// UsingResolverBox — static, stateful resolver helpers（インスタンス禁止・VM互換）
// Boundary memo:
//   - entry/using_resolver_box: file I/O + using 収集、modules_list を MapBox へ積む役。
//   - pipeline_v2/using_resolver_box: modules_json 上で alias/path をテキスト検索で解決する役。
// RegexFlow の単一路ループのみで continue/backedge 分岐を持たないため、Region+next_i 化は不要と判断。
// State layout (Map): {
//   alias_paths: Map, alias_names: Map, alias_keys: Array,
//   modules_map: Map, modules_keys: Array
// }

using selfhost.shared.common.string_helpers as StringHelpers
using selfhost.shared.common.box_helpers as BoxHelpers
using lang.compiler.pipeline_v2.regex_flow as RegexFlow

static box UsingResolverBox {
  // Lightweight state as String: holds modules_json only
  // Format: modules_json (raw JSON string from nyash.toml [modules])
  state_new() { return "" }

  // Load using.aliases JSON (not used in minimal impl, kept for compatibility)
  load_usings_json(state, usings_json) { return state }

  // Load modules JSON from nyash.toml [modules] section
  // Expected format: {"module.path": "file.hako", ...}
  load_modules_json(state, mod_json) {
    if mod_json == null { return "" }
    return ("" + mod_json)
  }

  // Resolve path from alias using modules map
  // Returns the file path if alias matches a module key, null otherwise
  resolve_path_alias(state, alias) {
    if alias == null { return null }
    local s = "" + state
    if s.length() == 0 { return null }

    // Search for exact match in modules JSON
    // Format: "alias":"path"
    local search_key = "\"" + alias + "\""
    local pos = RegexFlow.find_from(s, search_key, 0)
    if pos < 0 { return null }

    // Find the colon after the key
    local colon_pos = RegexFlow.find_from(s, ":", pos)
    if colon_pos < 0 { return null }

    // Find the opening quote of the value
    local val_start = RegexFlow.find_from(s, "\"", colon_pos)
    if val_start < 0 { return null }

    // Find the closing quote of the value
    local val_end = RegexFlow.find_from(s, "\"", val_start + 1)
    if val_end < 0 { return null }

    // Extract and return the path value
    return s.substring(val_start + 1, val_end)
  }

  // Resolve namespace alias by tail matching
  // Returns the full module path if unique match found, null if ambiguous or not found
  resolve_namespace_alias(state, alias) {
    if alias == null { return null }
    local s = "" + state
    if s.length() == 0 { return null }

    // Prefer unique tail match by last segment
    local i = 0
    local start = 0
    local found = null
    loop(true) {
      local kpos = RegexFlow.find_from(s, "\"", start)
      if kpos < 0 { break }
      local kend = RegexFlow.find_from(s, "\"", kpos + 1)
      if kend < 0 { break }
      local key = s.substring(kpos + 1, kend)
      local dot = RegexFlow.last_index_of(key, ".")
      local last = key
      if dot >= 0 { last = key.substring(dot + 1, key.length()) }
      if last == alias {
        if found == null { found = key } else { return null }
      } else {
        // first-letter case-insensitive match
        if last.length() == alias.length() && last.length() > 0 {
          local l0 = last.substring(0,1)
          local a0 = alias.substring(0,1)
          local restl = last.substring(1, last.length())
          local resta = alias.substring(1, alias.length())
          if restl == resta {
            local U = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; local L = "abcdefghijklmnopqrstuvwxyz"
            local idxL = L.indexOf(l0); local idxU = U.indexOf(l0)
            if (idxL >= 0 && U.substring(idxL, idxL+1) == a0) || (idxU >= 0 && L.substring(idxU, idxU+1) == a0) {
              if found == null { found = key } else { return null }
            }
          }
        }
      }
      start = kend + 1
    }
    return found
  }

  // Resolve module path from alias (delegates to resolve_path_alias)
  resolve_module_path_from_alias(state, alias) {
    return me.resolve_path_alias(state, alias)
  }

  // Guess namespace from tail segment (delegates to resolve_namespace_alias)
  guess_namespace_from_tail(state, tail) {
    return me.resolve_namespace_alias(state, tail)
  }

  // No-op for minimal implementation
  upgrade_aliases(state) { return 0 }

  // Convert state to context JSON for ParserBox
  // Format: {"modules": {...}, "aliases": {}}
  to_context_json(state) {
    if state == null { return "{\"modules\":{},\"aliases\":{}}" }
    local s = "" + state
    if s.length() == 0 { return "{\"modules\":{},\"aliases\":{}}" }

    // Wrap modules_json in context structure
    return "{\"modules\":" + s + ",\"aliases\":{}}"
  }

  // Helper to convert map to JSON (minimal stub)
  map_to_json(m) { return "{}" }
}

static box UsingResolverBoxMain { main(args) { return 0 } }
