import Mathlib.Algebra.BigOperators.Group.Finset.Basic
import Mathlib.Data.List.Range
import OAI.Computability.BinPacking.Computation.MachineUnaryEqualityBit
import OAI.Computability.BinPacking.Information.SourceFieldArray

namespace OAI

namespace BinPackingGames.Foundations.Complexity.MachineUnaryCounter

open Turing

variable {K Λ σ : Type} [DecidableEq K]

abbrev Alphabet (_ : K) := Bool

def guard (counter : K) (bodyLabel exitLabel : Λ) :
    TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool) :=
  .peek counter (fun state head => (state.1, head))
    (.branch (fun state => state.2.getD false)
      (.pop counter (fun state _ => (state.1, none)) (.goto fun _ => bodyLabel))
      (.load (fun state => (state.1, none)) (.goto fun _ => exitLabel)))

def counterTapes (counter : K) (base : K → List Bool) (n : Nat)
    (suffix : List Bool) : K → List Bool :=
  Function.update base counter (encodeWord n ++ suffix)

@[simp] theorem counterTapes_counter (counter : K) (base : K → List Bool)
    (n : Nat) (suffix : List Bool) :
    counterTapes counter base n suffix counter = encodeWord n ++ suffix := by
  simp [counterTapes]

theorem counterTapes_other (counter other : K) (hne : other ≠ counter)
    (base : K → List Bool) (n : Nat) (suffix : List Bool) :
    counterTapes counter base n suffix other = base other := by
  simp [counterTapes, hne]

omit [DecidableEq K] in
theorem guardPushBound (counter : K) (bodyLabel exitLabel : Λ) :
    Runtime.statementPushBound (guard (σ := σ) counter bodyLabel exitLabel) = 0 := by
  rfl

theorem stepAux_succ (counter : K) (bodyLabel exitLabel : Λ)
    (base : K → List Bool) (n : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    TM2.stepAux (guard counter bodyLabel exitLabel) (ambient, register)
      (counterTapes counter base (n + 1) suffix) =
      ⟨some bodyLabel, (ambient, none), counterTapes counter base n suffix⟩ := by
  simp [guard, TM2.stepAux, counterTapes, encodeWord, List.replicate_succ]

theorem stepAux_zero (counter : K) (bodyLabel exitLabel : Λ)
    (base : K → List Bool) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    TM2.stepAux (guard counter bodyLabel exitLabel) (ambient, register)
      (counterTapes counter base 0 suffix) =
      ⟨some exitLabel, (ambient, none), counterTapes counter base 0 suffix⟩ := by
  simp [guard, TM2.stepAux, counterTapes, encodeWord]

theorem guardStep_succ (counter : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atGuard : program guardLabel = guard counter bodyLabel exitLabel)
    (base : K → List Bool) (n : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    TM2.step program
      ⟨some guardLabel, (ambient, register), counterTapes counter base (n + 1) suffix⟩ =
      some ⟨some bodyLabel, (ambient, none), counterTapes counter base n suffix⟩ := by
  change some (TM2.stepAux (program guardLabel) (ambient, register)
    (counterTapes counter base (n + 1) suffix)) = _
  rw [atGuard, stepAux_succ]

theorem guardStep_zero (counter : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atGuard : program guardLabel = guard counter bodyLabel exitLabel)
    (base : K → List Bool) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    TM2.step program
      ⟨some guardLabel, (ambient, register), counterTapes counter base 0 suffix⟩ =
      some ⟨some exitLabel, (ambient, none), counterTapes counter base 0 suffix⟩ := by
  change some (TM2.stepAux (program guardLabel) (ambient, register)
    (counterTapes counter base 0 suffix)) = _
  rw [atGuard, stepAux_zero]

theorem guardTrace_succ (counter : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atGuard : program guardLabel = guard counter bodyLabel exitLabel)
    (base : K → List Bool) (n : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    (MachineComposition.advance (TM2.step program))^[1]
      (some ⟨some guardLabel, (ambient, register),
        counterTapes counter base (n + 1) suffix⟩) =
      some ⟨some bodyLabel, (ambient, none), counterTapes counter base n suffix⟩ := by
  simpa only [Function.iterate_one, MachineComposition.advance_some] using
    guardStep_succ counter guardLabel bodyLabel exitLabel program atGuard
      base n suffix ambient register

theorem guardTrace_zero (counter : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atGuard : program guardLabel = guard counter bodyLabel exitLabel)
    (base : K → List Bool) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    (MachineComposition.advance (TM2.step program))^[1]
      (some ⟨some guardLabel, (ambient, register), counterTapes counter base 0 suffix⟩) =
      some ⟨some exitLabel, (ambient, none), counterTapes counter base 0 suffix⟩ := by
  simpa only [Function.iterate_one, MachineComposition.advance_some] using
    guardStep_zero counter guardLabel bodyLabel exitLabel program atGuard
      base suffix ambient register

def guardInTime_succ (counter : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atGuard : program guardLabel = guard counter bodyLabel exitLabel)
    (base : K → List Bool) (n : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    StateTransition.EvalsToInTime (TM2.step program)
      ⟨some guardLabel, (ambient, register), counterTapes counter base (n + 1) suffix⟩
      (some ⟨some bodyLabel, (ambient, none), counterTapes counter base n suffix⟩) 1 where
  steps := 1
  evals_in_steps := by
    change (MachineComposition.advance (TM2.step program))^[1] _ = _
    exact guardTrace_succ counter guardLabel bodyLabel exitLabel program atGuard
      base n suffix ambient register
  steps_le_m := Nat.le_refl _

def guardInTime_zero (counter : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atGuard : program guardLabel = guard counter bodyLabel exitLabel)
    (base : K → List Bool) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    StateTransition.EvalsToInTime (TM2.step program)
      ⟨some guardLabel, (ambient, register), counterTapes counter base 0 suffix⟩
      (some ⟨some exitLabel, (ambient, none), counterTapes counter base 0 suffix⟩) 1 where
  steps := 1
  evals_in_steps := by
    change (MachineComposition.advance (TM2.step program))^[1] _ = _
    exact guardTrace_zero counter guardLabel bodyLabel exitLabel program atGuard
      base suffix ambient register
  steps_le_m := Nat.le_refl _

end BinPackingGames.Foundations.Complexity.MachineUnaryCounter

namespace BinPackingGames.Foundations.Complexity.MachineCountedLoop

open Turing
open scoped BigOperators
open MachineUnaryCounter

variable {K Λ σ : Type} [DecidableEq K]

