reverse := by
  simp [accumulatedVertices, accumulate_generatedWords]

def vertexBodyBudget {v d : Nat} (G : Table v (degree d)) : Nat :=
  rowFactor d * (80 * ((oldTableWord G).length + 1) + 2)

def vertexLoopBudget {v d : Nat} (G : Table v (degree d)) (remaining : Nat) : Nat :=
  remaining * (vertexBodyBudget G + 1) + 1

def vertexLoopTapes {v d : Nat} (G : Table v (degree d)) (H : Table (cloudSize d) d)
    (current remaining : Nat) (suffix : List Bool) : ∀ tape, List (Alphabet tape) :=
  boundaryTapes current remaining (oldTableWord G) (accumulatedVertices G H current) suffix []

structure VertexLoopRun {v d : Nat} {ρ : Type} [Fintype ρ]
    (positive : 0 < d) (G : Table v (degree d)) (H : Table (cloudSize d) d)
    (current remaining : Nat) (state : State ρ d) (suffix : List Bool) where
  finalState : State ρ d
  caller_preserved : caller finalState = caller state
  position_zero : finalState.2 = zeroPosition positive
  execution : StateTransition.EvalsToInTime (TM2.step (program positive H))
    ⟨some (.inr .vertexGuard), state, vertexLoopTapes G H current remaining suffix⟩
    (some ⟨some (.inr .reverseOutput), finalState, vertexLoopTapes G H v 0 suffix⟩)
    (vertexLoopBudget G remaining)

private def boundarySingleStep {S : Type*} (f : S → Option S) (a b : S)
    (h : f a = some b) : StateTransition.EvalsToInTime f a (some b) 1 where
  steps := 1
  evals_in_steps := by change f a = some b; exact h
  steps_le_m := Nat.le_refl _

def vertexLoopInTime {v d : Nat} {ρ : Type} [Fintype ρ]
    (positive : 0 < d) (G : Table v (degree d)) (H : Table (cloudSize d) d)
    (current remaining : Nat) (state : State ρ d) (suffix : List Bool)
    (count : current + remaining = v) (position : state.2 = zeroPosition positive) :
    VertexLoopRun positive G H current remaining state suffix := by
  induction remaining generalizing current state with
  | zero =>
      have hc : current = v := by omega
      subst current
      refine ⟨clearRegister state, caller_clearRegister state, ?_, ?_⟩
      · simpa only [clearRegister] using position
      · simpa only [vertexLoopBudget, Nat.zero_mul, Nat.zero_add, vertexLoopTapes] using
          boundarySingleStep _ _ _ (vertexGuard_boundary_zeroStep positive H v (oldTableWord G)
            (accumulatedVertices G H v) suffix [] state)
  | succ remaining ih =>
      have valid : current < v := by omega
      let vertex : Fin v := ⟨current, valid⟩
      let body := vertexInTime positive G H vertex (clearRegister state)
        (by simpa only [clearRegister] using position) remaining
        (accumulatedVertices G H current) suffix []
      have nextCount : current + 1 + remaining = v := by omega
      let rest := ih (current + 1) body.finalState nextCount body.position_zero
      have output_eq : accumulate (vertexWords G H vertex)
          (accumulatedVertices G H current) = accumulatedVertices G H (current + 1) :=
        (accumulatedVertices_succ G H current valid).symm
      let guard := boundarySingleStep _ _ _
        (vertexGuard_boundary_succStep positive H current remaining (oldTableWord G)
          (accumulatedVertices G H current) suffix [] state)
      have bodyRun : StateTransition.EvalsToInTime (TM2.step (program positive H))
          ⟨some (.inr .prepareRow), clearRegister state,
            boundaryTapes current remaining (oldTableWord G)
              (accumulatedVertices G H current) suffix []⟩
          (some ⟨some (.inr .vertexGuard), body.finalState,
            vertexLoopTapes G H (current + 1) remaining suffix⟩)
          (vertexBodyBudget G) := by
        simpa only [vertexLoopTapes, vertexBodyBudget, oldTableWord, output_eq] using body.execution
      let first := StateTransition.EvalsToInTime.trans (TM2.step (program positive H))
        _ _ _ _ _ guard bodyRun
      let all := StateTransition.EvalsToInTime.trans (TM2.step (program positive H))
        _ _ _ _ _ first rest.execution
      refine ⟨rest.finalState, ?_, rest.position_zero, ?_⟩
      · exact rest.caller_preserved.trans
          (body.caller_preserved.trans (caller_clearRegister state))
      · refine { toEvalsTo := all.toEvalsTo, steps_le_m := ?_ }
        have bound := all.steps_le_m
        simp only [vertexLoopBudget, Nat.succ_mul] at bound ⊢
        omega

