// LLVM MIR Call Instruction Box — Python mir_call.py のHakorune実装
// 統一Call命令（call/boxcall/externcall/newbox/plugin_invoke/newclosure）を
// JSON形式に変換し、C++バックエンドに渡す
//
// MIR Call は 6種類の callee.type をサポート:
//   - Global: グローバル関数呼び出し (print, panic等)
//   - Method: Boxメソッド呼び出し (receiver.method())
//   - Constructor: Boxコンストラクタ (new BoxType())
//   - Extern: 外部C ABI関数呼び出し
//   - Closure: クロージャ生成 (||{...})
//   - Value: 動的関数値呼び出し (func_value())
//
// 特徴:
// - CallEmitBox の既存資産を最大活用（60%の機能を提供済み）
// - JSON 構造生成のみ（LLVM IR 生成は C++ backend が担当）
// - Unified architecture（6つの命令を1つに統合）

using "lang/src/compiler/emit/common/call_emit_box.hako" as CallEmitBox
using "lang/src/compiler/emit/common/json_emit_box.hako" as JsonEmitBox

static box LLVMMirCallInstructionBox {

  // メインエントリーポイント - Pythonのlower_mir_call()に相当
  // Stage 1: スケルトン実装（既存 CallEmitBox を活用）
  //
  // Args:
  //   callee: calleeオブジェクト（MapBox）
  //     形式: {type: "Global|Method|Constructor|Extern|Closure|Value", ...}
  //   args: 引数配列（ArrayBox of register IDs）
  //   dst: 結果レジスタID
  //   options: オプション設定（MapBox、将来拡張用）
  //
  // Returns:
  //   JSON文字列（MIR Call 命令）
  lower_mir_call(self, callee, args, dst, options) {
    if callee == null {
      return me._mir_call_error_fallback(self, "callee is null")
    }

    local callee_type = callee.get("type")
    if callee_type == null {
      return me._mir_call_error_fallback(self, "callee.type is null")
    }

    // Dispatch by callee.type
    if callee_type == "Global" {
      return me._lower_global(self, callee, args, dst)
    }
    if callee_type == "Method" {
      return me._lower_method(self, callee, args, dst)
    }
    if callee_type == "Constructor" {
      return me._lower_constructor(self, callee, args, dst)
    }
    if callee_type == "Extern" {
      return me._lower_extern(self, callee, args, dst)
    }
    if callee_type == "Closure" {
      return me._lower_closure(self, callee, args, dst)
    }
    if callee_type == "Value" {
      return me._lower_value(self, callee, args, dst)
    }

    return me._mir_call_error_fallback(self, "Unknown callee type: " + callee_type)
  }

  // Stage 2: Global function call
  // 既存の CallEmitBox.make_mir_call_global を活用
  _lower_global(self, callee, args, dst) {
    local name = callee.get("name")
    if name == null {
      return me._mir_call_error_fallback(self, "Global: name is null")
    }
    local json_obj = CallEmitBox.make_mir_call_global(name, args, dst)
    return JsonEmitBox.to_json_instruction(json_obj)
  }

  // Stage 2: Method call
  // 既存の CallEmitBox.make_mir_call_method を活用
  _lower_method(self, callee, args, dst) {
    local method = callee.get("method")
    local receiver = callee.get("receiver")
    if method == null {
      return me._mir_call_error_fallback(self, "Method: method is null")
    }
    if receiver == null {
      return me._mir_call_error_fallback(self, "Method: receiver is null")
    }
    local json_obj = CallEmitBox.make_mir_call_method(method, receiver, args, dst)
    return JsonEmitBox.to_json_instruction(json_obj)
  }

  // Stage 2: Constructor call
  // 既存の CallEmitBox.make_mir_call_constructor を活用
  _lower_constructor(self, callee, args, dst) {
    local box_type = callee.get("box_type")
    if box_type == null {
      return me._mir_call_error_fallback(self, "Constructor: box_type is null")
    }
    local json_obj = CallEmitBox.make_mir_call_constructor(box_type, args, dst)
    return JsonEmitBox.to_json_instruction(json_obj)
  }

  // Stage 3: Extern call
  // 既存の CallEmitBox.make_mir_call_extern を活用
  _lower_extern(self, callee, args, dst) {
    local name = callee.get("name")
    if name == null {
      return me._mir_call_error_fallback(self, "Extern: name is null")
    }
    local json_obj = CallEmitBox.make_mir_call_extern(name, args, dst)
    return JsonEmitBox.to_json_instruction(json_obj)
  }

  // Stage 4: Closure creation
  // TODO: CallEmitBox に make_mir_call_closure を追加する必要あり
  _lower_closure(self, callee, args, dst) {
    // Placeholder: 将来実装
    local params = callee.get("params")
    local captures = callee.get("captures")

    local json = "{"
    json = json + "\"op\":\"mir_call\""
    json = json + ",\"dst\":" + dst.toString()
    json = json + ",\"callee\":{\"type\":\"Closure\""

    // params 配列
    if params != null {
      json = json + ",\"params\":" + me._array_to_json(self, params)
    }

    // captures 配列
    if captures != null {
      json = json + ",\"captures\":" + me._array_to_json(self, captures)
    }

    json = json + "}"
    json = json + ",\"args\":" + me._array_to_json(self, args)
    json = json + "}"

    return json
  }

  // Stage 4: Value call (dynamic function value)
  // TODO: CallEmitBox に make_mir_call_value を追加する必要あり
  _lower_value(self, callee, args, dst) {
    // Placeholder: 将来実装
    local func_vid = callee.get("value")
    if func_vid == null {
      return me._mir_call_error_fallback(self, "Value: value is null")
    }

    local json = "{"
    json = json + "\"op\":\"mir_call\""
    json = json + ",\"dst\":" + dst.toString()
    json = json + ",\"callee\":{\"type\":\"Value\",\"value\":" + func_vid.toString() + "}"
    json = json + ",\"args\":" + me._array_to_json(self, args)
    json = json + "}"

    return json
  }

  // Helper: ArrayBox を JSON 配列に変換
  _array_to_json(self, arr) {
    if arr == null {
      return "[]"
    }
    local json = "["
    local size = arr.size()
    local i = 0
    loop(i < size) {
      if i > 0 {
        json = json + ","
      }
      local val = arr.get(i)
      json = json + val.toString()
      i = i + 1
    }
    json = json + "]"
    return json
  }

  // エラーフォールバック: 空の MIR Call を返す
  _mir_call_error_fallback(self, error_msg) {
    print("[ERROR] LLVMMirCallInstructionBox: " + error_msg)
    return "{\"op\":\"mir_call\",\"dst\":0,\"callee\":{\"type\":\"Global\",\"name\":\"__error__\"},\"args\":[]}"
  }

  // デバッグ用: MIR Call 命令の構造を出力
  debug_mir_call(self, callee, args, dst, options) {
    local json = me.lower_mir_call(self, callee, args, dst, options)
    print("Generated mir_call instruction: " + json)
    return json
  }
}