def guardConfiguration (counter : K) (guardLabel : Λ) (suffix : List Bool)
    (ambient : Nat → σ) (register : Nat → Option Bool)
    (base : Nat → K → List Bool) (n : Nat) :
    TM2.Cfg (Alphabet (K := K)) Λ (σ × Option Bool) :=
  ⟨some guardLabel, (ambient n, register n), counterTapes counter (base n) n suffix⟩

def bodyConfiguration (counter : K) (bodyLabel : Λ) (suffix : List Bool)
    (ambient : Nat → σ) (base : Nat → K → List Bool) (n : Nat) :
    TM2.Cfg (Alphabet (K := K)) Λ (σ × Option Bool) :=
  ⟨some bodyLabel, (ambient (n + 1), none), counterTapes counter (base (n + 1)) n suffix⟩

def exitConfiguration (counter : K) (exitLabel : Λ) (suffix : List Bool)
    (ambient : Nat → σ) (base : Nat → K → List Bool) :
    TM2.Cfg (Alphabet (K := K)) Λ (σ × Option Bool) :=
  ⟨some exitLabel, (ambient 0, none), counterTapes counter (base 0) 0 suffix⟩

def BodyTraces (counter : K) (guardLabel bodyLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (suffix : List Bool) (ambient : Nat → σ) (register : Nat → Option Bool)
    (base : Nat → K → List Bool) (cost : Nat → Nat) (n : Nat) : Prop :=
  ∀ r, r < n →
    (MachineComposition.advance (TM2.step program))^[cost r]
      (some (bodyConfiguration counter bodyLabel suffix ambient base r)) =
      some (guardConfiguration counter guardLabel suffix ambient register base r)

def totalSteps (cost : Nat → Nat) (n : Nat) : Nat :=
  (∑ r ∈ Finset.range n, cost r) + n + 1

@[simp] theorem totalSteps_zero (cost : Nat → Nat) : totalSteps cost 0 = 1 := by
  simp [totalSteps]

theorem totalSteps_succ (cost : Nat → Nat) (n : Nat) :
    totalSteps cost (n + 1) = (totalSteps cost n + cost n) + 1 := by
  simp only [totalSteps, Finset.sum_range_succ]
  omega

theorem loopTrace (counter : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atGuard : program guardLabel = guard counter bodyLabel exitLabel)
    (suffix : List Bool) (ambient : Nat → σ) (register : Nat → Option Bool)
    (base : Nat → K → List Bool) (cost : Nat → Nat) (n : Nat)
    (bodyTraces : BodyTraces counter guardLabel bodyLabel program suffix
      ambient register base cost n) :
    (MachineComposition.advance (TM2.step program))^[totalSteps cost n]
      (some (guardConfiguration counter guardLabel suffix ambient register base n)) =
      some (exitConfiguration counter exitLabel suffix ambient base) := by
  revert bodyTraces
  induction n with
  | zero =>
      intro _
      simpa only [totalSteps_zero, guardConfiguration, exitConfiguration] using
        guardTrace_zero counter guardLabel bodyLabel exitLabel program atGuard
          (base 0) suffix (ambient 0) (register 0)
  | succ n ih =>
      intro bodyTraces
      rw [totalSteps_succ, Function.iterate_succ_apply]
      change (MachineComposition.advance (TM2.step program))^[totalSteps cost n + cost n]
        (TM2.step program
          ⟨some guardLabel, (ambient (n + 1), register (n + 1)),
            counterTapes counter (base (n + 1)) (n + 1) suffix⟩) = _
      rw [guardStep_succ counter guardLabel bodyLabel exitLabel program atGuard
        (base (n + 1)) n suffix (ambient (n + 1)) (register (n + 1)),
        Function.iterate_add_apply]
      change (MachineComposition.advance (TM2.step program))^[totalSteps cost n]
        ((MachineComposition.advance (TM2.step program))^[cost n]
          (some (bodyConfiguration counter bodyLabel suffix ambient base n))) = _
      rw [bodyTraces n (Nat.lt_succ_self n)]
      exact ih (fun r hr => bodyTraces r (Nat.lt_trans hr (Nat.lt_succ_self n)))

theorem totalSteps_le (cost : Nat → Nat) (n B : Nat)
    (bodyBound : ∀ r, r < n → cost r ≤ B) :
    totalSteps cost n ≤ n * (B + 1) + 1 := by
  have hsum : (∑ r ∈ Finset.range n, cost r) ≤ n * B := by
    calc
      (∑ r ∈ Finset.range n, cost r) ≤ ∑ _r ∈ Finset.range n, B :=
        Finset.sum_le_sum (fun r hr => bodyBound r (Finset.mem_range.mp hr))
      _ = n * B := by simp
  simpa only [totalSteps, Nat.mul_add, Nat.mul_one] using
    Nat.add_le_add_right (Nat.add_le_add_right hsum n) 1

def loopInTime (counter : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atGuard : program guardLabel = guard counter bodyLabel exitLabel)
    (suffix : List Bool) (ambient : Nat → σ) (register : Nat → Option Bool)
    (base : Nat → K → List Bool) (cost : Nat → Nat) (n B : Nat)
    (bodyTraces : BodyTraces counter guardLabel bodyLabel program suffix
      ambient register base cost n)
    (bodyBound : ∀ r, r < n → cost r ≤ B) :
    StateTransition.EvalsToInTime (TM2.step program)
      (guardConfiguration counter guardLabel suffix ambient register base n)
      (some (exitConfiguration counter exitLabel suffix ambient base))
      (n * (B + 1) + 1) where
  steps := totalSteps cost n
  evals_in_steps := by
    change (MachineComposition.advance (TM2.step program))^[totalSteps cost n] _ = _
    exact loopTrace counter guardLabel bodyLabel exitLabel program atGuard suffix
      ambient register base cost n bodyTraces
  steps_le_m := totalSteps_le cost n B bodyBound

omit [DecidableEq K] in

theorem baseFrame (base : Nat → K → List Bool) (frame : K → Prop) (n : Nat)
    (bodyFrame : ∀ r, r < n → ∀ k, frame k → base (r + 1) k = base r k) :
    ∀ k, frame k → base n k = base 0 k := by
  revert bodyFrame
  induction n with
  | zero => intro _ k _; rfl
  | succ n ih =>
      intro bodyFrame k hk
      exact (bodyFrame n (Nat.lt_succ_self n) k hk).trans
        (ih (fun r hr => bodyFrame r (Nat.lt_trans hr (Nat.lt_succ_self n))) k hk)

