import { JSDOM } from "jsdom";
import TurndownService from "turndown";
import { ExtractedWebpage, ImageMarker } from "../../cache/WebpageCache";
import {
  createExtractionVirtualConsole,
  normalizeWhitespace,
} from "../../extractors/htmlExtractor";

/**
 * Configures a TurndownService instance tailored for Reddit content.
 * Preserves anchor hrefs and image URLs to maintain full context for LLM readers.
 */
function createRedditTurndownService(baseUrl: string): TurndownService {
  const turndown = new TurndownService({
    headingStyle: "atx",
    codeBlockStyle: "fenced",
    bulletListMarker: "-",
    hr: "---",
  });

  // Strip script, style, iframe, svg, noscript
  turndown.remove((node) => {
    const tag = node.nodeName.toLowerCase();
    return ["script", "style", "noscript", "iframe", "svg"].includes(tag);
  });

  // Preserve links as [text](href) with absolute URLs
  turndown.addRule("preserveRedditLinks", {
    filter: "a",
    replacement: (content, node) => {
      const element = node as Element;
      const href = element.getAttribute("href")?.trim();
      const text = content.trim();

      if (!href || href.startsWith("javascript:") || href.startsWith("#")) {
        return text;
      }

      try {
        const absoluteUrl = new URL(href, baseUrl).href;
        if (!text) {
          return `<${absoluteUrl}>`;
        }
        return `[${text}](${absoluteUrl})`;
      } catch {
        return text || href;
      }
    },
  });

  // Format images as > **Image:** description (url)
  turndown.addRule("preserveRedditImages", {
    filter: "img",
    replacement: (content, node) => {
      const element = node as Element;
      const src = element.getAttribute("src")?.trim();
      const alt = element.getAttribute("alt")?.trim() || element.getAttribute("title")?.trim();

      if (!src || src.startsWith("data:")) return "";

      try {
        const absoluteSrc = new URL(src, baseUrl).href;
        const desc = alt && !["image", "icon", "photo"].includes(alt.toLowerCase()) ? alt : "Image";
        return `\n\n> **Image:** ${desc} (${absoluteSrc})\n\n`;
      } catch {
        return "";
      }
    },
  });

  // Escape reduction for direct LLM consumption
  turndown.escape = (str: string) =>
    str.replace(/\\/g, "\\\\").replace(/^(\s*)([#\-+*])/gm, "$1\\$2");

  return turndown;
}

/**
 * Extracts structured Markdown, hierarchy, and metadata from server-rendered old.reddit.com HTML.
 */
export function extractRedditContent(html: string, originalUrl: string): ExtractedWebpage {
  const rawSizeBytes = Buffer.byteLength(html || "", "utf-8");
  const dom = new JSDOM(html, {
    url: originalUrl,
    virtualConsole: createExtractionVirtualConsole(),
  });
  const doc = dom.window.document;
  const turndown = createRedditTurndownService(originalUrl);

  const imageMarkers: ImageMarker[] = [];
  let imagesFoundCount = 0;

  // 1. Extract Post Header & Metadata
  const postThing = doc.querySelector(".linklisting .thing.link, #siteTable .thing.link, .thing.link");
  let postTitle = doc.title?.replace(/\s*:?\s*r\/\w+$/i, "").trim() || "Reddit Post";
  let postAuthor: string | undefined;
  let postSubreddit: string | undefined;
  let postScore: string | undefined;
  let postDate: string | undefined;
  let postTargetUrl: string | undefined;
  let isLinkPost = false;
  let postBodyMarkdown = "";

  if (postThing) {
    const titleAnchor = postThing.querySelector("a.title");
    if (titleAnchor?.textContent?.trim()) {
      postTitle = titleAnchor.textContent.trim();
    }

    const rawHref = titleAnchor?.getAttribute("href")?.trim();
    if (rawHref) {
      try {
        postTargetUrl = new URL(rawHref, originalUrl).href;
      } catch {
        postTargetUrl = rawHref;
      }
    }

    const domainText = postThing.querySelector(".domain")?.textContent?.trim() || "";
    if (domainText && !domainText.includes("self.") && postTargetUrl && postTargetUrl !== originalUrl) {
      isLinkPost = true;
    }

    const authorEl = postThing.querySelector(".author");
    if (authorEl?.textContent?.trim()) {
      postAuthor = authorEl.textContent.trim();
    }

    const subEl = postThing.querySelector(".subreddit");
    if (subEl?.textContent?.trim()) {
      postSubreddit = subEl.textContent.trim();
    }

    const scoreEl =
      postThing.querySelector(".score.unvoted") ||
      postThing.querySelector(".score.likes") ||
      postThing.querySelector(".score.dislikes");
    postScore = scoreEl?.getAttribute("title")?.trim() || scoreEl?.textContent?.trim() || undefined;

    const timeEl = postThing.querySelector("time");
    postDate = timeEl?.getAttribute("datetime")?.trim() || timeEl?.textContent?.trim() || undefined;

