// tools/hako_shared/json_parser.hako - JsonParserBox (Phase 171 MVP)
// .hako native JSON parser for MIR/CFG JSON parsing
// Replaces 289 lines of hand-written JSON parsing in analysis_consumer.hako

// JsonParserBox: Main parser (static box, all static methods)
static box JsonParserBox {
  // Parse JSON string to MapBox (object) or ArrayBox (array) or primitive
  // Returns: MapBox (for objects), ArrayBox (for arrays), String, Integer, null
  method parse(json_str) {
    if json_str == null { return null }

    local s = me._trim(json_str)
    if s.length() == 0 { return null }

    return me._parse_value(s, 0).get("value")
  }

  // Parse JSON string expecting object, returns MapBox or null
  method parse_object(json_str) {
    local val = me.parse(json_str)
    if val == null { return null }

    // Check if it's a MapBox (which indicates object)
    local test = val.get
    if test == null { return null }
    return val
  }

  // Parse JSON string expecting array, returns ArrayBox or null
  method parse_array(json_str) {
    local val = me.parse(json_str)
    if val == null { return null }

    // Check if it's ArrayBox (which has size method)
    local test = val.size
    if test == null { return null }
    return val
  }

  // Internal: Parse value at position, returns {value: Any, pos: Integer, type: String} or null
  _parse_value(s, pos) {
    local p = me._skip_whitespace(s, pos)
    if p >= s.length() { return null }

    local ch = s.substring(p, p+1)

    // null
    if ch == "n" {
      if me._match_literal(s, p, "null") {
        local result = new MapBox()
        result.set("value", null)
        result.set("pos", p + 4)
        result.set("type", "null")
        return result
      }
      return null
    }

    // true
    if ch == "t" {
      if me._match_literal(s, p, "true") {
        local result = new MapBox()
        result.set("value", 1)
        result.set("pos", p + 4)
        result.set("type", "bool")
        return result
      }
      return null
    }

    // false
    if ch == "f" {
      if me._match_literal(s, p, "false") {
        local result = new MapBox()
        result.set("value", 0)
        result.set("pos", p + 5)
        result.set("type", "bool")
        return result
      }
      return null
    }

    // number (integer only for MVP)
    if ch == "-" || (ch >= "0" && ch <= "9") {
      return me._parse_number(s, p)
    }

    // string
    if ch == '"' {
      return me._parse_string(s, p)
    }

    // array
    if ch == "[" {
      return me._parse_array(s, p)
    }

    // object
    if ch == "{" {
      return me._parse_object(s, p)
    }

    return null
  }

  _parse_number(s, pos) {
    local num_str = ""
    local p = pos

    // Optional negative sign
    if p < s.length() {
      local ch = s.substring(p, p+1)
      if ch == "-" {
        num_str = num_str + ch
        p = p + 1
      }
    }

    // Digits (workaround: flatten to avoid MIR nested-if-in-loop bug)
    local parsing_done = 0
    loop(p < s.length()) {
      if parsing_done == 1 { break }

      local ch = s.substring(p, p+1)
      local digits = "0123456789"
      local digit_pos = digits.indexOf(ch)

      if digit_pos >= 0 {
        num_str = num_str + ch
        p = p + 1
      } else {
        parsing_done = 1
      }
    }

    if num_str == "" || num_str == "-" { return null }

    local result = new MapBox()
    result.set("value", me._atoi(num_str))
    result.set("pos", p)
    result.set("type", "number")
    return result
  }

  _parse_string(s, pos) {
    if s.substring(pos, pos+1) != '"' { return null }

    local p = pos + 1
    local str = ""

    loop(p < s.length()) {
      local ch = s.substring(p, p+1)

      if ch == '"' {
        // End of string
        local result = new MapBox()
        result.set("value", me._unescape_string(str))
        result.set("pos", p + 1)
        result.set("type", "string")
        return result
      }

      if ch == "\\" {
        // Escape sequence (workaround: flatten to avoid MIR nested-if bug)
        local has_next = 0
        if p + 1 < s.length() { has_next = 1 }

        if has_next == 0 { return null }

        str = str + ch
        p = p + 1
        str = str + s.substring(p, p+1)
        p = p + 1
        continue
      }

      str = str + ch
      p = p + 1
    }

    return null
  }

  _parse_array(s, pos) {
    if s.substring(pos, pos+1) != "[" { return null }

    local p = pos + 1
    local arr = new ArrayBox()

    p = me._skip_whitespace(s, p)

    // Empty array
    if p < s.length() {
      if s.substring(p, p+1) == "]" {
        local result = new MapBox()
        result.set("value", arr)
        result.set("pos", p + 1)
        result.set("type", "array")
        return result
      }
    }

    // Parse elements
    loop(p < s.length()) {
      local elem_result = me._parse_value(s, p)
      if elem_result == null { return null }

      local elem = elem_result.get("value")
      arr.push(elem)

      p = elem_result.get("pos")
      p = me._skip_whitespace(s, p)

      if p >= s.length() { return null }

      local ch = s.substring(p, p+1)
      if ch == "]" {
        local result = new MapBox()
        result.set("value", arr)
        result.set("pos", p + 1)
        result.set("type", "array")
        return result
      }

      if ch == "," {
        p = p + 1
        p = me._skip_whitespace(s, p)
        continue
      }

      return null
    }

    return null
  }

  _parse_object(s, pos) {
    if s.substring(pos, pos+1) != "{" { return null }

    local p = pos + 1
    local obj = new MapBox()

    p = me._skip_whitespace(s, p)

    // Empty object
    if p < s.length() {
      if s.substring(p, p+1) == "}" {
        local result = new MapBox()
        result.set("value", obj)
        result.set("pos", p + 1)
        result.set("type", "object")
        return result
      }
    }

