import Mathlib
import OAI.Computability.DirectedFeedback.Machines.MachineBinaryTotalInputMachine

namespace OAI

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namespace DFVSGames.BinaryTokenMachine

open Turing
open DFVSGames.Foundations.Complexity
open MachineComposition
open DFVSGames.Reduction.MachineTransfer
open BinaryFormula BinaryEncoding

abbrev Tape := Fin 3
abbrev Alphabet (_ : Tape) := Bool
abbrev State := Unit × Option Bool

inductive Label where
  | clause
  | sign (slot : Fin 3)
  | name (slot : Fin 3)
  | restore
  | accept
  | reject
  deriving DecidableEq, Fintype

def afterName (slot : Fin 3) : Label :=
  if slot = 0 then .sign 1 else if slot = 1 then .sign 2 else .clause

@[simp] theorem afterName_zero : afterName 0 = .sign 1 := rfl
@[simp] theorem afterName_one : afterName 1 = .sign 2 := rfl
@[simp] theorem afterName_two : afterName 2 = .clause := rfl

def jump (label : Label) : TM2.Stmt Alphabet Label State :=
  .load (fun _ => ((), none)) (.goto fun _ => label)

def clauseInstruction : TM2.Stmt Alphabet Label State :=
  .pop 0 (fun state head => (state.1, head))
    (.branch (fun state => state.2.isNone)
      (jump .reject)
      (.branch (fun state => state.2.getD false)
        (jump (.sign 0)) (jump .restore)))

def signInstruction (slot : Fin 3) : TM2.Stmt Alphabet Label State :=
  .pop 0 (fun state head => (state.1, head))
    (.branch (fun state => state.2.isSome)
      (.push 1 (fun state => state.2.getD false) (jump (.name slot)))
      (jump .reject))

def nameInstruction (slot : Fin 3) : TM2.Stmt Alphabet Label State :=
  .pop 0 (fun state head => (state.1, head))
    (.branch (fun state => state.2.isNone)
      (jump .reject)
      (.branch (fun state => state.2.getD false)
        (.push 1 (fun _ => true)
          (.pop 0 (fun state head => (state.1, head))
            (.branch (fun state => state.2.isSome)
              (.push 1 (fun state => state.2.getD false) (jump (.name slot)))
              (jump .reject))))
        (.push 1 (fun _ => false) (jump (afterName slot)))))

def program : Label → TM2.Stmt Alphabet Label State
  | .clause => clauseInstruction
  | .sign slot => signInstruction slot
  | .name slot => nameInstruction slot
  | .restore => loopAt 1 2 id false .restore (some .accept)
  | .accept => .halt
  | .reject => .halt

abbrev machine : FinTM2 where
  K := Tape
  k₀ := 0
  k₁ := 2
  Γ := Alphabet
  Λ := Label
  main := .clause
  σ := State
  initialState := ((), none)
  m := program

def tapes (input reversed output : List Bool) : Tape → List Bool :=
  fun k => if k = 0 then input else if k = 1 then reversed else output

def cfg (label : Option Label) (input reversed output : List Bool)
    (register : Option Bool := none) : machine.Cfg :=
  ⟨label, ((), register), tapes input reversed output⟩

@[simp] private theorem tapes_zero (input reversed output : List Bool) :
    tapes input reversed output 0 = input := rfl

@[simp] private theorem tapes_one (input reversed output : List Bool) :
    tapes input reversed output 1 = reversed := rfl

@[simp] private theorem tapes_two (input reversed output : List Bool) :
    tapes input reversed output 2 = output := rfl

private theorem update_zero_inline_MachineBinaryTokenMachine (input reversed output replacement : List Bool) :
    Function.update (tapes input reversed output) 0 replacement =
      tapes replacement reversed output := by
  funext k
  fin_cases k <;> simp [tapes]

private theorem update_one_inline_MachineBinaryTokenMachine (input reversed output replacement : List Bool) :
    Function.update (tapes input reversed output) 1 replacement =
      tapes input replacement output := by
  funext k
  fin_cases k <;> simp [tapes]

theorem clauseStep (input reversed output : List Bool) (register : Option Bool) :
    machine.step (cfg (some .clause) (true :: input) reversed output register) =
      some (cfg (some (.sign 0)) input reversed output) := by
  change some (TM2.stepAux (program .clause) _ _) = _
  simp [program, clauseInstruction, jump, cfg, TM2.stepAux, update_zero_inline_MachineBinaryTokenMachine]
  rfl

theorem finalStep (input reversed output : List Bool) (register : Option Bool) :
    machine.step (cfg (some .clause) (false :: input) reversed output register) =
      some (cfg (some .restore) input reversed output) := by
  change some (TM2.stepAux (program .clause) _ _) = _
  simp [program, clauseInstruction, jump, cfg, TM2.stepAux, update_zero_inline_MachineBinaryTokenMachine]
  rfl