    // Self post body
    const bodyEl = postThing.querySelector(".usertext-body .md");
    if (bodyEl) {
      postBodyMarkdown = normalizeWhitespace(turndown.turndown(bodyEl.innerHTML));
    }
  }

  // 2. Extract Comments Tree & Detect "More Comments" Indicators
  const commentArea = doc.querySelector(".commentarea");
  const commentLines: string[] = [];
  let extractedCommentCount = 0;
  let hasMoreComments = false;
  let moreCommentsText = "";

  function parseCommentElement(element: Element, depth: number): void {
    if (element.classList.contains("comment")) {
      extractedCommentCount++;
      const entry = element.querySelector(":scope > .entry");
      if (!entry) return;

      const authorEl = entry.querySelector(".author");
      const authorText = authorEl?.textContent?.trim() || "";
      const isDeleted = element.classList.contains("deleted") || authorText === "[deleted]";
      const isRemoved = authorText === "[removed]";

      const author = isDeleted ? "[deleted]" : isRemoved ? "[removed]" : authorText || "[anonymous]";

      const scoreEl = entry.querySelector(".score.unvoted, .score.likes, .score.dislikes");
      const score = scoreEl?.getAttribute("title")?.trim() || scoreEl?.textContent?.trim() || "";

      const timeEl = entry.querySelector("time");
      const time = timeEl?.getAttribute("datetime")?.trim() || timeEl?.textContent?.trim() || "";

      const prefix = ">".repeat(depth + 1) + " ";

      // Meta line
      const metaParts: string[] = [`**${author}**`];
      if (score) metaParts.push(score);
      if (time) metaParts.push(time);

      const permalinkEl = entry.querySelector("a.bfls, a.permalink");
      const rawPermalink = permalinkEl?.getAttribute("href");
      if (rawPermalink) {
        try {
          const absolutePermalink = new URL(rawPermalink, originalUrl).href;
          metaParts.push(`[link](${absolutePermalink})`);
        } catch {
          // Ignore URL error
        }
      }

      commentLines.push(`${prefix}${metaParts.join(" | ")}`);

      // Body line
      const bodyEl = entry.querySelector(".usertext-body .md");
      if (isDeleted) {
        commentLines.push(`${prefix}*[Comment deleted by user]*`);
      } else if (isRemoved) {
        commentLines.push(`${prefix}*[Comment removed by moderator]*`);
      } else if (bodyEl) {
        const bodyMd = normalizeWhitespace(turndown.turndown(bodyEl.innerHTML));
        if (bodyMd) {
          const bodyFormatted = bodyMd
            .split("\n")
            .map((line) => `${prefix}${line}`)
            .join("\n");
          commentLines.push(bodyFormatted);
        }
      }

      commentLines.push(`${prefix.trim()}`); // Empty spacer line with prefix

      // Process children
      const childContainer = element.querySelector(":scope > .child > .sitetable");
      if (childContainer) {
        Array.from(childContainer.children).forEach((child) => {
          parseCommentElement(child, depth + 1);
        });
      }
    } else if (
      element.classList.contains("morechildren") ||
      element.classList.contains("morerow")
    ) {
      hasMoreComments = true;
      const moreLink = element.querySelector("a");
      const label = moreLink?.textContent?.trim() || "load more comments";
      const prefix = ">".repeat(depth + 1) + " ";
      moreCommentsText = label;
      commentLines.push(`${prefix}*... ${label}*`);
    }
  }

  if (commentArea) {
    const topSiteTable = commentArea.querySelector(":scope > .sitetable, .nestedlisting");
    if (topSiteTable) {
      Array.from(topSiteTable.children).forEach((child) => {
        parseCommentElement(child, 0);
      });
    }

    // Secondary check for morechildren at commentarea root
    const rootMore = commentArea.querySelector(".morechildren, .morerow");
    if (rootMore) {
      hasMoreComments = true;
    }
  }

