// DOM scrapers for old.reddit.com and www.reddit.com (new / shreddit design).

(function (global) {
  function isOldReddit() {
    if (location.hostname === "old.reddit.com") return true;
    // www.reddit.com can still serve classic markup (user preference / redirects / extensions).
    // Prefer classic scrapers whenever those nodes exist — don't rely on hostname alone.
    return Boolean(
      document.querySelector(
        ".commentarea .thing.comment, #siteTable .thing.comment, .thing.comment[data-fullname^='t1_'], body.listing-page .thing.link"
      )
    );
  }

  function isShreddit() {
    return Boolean(document.querySelector("shreddit-post, shreddit-comment, shreddit-comment-tree, shreddit-app"));
  }

  function cleanText(value) {
    return (value || "").replace(/\s+/g, " ").trim();
  }

  function absoluteUrl(href) {
    if (!href) return "";
    try {
      return new URL(href, location.origin).href;
    } catch {
      return href;
    }
  }

  function normalizeThingId(raw, kind) {
    if (!raw) return "";
    raw = String(raw);
    if (raw.startsWith("t1_") || raw.startsWith("t3_")) return raw;
    if (kind === "comment") return `t1_${raw.replace(/^t1_/, "")}`;
    if (kind === "post") return `t3_${raw.replace(/^t3_/, "")}`;
    return raw;
  }

  // querySelectorAll does not pierce shadow roots; Reddit nests comments there.
  function queryAllDeep(root, selector) {
    const results = [];
    const seen = new Set();

    function visit(node) {
      if (!node || !node.querySelectorAll) return;
      let matches;
      try {
        matches = node.querySelectorAll(selector);
      } catch {
        return;
      }
      matches.forEach((el) => {
        if (seen.has(el)) return;
        seen.add(el);
        results.push(el);
      });
      node.querySelectorAll("*").forEach((el) => {
        if (el.shadowRoot) visit(el.shadowRoot);
      });
    }

    visit(root);
    return results;
  }

  function debugDomHints() {
    const tags = new Set();
    let openShadows = 0;
    walkDom(document.documentElement, (el) => {
      const name = (el.tagName || "").toLowerCase();
      if (
        name.includes("comment") ||
        name.includes("shreddit") ||
        name.includes("faceplate") ||
        (el.id && String(el.id).includes("t1_")) ||
        (el.getAttribute && (el.getAttribute("thingid") || "").includes("t1_"))
      ) {
        tags.add(name || "(anon)");
      }
      if (el.shadowRoot) openShadows += 1;
    });
    return { tags: [...tags].sort().slice(0, 40), openShadows };
  }

  function scrapeOldPost() {
    const thing = document.querySelector("#siteTable .thing.link");
    if (!thing) return null;
    const postId = normalizeThingId(thing.getAttribute("data-fullname") || thing.id.replace(/^thing_/, ""), "post");
    const titleEl = thing.querySelector("a.title");
    const authorEl = thing.querySelector("a.author");
    const selftext = thing.querySelector(".usertext-body .md");
    const subreddit = thing.getAttribute("data-subreddit") || "";
    return {
      reddit_post_id: postId,
      title: cleanText(titleEl && titleEl.textContent),
      body: selftext ? selftext.innerText.trim() : "",
      author_id: thing.getAttribute("data-author-fullname") || "",
      author_name: cleanText((authorEl && authorEl.textContent) || thing.getAttribute("data-author") || "[deleted]"),
      permalink: absoluteUrl(thing.getAttribute("data-permalink") || (titleEl && titleEl.getAttribute("href"))),
      subreddit,
      element: thing,
    };
  }

  function scrapeOldComments(post) {
    const nodes = document.querySelectorAll(".commentarea .thing.comment");
    const comments = [];
    nodes.forEach((node) => {
      if (!node.getBoundingClientRect) return;
      const id = normalizeThingId(node.getAttribute("data-fullname") || node.id.replace(/^thing_/, ""), "comment");
      if (!id) return;
      const authorEl = node.querySelector(":scope > .entry a.author, :scope > .entry .tagline a.author");
      const bodyEl = node.querySelector(":scope > .entry .usertext-body .md, :scope > .entry .usertext-body");
      const permalinkEl = node.querySelector(':scope > .entry a[data-event-action="permalink"], :scope > .entry a.bylink');
      const shotTarget = node.querySelector(":scope > .entry") || node;
      comments.push({
        reddit_comment_id: id,
        body: bodyEl ? bodyEl.innerText.trim() : "",
        author_id: node.getAttribute("data-author-fullname") || "",
        author_name: cleanText((authorEl && authorEl.textContent) || node.getAttribute("data-author") || "[deleted]"),
        reddit_post_id: post ? post.reddit_post_id : "",
        post_title: post ? post.title : "",
        post_body: post ? post.body : "",
        post_author_id: post ? post.author_id : "",
        post_author_name: post ? post.author_name : "",
        post_permalink: post ? post.permalink : "",
        subreddit: post ? post.subreddit : (node.getAttribute("data-subreddit") || ""),
        permalink: absoluteUrl(permalinkEl && permalinkEl.getAttribute("href")),
        element: shotTarget,
      });
    });
    return comments;
  }

