"use strict";

/**
 * 从混杂文本中提取抖音分享内容（链接、文案、话题）。
 * 自 zhenqianba DouyinContentParser 移植，CommonJS 导出供 require。
 */

const DIRECT_VIDEO_PATTERN =
  /https?:\/\/[^\s"'<>]+?\.(mp4|mov|m4v|webm|avi|mkv)(\?[^\s"'<>]*)?/i;

class DouyinContentParser {
  /**
   * @param {string} input
   * @returns {{ success: true, content: object } | { success: false, error: string }}
   */
  static parseContent(input) {
    try {
      const raw = String(input || "").trim();
      if (!raw) {
        return { success: false, error: "输入内容为空" };
      }
      const videoUrl = this.extractVideoUrl(raw);
      if (!videoUrl) {
        return { success: false, error: "未找到有效的抖音视频链接" };
      }
      const description = this.extractDescription(raw, videoUrl);
      const hashtags = this.extractHashtags(raw);
      return {
        success: true,
        content: {
          videoUrl,
          description,
          hashtags,
          rawText: raw,
        },
      };
    } catch (error) {
      return {
        success: false,
        error: `解析失败: ${error instanceof Error ? error.message : String(error)}`,
      };
    }
  }

  static extractVideoUrl(text) {
    const directVideoMatch = text.match(DIRECT_VIDEO_PATTERN);
    if (directVideoMatch && directVideoMatch[0]) {
      return directVideoMatch[0];
    }
    const patterns = [
      /https:\/\/v\.douyin\.com\/[\w_\-@]+\/?/i,
      /https:\/\/(?:www\.)?douyin\.com\/(?:video|modal)\/\d+/i,
      /https:\/\/iesdouyin\.com\/(?:share\/video|video)\/\d+/i,
      /v\.douyin\.com\/[\w_\-@]+/i,
      /douyin\.com\/(?:video|modal)\/\d+/i,
    ];
    for (const pattern of patterns) {
      const match = text.match(pattern);
      if (match) {
        let url = match[0];
        if (!url.startsWith("http")) {
          url = "https://" + url;
        }
        return url;
      }
    }
    return null;
  }

  static isDirectVideoUrl(url) {
    return DIRECT_VIDEO_PATTERN.test(String(url || "").trim());
  }

  static extractDescription(text, videoUrl) {
    const urlIndex = text.indexOf(videoUrl);
    let descriptionText = "";
    if (urlIndex > 0) {
      descriptionText = text.substring(0, urlIndex).trim();
    } else {
      const descriptionMatch = text.match(/^([^h]*?)(?:https?:\/\/|$)/);
      if (descriptionMatch && descriptionMatch[1]) {
        descriptionText = descriptionMatch[1].trim();
      }
    }
    return this.cleanDescription(descriptionText);
  }

  static cleanDescription(text) {
    if (!text) return "";
    let cleaned = text.replace(/^[\d\s./]+/, "").trim();
    const startMatch = cleaned.match(/^[^\u4e00-\u9fff\w\s]*(.*)$/);
    if (startMatch && startMatch[1]) {
      const potential = startMatch[1].trim();
      if (potential.length > 0) {
        cleaned = potential;
      }
    }
    if (/^[\W_]+$/.test(cleaned)) {
      return "";
    }
    return cleaned;
  }

  static extractHashtags(text) {
    const hashtagPattern = /#[\w\u4e00-\u9fff_]+/g;
    const matches = text.match(hashtagPattern);
    if (!matches) return [];
    return Array.from(new Set(matches));
  }

  static extractVideoId(videoUrl) {
    const shortMatch = videoUrl.match(/v\.douyin\.com\/([\w_\-@]+)/i);
    if (shortMatch) return shortMatch[1];
    const standardMatch = videoUrl.match(/\/(?:video|modal)\/(\d+)/i);
    if (standardMatch) return standardMatch[1];
    return null;
  }

  static generateTitleFromDescription(description, maxLength = 30) {
    if (!description) {
      return "分享精彩内容";
    }
    const sentenceEnd = description.match(/[。！？\n]/);
    let title = "";
    if (sentenceEnd) {
      title = description.substring(0, sentenceEnd.index).trim();
    } else {
      title = description;
    }
    if (title.length > maxLength) {
      title = title.substring(0, maxLength) + "...";
    }
    return title || "精彩分享";
  }

  static quickExtractUrl(text) {
    const r = this.parseContent(text);
    return r.success && r.content ? r.content.videoUrl : null;
  }

  static quickExtractDescription(text) {
    const r = this.parseContent(text);
    return r.success && r.content ? r.content.description : null;
  }
}

module.exports = { DouyinContentParser, DIRECT_VIDEO_PATTERN };