theorem signStep (slot : Fin 3) (bit : Bool) (input reversed output : List Bool)
    (register : Option Bool) :
    machine.step (cfg (some (.sign slot)) (bit :: input) reversed output register) =
      some (cfg (some (.name slot)) input (bit :: reversed) output) := by
  change some (TM2.stepAux (program (.sign slot)) _ _) = _
  simp [program, signInstruction, jump, cfg, TM2.stepAux, update_zero_inline_MachineBinaryTokenMachine, update_one_inline_MachineBinaryTokenMachine]
  rfl

theorem nameEndStep (slot : Fin 3) (input reversed output : List Bool)
    (register : Option Bool) :
    machine.step (cfg (some (.name slot)) (false :: input) reversed output register) =
      some (cfg (some (afterName slot)) input (false :: reversed) output) := by
  change some (TM2.stepAux (program (.name slot)) _ _) = _
  simp [program, nameInstruction, jump, cfg, TM2.stepAux, update_zero_inline_MachineBinaryTokenMachine, update_one_inline_MachineBinaryTokenMachine]
  rfl

theorem nameDigitStep (slot : Fin 3) (bit : Bool) (input reversed output : List Bool)
    (register : Option Bool) :
    machine.step
      (cfg (some (.name slot)) (true :: bit :: input) reversed output register) =
      some (cfg (some (.name slot)) input (bit :: true :: reversed) output) := by
  change some (TM2.stepAux (program (.name slot)) _ _) = _
  simp [program, nameInstruction, jump, cfg, TM2.stepAux, update_zero_inline_MachineBinaryTokenMachine, update_one_inline_MachineBinaryTokenMachine]
  rfl

theorem nameTrace (slot : Fin 3) (bits suffix reversed output : List Bool)
    (register : Option Bool) :
    (advance machine.step)^[bits.length + 1]
      (some (cfg (some (.name slot)) (frame bits ++ suffix) reversed output register)) =
      some (cfg (some (afterName slot)) suffix ((frame bits).reverse ++ reversed) output) := by
  induction bits generalizing reversed register with
  | nil =>
      simpa only [List.length_nil, Nat.zero_add, Function.iterate_one, advance_some,
        frame, List.singleton_append, List.reverse_singleton] using
        nameEndStep slot suffix reversed output register
  | cons bit bits ih =>
      rw [List.length_cons, Function.iterate_succ_apply]
      simp only [frame, List.cons_append, advance_some]
      rw [nameDigitStep, ih]
      simp only [List.reverse_cons, List.append_assoc,
        List.cons_append, List.nil_append]

theorem literalTrace (slot : Fin 3) (literal : Literal)
    (suffix reversed output : List Bool) (register : Option Bool) :
    (advance machine.step)^[literal.name.size + 2]
      (some (cfg (some (.sign slot)) (literalBits literal ++ suffix) reversed output register)) =
      some (cfg (some (afterName slot)) suffix
        ((literalBits literal).reverse ++ reversed) output) := by
  rw [show literal.name.size + 2 = (literal.name.bits.length + 1) + 1 by
    rw [Nat.size_eq_bits_len]]
  rw [Function.iterate_succ_apply]
  simp only [literalBits, List.cons_append, advance_some]
  rw [signStep]
  change (advance machine.step)^[literal.name.bits.length + 1]
    (some (cfg (some (.name slot)) (frame literal.name.bits ++ suffix)
      (literal.positive :: reversed) output)) = _
  rw [nameTrace]
  simp only [nameBits, List.reverse_cons, List.append_assoc, List.singleton_append]

private theorem joinTrace_inline_MachineBinaryTokenMachine {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 clauseTrace (clause : Clause) (suffix reversed output : List Bool)
    (register : Option Bool) :
    (advance machine.step)^[clauseNameSize clause + 6]
      (some (cfg (some (.sign 0)) (clauseBits clause ++ suffix) reversed output register)) =
      some (cfg (some .clause) suffix ((clauseBits clause).reverse ++ reversed) output) := by
  have first := literalTrace 0 clause[0]
    (literalBits clause[1] ++ literalBits clause[2] ++ suffix) reversed output register
  have second := literalTrace 1 clause[1] (literalBits clause[2] ++ suffix)
    ((literalBits clause[0]).reverse ++ reversed) output none
  have third := literalTrace 2 clause[2] suffix
    ((literalBits clause[1]).reverse ++ ((literalBits clause[0]).reverse ++ reversed)) output none
  simp only [afterName_zero, afterName_one, afterName_two, List.append_assoc]
    at first second third
  have full := joinTrace_inline_MachineBinaryTokenMachine (joinTrace_inline_MachineBinaryTokenMachine first second) third
  have htime : (clause[0].name.size + 2 + (clause[1].name.size + 2)) +
      (clause[2].name.size + 2) = clauseNameSize clause + 6 := by
    simp [clauseNameSize, clauseNames]
    omega
  rw [htime] at full
  simpa only [clauseBits, List.append_assoc, List.reverse_append] using full

def tokens (clauses : List Clause) : List Bool := clauses.flatMap clauseBits

@[simp] theorem tokens_nil : tokens [] = [] := rfl

@[simp] theorem tokens_cons (clause : Clause) (clauses : List Clause) :
    tokens (clause :: clauses) = clauseBits clause ++ tokens clauses := by
  simp [tokens]