theorem counterFrame (counter : K) (suffix : List Bool)
    (base : Nat → K → List Bool) (frame : K → Prop) (n : Nat)
    (counterOutside : ∀ k, frame k → k ≠ counter)
    (bodyFrame : ∀ r, r < n → ∀ k, frame k → base (r + 1) k = base r k) :
    ∀ k, frame k →
      counterTapes counter (base n) n suffix k = counterTapes counter (base 0) 0 suffix k := by
  intro k hk
  rw [counterTapes_other counter k (counterOutside k hk),
    counterTapes_other counter k (counterOutside k hk)]
  exact baseFrame base frame n bodyFrame k hk

theorem loopTrace_framed (counter : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atGuard : program guardLabel = guard counter bodyLabel exitLabel)
    (suffix : List Bool) (ambient : Nat → σ) (register : Nat → Option Bool)
    (base : Nat → K → List Bool) (cost : Nat → Nat) (n : Nat)
    (bodyTraces : BodyTraces counter guardLabel bodyLabel program suffix
      ambient register base cost n)
    (frame : K → Prop) (counterOutside : ∀ k, frame k → k ≠ counter)
    (bodyFrame : ∀ r, r < n → ∀ k, frame k → base (r + 1) k = base r k) :
    ((MachineComposition.advance (TM2.step program))^[totalSteps cost n]
      (some (guardConfiguration counter guardLabel suffix ambient register base n)) =
      some (exitConfiguration counter exitLabel suffix ambient base)) ∧
    (∀ k, frame k →
      (guardConfiguration counter guardLabel suffix ambient register base n).stk k =
        (exitConfiguration counter exitLabel suffix ambient base).stk k) :=
  ⟨loopTrace counter guardLabel bodyLabel exitLabel program atGuard suffix
      ambient register base cost n bodyTraces,
    counterFrame counter suffix base frame n counterOutside bodyFrame⟩

end BinPackingGames.Foundations.Complexity.MachineCountedLoop

namespace BinPackingGames.Foundations.Complexity.MachineLookup

open Turing

variable {K Λ σ : Type} [DecidableEq K]

abbrev Alphabet (_ : K) := Bool

def discard (source : K) (loopLabel returnLabel : Λ) :
    TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool) :=
  .pop source (fun state head => (state.1, head))
    (.branch (fun state => state.2.getD false)
      (.goto fun _ => loopLabel)
      (.load (fun state => (state.1, none)) (.goto fun _ => returnLabel)))

def select (source destination : K) (copyLabel rejected : Λ) :
    TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool) :=
  .peek source (fun state head => (state.1, head))
    (.branch (fun state => state.2.isSome)
      (Hastad.SourceMachine.fieldStart destination copyLabel)
      (.load (fun state => (state.1, none)) (.goto fun _ => rejected)))

inductive Label
  | guard | skip | select | copy | accepted | rejected
  deriving DecidableEq

protected abbrev Label.enumList : List Label := [.guard, .skip, .select, .copy, .accepted,
  .rejected]

protected theorem Label.enumList_getElem?_ctorIdx_eq (x : Label) :
    Label.enumList[x.ctorIdx]? = some x := by
  cases x <;> rfl

protected theorem Label.enumList_nodup : Label.enumList.Nodup := by decide

instance : Fintype Label where
  elems := ⟨Label.enumList, Label.enumList_nodup⟩
  complete x := by cases x <;> decide

def program (index source destination : K) :
    Label → TM2.Stmt (Alphabet (K := K)) Label (σ × Option Bool)
  | .guard => MachineUnaryCounter.guard index .skip .select
  | .skip => discard source .skip .guard
  | .select => select source destination .copy .rejected
  | .copy => Hastad.SourceMachine.fieldLoop source destination .copy (some .accepted)
  | .accepted => .halt
  | .rejected => .halt

def tapes (index source destination : K) (base : K → List Bool)
    (counter input output : List Bool) : K → List Bool :=
  Function.update (Function.update (Function.update base index counter) source input)
    destination output

@[simp] theorem tapes_index (index source destination : K)
    (his : index ≠ source) (hid : index ≠ destination)
    (base : K → List Bool) (counter input output : List Bool) :
    tapes index source destination base counter input output index = counter := by
  simp [tapes, his, hid]

@[simp] theorem tapes_source (index source destination : K)
    (hsd : source ≠ destination) (base : K → List Bool)
    (counter input output : List Bool) :
    tapes index source destination base counter input output source = input := by
  simp [tapes, hsd]

@[simp] theorem tapes_destination (index source destination : K)
    (base : K → List Bool) (counter input output : List Bool) :
    tapes index source destination base counter input output destination = output := by
  simp [tapes]

theorem tapes_other (index source destination p : K)
    (hi : p ≠ index) (hs : p ≠ source) (hd : p ≠ destination)
    (base : K → List Bool) (counter input output : List Bool) :
    tapes index source destination base counter input output p = base p := by
  simp [tapes, hi, hs, hd]

theorem update_index (index source destination : K)
    (his : index ≠ source) (hid : index ≠ destination)
    (base : K → List Bool) (counter input output replacement : List Bool) :
    Function.update (tapes index source destination base counter input output) index replacement =
      tapes index source destination base replacement input output := by
  funext p
  by_cases hi : p = index
  · subst p; simp [tapes, his, hid]
  · by_cases hs : p = source
    · subst p; by_cases hs : source = destination <;> simp [tapes, hi, hs, Ne.symm hid]
    · by_cases hd : p = destination
      · subst p; simp [tapes, hi]
      · simp [tapes, hi, hs, hd]

theorem update_source (index source destination : K) (hsd : source ≠ destination)
    (base : K → List Bool) (counter input output replacement : List Bool) :
    Function.update (tapes index source destination base counter input output) source replacement =
      tapes index source destination base counter replacement output := by
  funext p
  by_cases hs : p = source
  · subst p; simp [tapes, hsd]
  · by_cases hd : p = destination
    · subst p; simp [tapes, hs]
    · simp [tapes, hs, hd]

theorem update_destination (index source destination : K)
    (base : K → List Bool) (counter input output replacement : List Bool) :
    Function.update (tapes index source destination base counter input output)
      destination replacement = tapes index source destination base counter input replacement := by
  simp [tapes]

theorem fieldTapes_eq (index source destination : K) (hsd : source ≠ destination)
    (base : K → List Bool) (counter input output input' output' : List Bool) :
    Hastad.SourceMachine.fieldTapes source destination
      (tapes index source destination base counter input output) input' output' =
      tapes index source destination base counter input' output' := by
  rw [Hastad.SourceMachine.fieldTapes, update_source _ _ _ hsd, update_destination]