  // 3. Assemble Markdown Document
  const docLines: string[] = [];
  docLines.push(`# ${postTitle}`);

  const headerMeta: string[] = [];
  if (postSubreddit) headerMeta.push(`**Subreddit:** ${postSubreddit}`);
  if (postAuthor) headerMeta.push(`**Author:** ${postAuthor}`);
  if (postScore) headerMeta.push(`**Score:** ${postScore}`);
  if (postDate) headerMeta.push(`**Published:** ${postDate}`);

  if (headerMeta.length > 0) {
    docLines.push(headerMeta.join(" | "));
  }

  if (isLinkPost && postTargetUrl) {
    docLines.push(`**Link Target:** [${postTargetUrl}](${postTargetUrl})`);
  }

  if (postBodyMarkdown) {
    docLines.push("");
    docLines.push(postBodyMarkdown);
  }

  docLines.push("");
  docLines.push("---");
  docLines.push("");

  const commentHeader = `## Comments (${extractedCommentCount} extracted${
    hasMoreComments ? `, more comments available on page` : ""
  })`;
  docLines.push(commentHeader);
  docLines.push("");

  if (commentLines.length > 0) {
    docLines.push(commentLines.join("\n"));
  } else {
    docLines.push("*No comments found on this post.*");
  }

  const fullMarkdown = normalizeWhitespace(docLines.join("\n"));

  // Track images
  if (doc) {
    const imgs = doc.querySelectorAll(".linklisting img, #siteTable img, .usertext-body img");
    imagesFoundCount = imgs.length;
    imgs.forEach((img, idx) => {
      const src = img.getAttribute("src");
      if (src && !src.startsWith("data:")) {
        try {
          const absoluteSrc = new URL(src, originalUrl).href;
          imageMarkers.push({
            src: absoluteSrc,
            alt: img.getAttribute("alt") || undefined,
            insertionIndex: idx,
          });
        } catch {
          // Ignore
        }
      }
    });
  }

  return {
    url: originalUrl,
    metadata: {
      site: postSubreddit || "Reddit",
      title: postTitle,
      author: postAuthor,
      publishedDate: postDate,
      excerpt: postBodyMarkdown ? postBodyMarkdown.substring(0, 200) : undefined,
    },
    fullMarkdown,
    totalChars: fullMarkdown.length,
    rawHtmlLength: rawSizeBytes,
    readabilityLength: postBodyMarkdown.length,
    tablesDetected: fullMarkdown.includes("| --- |"),
    imageMarkers,
    imagesFoundCount,
    imagesFilteredCount: 0,
  };
}

import { JSDOM } from "jsdom";
import TurndownService from "turndown";
import { ExtractedWebpage, ImageMarker } from "../../cache/WebpageCache";
import {
  createExtractionVirtualConsole,
  normalizeWhitespace,
} from "../../extractors/htmlExtractor";

/**
 * Configures a TurndownService instance tailored for Reddit content.
 * Preserves anchor hrefs and image URLs to maintain full context for LLM readers.
 */
function createRedditTurndownService(baseUrl: string): TurndownService {
  const turndown = new TurndownService({
    headingStyle: "atx",
    codeBlockStyle: "fenced",
    bulletListMarker: "-",
    hr: "---",
  });

  // Strip script, style, iframe, svg, noscript
  turndown.remove((node) => {
    const tag = node.nodeName.toLowerCase();
    return ["script", "style", "noscript", "iframe", "svg"].includes(tag);
  });

  // Preserve links as [text](href) with absolute URLs
  turndown.addRule("preserveRedditLinks", {
    filter: "a",
    replacement: (content, node) => {
      const element = node as Element;
      const href = element.getAttribute("href")?.trim();
      const text = content.trim();

      if (!href || href.startsWith("javascript:") || href.startsWith("#")) {
        return text;
      }

      try {
        const absoluteUrl = new URL(href, baseUrl).href;
        if (!text) {
          return `<${absoluteUrl}>`;
        }
        return `[${text}](${absoluteUrl})`;
      } catch {
        return text || href;
      }
    },
  });

  // Format images as > **Image:** description (url)
  turndown.addRule("preserveRedditImages", {
    filter: "img",
    replacement: (content, node) => {
      const element = node as Element;
      const src = element.getAttribute("src")?.trim();
      const alt = element.getAttribute("alt")?.trim() || element.getAttribute("title")?.trim();

      if (!src || src.startsWith("data:")) return "";

      try {
        const absoluteSrc = new URL(src, baseUrl).href;
        const desc = alt && !["image", "icon", "photo"].includes(alt.toLowerCase()) ? alt : "Image";
        return `\n\n> **Image:** ${desc} (${absoluteSrc})\n\n`;
      } catch {
        return "";
      }
    },
  });