@[simp] theorem tokens_length (clauses : List Clause) :
    (tokens clauses).length = 6 * clauses.length + 2 * namesBitSize clauses := by
  induction clauses with
  | nil => rfl
  | cons clause clauses ih =>
      simp only [tokens_cons, List.length_append, clauseBits_length, ih,
        List.length_cons, namesBitSize_cons]
      omega

theorem stripTrace (clauses : List Clause) (suffix reversed output : List Bool)
    (register : Option Bool) :
    (advance machine.step)^[7 * clauses.length + namesBitSize clauses + 1]
      (some (cfg (some .clause) (clausesBits clauses ++ suffix) reversed output register)) =
      some (cfg (some .restore) suffix ((tokens clauses).reverse ++ reversed) output) := by
  induction clauses generalizing reversed register with
  | nil =>
      simpa only [List.length_nil, Nat.mul_zero, namesBitSize_nil, Nat.add_zero,
        Nat.zero_add, Function.iterate_one, advance_some, clausesBits,
        List.singleton_append, tokens_nil, List.reverse_nil, List.nil_append] using
        finalStep suffix reversed output register
  | cons clause clauses ih =>
      have first : (advance machine.step)^[1]
          (some (cfg (some .clause)
            (true :: (clauseBits clause ++ (clausesBits clauses ++ suffix)))
            reversed output register)) =
          some (cfg (some (.sign 0))
            (clauseBits clause ++ (clausesBits clauses ++ suffix)) reversed output) := by
        simpa only [Function.iterate_one, advance_some] using
          clauseStep (clauseBits clause ++ (clausesBits clauses ++ suffix)) reversed output register
      have second := clauseTrace clause (clausesBits clauses ++ suffix) reversed output none
      have third := ih ((clauseBits clause).reverse ++ reversed) none
      have full := joinTrace_inline_MachineBinaryTokenMachine (joinTrace_inline_MachineBinaryTokenMachine first second) third
      have htime : (1 + (clauseNameSize clause + 6)) +
          (7 * clauses.length + namesBitSize clauses + 1) =
          7 * (clause :: clauses).length + namesBitSize (clause :: clauses) + 1 := by
        simp only [List.length_cons, namesBitSize_cons]
        omega
      rw [htime] at full
      simpa only [clausesBits, List.cons_append, List.append_assoc,
        tokens_cons, List.reverse_append] using full

theorem restoreTrace (input unread output : List Bool) (register : Option Bool) :
    (advance machine.step)^[input.length + 1]
      (some (cfg (some .restore) unread input.reverse output register)) =
      some (cfg (some .accept) unread [] (input ++ output)) := by
  have h := transferAt_fromTapes (Γ := Alphabet) (σ := Unit) 1 2 (by decide)
    id false .restore (some .accept) program rfl
    (tapes unread input.reverse output) () register
  have ht : tapesAt 1 2 (tapes unread input.reverse output) [] (input ++ output) =
      tapes unread [] (input ++ output) := by
    funext k
    fin_cases k <;> simp [tapesAt, tapes]
  change (nextAt 2 program)^[input.length + 1]
    (some (cfg (some .restore) unread input.reverse output register)) = _
  simp only [tapes_one, tapes_two, List.length_reverse, List.reverse_reverse,
    List.map_id_fun, id_eq, ht] at h
  exact h

theorem initList_eq (input : List Bool) :
    initList machine input = cfg (some .clause) input [] [] := by
  unfold initList cfg
  congr 1
  funext k
  fin_cases k <;> simp [tapes, machine]

theorem haltList_eq (output : List Bool) :
    haltList machine output = cfg none [] [] output := by
  unfold haltList cfg
  congr 1
  funext k
  fin_cases k <;> simp [tapes, machine]