open Turing
open MachineComposition
open PCP.ExpanderTables PCP.ExpanderRowControl

variable {ρ : Type} {d : Nat}

@[simp] theorem clearRegister_position (state : State ρ d) :
    (clearRegister state).2 = state.2 := rfl

@[simp] theorem clearRegister_register (state : State ρ d) :
    (clearRegister state).1.2 = none := rfl

@[simp] theorem clearRegister_idempotent (state : State ρ d) :
    clearRegister (clearRegister state) = clearRegister state := rfl

theorem boundaryTapes_reverse_update (vertex remaining : Nat)
    (oldTable output countSuffix result nextOutput nextResult : List Bool) :
    Function.update
      (Function.update (boundaryTapes vertex remaining oldTable output countSuffix result)
        (.inl .output) nextOutput)
      (.inr .result) nextResult =
      boundaryTapes vertex remaining oldTable nextOutput countSuffix nextResult := by
  funext tape
  rcases tape with row | extra
  · cases row <;>
      simp [boundaryTapes, rowTapes, MachineEmbedding.tapes, Function.update]
  · cases extra <;>
      simp [boundaryTapes, extraTapes, MachineEmbedding.tapes, Function.update]

variable [Fintype ρ]

theorem reverseOutputTrace (positive : 0 < d) (H : Table (cloudSize d) d)
    (vertex remaining : Nat) (oldTable output countSuffix result : List Bool)
    (state : State ρ d) :
    (advance (TM2.step (program positive H)))^[output.length + 1]
      (some ⟨some (.inr .reverseOutput), state,
        boundaryTapes vertex remaining oldTable output countSuffix result⟩) =
      some ⟨some (.inr .done), clearRegister state,
        boundaryTapes vertex remaining oldTable [] countSuffix (output.reverse ++ result)⟩ := by
  induction output generalizing result state with
  | nil =>
      simpa only [List.length_nil, Nat.zero_add, Function.iterate_one, advance_some,
        List.reverse_nil, List.nil_append] using
        reverseOutput_nilStep positive H
          (boundaryTapes vertex remaining oldTable [] countSuffix result) state rfl
  | cons symbol output ih =>
      rw [List.length_cons, Function.iterate_succ_apply]
      simp only [advance_some]
      rw [reverseOutput_consStep positive H
        (boundaryTapes vertex remaining oldTable (symbol :: output) countSuffix result)
        state symbol output rfl]
      change (advance (TM2.step (program positive H)))^[output.length + 1]
        (some ⟨some (.inr .reverseOutput), ((state.1.1, some symbol), state.2),
          Function.update
            (Function.update
              (boundaryTapes vertex remaining oldTable (symbol :: output) countSuffix result)
              (.inl .output) output)
            (.inr .result) (symbol :: result)⟩) = _
      rw [boundaryTapes_reverse_update]
      simpa only [clearRegister, List.reverse_cons, List.append_assoc,
        List.singleton_append] using
        ih (symbol :: result) ((state.1.1, some symbol), state.2)

theorem reverseOutputHaltTrace (positive : 0 < d) (H : Table (cloudSize d) d)
    (vertex remaining : Nat) (oldTable output countSuffix result : List Bool)
    (state : State ρ d) :
    (advance (TM2.step (program positive H)))^[output.length + 2]
      (some ⟨some (.inr .reverseOutput), state,
        boundaryTapes vertex remaining oldTable output countSuffix result⟩) =
      some ⟨none, clearRegister state,
        boundaryTapes vertex remaining oldTable [] countSuffix (output.reverse ++ result)⟩ := by
  rw [show output.length + 2 = (output.length + 1) + 1 by omega,
    Function.iterate_succ_apply',
    reverseOutputTrace positive H vertex remaining oldTable output countSuffix result state]
  exact doneStep positive H
    (boundaryTapes vertex remaining oldTable [] countSuffix (output.reverse ++ result))
    (clearRegister state)