def machine : FinTM2 where
  K := Fin 3
  k₀ := 1
  k₁ := 2
  Γ _ := Bool
  Λ := Label
  main := .guard
  σ := Unit × Option Bool
  initialState := ((), none)
  m := program 0 1 2

end BinPackingGames.Foundations.Complexity.MachineLookup

namespace BinPackingGames.Foundations.Complexity.PoweringMachineLoop

open Turing

inductive HeaderTape
  | source | counter | vertices | darts
  deriving DecidableEq

protected abbrev HeaderTape.enumList : List HeaderTape := [.source, .counter, .vertices, .darts]

protected theorem HeaderTape.enumList_getElem?_ctorIdx_eq (x : HeaderTape) :
    HeaderTape.enumList[x.ctorIdx]? = some x := by
  cases x <;> rfl

protected theorem HeaderTape.enumList_nodup : HeaderTape.enumList.Nodup := by decide

instance : Fintype HeaderTape where
  elems := ⟨HeaderTape.enumList, HeaderTape.enumList_nodup⟩
  complete x := by cases x <;> decide

inductive HeaderLabel
  | initialize | scan
  deriving DecidableEq

protected abbrev HeaderLabel.enumList : List HeaderLabel := [.initialize, .scan]

protected theorem HeaderLabel.enumList_getElem?_ctorIdx_eq (x : HeaderLabel) :
    HeaderLabel.enumList[x.ctorIdx]? = some x := by
  cases x <;> rfl

protected theorem HeaderLabel.enumList_nodup : HeaderLabel.enumList.Nodup := by decide

instance : Fintype HeaderLabel where
  elems := ⟨HeaderLabel.enumList, HeaderLabel.enumList_nodup⟩
  complete x := by cases x <;> decide

abbrev HeaderAlphabet (_ : HeaderTape) := Bool
abbrev HeaderState (σ : Type) := σ × Option Bool

def pushTrue {K Λ σ : Type} (destination : K) : Nat →
    TM2.Stmt (fun _ : K => Bool) Λ σ → TM2.Stmt (fun _ : K => Bool) Λ σ
  | 0, next => next
  | count + 1, next => pushTrue destination count (.push destination (fun _ => true) next)

theorem stepAux_pushTrue {K Λ σ : Type} [DecidableEq K]
    (destination : K) (count : Nat) (next : TM2.Stmt (fun _ : K => Bool) Λ σ)
    (state : σ) (tapes : K → List Bool) :
    TM2.stepAux (pushTrue destination count next) state tapes =
      TM2.stepAux next state
        (Function.update tapes destination (List.replicate count true ++ tapes destination)) := by
  induction count generalizing next with
  | zero => simp [pushTrue]
  | succ count ih =>
    rw [pushTrue, ih]
    simp [TM2.stepAux, List.replicate_succ, Function.update_idem]

theorem pushTrue_pushBound {K Λ σ : Type} (destination : K) (count : Nat)
    (next : TM2.Stmt (fun _ : K => Bool) Λ σ) :
    Runtime.statementPushBound (pushTrue destination count next) =
      count + Runtime.statementPushBound next := by
  induction count generalizing next with
  | zero => simp [pushTrue]
  | succ count ih => simp only [pushTrue, ih, Runtime.statementPushBound]; omega

def headerProgram {σ : Type} (B : Nat) :
    HeaderLabel → TM2.Stmt HeaderAlphabet HeaderLabel (HeaderState σ)
  | .initialize =>
      .push .counter (fun _ => false)
        (.push .vertices (fun _ => false)
          (.push .darts (fun _ => false)
            (.load (fun state => (state.1, none)) (.goto fun _ => .scan))))
  | .scan =>
      .pop .source (fun state head => (state.1, head))
        (.branch (fun state => state.2.getD false)
          (.push .counter (fun _ => true)
            (.push .vertices (fun _ => true)
              (pushTrue .darts B
                (.load (fun state => (state.1, none)) (.goto fun _ => .scan)))))
          (.load (fun state => (state.1, none)) .halt))

def headerMachine (B : Nat) : FinTM2 where
  K := HeaderTape
  k₀ := .source
  k₁ := .darts
  Γ := HeaderAlphabet
  Λ := HeaderLabel
  main := .initialize
  σ := HeaderState Unit
  initialState := ((), none)
  m := headerProgram B

def initialTapes (n : Nat) (suffix : List Bool) : HeaderTape → List Bool
  | .source => encodeWord n ++ suffix
  | _ => []

def scanTapes (B remaining processed : Nat) (suffix : List Bool) : HeaderTape → List Bool
  | .source => encodeWord remaining ++ suffix
  | .counter => encodeWord processed
  | .vertices => encodeWord processed
  | .darts => encodeWord (B * processed)

def finalTapes (B n : Nat) (suffix : List Bool) : HeaderTape → List Bool
  | .source => suffix
  | .counter => encodeWord n
  | .vertices => encodeWord n
  | .darts => encodeWord (B * n)

def scanConfiguration {σ : Type} (B remaining processed : Nat)
    (suffix : List Bool) (ambient : σ) (register : Option Bool) :
    TM2.Cfg HeaderAlphabet HeaderLabel (HeaderState σ) :=
  ⟨some .scan, (ambient, register), scanTapes B remaining processed suffix⟩

def finalConfiguration {σ : Type} (B n : Nat) (suffix : List Bool) (ambient : σ) :
    TM2.Cfg HeaderAlphabet HeaderLabel (HeaderState σ) :=
  ⟨none, (ambient, none), finalTapes B n suffix⟩

theorem initializeStep {σ : Type} (B n : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    TM2.step (headerProgram B)
      ⟨some .initialize, (ambient, register), initialTapes n suffix⟩ =
        some (scanConfiguration B n 0 suffix ambient none) := by
  simp only [TM2.step, headerProgram, TM2.stepAux]
  congr 2
  funext tape
  cases tape <;> simp [initialTapes, scanTapes, encodeWord]

theorem scanStep_zero {σ : Type} (B processed : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    TM2.step (headerProgram B) (scanConfiguration B 0 processed suffix ambient register) =
      some (finalConfiguration B processed suffix ambient) := by
  simp only [TM2.step, scanConfiguration, headerProgram, TM2.stepAux,
    scanTapes, encodeWord, List.replicate_zero, List.nil_append, List.singleton_append,
    List.head?_cons, List.tail_cons, Option.getD_some, Bool.cond_false]
  congr 2
  funext tape
  cases tape <;> simp [finalTapes, scanTapes]