  // Escape reduction for direct LLM consumption
  turndown.escape = (str: string) =>
    str.replace(/\\/g, "\\\\").replace(/^(\s*)([#\-+*])/gm, "$1\\$2");

  return turndown;
}

/**
 * Extracts structured Markdown, hierarchy, and metadata from server-rendered old.reddit.com HTML.
 */
export function extractRedditContent(html: string, originalUrl: string): ExtractedWebpage {
  const rawSizeBytes = Buffer.byteLength(html || "", "utf-8");
  const dom = new JSDOM(html, {
    url: originalUrl,
    virtualConsole: createExtractionVirtualConsole(),
  });
  const doc = dom.window.document;
  const turndown = createRedditTurndownService(originalUrl);

  const imageMarkers: ImageMarker[] = [];
  let imagesFoundCount = 0;

  // 1. Extract Post Header & Metadata
  const postThing = doc.querySelector(".linklisting .thing.link, #siteTable .thing.link, .thing.link");
  let postTitle = doc.title?.replace(/\s*:?\s*r\/\w+$/i, "").trim() || "Reddit Post";
  let postAuthor: string | undefined;
  let postSubreddit: string | undefined;
  let postScore: string | undefined;
  let postDate: string | undefined;
  let postTargetUrl: string | undefined;
  let isLinkPost = false;
  let postBodyMarkdown = "";

  if (postThing) {
    const titleAnchor = postThing.querySelector("a.title");
    if (titleAnchor?.textContent?.trim()) {
      postTitle = titleAnchor.textContent.trim();
    }

    const rawHref = titleAnchor?.getAttribute("href")?.trim();
    if (rawHref) {
      try {
        postTargetUrl = new URL(rawHref, originalUrl).href;
      } catch {
        postTargetUrl = rawHref;
      }
    }

    const domainText = postThing.querySelector(".domain")?.textContent?.trim() || "";
    if (domainText && !domainText.includes("self.") && postTargetUrl && postTargetUrl !== originalUrl) {
      isLinkPost = true;
    }

    const authorEl = postThing.querySelector(".author");
    if (authorEl?.textContent?.trim()) {
      postAuthor = authorEl.textContent.trim();
    }

    const subEl = postThing.querySelector(".subreddit");
    if (subEl?.textContent?.trim()) {
      postSubreddit = subEl.textContent.trim();
    }

    const scoreEl =
      postThing.querySelector(".score.unvoted") ||
      postThing.querySelector(".score.likes") ||
      postThing.querySelector(".score.dislikes");
    postScore = scoreEl?.getAttribute("title")?.trim() || scoreEl?.textContent?.trim() || undefined;

    const timeEl = postThing.querySelector("time");
    postDate = timeEl?.getAttribute("datetime")?.trim() || timeEl?.textContent?.trim() || undefined;

    // Self post body
    const bodyEl = postThing.querySelector(".usertext-body .md");
    if (bodyEl) {
      postBodyMarkdown = normalizeWhitespace(turndown.turndown(bodyEl.innerHTML));
    }
  }

  // 2. Extract Comments Tree & Detect "More Comments" Indicators
  const commentArea = doc.querySelector(".commentarea");
  const commentLines: string[] = [];
  let extractedCommentCount = 0;
  let hasMoreComments = false;
  let moreCommentsText = "";

  function parseCommentElement(element: Element, depth: number): void {
    if (element.classList.contains("comment")) {
      extractedCommentCount++;
      const entry = element.querySelector(":scope > .entry");
      if (!entry) return;

      const authorEl = entry.querySelector(".author");
      const authorText = authorEl?.textContent?.trim() || "";
      const isDeleted = element.classList.contains("deleted") || authorText === "[deleted]";
      const isRemoved = authorText === "[removed]";

      const author = isDeleted ? "[deleted]" : isRemoved ? "[removed]" : authorText || "[anonymous]";

      const scoreEl = entry.querySelector(".score.unvoted, .score.likes, .score.dislikes");
      const score = scoreEl?.getAttribute("title")?.trim() || scoreEl?.textContent?.trim() || "";

      const timeEl = entry.querySelector("time");
      const time = timeEl?.getAttribute("datetime")?.trim() || timeEl?.textContent?.trim() || "";

      const prefix = ">".repeat(depth + 1) + " ";

      // Meta line
      const metaParts: string[] = [`**${author}**`];
      if (score) metaParts.push(score);
      if (time) metaParts.push(time);

      const permalinkEl = entry.querySelector("a.bfls, a.permalink");
      const rawPermalink = permalinkEl?.getAttribute("href");
      if (rawPermalink) {
        try {
          const absolutePermalink = new URL(rawPermalink, originalUrl).href;
          metaParts.push(`[link](${absolutePermalink})`);
        } catch {
          // Ignore URL error
        }
      }

      commentLines.push(`${prefix}${metaParts.join(" | ")}`);