def reverseOutputInTime (positive : 0 < d) (H : Table (cloudSize d) d)
    (vertex remaining : Nat) (oldTable output countSuffix result : List Bool)
    (state : State ρ d) :
    StateTransition.EvalsToInTime (TM2.step (program positive H))
      ⟨some (.inr .reverseOutput), state,
        boundaryTapes vertex remaining oldTable output countSuffix result⟩
      (some ⟨some (.inr .done), clearRegister state,
        boundaryTapes vertex remaining oldTable [] countSuffix (output.reverse ++ result)⟩)
      (output.length + 1) where
  steps := output.length + 1
  evals_in_steps := reverseOutputTrace positive H vertex remaining oldTable output countSuffix result state
  steps_le_m := Nat.le_refl _

def reverseOutputHaltInTime (positive : 0 < d) (H : Table (cloudSize d) d)
    (vertex remaining : Nat) (oldTable output countSuffix result : List Bool)
    (state : State ρ d) :
    StateTransition.EvalsToInTime (TM2.step (program positive H))
      ⟨some (.inr .reverseOutput), state,
        boundaryTapes vertex remaining oldTable output countSuffix result⟩
      (some ⟨none, clearRegister state,
        boundaryTapes vertex remaining oldTable [] countSuffix (output.reverse ++ result)⟩)
      (output.length + 2) where
  steps := output.length + 2
  evals_in_steps := reverseOutputHaltTrace positive H vertex remaining oldTable output countSuffix result state
  steps_le_m := Nat.le_refl _

open Turing MachineComposition
open PCP.ExpanderTables PCP.ExpanderRowControl PCP.ExpanderTableWords
open PCP.ExpanderTableEnumeration

def completeBudget {v d : Nat} (G : Table v (degree d)) (H : Table (cloudSize d) d) : Nat :=
  1 + vertexLoopBudget G v + ((encodeWords (rotationWords (step G H))).length + 2)

def timeCoefficient (d : Nat) : Nat :=
  rowFactor d * (rowFactor d + 1) + 82 * rowFactor d + 5

noncomputable def timePolynomial (d : Nat) : Polynomial Nat :=
  Polynomial.C (timeCoefficient d) * (Polynomial.X + 1) ^ 2

theorem vertices_le_word_length {v d : Nat} (positive : 0 < d)
    (G : Table v (degree d)) : v ≤ (oldTableWord G).length := by
  have hq : 1 ≤ degree d := Nat.mul_pos positive positive
  have hv : v ≤ v * degree d := by simpa using Nat.mul_le_mul_left v hq
  have hr : v * degree d ≤ (oldTableWord G).length := by
    simp only [oldTableWord, encodeWords_length, rotationWords_length]
    omega
  exact hv.trans hr

theorem completeBudget_le {v d : Nat} (positive : 0 < d)
    (G : Table v (degree d)) (H : Table (cloudSize d) d) :
    completeBudget G H ≤ (timePolynomial d).eval (oldTableWord G).length := by
  let L := (oldTableWord G).length
  let M := rowFactor d
  have vBound : v ≤ L + 1 := (vertices_le_word_length positive G).trans (Nat.le_succ L)
  have emitBound : 80 * (L + 1) + 2 ≤ 82 * (L + 1) := by omega
  have bodyBound : vertexBodyBudget G + 1 ≤ (82 * M + 1) * (L + 1) := by
    have mulBound := Nat.mul_le_mul_left M emitBound
    change M * (80 * (L + 1) + 2) + 1 ≤ _
    nlinarith
  have iterations := Nat.mul_le_mul vBound bodyBound
  have loopBound : v * (vertexBodyBudget G + 1) ≤ (82 * M + 1) * (L + 1)^2 := by
    calc
      _ ≤ (L + 1) * ((82 * M + 1) * (L + 1)) := iterations
      _ = _ := by ring
  have rowBound : v * M ≤ M * (L + 1) := by
    simpa only [Nat.mul_comm v M] using Nat.mul_le_mul_left M vBound
  have rowSuccBound : v * M + 1 ≤ (M + 1) * (L + 1) := by nlinarith
  have productBound := Nat.mul_le_mul rowBound rowSuccBound
  have lengthBound : (encodeWords (rotationWords (step G H))).length ≤
      M * (M + 1) * (L + 1)^2 := by
    calc
      _ ≤ (v * M) * (v * M + 1) := by
        simpa only [generatedWords_eq_rotationWords] using encode_generatedWords_length_le G H
      _ ≤ (M * (L + 1)) * ((M + 1) * (L + 1)) := productBound
      _ = _ := by ring
  have oneBound : 1 ≤ (L + 1)^2 := by nlinarith
  have combined := Nat.add_le_add loopBound lengthBound
  simp only [timePolynomial, Polynomial.eval_mul, Polynomial.eval_C, Polynomial.eval_pow,
    Polynomial.eval_add, Polynomial.eval_X, Polynomial.eval_one]
  change completeBudget G H ≤ (M * (M + 1) + 82 * M + 5) * (L + 1)^2
  unfold completeBudget vertexLoopBudget
  nlinarith