theorem scanStep_succ {σ : Type} (B remaining processed : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    TM2.step (headerProgram B)
      (scanConfiguration B (remaining + 1) processed suffix ambient register) =
      some (scanConfiguration B remaining (processed + 1) suffix ambient none) := by
  simp only [TM2.step, scanConfiguration, headerProgram, TM2.stepAux,
    scanTapes, encodeWord, List.replicate_succ, List.cons_append,
    List.head?_cons, List.tail_cons, Option.getD_some, Bool.cond_true]
  rw [stepAux_pushTrue]
  simp only [TM2.stepAux]
  congr 2
  funext tape
  cases tape <;>
    simp [scanTapes, encodeWord, Nat.mul_add, List.replicate_add,
      List.replicate_succ, List.append_assoc, Nat.add_comm,
      -List.replicate_append_replicate]

theorem scanTrace {σ : Type} (B remaining processed : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    (MachineComposition.advance (TM2.step (headerProgram B)))^[remaining + 1]
      (some (scanConfiguration B remaining processed suffix ambient register)) =
      some (finalConfiguration B (processed + remaining) suffix ambient) := by
  induction remaining generalizing processed register with
  | zero =>
    simpa only [Nat.add_zero, Nat.zero_add, Function.iterate_one, MachineComposition.advance_some] using
      scanStep_zero B processed suffix ambient register
  | succ remaining ih =>
    rw [Function.iterate_succ_apply]
    change (MachineComposition.advance (TM2.step (headerProgram B)))^[remaining + 1]
      (TM2.step (headerProgram B)
        (scanConfiguration B (remaining + 1) processed suffix ambient register)) = _
    rw [scanStep_succ, ih]
    simp only [Nat.add_comm, Nat.add_left_comm]

theorem headerTrace {σ : Type} (B n : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    (MachineComposition.advance (TM2.step (headerProgram B)))^[n + 2]
      (some ⟨some .initialize, (ambient, register), initialTapes n suffix⟩) =
      some (finalConfiguration B n suffix ambient) := by
  rw [show n + 2 = (n + 1) + 1 by omega, Function.iterate_succ_apply]
  change (MachineComposition.advance (TM2.step (headerProgram B)))^[n + 1]
    (TM2.step (headerProgram B)
      ⟨some .initialize, (ambient, register), initialTapes n suffix⟩) = _
  rw [initializeStep]
  simpa only [Nat.zero_add] using scanTrace B n 0 suffix ambient none

def headerInTime {σ : Type} (B n : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    StateTransition.EvalsToInTime (TM2.step (headerProgram B))
      ⟨some .initialize, (ambient, register), initialTapes n suffix⟩
      (some (finalConfiguration B n suffix ambient)) (n + 2) where
  steps := n + 2
  evals_in_steps := headerTrace B n suffix ambient register
  steps_le_m := Nat.le_refl _

def remainingRows (rowBlock : Nat → List Bool) (n r : Nat) : List Bool :=
  (List.range' r (n - r)).flatMap rowBlock

@[simp] theorem remainingRows_top (rowBlock : Nat → List Bool) (n : Nat) :
    remainingRows rowBlock n n = [] := by simp [remainingRows]

theorem remainingRows_step (rowBlock : Nat → List Bool) (n r : Nat) (hr : r < n) :
    remainingRows rowBlock n r = rowBlock r ++ remainingRows rowBlock n (r + 1) := by
  have h : n - r = (n - (r + 1)) + 1 := by omega
  simp only [remainingRows, h, List.range'_succ, List.flatMap_cons]

variable {K Λ σ : Type} [DecidableEq K]

def rowBase (output : K) (base : K → List Bool)
    (rowBlock : Nat → List Bool) (n r : Nat) : K → List Bool :=
  Function.update base output (remainingRows rowBlock n r ++ base output)

def VertexBodyTraces (counter output : K) (guardLabel bodyLabel : Λ)
    (program : Λ → TM2.Stmt (fun _ : K => Bool) Λ (σ × Option Bool))
    (base : K → List Bool) (suffix : List Bool) (ambient : σ)
    (rowBlock : Nat → List Bool) (cost : Nat → Nat) (n : Nat) : Prop :=
  ∀ r, r < n → ∀ accumulator : List Bool,
    (MachineComposition.advance (TM2.step program))^[cost r]
      (some ⟨some bodyLabel, (ambient, none),
        MachineUnaryCounter.counterTapes counter
          (Function.update base output accumulator) r suffix⟩) =
      some ⟨some guardLabel, (ambient, none),
        MachineUnaryCounter.counterTapes counter
          (Function.update base output (rowBlock r ++ accumulator)) r suffix⟩

theorem vertexBodyTraces_to_counted (counter output : K) (guardLabel bodyLabel : Λ)
    (program : Λ → TM2.Stmt (fun _ : K => Bool) Λ (σ × Option Bool))
    (base : K → List Bool) (suffix : List Bool) (ambient : σ)
    (rowBlock : Nat → List Bool) (cost : Nat → Nat) (n : Nat)
    (bodies : VertexBodyTraces counter output guardLabel bodyLabel program
      base suffix ambient rowBlock cost n) :
    MachineCountedLoop.BodyTraces counter guardLabel bodyLabel program suffix
      (fun _ => ambient) (fun _ => none) (rowBase output base rowBlock n) cost n := by
  intro r hr
  have h := bodies r hr (remainingRows rowBlock n (r + 1) ++ base output)
  simpa only [MachineCountedLoop.bodyConfiguration, MachineCountedLoop.guardConfiguration,
    rowBase, remainingRows_step rowBlock n r hr, List.append_assoc] using h

def vertexLoopInTime (counter output : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (fun _ : K => Bool) Λ (σ × Option Bool))
    (atGuard : program guardLabel = MachineUnaryCounter.guard counter bodyLabel exitLabel)
    (base : K → List Bool) (suffix : List Bool) (ambient : σ)
    (rowBlock : Nat → List Bool) (cost : Nat → Nat) (n bodyBound : Nat)
    (bodies : VertexBodyTraces counter output guardLabel bodyLabel program
      base suffix ambient rowBlock cost n)
    (bounded : ∀ r, r < n → cost r ≤ bodyBound) :
    StateTransition.EvalsToInTime (TM2.step program)
      ⟨some guardLabel, (ambient, none),
        MachineUnaryCounter.counterTapes counter base n suffix⟩
      (some ⟨some exitLabel, (ambient, none),
        MachineUnaryCounter.counterTapes counter
          (rowBase output base rowBlock n 0) 0 suffix⟩)
      (n * (bodyBound + 1) + 1) := by
  have h := MachineCountedLoop.loopInTime counter guardLabel bodyLabel exitLabel
    program atGuard suffix (fun _ => ambient) (fun _ => none)
    (rowBase output base rowBlock n) cost n bodyBound
    (vertexBodyTraces_to_counted counter output guardLabel bodyLabel program
      base suffix ambient rowBlock cost n bodies) bounded
  simpa [MachineCountedLoop.guardConfiguration, MachineCountedLoop.exitConfiguration,
    rowBase] using h

