// flow_debugger.hako — Mini‑VM JSON v0 デバッグ用の軽量箱
// 責務:
//  - JSON v0 の関数/ブロック/命令を静的に走査し、
//    - ブロックID集合の抽出
//    - branch/jump の then/else/target が妥当なIDか検証
//    - op シーケンスの要約出力（最初の N 件）
// 非責務:
//  - 実行・評価（それは MirVmMin に委譲）

using selfhost.shared.common.string_helpers as StringHelpers

static box FlowDebugBox {
  // ユーティリティ — 文字列検索
  _index_of_from(hay, needle, pos) { if pos < 0 { pos = 0 } local n = hay.length() if pos > n { return -1 } local i = pos local m = needle.length() if m <= 0 { return pos } local limit = n - m loop(i <= limit) { if hay.substring(i, i+m) == needle { return i } i = i + 1 } return -1 }
  _read_digits(text, pos) { return StringHelpers.read_digits(text, pos) }
  _int_to_str(n) { return StringHelpers.int_to_str(n) }

  // ブロックID集合を抽出
  collect_block_ids(mjson) {
    local ids = new ArrayBox()
    local pos = 0
    loop(true) {
      local p = me._index_of_from(mjson, "\"id\":", pos)
      if p < 0 { break }
      local d = me._read_digits(mjson, p + 5)
      if d != "" { ids.push(d) }
      pos = p + 5
    }
    return ids
  }

  // op シーケンスを先頭から limit 件だけ抽出
  collect_ops(mjson, limit) {
    if limit == null { limit = 50 }
    local ops = new ArrayBox()
    local pos = 0
    loop(ops.length() < limit) {
      local p = me._index_of_from(mjson, "\"op\":\"", pos)
      if p < 0 { break }
      local q = me._index_of_from(mjson, "\"", p + 6)
      if q < 0 { break }
      local op = mjson.substring(p + 6, q)
      ops.push(op)
      pos = q + 1
    }
    return ops
  }

  // branch/jump の then/else/target を抽出し、集合 membership を検査
  validate_cf_targets(mjson) {
    local ids = me.collect_block_ids(mjson)
    // Set 風マップ化
    local idset = {}
    local i = 0
    loop(i < ids.length()) { idset.set(ids.get(i), 1) i = i + 1 }

    local errs = new ArrayBox()
    local pos = 0
    loop(true) {
      local p = me._index_of_from(mjson, "\"op\":\"branch\"", pos)
      if p < 0 { break }
      // then
      local pt = me._index_of_from(mjson, "\"then\":", p)
      local pe = me._index_of_from(mjson, "\"else\":", p)
      if pt >= 0 { local t = me._read_digits(mjson, pt + 7) if t != "" && idset.get(t) == null { errs.push("branch.then invalid:" + t) } }
      if pe >= 0 { local e = me._read_digits(mjson, pe + 7) if e != "" && idset.get(e) == null { errs.push("branch.else invalid:" + e) } }
      pos = p + 14
    }

    // jump
    pos = 0
    loop(true) {
      local p = me._index_of_from(mjson, "\"op\":\"jump\"", pos)
      if p < 0 { break }
      local pt = me._index_of_from(mjson, "\"target\":", p)
      if pt >= 0 { local t = me._read_digits(mjson, pt + 9) if t != "" && idset.get(t) == null { errs.push("jump.target invalid:" + t) } }
      pos = p + 12
    }

    // レポート
    if errs.length() == 0 { print("{\"kind\":\"flow_debug\",\"ok\":true,\"blocks\":" + (""+ids.length()) + "}") }
    else {
      local k = 0
      loop(k < errs.length()) { print("{\"kind\":\"flow_debug\",\"ok\":false,\"msg\":\"" + errs.get(k) + "\"}") k = k + 1 }
    }
    return errs.length()
  }

  // 要約: 先頭の op を列挙
  summarize_ops(mjson, limit) {
    local ops = me.collect_ops(mjson, limit)
    local i = 0
    loop(i < ops.length()) { print("{\"kind\":\"flow_ops\",\"op\":\"" + ops.get(i) + "\"}") i = i + 1 }
    return ops.length()
  }

  main(args) { return 0 }
}