structure TableRun {v d : Nat} {ρ : Type} [Fintype ρ]
    (positive : 0 < d) (G : Table v (degree d)) (H : Table (cloudSize d) d)
    (state : State ρ d) (suffix : List Bool) where
  finalState : State ρ d
  caller_preserved : caller finalState = caller state
  position_zero : finalState.2 = zeroPosition positive
  execution : StateTransition.EvalsToInTime (TM2.step (program positive H))
    ⟨some (.inr .initialize), state, initialTapes v (oldTableWord G) suffix⟩
    (some ⟨none, finalState,
      finalTapes v (oldTableWord G) (encodeWords (rotationWords (step G H))) suffix⟩)
    ((timePolynomial d).eval (oldTableWord G).length)

private def initializeInTime {v d : Nat} {ρ : Type} [Fintype ρ]
    (positive : 0 < d) (G : Table v (degree d)) (H : Table (cloudSize d) d)
    (state : State ρ d) (suffix : List Bool) :
    StateTransition.EvalsToInTime (TM2.step (program positive H))
      ⟨some (.inr .initialize), state, initialTapes v (oldTableWord G) suffix⟩
      (some ⟨some (.inr .vertexGuard), initialState positive H (caller state),
        vertexLoopTapes G H 0 v suffix⟩) 1 where
  steps := 1
  evals_in_steps := by
    change TM2.step (program (ρ := ρ) positive H)
      ⟨some (.inr .initialize), state, initialTapes v (oldTableWord G) suffix⟩ =
      some ⟨some (.inr .vertexGuard), initialState positive H (caller state),
        vertexLoopTapes G H 0 v suffix⟩
    simpa only [vertexLoopTapes, accumulatedVertices_zero] using
      initialize_boundaryStep positive H v (oldTableWord G) suffix state
  steps_le_m := Nat.le_refl _

def tableInTime {v d : Nat} {ρ : Type} [Fintype ρ]
    (positive : 0 < d) (G : Table v (degree d)) (H : Table (cloudSize d) d)
    (state : State ρ d) (suffix : List Bool) : TableRun positive G H state suffix := by
  let loop := vertexLoopInTime positive G H 0 v
    (initialState positive H (caller state)) suffix (by omega) rfl
  let initialRun := initializeInTime positive G H state suffix
  have finish : StateTransition.EvalsToInTime (TM2.step (program positive H))
      ⟨some (.inr .reverseOutput), loop.finalState, vertexLoopTapes G H v 0 suffix⟩
      (some ⟨none, clearRegister loop.finalState,
        finalTapes v (oldTableWord G) (encodeWords (rotationWords (step G H))) suffix⟩)
      ((encodeWords (rotationWords (step G H))).length + 2) := by
    simpa only [vertexLoopTapes, finalTapes, accumulatedVertices_full, List.reverse_reverse,
      List.append_nil, List.length_reverse] using
      reverseOutputHaltInTime positive H v 0 (oldTableWord G)
        (accumulatedVertices G H v) suffix [] loop.finalState
  let first := StateTransition.EvalsToInTime.trans (TM2.step (program positive H))
    _ _ _ _ _ initialRun loop.execution
  let all := StateTransition.EvalsToInTime.trans (TM2.step (program positive H))
    _ _ _ _ _ first finish
  refine ⟨clearRegister loop.finalState, ?_, ?_, ?_⟩
  · exact (caller_clearRegister loop.finalState).trans loop.caller_preserved
  · simpa only [clearRegister] using loop.position_zero
  · refine { toEvalsTo := all.toEvalsTo, steps_le_m := ?_ }
    have bound := all.steps_le_m
    have polynomialBound := completeBudget_le positive G H
    unfold completeBudget at polynomialBound
    omega