theorem vertexLoop_output (counter output : K) (different : output ≠ counter)
    (base : K → List Bool) (suffix : List Bool) (rowBlock : Nat → List Bool) (n : Nat) :
    MachineUnaryCounter.counterTapes counter (rowBase output base rowBlock n 0) 0 suffix output =
      remainingRows rowBlock n 0 ++ base output := by
  simp [MachineUnaryCounter.counterTapes, rowBase, different]

def varyingRowBase (output : K) (base : Nat → K → List Bool)
    (rowBlock : Nat → List Bool) (n r : Nat) : K → List Bool :=
  Function.update (base r) output (remainingRows rowBlock n r ++ base n output)

def VaryingVertexBodyTraces (counter output : K) (guardLabel bodyLabel : Λ)
    (program : Λ → TM2.Stmt (fun _ : K => Bool) Λ (σ × Option Bool))
    (base : Nat → K → List Bool) (suffix : List Bool) (ambient : Nat → σ)
    (rowBlock : Nat → List Bool) (cost : Nat → Nat) (n : Nat) : Prop :=
  ∀ r, r < n → ∀ accumulator : List Bool,
    (MachineComposition.advance (TM2.step program))^[cost r]
      (some ⟨some bodyLabel, (ambient (r + 1), none),
        MachineUnaryCounter.counterTapes counter
          (Function.update (base (r + 1)) output accumulator) r suffix⟩) =
      some ⟨some guardLabel, (ambient r, none),
        MachineUnaryCounter.counterTapes counter
          (Function.update (base r) output (rowBlock r ++ accumulator)) r suffix⟩

theorem varyingVertexBodyTraces_to_counted (counter output : K) (guardLabel bodyLabel : Λ)
    (program : Λ → TM2.Stmt (fun _ : K => Bool) Λ (σ × Option Bool))
    (base : Nat → K → List Bool) (suffix : List Bool) (ambient : Nat → σ)
    (rowBlock : Nat → List Bool) (cost : Nat → Nat) (n : Nat)
    (bodies : VaryingVertexBodyTraces counter output guardLabel bodyLabel program
      base suffix ambient rowBlock cost n) :
    MachineCountedLoop.BodyTraces counter guardLabel bodyLabel program suffix
      ambient (fun _ => none) (varyingRowBase output base rowBlock n) cost n := by
  intro r hr
  have h := bodies r hr (remainingRows rowBlock n (r + 1) ++ base n output)
  simpa only [MachineCountedLoop.bodyConfiguration, MachineCountedLoop.guardConfiguration,
    varyingRowBase, remainingRows_step rowBlock n r hr, List.append_assoc] using h

def vertexLoopInTime_varying (counter output : K) (guardLabel bodyLabel exitLabel : Λ)
    (program : Λ → TM2.Stmt (fun _ : K => Bool) Λ (σ × Option Bool))
    (atGuard : program guardLabel = MachineUnaryCounter.guard counter bodyLabel exitLabel)
    (base : Nat → K → List Bool) (suffix : List Bool) (ambient : Nat → σ)
    (rowBlock : Nat → List Bool) (cost : Nat → Nat) (n bodyBound : Nat)
    (bodies : VaryingVertexBodyTraces counter output guardLabel bodyLabel program
      base suffix ambient rowBlock cost n)
    (bounded : ∀ r, r < n → cost r ≤ bodyBound) :
    StateTransition.EvalsToInTime (TM2.step program)
      ⟨some guardLabel, (ambient n, none),
        MachineUnaryCounter.counterTapes counter (base n) n suffix⟩
      (some ⟨some exitLabel, (ambient 0, none),
        MachineUnaryCounter.counterTapes counter
          (varyingRowBase output base rowBlock n 0) 0 suffix⟩)
      (n * (bodyBound + 1) + 1) := by
  have h := MachineCountedLoop.loopInTime counter guardLabel bodyLabel exitLabel
    program atGuard suffix ambient (fun _ => none)
    (varyingRowBase output base rowBlock n) cost n bodyBound
    (varyingVertexBodyTraces_to_counted counter output guardLabel bodyLabel program
      base suffix ambient rowBlock cost n bodies) bounded
  simpa [MachineCountedLoop.guardConfiguration, MachineCountedLoop.exitConfiguration,
    varyingRowBase] using h

theorem vertexLoop_varying_output (counter output : K) (different : output ≠ counter)
    (base : Nat → K → List Bool) (suffix : List Bool)
    (rowBlock : Nat → List Bool) (n : Nat) :
    MachineUnaryCounter.counterTapes counter
        (varyingRowBase output base rowBlock n 0) 0 suffix output =
      remainingRows rowBlock n 0 ++ base n output := by
  simp [MachineUnaryCounter.counterTapes, varyingRowBase, different]

end BinPackingGames.Foundations.Complexity.PoweringMachineLoop

namespace BinPackingGames.Foundations.Complexity.MachineLookup

open Turing

variable {K Λ σ : Type} [DecidableEq K]

private theorem discard_update_twice (source : K) (base : K → List Bool)
    (input replacement : List Bool) :
    Function.update (Function.update base source input) source replacement =
      Function.update base source replacement := by
  funext p
  by_cases hp : p = source
  · subst p; simp
  · simp [hp]

theorem discardStep_delimiter (source : K) (loopLabel returnLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atLoop : program loopLabel = discard source loopLabel returnLabel)
    (base : K → List Bool) (suffix : List Bool) (ambient : σ)
    (register : Option Bool) :
    TM2.step program
      ⟨some loopLabel, (ambient, register), Function.update base source (false :: suffix)⟩ =
      some ⟨some returnLabel, (ambient, none), Function.update base source suffix⟩ := by
  change some (TM2.stepAux (program loopLabel) (ambient, register)
    (Function.update base source (false :: suffix))) = _
  rw [atLoop]
  simp [discard, TM2.stepAux]

theorem discardStep_true (source : K) (loopLabel returnLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atLoop : program loopLabel = discard source loopLabel returnLabel)
    (base : K → List Bool) (input : List Bool) (ambient : σ)
    (register : Option Bool) :
    TM2.step program
      ⟨some loopLabel, (ambient, register), Function.update base source (true :: input)⟩ =
      some ⟨some loopLabel, (ambient, some true), Function.update base source input⟩ := by
  change some (TM2.stepAux (program loopLabel) (ambient, register)
    (Function.update base source (true :: input))) = _
  rw [atLoop]
  simp [discard, TM2.stepAux]

