/-
Copyright (c) 2022 Henrik Böving. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Henrik Böving
-/
import Lean

import DocGen4.Process.Base
import DocGen4.Process.NameInfo

namespace DocGen4.Process

open Lean Meta Widget

partial def stripArgs (e : Expr) (k : Expr → MetaM α) : MetaM α :=
  match e.consumeMData with
  | Expr.forallE name type body bi =>
    let name := name.eraseMacroScopes
    Meta.withLocalDecl name bi type fun fvar => do
      stripArgs (Expr.instantiate1 body fvar) k
  | _ => k e

def valueToEq (v : DefinitionVal) : MetaM Expr := withLCtx {} {} do
  withOptions (tactic.hygienic.set . false) do
    lambdaTelescope v.value fun xs body => do
      let us := v.levelParams.map mkLevelParam
      let type ← mkEq (mkAppN (Lean.mkConst v.name us) xs) body
      let type ← mkForallFVars xs type
      return type

def processEq (eq : Name) : MetaM CodeWithInfos := do
  let type ← (mkConstWithFreshMVarLevels eq >>= inferType)
  stripArgs type prettyPrintTerm

def DefinitionInfo.ofDefinitionVal (v : DefinitionVal) : MetaM DefinitionInfo := do
  let info ← Info.ofConstantVal v.toConstantVal
  let isUnsafe := v.safety == DefinitionSafety.unsafe
  let isNonComputable := isNoncomputable (← getEnv) v.name

  try
    -- Temporary workaround until
    -- https://leanprover.zulipchat.com/#narrow/stream/270676-lean4/topic/maxRecDepth.20in.20getEqnsFor.3F/near/402917295
    -- is adddressed
    let eqs? : Option (Array Name) := none
    -- let eqs? ←  getEqnsFor? v.name

    match eqs? with
    | some eqs =>
      let equations ← eqs.mapM processEq
      return {
        toInfo := info,
        isUnsafe,
        hints := v.hints,
        equations,
        isNonComputable
      }
    | none =>
      let equations := #[← stripArgs (← valueToEq v) prettyPrintTerm]
      return {
        toInfo := info,
        isUnsafe,
        hints := v.hints,
        equations,
        isNonComputable
      }
  catch err =>
    IO.println s!"WARNING: Failed to calculate equational lemmata for {v.name}: {← err.toMessageData.toString}"
    return {
      toInfo := info,
      isUnsafe,
      hints := v.hints,
      equations := none,
      isNonComputable
    }



end DocGen4.Process