end MinUncutGames.Foundations.Complexity.MachineExpanderTable

namespace MinUncutGames.Foundations.Complexity.MachineExpanderFamily

open PCP.ExpanderTables PCP.ExpanderRowControl PCP.ExpanderTableWords

def cycleWords (remaining : Nat) (word current vertex count result suffix : List Bool) :
    Tape → List Bool
  | .inl (.inl .table) => word
  | .inl (.inl .inputVertex) => vertex
  | .inl (.inr .vertexCount) => count
  | .inl (.inr .result) => result
  | .inr .remainingLevel => encodeWord remaining ++ suffix
  | .inr .currentSize => current
  | _ => []

def cycleTapes (remaining : Nat) (word current vertex count result suffix : List Bool) :
    (tape : Tape) → List (Alphabet tape) :=
  fromBoolTapes (cycleWords remaining word current vertex count result suffix)

@[simp] theorem toBool_cycleTapes (remaining : Nat)
    (word current vertex count result suffix : List Bool) :
    toBoolTapes (cycleTapes remaining word current vertex count result suffix) =
      cycleWords remaining word current vertex count result suffix := toBool_fromBool _

theorem boundaryTapes_eq_cycleTapes (remaining current : Nat) (word suffix : List Bool) :
    boundaryTapes remaining current word suffix =
      cycleTapes remaining word (encodeWord current) [] [] [] suffix := by
  funext tape
  rcases tape with tape | tape
  · rcases tape with row | extra
    · cases row <;> rfl
    · cases extra <;> rfl
  · cases tape <;> rfl

def copyFrame (remaining current : Nat) (word suffix : List Bool) :
    (tape : Tape) → List (Alphabet tape) :=
  MachineEmbedding.tapes (MachineExpanderTable.initialTapes current word [])
    (extraFrame remaining current suffix)

def returnFrame (remaining current : Nat) (oldWord newWord suffix : List Bool) :
    (tape : Tape) → List (Alphabet tape) :=
  MachineEmbedding.tapes (MachineExpanderTable.finalTapes current oldWord newWord [])
    (extraFrame remaining current suffix)

def installedFrame (remaining current : Nat) (newWord suffix : List Bool) :
    (tape : Tape) → List (Alphabet tape) :=
  cycleTapes remaining newWord [] (encodeWord current) (encodeWord 0) [] suffix

def multipliedFrame (d remaining current : Nat) (newWord suffix : List Bool) :
    (tape : Tape) → List (Alphabet tape) :=
  cycleTapes remaining newWord (encodeWord (cloudSize d * current))
    (encodeWord current) (encodeWord 0) [] suffix

theorem copyFrame_eq_cycleTapes (remaining current : Nat) (word suffix : List Bool) :
    copyFrame remaining current word suffix =
      cycleTapes remaining word (encodeWord current) [] (encodeWord current) [] suffix := by
  funext tape
  rcases tape with tape | tape
  · rcases tape with row | extra
    · cases row <;> rfl
    · cases extra <;> simp [copyFrame, MachineEmbedding.tapes,
        MachineExpanderTable.initialTapes, MachineExpanderTable.extraTapes,
        cycleTapes, fromBoolTapes, boolWord, cycleWords]
  · cases tape <;> rfl