theorem discard_empty_step (source : K) (loopLabel returnLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atLoop : program loopLabel = discard source loopLabel returnLabel)
    (base : K → List Bool) (hinput : base source = [])
    (ambient : σ) (register : Option Bool) :
    TM2.step program ⟨some loopLabel, (ambient, register), base⟩ =
      some ⟨some returnLabel, (ambient, none), base⟩ := by
  have hupdate : Function.update base source [] = base := by
    funext p
    by_cases hp : p = source
    · subst p; simp [hinput]
    · simp [hp]
  change some (TM2.stepAux (program loopLabel) (ambient, register) base) = _
  rw [atLoop]
  simp [discard, TM2.stepAux, hinput, hupdate]

theorem discardTrace_update (source : K) (loopLabel returnLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atLoop : program loopLabel = discard source loopLabel returnLabel)
    (base : K → List Bool) (n : Nat) (suffix : List Bool)
    (ambient : σ) (register : Option Bool) :
    (MachineComposition.advance (TM2.step program))^[n + 1]
      (some ⟨some loopLabel, (ambient, register),
        Function.update base source (encodeWord n ++ suffix)⟩) =
      some ⟨some returnLabel, (ambient, none), Function.update base source suffix⟩ := by
  induction n generalizing register with
  | zero =>
    simpa only [Nat.zero_add, Function.iterate_one, MachineComposition.advance_some,
      encodeWord, List.replicate_zero, List.nil_append, List.singleton_append] using
      discardStep_delimiter source loopLabel returnLabel program atLoop
        base suffix ambient register
  | succ n ih =>
    rw [Function.iterate_succ_apply]
    simp only [encodeWord, List.replicate_succ, List.cons_append]
    change (MachineComposition.advance (TM2.step program))^[n + 1]
      (TM2.step program ⟨some loopLabel, (ambient, register),
        Function.update base source (true :: (encodeWord n ++ suffix))⟩) = _
    rw [discardStep_true source loopLabel returnLabel program atLoop, ih]

theorem discardTrace (source : K) (loopLabel returnLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atLoop : program loopLabel = discard source loopLabel returnLabel)
    (base : K → List Bool) (n : Nat) (suffix : List Bool)
    (hinput : base source = encodeWord n ++ suffix)
    (ambient : σ) (register : Option Bool) :
    (MachineComposition.advance (TM2.step program))^[n + 1]
      (some ⟨some loopLabel, (ambient, register), base⟩) =
      some ⟨some returnLabel, (ambient, none), Function.update base source suffix⟩ := by
  have hbase : Function.update base source (encodeWord n ++ suffix) = base := by
    funext p
    by_cases hp : p = source
    · subst p; simp [hinput]
    · simp [hp]
  have h := discardTrace_update source loopLabel returnLabel program atLoop
    base n suffix ambient register
  rw [hbase] at h
  exact h

def discardInTime (source : K) (loopLabel returnLabel : Λ)
    (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (σ × Option Bool))
    (atLoop : program loopLabel = discard source loopLabel returnLabel)
    (base : K → List Bool) (n : Nat) (suffix : List Bool)
    (hinput : base source = encodeWord n ++ suffix)
    (ambient : σ) (register : Option Bool) :
    StateTransition.EvalsToInTime (TM2.step program)
      ⟨some loopLabel, (ambient, register), base⟩
      (some ⟨some returnLabel, (ambient, none), Function.update base source suffix⟩)
      (n + 1) where
  steps := n + 1
  evals_in_steps := discardTrace source loopLabel returnLabel program atLoop
    base n suffix hinput ambient register
  steps_le_m := Nat.le_refl _

end BinPackingGames.Foundations.Complexity.MachineLookup

namespace BinPackingGames.Foundations.Complexity.PoweringMasterState

open Turing
open MachineFixedBlockMap

abbrev OtherRegisters (N : Nat) := Buffer N × (Bool × Option Bool)
abbrev Master (N : Nat) := OtherRegisters N × Option Bool
abbrev CompareState (N : Nat) := Buffer N × (Bool × (Option Bool × Option Bool))
abbrev RowState (N : Nat) := (Bool × (Option Bool × Option Bool)) × Buffer N

def compareEquiv (N : Nat) : Master N ≃ CompareState N :=
  (MachineUnaryEqualityBit.compareStateEquiv (Buffer N)).symm

def rowEquiv (N : Nat) : Master N ≃ RowState N where
  toFun state := ((state.1.2.1, (state.1.2.2, state.2)), state.1.1)
  invFun state := ((state.2, (state.1.1, state.1.2.1)), state.1.2.2)
  left_inv := by rintro ⟨⟨buffer, ⟨flag, left⟩⟩, right⟩; rfl
  right_inv := by rintro ⟨⟨flag, ⟨left, right⟩⟩, buffer⟩; rfl

@[simp] theorem compareEquiv_apply (N : Nat) (buffer : Buffer N)
    (flag : Bool) (left right : Option Bool) :
    compareEquiv N ((buffer, (flag, left)), right) = (buffer, (flag, (left, right))) := rfl

@[simp] theorem compareEquiv_symm_apply (N : Nat) (buffer : Buffer N)
    (flag : Bool) (left right : Option Bool) :
    (compareEquiv N).symm (buffer, (flag, (left, right))) = ((buffer, (flag, left)), right) := rfl

@[simp] theorem rowEquiv_apply (N : Nat) (buffer : Buffer N)
    (flag : Bool) (left right : Option Bool) :
    rowEquiv N ((buffer, (flag, left)), right) = ((flag, (left, right)), buffer) := rfl

@[simp] theorem rowEquiv_symm_apply (N : Nat) (buffer : Buffer N)
    (flag : Bool) (left right : Option Bool) :
    (rowEquiv N).symm ((flag, (left, right)), buffer) = ((buffer, (flag, left)), right) := rfl

def withBuffer {N : Nat} (buffer : Buffer N) : Master N :=
  ((buffer, (false, none)), none)

def clean (N : Nat) : Master N := withBuffer (emptyBuffer N)

@[simp] theorem equalityBit_clean {N : Nat} (buffer : Buffer N) :
    MachineUnaryEqualityBit.clean buffer = withBuffer buffer := rfl

@[simp] theorem rowEquiv_withBuffer {N : Nat} (buffer : Buffer N) :
    rowEquiv N (withBuffer buffer) = ((false, (none, none)), buffer) := rfl