    // Parse key-value pairs
    loop(p < s.length()) {
      p = me._skip_whitespace(s, p)

      // Parse key (must be string)
      if s.substring(p, p+1) != '"' { return null }

      local key_result = me._parse_string(s, p)
      if key_result == null { return null }

      local key = key_result.get("value")

      p = key_result.get("pos")
      p = me._skip_whitespace(s, p)

      // Expect colon
      if p >= s.length() { return null }
      if s.substring(p, p+1) != ":" { return null }
      p = p + 1

      p = me._skip_whitespace(s, p)

      // Parse value
      local value_result = me._parse_value(s, p)
      if value_result == null { return null }

      local value = value_result.get("value")
      obj.set(key, value)

      p = value_result.get("pos")
      p = me._skip_whitespace(s, p)

      if p >= s.length() { return null }

      local ch = s.substring(p, p+1)
      if ch == "}" {
        local result = new MapBox()
        result.set("value", obj)
        result.set("pos", p + 1)
        result.set("type", "object")
        return result
      }

      if ch == "," {
        p = p + 1
        continue
      }

      return null
    }

    return null
  }

  // Helper functions
  _skip_whitespace(s, pos) {
    local p = pos
    loop(p < s.length()) {
      local ch = s.substring(p, p+1)
      if ch == " " || ch == "\t" || ch == "\n" || ch == "\r" {
        p = p + 1
      } else {
        break
      }
    }
    return p
  }

  _trim(s) {
    if s == null { return "" }

    local start = 0
    local end = s.length()

    // Trim leading whitespace
    loop(start < end) {
      local ch = s.substring(start, start+1)
      if ch == " " || ch == "\t" || ch == "\n" || ch == "\r" {
        start = start + 1
      } else {
        break
      }
    }

    // Trim trailing whitespace
    loop(end > start) {
      local ch = s.substring(end-1, end)
      if ch == " " || ch == "\t" || ch == "\n" || ch == "\r" {
        end = end - 1
      } else {
        break
      }
    }

    return s.substring(start, end)
  }

  _match_literal(s, pos, literal) {
    local len = literal.length()
    if pos + len > s.length() { return 0 }

    local i = 0
    loop(i < len) {
      if s.substring(pos + i, pos + i + 1) != literal.substring(i, i + 1) {
        return 0
      }
      i = i + 1
    }

    return 1
  }

  _unescape_string(s) {
    if s == null { return "" }

    local result = ""
    local i = 0

    loop(i < s.length()) {
      local ch = s.substring(i, i+1)

      // Workaround: flatten to avoid MIR nested-if bug
      local is_escape = 0
      local has_next = 0

      if ch == "\\" { is_escape = 1 }
      if i + 1 < s.length() { has_next = 1 }

      local process_escape = 0
      if is_escape == 1 {
        if has_next == 1 {
          process_escape = 1
        }
      }

      if process_escape == 1 {
        local next = s.substring(i+1, i+2)

        if next == "n" {
          result = result + "\n"
          i = i + 2
          continue
        }

        if next == "t" {
          result = result + "\t"
          i = i + 2
          continue
        }

        if next == "r" {
          result = result + "\r"
          i = i + 2
          continue
        }

        if next == '"' {
          result = result + '"'
          i = i + 2
          continue
        }

        if next == "\\" {
          result = result + "\\"
          i = i + 2
          continue
        }

        // Other escapes: keep as-is for MVP
        result = result + ch
        i = i + 1
        continue
      }

      result = result + ch
      i = i + 1
    }

    return result
  }

  _atoi(s) {
    if s == null { return 0 }

    local n = s.length()
    if n == 0 { return 0 }

    local i = 0
    local v = 0
    local negative = 0

    // Check for negative sign
    if s.substring(0, 1) == "-" {
      negative = 1
      i = 1
    }

    local digits = "0123456789"
    loop(i < n) {
      local ch = s.substring(i, i+1)
      if ch < "0" || ch > "9" { break }
      local pos = digits.indexOf(ch)
      if pos < 0 { break }
      v = v * 10 + pos
      i = i + 1
    }

    if negative == 1 {
      v = 0 - v
    }

    return v
  }

  // Parse Program JSON v0 (Phase 172)
  // Returns ProgramJSONBox or null
  method parse_program(json_str) {
    local obj = me.parse_object(json_str)
    if obj == null { return null }

    // Program JSON必須フィールド確認
    local version = obj.get("version")
    local kind = obj.get("kind")

    if version == null { return null }
    if kind != "Program" { return null }

    // ProgramJSONBox を返す
    return new ProgramJSONBox(obj)
  }
}

// ProgramJSONBox: Program JSON v0 wrapper (Phase 172)
// Provides type-safe access to Program JSON structure
box ProgramJSONBox {
  _obj: MapBox  // Internal: parsed JSON object

  birth(obj) {
    me._obj = obj
  }

  method get_version() {
    return me._obj.get("version")
  }

  method get_kind() {
    return me._obj.get("kind")
  }

  method get_defs() {
    // Returns ArrayBox (definitions: Box/Method/etc)
    return me._obj.get("defs")
  }

  method get_meta() {
    // Returns MapBox (metadata)
    return me._obj.get("meta")
  }

  method get_usings() {
    // Returns ArrayBox or null (using declarations)
    local meta = me.get_meta()
    if meta == null { return null }
    return meta.get("usings")
  }

  // Get all objects (for backward compatibility)
  method get_object() {
    return me._obj
  }
}

// Main entry point (required for standalone execution)
static box JsonParserMain {
  main(args) {
    return 0
  }
}