theorem returnFrame_eq_cycleTapes (remaining current : Nat)
    (oldWord newWord suffix : List Bool) :
    returnFrame remaining current oldWord newWord suffix =
      cycleTapes remaining oldWord (encodeWord current) (encodeWord current)
        (encodeWord 0) newWord suffix := by
  funext tape
  rcases tape with tape | tape
  · rcases tape with row | extra
    · cases row <;> rfl
    · cases extra <;> simp [returnFrame, MachineEmbedding.tapes,
        MachineExpanderTable.finalTapes, MachineExpanderTable.boundaryTapes,
        MachineExpanderTable.extraTapes, cycleTapes, fromBoolTapes, boolWord, cycleWords]
  · cases tape <;> rfl

theorem copyFrame_eq_update (remaining current : Nat) (word suffix : List Bool) :
    Function.update (boundaryTapes remaining current word suffix)
      vertexCountTape (encodeWord current) = copyFrame remaining current word suffix := by
  rw [boundaryTapes_eq_cycleTapes, copyFrame_eq_cycleTapes]
  funext tape
  rcases tape with tape | tape
  · rcases tape with row | extra
    · cases row <;> rfl
    · cases extra <;> rfl
  · cases tape <;> rfl

theorem multipliedFrame_eq_update (d remaining current : Nat) (word suffix : List Bool) :
    Function.update (installedFrame remaining current word suffix)
      (.inr .currentSize) (encodeWord (cloudSize d * current)) =
      multipliedFrame d remaining current word suffix := by
  funext tape
  rcases tape with tape | tape
  · rcases tape with row | extra
    · cases row <;> rfl
    · cases extra <;> rfl
  · cases tape <;> rfl

end MinUncutGames.Foundations.Complexity.MachineExpanderFamily

namespace MinUncutGames.Foundations.Complexity.MachineExpanderFamilyBounds

open PCP.ExpanderTables PCP.ExpanderRowControl PCP.ExpanderTableWords

noncomputable def resizeCost {v d : Nat} (G : Table v (degree d))
    (H : Table (cloudSize d) d) : Nat :=
  (MachineExpanderTable.timePolynomial d).eval (MachineExpanderTable.oldTableWord G).length +
    6 * v + (MachineExpanderTable.oldTableWord G).length +
    2 * (encodeWords (rotationWords (step G H))).length + 15

def resizeCoefficient (d : Nat) : Nat :=
  MachineExpanderTable.timeCoefficient d * (degree d + 1) ^ 4 +
    3 * (degree d + 1) ^ 2 + 21

theorem wordLength_add_one_le {v q N : Nat} (G : Table v q) (hv : v ≤ N) :
    (encodeWords (rotationWords G)).length + 1 ≤ (q + 1)^2 * (N + 1)^2 := by
  have hlength := encode_rotationWords_length_le G
  have hrow : v * q + 1 ≤ (q + 1) * (N + 1) := by
    have h := Nat.mul_le_mul_right q hv
    nlinarith
  calc
    _ ≤ (v * q + 1)^2 := by nlinarith
    _ ≤ ((q + 1) * (N + 1))^2 := Nat.pow_le_pow_left hrow 2
    _ = _ := by ring

theorem resizeCost_le {v d : Nat} (G : Table v (degree d))
    (H : Table (cloudSize d) d) (N : Nat) (hv : v ≤ N)
    (hnext : v * cloudSize d ≤ N) :
    resizeCost G H ≤ resizeCoefficient d * (N + 1)^4 := by
  let oldL := (MachineExpanderTable.oldTableWord G).length
  let newL := (encodeWords (rotationWords (step G H))).length
  have oldBound : oldL + 1 ≤ (degree d + 1)^2 * (N + 1)^2 :=
    wordLength_add_one_le G hv
  have newBound : newL + 1 ≤ (degree d + 1)^2 * (N + 1)^2 :=
    wordLength_add_one_le (step G H) hnext
  have timeBound : (MachineExpanderTable.timePolynomial d).eval oldL ≤
      MachineExpanderTable.timeCoefficient d * (degree d + 1)^4 * (N + 1)^4 := by
    simp only [MachineExpanderTable.timePolynomial, Polynomial.eval_mul,
      Polynomial.eval_C, Polynomial.eval_pow, Polynomial.eval_add,
      Polynomial.eval_X, Polynomial.eval_one]
    calc
      _ ≤ MachineExpanderTable.timeCoefficient d *
          ((degree d + 1)^2 * (N + 1)^2)^2 :=
        Nat.mul_le_mul_left _ (Nat.pow_le_pow_left oldBound 2)
      _ = _ := by ring
  have pow24 : (N + 1)^2 ≤ (N + 1)^4 :=
    Nat.pow_le_pow_right (Nat.succ_pos N) (by decide)
  have overheadBound : oldL + 2 * newL ≤
      3 * (degree d + 1)^2 * (N + 1)^4 := by
    have h := Nat.mul_le_mul_left ((degree d + 1)^2) pow24
    calc
      _ ≤ 3 * ((degree d + 1)^2 * (N + 1)^2) := by omega
      _ ≤ 3 * ((degree d + 1)^2 * (N + 1)^4) := Nat.mul_le_mul_left 3 h
      _ = _ := by ring
  have npow : N + 1 ≤ (N + 1)^4 := by
    simpa only [pow_one] using
      Nat.pow_le_pow_right (Nat.succ_pos N) (show 1 ≤ 4 by decide)
  have linearBound : 6 * v + 15 ≤ 21 * (N + 1)^4 := by omega
  change (MachineExpanderTable.timePolynomial d).eval oldL + 6 * v + oldL +
    2 * newL + 15 ≤ _
  unfold resizeCoefficient
  nlinarith only [timeBound, overheadBound, linearBound]

