// flow_entry.hako — Pipeline v2 entry box（emit-only）
// Guard: This box performs no execution. Returns MIR(JSON) as text.

using lang.compiler.pipeline_v2.pipeline as PipelineV2
using selfhost.shared.json.mir_v1_adapter as MirJsonV1Adapter

static box FlowEntryBox {
  // Emit legacy v0 JSON（call/boxcall/newbox）。最小入力: Stage‑1 JSON 文字列
  emit_v0_from_ast(ast_json, prefer_cfg) {
    return PipelineV2.lower_stage1_to_mir(ast_json, prefer_cfg)
  }
  // Emit v0 with using context（alias/module maps）
  emit_v0_from_ast_with_usings(ast_json, prefer_cfg, usings_json, modules_json) {
    return PipelineV2.lower_stage1_to_mir_with_usings(ast_json, prefer_cfg, usings_json, modules_json)
  }

  // Emit v0 with optional using / extern metadata（Stage‑B entry）
  emit_v0_from_ast_with_context(ast_json, prefer_cfg, usings_json, modules_json, externs_json) {
    // 1) Prefer lightweight v1→v0 経路（簡単な return/binop/compare/call/new はここで完結）
    {
      local j1 = PipelineV2.lower_stage1_to_mir_v1(ast_json, prefer_cfg)
      if j1 != null { return MirJsonV1Adapter.to_v0(j1) }
    }

    // 2) using 情報があれば using 解決つきの v0 経路を試す
    local used_with_usings = 0
    local out = null
    if usings_json != null && usings_json != "" && usings_json != "[]" {
      out = PipelineV2.lower_stage1_to_mir_with_usings(ast_json, prefer_cfg, usings_json, modules_json)
      if out != null { used_with_usings = 1 }
    }
    if out == null {
      out = PipelineV2.lower_stage1_to_mir(ast_json, prefer_cfg)
    }
    // 3) externs が指定され、まだ v1 経路を使っていない場合は v1+meta → v0 を試す
    if externs_json != null && externs_json != "" && externs_json != "[]" && used_with_usings == 0 {
      local j2 = PipelineV2.lower_stage1_to_mir_v1_with_meta(ast_json, prefer_cfg, externs_json)
      if j2 != null { out = MirJsonV1Adapter.to_v0(j2) }
    }
    return out
  }

  // Emit v1 → v0 互換 JSON（unified mir_call を一旦生成して適応）。自己ホスト実行向け
  emit_v1_compat_from_ast(ast_json, prefer_cfg) {
    return PipelineV2.lower_stage1_to_mir_v1_compat(ast_json, prefer_cfg)
  }

  // Emit v1 JSON with metadata.extern_c（externs を v1 の metadata に反映）
  // externs_json: JSON array text, e.g. [{"func":"Name/Arity","symbol":"c_symbol"}]
  emit_v1_from_ast_with_meta(ast_json, prefer_cfg, externs_json) {
    return PipelineV2.lower_stage1_to_mir_v1_with_meta(ast_json, prefer_cfg, externs_json)
  }

  // Emit v1 JSON + metadata.extern_c を注入し、v0互換に変換
  emit_v1_compat_from_ast_with_meta(ast_json, prefer_cfg, externs_json) {
    local j1 = PipelineV2.lower_stage1_to_mir_v1_with_meta(ast_json, prefer_cfg, externs_json)
    return MirJsonV1Adapter.to_v0(j1)
  }

  // No-op entry（箱ガード用）
  main(args) { return 0 }
}