theorem acceptTrace (formula : Formula) :
    (advance machine.step)^[13 * formula.clauses.length +
        3 * namesBitSize formula.clauses + 2]
      (some (initList machine (formulaBits formula))) =
      some (cfg (some .accept) [] [] (tokens formula.clauses)) := by
  have first := stripTrace formula.clauses [] [] [] none
  simp only [List.append_nil] at first
  have second := restoreTrace (tokens formula.clauses) [] [] none
  simp only [List.append_nil] at second
  have full := joinTrace_inline_MachineBinaryTokenMachine first second
  have htime : (7 * formula.clauses.length + namesBitSize formula.clauses + 1) +
      ((tokens formula.clauses).length + 1) =
      13 * formula.clauses.length + 3 * namesBitSize formula.clauses + 2 := by
    rw [tokens_length]
    omega
  rw [htime] at full
  simpa only [initList_eq, BinaryEncoding.formulaBits] using full

theorem haltStep (output : List Bool) :
    machine.step (cfg (some .accept) [] [] output) = some (cfg none [] [] output) := by
  change some (TM2.stepAux (program .accept) _ _) = _
  rfl

theorem tokenTrace (formula : Formula) :
    (advance machine.step)^[13 * formula.clauses.length +
        3 * namesBitSize formula.clauses + 3]
      (some (initList machine (formulaBits formula))) =
      some (haltList machine (tokens formula.clauses)) := by
  rw [show 13 * formula.clauses.length + 3 * namesBitSize formula.clauses + 3 =
    (13 * formula.clauses.length + 3 * namesBitSize formula.clauses + 2) + 1 by omega,
    Function.iterate_succ_apply', acceptTrace, advance_some, haltStep, haltList_eq]

theorem tokenSteps_le (formula : Formula) :
    13 * formula.clauses.length + 3 * namesBitSize formula.clauses + 3 ≤
      3 * (formulaBits formula).length + 3 := by
  rw [BinaryEncoding.formulaBits_length]
  omega

def outputsInTime (formula : Formula) :
    TM2OutputsInTime machine (formulaBits formula) (some (tokens formula.clauses))
      (3 * (formulaBits formula).length + 3) where
  steps := 13 * formula.clauses.length + 3 * namesBitSize formula.clauses + 3
  evals_in_steps := tokenTrace formula
  steps_le_m := tokenSteps_le formula

noncomputable def computableInPolyTime :
    TM2ComputableInPolyTime BinaryEncoding.formulaBits (id : List Bool → List Bool)
      (fun formula => tokens formula.clauses) where
  tm := machine
  inputAlphabet := Equiv.refl Bool
  outputAlphabet := Equiv.refl Bool
  time := Polynomial.C 3 * Polynomial.X + Polynomial.C 3
  outputsFun formula := by
    change TM2OutputsInTime machine ((formulaBits formula).map id)
      (some ((tokens formula.clauses).map id))
      ((Polynomial.C 3 * Polynomial.X + Polynomial.C 3 : Polynomial Nat).eval
        (formulaBits formula).length)
    simpa only [List.map_id_fun, id_eq, Polynomial.eval_add, Polynomial.eval_mul,
      Polynomial.eval_C, Polynomial.eval_X] using outputsInTime formula

theorem machine_finiteAlphabet (k : machine.K) : Finite (machine.Γ k) := by
  change Finite Bool
  infer_instance

end DFVSGames.BinaryTokenMachine

end

section

namespace DFVSGames.BinaryRenameWords

open BinaryFormula DFVSGames.Foundations

def clauseLiterals (c : Clause) : List Literal := [(c)[0], (c)[1], (c)[2]]

def literals (clauses : List Clause) : List Literal := clauses.flatMap clauseLiterals

def token (literal : Literal) : BinaryNameSearch.Token :=
  (literal.positive, literal.name.bits)

def tokens (clauses : List Clause) : List BinaryNameSearch.Token :=
  (literals clauses).map token

@[simp] theorem literals_nil : literals [] = [] := rfl

@[simp] theorem literals_cons (c : Clause) (cs : List Clause) :
    literals (c :: cs) = (c)[0] :: (c)[1] :: (c)[2] :: literals cs := rfl

@[simp] theorem literals_length (cs : List Clause) :
    (literals cs).length = 3 * cs.length := by
  induction cs with
  | nil => rfl
  | cons c cs ih => simp only [literals_cons, List.length_cons, ih]; omega