      // Body line
      const bodyEl = entry.querySelector(".usertext-body .md");
      if (isDeleted) {
        commentLines.push(`${prefix}*[Comment deleted by user]*`);
      } else if (isRemoved) {
        commentLines.push(`${prefix}*[Comment removed by moderator]*`);
      } else if (bodyEl) {
        const bodyMd = normalizeWhitespace(turndown.turndown(bodyEl.innerHTML));
        if (bodyMd) {
          const bodyFormatted = bodyMd
            .split("\n")
            .map((line) => `${prefix}${line}`)
            .join("\n");
          commentLines.push(bodyFormatted);
        }
      }

      commentLines.push(`${prefix.trim()}`); // Empty spacer line with prefix

      // Process children
      const childContainer = element.querySelector(":scope > .child > .sitetable");
      if (childContainer) {
        Array.from(childContainer.children).forEach((child) => {
          parseCommentElement(child, depth + 1);
        });
      }
    } else if (
      element.classList.contains("morechildren") ||
      element.classList.contains("morerow")
    ) {
      hasMoreComments = true;
      const moreLink = element.querySelector("a");
      const label = moreLink?.textContent?.trim() || "load more comments";
      const prefix = ">".repeat(depth + 1) + " ";
      moreCommentsText = label;
      commentLines.push(`${prefix}*... ${label}*`);
    }
  }

  if (commentArea) {
    const topSiteTable = commentArea.querySelector(":scope > .sitetable, .nestedlisting");
    if (topSiteTable) {
      Array.from(topSiteTable.children).forEach((child) => {
        parseCommentElement(child, 0);
      });
    }

    // Secondary check for morechildren at commentarea root
    const rootMore = commentArea.querySelector(".morechildren, .morerow");
    if (rootMore) {
      hasMoreComments = true;
    }
  }

  // 3. Assemble Markdown Document
  const docLines: string[] = [];
  docLines.push(`# ${postTitle}`);

  const headerMeta: string[] = [];
  if (postSubreddit) headerMeta.push(`**Subreddit:** ${postSubreddit}`);
  if (postAuthor) headerMeta.push(`**Author:** ${postAuthor}`);
  if (postScore) headerMeta.push(`**Score:** ${postScore}`);
  if (postDate) headerMeta.push(`**Published:** ${postDate}`);

  if (headerMeta.length > 0) {
    docLines.push(headerMeta.join(" | "));
  }

  if (isLinkPost && postTargetUrl) {
    docLines.push(`**Link Target:** [${postTargetUrl}](${postTargetUrl})`);
  }

  if (postBodyMarkdown) {
    docLines.push("");
    docLines.push(postBodyMarkdown);
  }

  docLines.push("");
  docLines.push("---");
  docLines.push("");

  const commentHeader = `## Comments (${extractedCommentCount} extracted${
    hasMoreComments ? `, more comments available on page` : ""
  })`;
  docLines.push(commentHeader);
  docLines.push("");

  if (commentLines.length > 0) {
    docLines.push(commentLines.join("\n"));
  } else {
    docLines.push("*No comments found on this post.*");
  }

  const fullMarkdown = normalizeWhitespace(docLines.join("\n"));

  // Track images
  if (doc) {
    const imgs = doc.querySelectorAll(".linklisting img, #siteTable img, .usertext-body img");
    imagesFoundCount = imgs.length;
    imgs.forEach((img, idx) => {
      const src = img.getAttribute("src");
      if (src && !src.startsWith("data:")) {
        try {
          const absoluteSrc = new URL(src, originalUrl).href;
          imageMarkers.push({
            src: absoluteSrc,
            alt: img.getAttribute("alt") || undefined,
            insertionIndex: idx,
          });
        } catch {
          // Ignore
        }
      }
    });
  }

  return {
    url: originalUrl,
    metadata: {
      site: postSubreddit || "Reddit",
      title: postTitle,
      author: postAuthor,
      publishedDate: postDate,
      excerpt: postBodyMarkdown ? postBodyMarkdown.substring(0, 200) : undefined,
    },
    fullMarkdown,
    totalChars: fullMarkdown.length,
    rawHtmlLength: rawSizeBytes,
    readabilityLength: postBodyMarkdown.length,
    tablesDetected: fullMarkdown.includes("| --- |"),
    imageMarkers,
    imagesFoundCount,
    imagesFilteredCount: 0,
  };
}