import { readFileSync, writeFileSync, existsSync } from "fs";
import { relative } from "path";
import { execSync } from "child_process";
import {
  buildDeckComponent,
  titleFromCsvPath,
  defaultMdPath,
  readDeckConfig,
  generateDeckPreviewMd,
} from "./deck-utils.js";

/**
 * 预览 Deck 的参数
 */
export interface PreviewDeckParams {
  /**
   * CSV 文件路径
   */
  csv_file: string;
  /**
   * Markdown 文件路径（可选，默认与 CSV 同名）
   */
  md_file?: string;
  /**
   * 标题（可选，默认从 CSV 文件名推断）
   */
  title?: string;
  /**
   * 描述（可选）
   */
  description?: string;
}

/**
 * 预览 Deck 的结果
 */
export interface PreviewDeckResult {
  success: boolean;
  message: string;
  md_file?: string;
  created?: boolean;
  preview_url?: string;
}

/**
 * 打开浏览器
 */
function openBrowser(url: string) {
  try {
    if (process.platform === "win32") {
      execSync(`start "" "${url}"`, { stdio: "ignore" });
    } else if (process.platform === "darwin") {
      execSync(`open "${url}"`, { stdio: "ignore" });
    } else {
      execSync(`xdg-open "${url}"`, { stdio: "ignore" });
    }
    console.error(`已打开浏览器：${url}`);
  } catch (error) {
    console.error("打开浏览器失败:", error);
  }
}

/**
 * 计算预览 URL
 */
function computePreviewUrl(mdFilePath: string): string {
  const relativeMdPath = relative(process.cwd(), mdFilePath)
    .split("\\")
    .join("/")
    .replace(/\.md$/, "");
  return `http://localhost:3000/${relativeMdPath}`;
}

/**
 * 预览 Deck - 保存 Markdown 并打开浏览器
 */
export function previewDeck(params: PreviewDeckParams): PreviewDeckResult {
  const { csv_file, md_file, title, description } = params;

  // 检查 CSV 文件是否存在
  if (!existsSync(csv_file)) {
    return {
      success: false,
      message: `CSV 文件不存在：${csv_file}`,
    };
  }

  // 确定 Markdown 文件路径
  const mdFilePath = md_file || defaultMdPath(csv_file);
  const created = !existsSync(mdFilePath);

  // 如果文件已存在，检查是否已有 md-deck 组件
  if (!created) {
    try {
      const existingContent = readFileSync(mdFilePath, "utf-8");
      if (
        existingContent.includes(`:md-deck[${csv_file}]`) ||
        existingContent.includes(`:md-deck[./${csv_file.split("/").pop()}]`)
      ) {
        const previewUrl = computePreviewUrl(mdFilePath);
        openBrowser(previewUrl);
        return {
          success: true,
          message: `预览文件 ${mdFilePath} 已存在`,
          md_file: mdFilePath,
          created: false,
          preview_url: previewUrl,
        };
      }
    } catch {
      // 读取失败，继续创建
    }
  }

  // 读取 CSV 的 frontmatter 获取配置
  const deckConfig = readDeckConfig(csv_file);

  // 确定标题
  const deckTitle = title || titleFromCsvPath(csv_file);

  // 构建 md-deck 组件代码
  const deckComponent = buildDeckComponent(
    `./${csv_file.split("/").pop()}`,
    deckConfig,
  );

  // 生成 Markdown 内容
  const mdContent = generateDeckPreviewMd(
    deckTitle,
    deckComponent,
    description,
  );

  // 写入文件
  try {
    writeFileSync(mdFilePath, mdContent, "utf-8");

    const previewUrl = computePreviewUrl(mdFilePath);
    openBrowser(previewUrl);

    return {
      success: true,
      message: created
        ? `创建预览文件 ${mdFilePath}`
        : `更新预览文件 ${mdFilePath}`,
      md_file: mdFilePath,
      created,
      preview_url: previewUrl,
    };
  } catch (error) {
    return {
      success: false,
      message: `写入失败：${error instanceof Error ? error.message : "未知错误"}`,
    };
  }
}