@[simp] theorem tokens_length (cs : List Clause) :
    (tokens cs).length = 3 * cs.length := by simp [tokens]

theorem literals_names (F : Formula) :
    (literals F.clauses).map Literal.name = sourceNames F := by
  simp only [literals, sourceNames, List.map_flatMap]
  rfl

theorem tokens_payloads (F : Formula) :
    BinaryNameSearch.payloads (tokens F.clauses) = (sourceNames F).map Nat.bits := by
  rw [← literals_names]
  simp only [BinaryNameSearch.payloads, tokens, List.map_map, token, Function.comp_def]

theorem token_bits (literal : Literal) :
    BinaryNameSearch.tokenBits (token literal) = BinaryEncoding.literalBits literal := by
  simp only [BinaryNameSearch.tokenBits, token, BinaryEncoding.literalBits,
    BinaryEncoding.nameBits, BinaryParsing.frame_eq]

theorem tokens_stream (cs : List Clause) :
    BinaryNameSearch.stream (tokens cs) = BinaryTokenMachine.tokens cs := by
  induction cs with
  | nil => rfl
  | cons c cs ih =>
      simp only [tokens, literals_cons, List.map_cons, BinaryNameSearch.stream_cons,
        token_bits, BinaryTokenMachine.tokens_cons, BinaryEncoding.clauseBits]
      simpa only [tokens, List.append_assoc] using
        congrArg (fun tail => BinaryEncoding.literalBits (c)[0] ++
          BinaryEncoding.literalBits (c)[1] ++ BinaryEncoding.literalBits (c)[2] ++ tail) ih

theorem tokens_canonical (cs : List Clause) :
    ∀ t ∈ tokens cs, BinaryNameMachine.canonical t.2 = true := by
  intro t mem
  obtain ⟨literal, _, rfl⟩ := List.mem_map.mp mem
  exact BinaryParsing.canonical_nat_bits literal.name

theorem payload_index (F : Formula) (name : Nat) :
    (BinaryNameSearch.payloads (tokens F.clauses)).idxOf name.bits =
      (sourceNames F).idxOf name := by
  rw [tokens_payloads, BinaryOccurrenceRename.idxOf_binary_payloads]

theorem token_payload_mem (cs : List Clause) (literal : Literal)
    (mem : literal ∈ literals cs) :
    literal.name.bits ∈ BinaryNameSearch.payloads (tokens cs) := by
  apply List.mem_map.mpr
  refine ⟨token literal, ?_, rfl⟩
  exact List.mem_map.mpr ⟨literal, mem, rfl⟩

theorem payloadSize_tokens (cs : List Clause) :
    BinaryNameSearch.payloadSize (tokens cs) = BinaryEncoding.namesBitSize cs := by
  induction cs with
  | nil => rfl
  | cons c cs ih =>
      simp only [tokens, literals_cons, List.map_cons,
        BinaryNameSearch.payloadSize_cons, token, Nat.size_eq_bits_len,
        BinaryEncoding.namesBitSize_cons] at *
      simpa only [BinaryEncoding.clauseNameSize, BinaryFormula.clauseNames,
        List.map_cons, List.map_nil, List.sum_cons, List.sum_nil,
        Nat.add_zero, Nat.add_assoc] using congrArg
        (fun tail => (c)[0].name.size + ((c)[1].name.size + ((c)[2].name.size + tail))) ih

def outputLiteral (names : List Nat) (literal : Literal) : List Bool :=
  Complexity.encodeWord (names.idxOf literal.name) ++
    Complexity.encodeWord (if literal.positive then 1 else 0)

def body (F : Formula) : List Bool :=
  (literals F.clauses).flatMap (outputLiteral (sourceNames F))

theorem encoded_clause (F : Formula) (c : Clause) (mem : c ∈ F.clauses) :
    Complexity.encodeWords (Complexity.clauseWords (BinaryOccurrenceRename.clause F c mem)) =
      (clauseLiterals c).flatMap (outputLiteral (sourceNames F)) := by
  simp [Complexity.clauseWords, Complexity.literalWords, Complexity.encodeWords,
    BinaryOccurrenceRename.clause, BinaryOccurrenceRename.literal,
    BinaryOccurrenceRename.nameIndex, clauseLiterals, outputLiteral, List.append_assoc]
  rfl

private theorem encodeWords_flatMap_inline_MachineBinaryRenameWords {α : Type} (xs : List α) (f : α → List Nat) :
    Complexity.encodeWords (xs.flatMap f) =
      xs.flatMap (fun x => Complexity.encodeWords (f x)) := by
  induction xs with
  | nil => rfl
  | cons x xs ih => simp only [List.flatMap_cons, Complexity.encodeWords_append, ih]

theorem encoded_body (F : Formula) :
    Complexity.encodeWords ((BinaryOccurrenceRename.renamed F).clauses.flatMap
      Complexity.clauseWords) = body F := by
  rw [encodeWords_flatMap_inline_MachineBinaryRenameWords]
  change (F.clauses.attach.map (fun c => BinaryOccurrenceRename.clause F c.val c.property)).flatMap
    (fun c => Complexity.encodeWords (Complexity.clauseWords c)) = body F
  rw [List.flatMap_map]
  simp only [encoded_clause]
  have h := congrArg (fun cs : List Clause =>
    cs.flatMap (fun c => (clauseLiterals c).flatMap (outputLiteral (sourceNames F))))
    (List.attach_map_subtype_val F.clauses)
  simpa only [List.flatMap_map, body, literals, List.flatMap_assoc] using h

