import type { CommitConfig, GeneratedCommitMessage } from "../types.ts";

import { BorderedLoader, type ExtensionCommandContext } from "@earendil-works/pi-coding-agent";

import { GenerationCancelledError, generateCommitMessage } from "../llm/generate-message.ts";

interface GenerationOutcome {
  ok: boolean;
  generated?: GeneratedCommitMessage;
  error?: string;
  cancelled?: boolean;
}

/** 把未知错误转换为可跨 UI 边界传递的文本。 */
function getGenerationError(error: unknown): string {
  return error instanceof Error ? error.message : String(error);
}

/**
 * 使用 Pi 原生 BorderedLoader 展示 working 状态，并阻塞等待完整 LLM 结果。
 */
export async function generateWithWorkingState(
  config: CommitConfig,
  systemPrompt: string,
  prompt: string,
  ctx: ExtensionCommandContext,
  isRegeneration: boolean,
): Promise<GeneratedCommitMessage> {
  const message = isRegeneration ? "Regenerating commit message…" : "Generating commit message…";

  if (ctx.mode !== "tui") {
    ctx.ui.notify(message, "info");
    return generateCommitMessage(config, systemPrompt, prompt, ctx);
  }

  const outcome = await ctx.ui.custom<GenerationOutcome>((tui, theme, _keybindings, done) => {
    const loader = new BorderedLoader(tui, theme, message, {
      cancellable: true,
    });

    generateCommitMessage(config, systemPrompt, prompt, ctx, loader.signal).then(
      (generated) => done({ ok: true, generated }),
      (error: unknown) =>
        done({
          ok: false,
          error: getGenerationError(error),
          cancelled: error instanceof GenerationCancelledError,
        }),
    );

    return loader;
  });

  if (!outcome) {
    throw new Error("The commit message loading view closed unexpectedly.");
  }
  if (!outcome.ok || !outcome.generated) {
    // 跨 UI 边界只能传递纯数据，这里按标记还原取消错误类型。
    if (outcome.cancelled) {
      throw new GenerationCancelledError();
    }
    throw new Error(outcome.error || "Failed to generate commit message.");
  }
  return outcome.generated;
}