@[simp] theorem compareEquiv_withBuffer {N : Nat} (buffer : Buffer N) :
    compareEquiv N (withBuffer buffer) = (buffer, (false, (none, none))) := rfl

def clearBuffer {N : Nat} (state : Master N) : Master N :=
  (rowEquiv N).symm ((rowEquiv N state).1, emptyBuffer N)

@[simp] theorem clearBuffer_apply {N : Nat} (buffer : Buffer N)
    (flag : Bool) (left right : Option Bool) :
    clearBuffer ((buffer, (flag, left)), right) =
      ((emptyBuffer N, (flag, left)), right) := rfl

@[simp] theorem clearBuffer_withBuffer {N : Nat} (buffer : Buffer N) :
    clearBuffer (withBuffer buffer) = clean N := rfl

section Row

variable {K Λ : Type} [DecidableEq K] {N M : Nat}

def encodedBlockAt (src dst : K) (F : Buffer N → Buffer M) (exit : Option Λ) :
    TM2.Stmt (fun _ : K => Bool) Λ (Master N) :=
  MachineStateEquiv.statement (rowEquiv N).symm
    (PoweringMachineRow.encodedBlockAt src dst F exit)

theorem stepAux_encodedBlockAt (src dst : K) (F : Buffer N → Buffer M)
    (exit : Option Λ) (hne : src ≠ dst) (bits : Buffer N) (suffix : List Bool)
    (state : Master N) (tapes : K → List Bool)
    (hinput : tapes src = PoweringMachineRow.encodeBits (List.ofFn bits) ++ suffix) :
    TM2.stepAux (encodedBlockAt src dst F exit) state tapes =
      { l := exit, var := clearBuffer state,
        stk := Function.update (Function.update tapes src suffix) dst
          (PoweringMachineRow.encodeBits (List.ofFn (F bits)) ++ tapes dst) } := by
  rw [encodedBlockAt, MachineStateEquiv.stepAux_transport_symm, Equiv.symm_symm]
  rw [PoweringMachineRow.stepAux_encodedBlockAt src dst F exit hne bits suffix
    (rowEquiv N state) tapes hinput]
  rfl

theorem step_encodedBlockAt (src dst : K) (F : Buffer N → Buffer M) (exit : Option Λ)
    (program : Λ → TM2.Stmt (fun _ : K => Bool) Λ (Master N))
    (label : Λ) (atLabel : program label = encodedBlockAt src dst F exit)
    (hne : src ≠ dst) (bits : Buffer N) (suffix : List Bool)
    (state : Master N) (tapes : K → List Bool)
    (hinput : tapes src = PoweringMachineRow.encodeBits (List.ofFn bits) ++ suffix) :
    TM2.step program ⟨some label, state, tapes⟩ =
      some ⟨exit, clearBuffer state,
        Function.update (Function.update tapes src suffix) dst
          (PoweringMachineRow.encodeBits (List.ofFn (F bits)) ++ tapes dst)⟩ := by
  simp only [TM2.step, atLabel, stepAux_encodedBlockAt src dst F exit hne bits suffix state tapes hinput]

def rowAt {t S q : Nat} (src dst : K)
    (labelAt : Fin q → Fin S → PCP.GraphTables.Label) (exit : Option Λ) :
    TM2.Stmt (fun _ : K => Bool) Λ (Master (PoweringMachineRow.inputSize t S)) :=
  encodedBlockAt src dst (PoweringMachineRow.rowBlock labelAt) exit

theorem step_rowAt_clean {t S q : Nat} (src dst : K)
    (labelAt : Fin q → Fin S → PCP.GraphTables.Label) (exit : Option Λ)
    (program : Λ → TM2.Stmt (fun _ : K => Bool) Λ
      (Master (PoweringMachineRow.inputSize t S)))
    (label : Λ) (atLabel : program label = rowAt (t := t) src dst labelAt exit)
    (hne : src ≠ dst) (bits register : Buffer (PoweringMachineRow.inputSize t S))
    (suffix : List Bool) (tapes : K → List Bool)
    (hinput : tapes src = PoweringMachineRow.encodeBits (List.ofFn bits) ++ suffix) :
    TM2.step program ⟨some label, withBuffer register, tapes⟩ =
      some ⟨exit, clean (PoweringMachineRow.inputSize t S),
        Function.update (Function.update tapes src suffix) dst
          (PoweringMachineRow.encodeBits (List.ofFn (PoweringMachineRow.rowBlock labelAt bits)) ++
            tapes dst)⟩ := by
  simpa only [rowAt, clearBuffer_withBuffer] using
    step_encodedBlockAt src dst (PoweringMachineRow.rowBlock labelAt) exit
      program label atLabel hne bits suffix (withBuffer register) tapes hinput

def rowInTime {t S q : Nat} (src dst : K)
    (labelAt : Fin q → Fin S → PCP.GraphTables.Label) (exit : Option Λ)
    (program : Λ → TM2.Stmt (fun _ : K => Bool) Λ
      (Master (PoweringMachineRow.inputSize t S)))
    (label : Λ) (atLabel : program label = rowAt (t := t) src dst labelAt exit)
    (hne : src ≠ dst) (bits register : Buffer (PoweringMachineRow.inputSize t S))
    (suffix : List Bool) (tapes : K → List Bool)
    (hinput : tapes src = PoweringMachineRow.encodeBits (List.ofFn bits) ++ suffix) :
    StateTransition.EvalsToInTime (TM2.step program)
      ⟨some label, withBuffer register, tapes⟩
      (some ⟨exit, clean (PoweringMachineRow.inputSize t S),
        Function.update (Function.update tapes src suffix) dst
          (PoweringMachineRow.encodeBits (List.ofFn (PoweringMachineRow.rowBlock labelAt bits)) ++
            tapes dst)⟩) 1 where
  steps := 1
  evals_in_steps := by
    simpa only [Function.iterate_one, flip, bind, Option.bind] using
      step_rowAt_clean src dst labelAt exit program label atLabel hne bits register suffix tapes hinput
  steps_le_m := le_rfl

end Row

def headerInTime (N B n : Nat) (suffix : List Bool) (state : Master N) :
    StateTransition.EvalsToInTime
      (TM2.step (PoweringMachineLoop.headerProgram (σ := OtherRegisters N) B))
      ⟨some .initialize, state, PoweringMachineLoop.initialTapes n suffix⟩
      (some (PoweringMachineLoop.finalConfiguration B n suffix state.1)) (n + 2) :=
  PoweringMachineLoop.headerInTime B n suffix state.1 state.2

end BinPackingGames.Foundations.Complexity.PoweringMasterState

end OAI