theorem encoded_renamed (F : Formula) :
    Complexity.formulaBits (BinaryOccurrenceRename.renamed F) =
      Complexity.encodeWord (3 * F.clauses.length) ++
        Complexity.encodeWord F.clauses.length ++ body F := by
  simp only [Complexity.formulaBits, Complexity.formulaWords, Complexity.encodeWords_append,
    Complexity.encodeWords, List.append_nil,
    BinaryOccurrenceRename.renamed_variable_count,
    BinaryOccurrenceRename.renamed_clause_count, encoded_body, List.append_assoc]

end DFVSGames.BinaryRenameWords

end

section

namespace DFVSGames.BinaryHeaderMachine

open Turing
open DFVSGames.Foundations.Complexity
open MachineComposition
open DFVSGames.Reduction.MachineTransfer

abbrev Alphabet {K : Type} (_ : K) := Bool
abbrev State (A : Type) := A × Option Bool

section Placement

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

def delimiter (destination : K) (next : Λ) : TM2.Stmt (Alphabet (K := K)) Λ (State A) :=
  .push destination (fun _ => false)
    (.load (fun state => (state.1, none)) (.goto fun _ => next))

def tapes (variableTape clauses destination : K) (base : K → List Bool)
    (variableCounter clauseCounter output : List Bool) : K → List Bool :=
  Function.update (Function.update (Function.update base variableTape variableCounter)
    clauses clauseCounter) destination output

@[simp] theorem tapes_variables (variableTape clauses destination : K)
    (vc : variableTape ≠ clauses) (vd : variableTape ≠ destination) (base : K → List Bool)
    (variableCounter clauseCounter output : List Bool) :
    tapes variableTape clauses destination base variableCounter clauseCounter output variableTape =
      variableCounter := by
  simp [tapes, vc, vd]

@[simp] theorem tapes_clauses (variableTape clauses destination : K)
    (cd : clauses ≠ destination) (base : K → List Bool)
    (variableCounter clauseCounter output : List Bool) :
    tapes variableTape clauses destination base variableCounter clauseCounter output clauses =
      clauseCounter := by
  simp [tapes, cd]

@[simp] theorem tapes_destination (variableTape clauses destination : K) (base : K → List Bool)
    (variableCounter clauseCounter output : List Bool) :
    tapes variableTape clauses destination base variableCounter clauseCounter output destination =
      output := by
  simp [tapes]

theorem tapes_other (variableTape clauses destination k : K)
    (kv : k ≠ variableTape) (kc : k ≠ clauses) (kd : k ≠ destination)
    (base : K → List Bool) (variableCounter clauseCounter output : List Bool) :
    tapes variableTape clauses destination base variableCounter clauseCounter output k = base k := by
  simp [tapes, kv, kc, kd]

private theorem update_variables_inline_MachineBinaryHeaderMachine (variableTape clauses destination : K)
    (vc : variableTape ≠ clauses) (vd : variableTape ≠ destination) (base : K → List Bool)
    (variableCounter clauseCounter output replacement : List Bool) :
    Function.update (tapes variableTape clauses destination base variableCounter clauseCounter output)
      variableTape replacement = tapes variableTape clauses destination base replacement clauseCounter output := by
  funext k
  by_cases hv : k = variableTape
  · subst k
    simp [tapes, vc, vd]
  · by_cases hd : k = destination
    · subst k
      simp [tapes, hv]
    · by_cases hc : k = clauses
      · subst k
        simp [tapes, hv, hd]
      · simp [tapes, hv, hc, hd]

private theorem update_clauses_inline_MachineBinaryHeaderMachine (variableTape clauses destination : K)
    (cd : clauses ≠ destination) (base : K → List Bool)
    (variableCounter clauseCounter output replacement : List Bool) :
    Function.update (tapes variableTape clauses destination base variableCounter clauseCounter output)
      clauses replacement = tapes variableTape clauses destination base variableCounter replacement output := by
  funext k
  by_cases hc : k = clauses
  · subst k
    simp [tapes, cd]
  · by_cases hd : k = destination
    · subst k
      simp [tapes, hc]
    · simp [tapes, hc, hd]

private theorem update_destination_inline_MachineBinaryHeaderMachine (variableTape clauses destination : K) (base : K → List Bool)
    (variableCounter clauseCounter output replacement : List Bool) :
    Function.update (tapes variableTape clauses destination base variableCounter clauseCounter output)
      destination replacement = tapes variableTape clauses destination base variableCounter clauseCounter replacement := by
  simp [tapes]