theorem vertexCount_monotone {q : Nat} (positive : 0 < q) :
    Monotone (vertexCount q) := by
  intro m n hmn
  rw [vertexCount_eq, vertexCount_eq]
  exact Nat.pow_le_pow_right (Nat.mul_pos positive positive) hmn

theorem level_le_vertexCount {q : Nat} (growth : 1 < q * q) (level : Nat) :
    level ≤ vertexCount q level := by
  have positive : 0 < q := by nlinarith
  induction level with
  | zero => exact Nat.zero_le _
  | succ level ih =>
    have hpos := vertexCount_positive positive level
    have hmul := Nat.mul_le_mul_left (vertexCount q level)
      (show 2 ≤ q * q by omega)
    change level + 1 ≤ vertexCount q level * (q * q)
    nlinarith

noncomputable def resizeSum {d : Nat} (H : Table (cloudSize d) d) (level : Nat) : Nat :=
  ∑ i ∈ Finset.range level, resizeCost (family H i) H

@[simp] theorem resizeSum_zero {d : Nat} (H : Table (cloudSize d) d) :
    resizeSum H 0 = 0 := by simp [resizeSum]

theorem resizeSum_succ {d : Nat} (H : Table (cloudSize d) d) (level : Nat) :
    resizeSum H (level + 1) = resizeSum H level + resizeCost (family H level) H := by
  simp only [resizeSum, Finset.sum_range_succ]

theorem resizeSum_add {d : Nat} (H : Table (cloudSize d) d) (start count : Nat) :
    resizeSum H (start + count) = resizeSum H start +
      ∑ i ∈ Finset.range count, resizeCost (family H (start + i)) H :=
  Finset.sum_range_add (fun i => resizeCost (family H i) H) start count

noncomputable def familyBudget {d : Nat} (H : Table (cloudSize d) d) (level : Nat) : Nat :=
  resizeSum H level + level + 3

@[simp] theorem familyBudget_zero {d : Nat} (H : Table (cloudSize d) d) :
    familyBudget H 0 = 3 := by simp [familyBudget]

theorem familyBudget_succ {d : Nat} (H : Table (cloudSize d) d) (level : Nat) :
    familyBudget H (level + 1) =
      familyBudget H level + resizeCost (family H level) H + 1 := by
  simp only [familyBudget, resizeSum_succ]
  omega