variable (variableTape clauses destination : K)
variable (vc : variableTape ≠ clauses) (vd : variableTape ≠ destination) (cd : clauses ≠ destination)
variable (clauseStart clauseLoop variableStart variableLoop : Λ) (exit : Option Λ)
variable (program : Λ → TM2.Stmt (Alphabet (K := K)) Λ (State A))
variable (atClauseStart : program clauseStart = delimiter destination clauseLoop)
variable (atClauseLoop : program clauseLoop =
  loopAt clauses destination id false clauseLoop (some variableStart))
variable (atVariableStart : program variableStart = delimiter destination variableLoop)
variable (atVariableLoop : program variableLoop =
  loopAt variableTape destination id false variableLoop exit)
variable (base : K → List Bool) (ambient : A)

include atClauseStart in
theorem clauseDelimiterStep (variableCounter clauseCounter output : List Bool)
    (register : Option Bool) :
    TM2.step program
      ⟨some clauseStart, (ambient, register),
        tapes variableTape clauses destination base variableCounter clauseCounter output⟩ =
      some ⟨some clauseLoop, (ambient, none),
        tapes variableTape clauses destination base variableCounter clauseCounter (false :: output)⟩ := by
  change some (TM2.stepAux (program clauseStart) _ _) = _
  rw [atClauseStart]
  simp [delimiter, TM2.stepAux, update_destination_inline_MachineBinaryHeaderMachine]

include atVariableStart in
theorem variableDelimiterStep (variableCounter clauseCounter output : List Bool)
    (register : Option Bool) :
    TM2.step program
      ⟨some variableStart, (ambient, register),
        tapes variableTape clauses destination base variableCounter clauseCounter output⟩ =
      some ⟨some variableLoop, (ambient, none),
        tapes variableTape clauses destination base variableCounter clauseCounter (false :: output)⟩ := by
  change some (TM2.stepAux (program variableStart) _ _) = _
  rw [atVariableStart]
  simp [delimiter, TM2.stepAux, update_destination_inline_MachineBinaryHeaderMachine]

include cd atClauseLoop in
theorem clauseCounterTrace (m : Nat) (variableCounter output : List Bool)
    (register : Option Bool) :
    (advance (TM2.step program))^[m + 1]
      (some ⟨some clauseLoop, (ambient, register),
        tapes variableTape clauses destination base variableCounter (List.replicate m true) output⟩) =
      some ⟨some variableStart, (ambient, none),
        tapes variableTape clauses destination base variableCounter [] (List.replicate m true ++ output)⟩ := by
  have h := transferAt_fromTapes (Γ := Alphabet) clauses destination cd id false
    clauseLoop (some variableStart) program atClauseLoop
    (tapes variableTape clauses destination base variableCounter (List.replicate m true) output)
    ambient register
  change (nextAt destination program)^[m + 1]
    (some ⟨some clauseLoop, (ambient, register),
      tapes variableTape clauses destination base variableCounter (List.replicate m true) output⟩) = _
  simpa only [tapes_clauses variableTape clauses destination cd, tapes_destination,
    List.length_replicate, List.reverse_replicate, List.map_id_fun, id_eq,
    tapesAt, update_clauses_inline_MachineBinaryHeaderMachine variableTape clauses destination cd, update_destination_inline_MachineBinaryHeaderMachine,
    nextAt, advance] using h

include vc vd atVariableLoop in
theorem variableCounterTrace (n : Nat) (clauseCounter output : List Bool)
    (register : Option Bool) :
    (advance (TM2.step program))^[n + 1]
      (some ⟨some variableLoop, (ambient, register),
        tapes variableTape clauses destination base (List.replicate n true) clauseCounter output⟩) =
      some ⟨exit, (ambient, none),
        tapes variableTape clauses destination base [] clauseCounter (List.replicate n true ++ output)⟩ := by
  have h := transferAt_fromTapes (Γ := Alphabet) variableTape destination vd id false
    variableLoop exit program atVariableLoop
    (tapes variableTape clauses destination base (List.replicate n true) clauseCounter output)
    ambient register
  change (nextAt destination program)^[n + 1]
    (some ⟨some variableLoop, (ambient, register),
      tapes variableTape clauses destination base (List.replicate n true) clauseCounter output⟩) = _
  simpa only [tapes_variables variableTape clauses destination vc vd, tapes_destination,
    List.length_replicate, List.reverse_replicate, List.map_id_fun, id_eq,
    tapesAt, update_variables_inline_MachineBinaryHeaderMachine variableTape clauses destination vc vd, update_destination_inline_MachineBinaryHeaderMachine,
    nextAt, advance] using h

private theorem joinTrace_inline_MachineBinaryHeaderMachine {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]

include vc vd cd atClauseStart atClauseLoop atVariableStart atVariableLoop

theorem headerTrace (n m : Nat) (body : List Bool) (register : Option Bool) :
    (advance (TM2.step program))^[n + m + 4]
      (some ⟨some clauseStart, (ambient, register),
        tapes variableTape clauses destination base
          (List.replicate n true) (List.replicate m true) body⟩) =
      some ⟨exit, (ambient, none),
        tapes variableTape clauses destination base [] [] (encodeWord n ++ encodeWord m ++ body)⟩ := by
  have first := clauseDelimiterStep variableTape clauses destination clauseStart clauseLoop program
    atClauseStart base ambient (List.replicate n true) (List.replicate m true) body register
  change (advance (TM2.step program))^[1]
    (some ⟨some clauseStart, (ambient, register),
      tapes variableTape clauses destination base (List.replicate n true) (List.replicate m true) body⟩) = _ at first
  have second := clauseCounterTrace variableTape clauses destination cd clauseLoop variableStart program
    atClauseLoop base ambient m (List.replicate n true) (false :: body) none
  have third := variableDelimiterStep variableTape clauses destination variableStart variableLoop program
    atVariableStart base ambient (List.replicate n true) []
    (List.replicate m true ++ false :: body) none
  change (advance (TM2.step program))^[1]
    (some ⟨some variableStart, (ambient, none),
      tapes variableTape clauses destination base (List.replicate n true) []
        (List.replicate m true ++ false :: body)⟩) = _ at third
  have fourth := variableCounterTrace variableTape clauses destination vc vd variableLoop exit program
    atVariableLoop base ambient n [] (false :: (List.replicate m true ++ false :: body)) none
  have full := joinTrace_inline_MachineBinaryHeaderMachine (joinTrace_inline_MachineBinaryHeaderMachine (joinTrace_inline_MachineBinaryHeaderMachine first second) third) fourth
  have htime : ((1 + (m + 1)) + 1) + (n + 1) = n + m + 4 := by omega
  rw [htime] at full
  simpa only [encodeWord, List.append_assoc, List.singleton_append,
    List.cons_append, List.nil_append] using full

def headerInTime (n m : Nat) (body : List Bool) (register : Option Bool) :
    StateTransition.EvalsToInTime (TM2.step program)
      ⟨some clauseStart, (ambient, register),
        tapes variableTape clauses destination base (List.replicate n true) (List.replicate m true) body⟩
      (some ⟨exit, (ambient, none),
        tapes variableTape clauses destination base [] [] (encodeWord n ++ encodeWord m ++ body)⟩)
      (n + m + 4) where
  steps := n + m + 4
  evals_in_steps := headerTrace variableTape clauses destination vc vd cd
    clauseStart clauseLoop variableStart variableLoop exit program
    atClauseStart atClauseLoop atVariableStart atVariableLoop base ambient n m body register
  steps_le_m := Nat.le_refl _

end Placement

abbrev ConcreteTape := Fin 3
abbrev ConcreteLabel := Fin 4

def concreteProgram (label : ConcreteLabel) :
    TM2.Stmt (Alphabet (K := ConcreteTape)) ConcreteLabel (State Unit) :=
  if label = 0 then delimiter 2 1
  else if label = 1 then loopAt 1 2 id false 1 (some 2)
  else if label = 2 then delimiter 2 3
  else loopAt 0 2 id false 3 none

abbrev machine : FinTM2 where
  K := ConcreteTape
  k₀ := 0
  k₁ := 2
  Γ := Alphabet
  Λ := ConcreteLabel
  main := 0
  σ := State Unit
  initialState := ((), none)
  m := concreteProgram

def start (n m : Nat) (body : List Bool) : machine.Cfg :=
  ⟨some 0, ((), none),
    tapes 0 1 2 (fun _ : ConcreteTape => []) (List.replicate n true) (List.replicate m true) body⟩

theorem haltList_eq (body : List Bool) :
    haltList machine body =
      ⟨none, ((), none), tapes 0 1 2 (fun _ : ConcreteTape => []) [] [] body⟩ := by
  unfold haltList
  congr 1
  funext k
  fin_cases k <;> simp [machine, tapes]

def machineInTime (n m : Nat) (body : List Bool) :
    StateTransition.EvalsToInTime machine.step (start n m body)
      (some (haltList machine (encodeWord n ++ encodeWord m ++ body))) (n + m + 4) := by
  rw [haltList_eq]
  exact headerInTime (0 : ConcreteTape) 1 2 (by decide) (by decide) (by decide)
    (0 : ConcreteLabel) 1 2 3 none concreteProgram
    (by simp [concreteProgram]) (by simp [concreteProgram])
    (by simp [concreteProgram]) (by simp [concreteProgram])
    (fun _ => []) () n m body none

theorem machine_finiteAlphabet (k : machine.K) : Finite (machine.Γ k) := by
  change Finite Bool
  infer_instance

end DFVSGames.BinaryHeaderMachine

end

end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end
end

end OAI