theorem resizeSum_le {d : Nat} (H : Table (cloudSize d) d)
    (growth : 1 < cloudSize d) (level : Nat) :
    resizeSum H level ≤ resizeCoefficient d * (vertexCount (degree d) level + 1)^5 := by
  let N := vertexCount (degree d) level
  have positive : 0 < degree d := by
    have h : 1 < degree d * degree d := growth
    nlinarith
  have hmono := vertexCount_monotone positive
  have hlevel : level ≤ N := level_le_vertexCount growth level
  have eachBound : ∀ i ∈ Finset.range level,
      resizeCost (family H i) H ≤ resizeCoefficient d * (N + 1)^4 := by
    intro i hi
    have hi' : i < level := Finset.mem_range.mp hi
    apply resizeCost_le (family H i) H N
    · exact hmono (by omega)
    · exact hmono (show i + 1 ≤ level by omega)
  have sumBound : resizeSum H level ≤ level * (resizeCoefficient d * (N + 1)^4) := by
    calc
      _ ≤ ∑ _i ∈ Finset.range level, resizeCoefficient d * (N + 1)^4 :=
        Finset.sum_le_sum eachBound
      _ = _ := by simp
  calc
    _ ≤ level * (resizeCoefficient d * (N + 1)^4) := sumBound
    _ ≤ (N + 1) * (resizeCoefficient d * (N + 1)^4) :=
      Nat.mul_le_mul_right _ (hlevel.trans (Nat.le_succ N))
    _ = _ := by ring

theorem familyBudget_le {d : Nat} (H : Table (cloudSize d) d)
    (growth : 1 < cloudSize d) (level : Nat) :
    familyBudget H level ≤
      (resizeCoefficient d + 4) * (vertexCount (degree d) level + 1)^5 := by
  have hsum := resizeSum_le H growth level
  have hlevel := level_le_vertexCount growth level
  have hpow : vertexCount (degree d) level + 1 ≤
      (vertexCount (degree d) level + 1)^5 := by
    simpa only [pow_one] using Nat.pow_le_pow_right
      (Nat.succ_pos (vertexCount (degree d) level)) (show 1 ≤ 5 by decide)
  have overhead : level + 3 ≤ 4 * (vertexCount (degree d) level + 1)^5 := by omega
  unfold familyBudget
  nlinarith only [hsum, overhead]

theorem paddedSize_le_succ_input (k : Nat) :
    PCP.PreprocessingLevels.paddedSize k ≤ PCP.ExpanderFamily.growth * (k + 1) := by
  by_cases hk : k = 0
  · subst k
    have h := PCP.ExpanderFamily.growth_gt_one
    simp only [PCP.PreprocessingLevels.paddedSize_zero, Nat.zero_add, Nat.mul_one]
    omega
  · exact (PCP.PreprocessingLevels.paddedSize_bounds (Nat.pos_of_ne_zero hk)).2.trans
      (Nat.mul_le_mul_left _ (Nat.le_succ k))

def inputCoefficient : Nat :=
  (resizeCoefficient PCP.Expanders.baseDegree + 4) * (PCP.ExpanderFamily.growth + 1)^5

theorem familyBudget_at_boundedLevel_le
    (H : Table (cloudSize PCP.Expanders.baseDegree) PCP.Expanders.baseDegree) (k : Nat) :
    familyBudget H (PCP.PreprocessingLevels.boundedLevel k) ≤ inputCoefficient * (k + 1)^5 := by
  have hg : cloudSize PCP.Expanders.baseDegree = PCP.ExpanderFamily.growth := by
    unfold cloudSize degree PCP.ExpanderFamily.growth
    ring
  have growth : 1 < cloudSize PCP.Expanders.baseDegree := by
    rw [hg]
    exact PCP.ExpanderFamily.growth_gt_one
  have bound := familyBudget_le H growth (PCP.PreprocessingLevels.boundedLevel k)
  rw [PCP.PreprocessingLevels.table_vertexCount_eq_paddedSize] at bound
  have sizeBound : PCP.PreprocessingLevels.paddedSize k + 1 ≤
      (PCP.ExpanderFamily.growth + 1) * (k + 1) := by
    have h := paddedSize_le_succ_input k
    nlinarith
  calc
    _ ≤ (resizeCoefficient PCP.Expanders.baseDegree + 4) *
        (PCP.PreprocessingLevels.paddedSize k + 1)^5 := bound
    _ ≤ (resizeCoefficient PCP.Expanders.baseDegree + 4) *
        ((PCP.ExpanderFamily.growth + 1) * (k + 1))^5 :=
      Nat.mul_le_mul_left _ (Nat.pow_le_pow_left sizeBound 5)
    _ = _ := by unfold inputCoefficient; ring

end MinUncutGames.Foundations.Complexity.MachineExpanderFamilyBounds

end OAI