  function scrapeNewPost() {
    const post =
      queryAllDeep(document, "shreddit-post")[0] ||
      document.querySelector('[id^="t3_"]') ||
      document.querySelector('div[data-testid="post-container"]');
    if (!post) {
      const match = location.pathname.match(/\/comments\/([a-z0-9]+)\//i);
      if (!match) return null;
      return {
        reddit_post_id: normalizeThingId(match[1], "post"),
        title: cleanText(document.title.replace(/\s*:\s*r\/.*$/, "")),
        body: "",
        author_id: "",
        author_name: "",
        permalink: location.href.split("?")[0],
        subreddit: (location.pathname.match(/\/r\/([^/]+)/) || [])[1] || "",
        element: document.querySelector("main") || document.body,
      };
    }

    const postId =
      normalizeThingId(post.getAttribute("id") || post.getAttribute("thingid") || post.getAttribute("post-id"), "post") ||
      (() => {
        const m = location.pathname.match(/\/comments\/([a-z0-9]+)\//i);
        return m ? normalizeThingId(m[1], "post") : "";
      })();

    const title =
      post.getAttribute("post-title") ||
      cleanText((post.querySelector('h1, [slot="title"], a[slot="title"]') || {}).textContent) ||
      cleanText(document.title);

    const authorName =
      post.getAttribute("author") ||
      cleanText((post.querySelector('a[href*="/user/"], [slot="authorName"]') || {}).textContent) ||
      "";

    const bodyEl =
      post.querySelector('[slot="text-body"], .text-container, [data-testid="post-content"]') ||
      post.querySelector("p");

    const subreddit =
      post.getAttribute("subreddit-name") ||
      (location.pathname.match(/\/r\/([^/]+)/) || [])[1] ||
      "";

    const permalink =
      absoluteUrl(post.getAttribute("permalink") || post.getAttribute("content-href")) ||
      location.href.split("?")[0];

    return {
      reddit_post_id: postId,
      title,
      body: bodyEl ? bodyEl.innerText.trim() : "",
      author_id: post.getAttribute("author-id") || "",
      author_name: authorName || "[deleted]",
      permalink,
      subreddit,
      element: post,
    };
  }

  function findCommentElement(commentId) {
    const bare = String(commentId || "").replace(/^t1_/, "");
    const full = String(commentId || "").startsWith("t1_") ? String(commentId) : `t1_${bare}`;
    const want = new Set([full, `t1_${bare}`, bare, `thing_${full}`, `thing_${bare}`].filter(Boolean));

    // Classic old Reddit markup (www or old.reddit.com).
    const classic =
      document.querySelector(`.thing.comment[data-fullname="${full}"]`) ||
      document.querySelector(`.thing.comment[data-fullname="${bare}"]`) ||
      document.querySelector(`#thing_${full}`) ||
      document.querySelector(`#thing_${bare}`);
    if (classic) {
      return classic.querySelector(":scope > .entry") || classic;
    }

    const selectors = [
      `shreddit-comment[thingid="${full}"]`,
      `shreddit-comment[thingid="t1_${bare}"]`,
      `shreddit-comment[id="${full}"]`,
      `[thingid="${full}"]`,
      `[thingid="t1_${bare}"]`,
      `[comment-id="${full}"]`,
      `[data-fullname="${full}"]`,
      `[data-fullname="${bare}"]`,
      `[id="t1_${bare}"]`,
      `[id="${bare}"]`,
      `[id="thing_${full}"]`,
      `[id="thing_${bare}"]`,
    ];
    for (const selector of selectors) {
      try {
        const hit = queryAllDeep(document, selector)[0];
        if (hit) {
          if (hit.classList && hit.classList.contains("comment")) {
            return hit.querySelector(":scope > .entry") || hit;
          }
          return preferShotTarget(hit);
        }
      } catch {
        // ignore
      }
    }

    let found = null;
    walkDom(document.documentElement, (el) => {
      if (found || !el.getAttribute) return;
      const candidates = [
        el.getAttribute("thingid"),
        el.getAttribute("comment-id"),
        el.getAttribute("data-fullname"),
        el.getAttribute("id"),
        el.getAttribute("data-comment-id"),
        el.getAttribute("name"),
      ];
      for (const raw of candidates) {
        if (!raw) continue;
        const cleaned = String(raw).replace(/^thing_/, "");
        const normalized = normalizeThingId(cleaned, "comment");
        const stripped = cleaned.replace(/^t1_/, "");
        if (want.has(raw) || want.has(cleaned) || want.has(normalized) || want.has(stripped)) {
          if (el.classList && el.classList.contains("comment")) {
            found = el.querySelector(":scope > .entry") || el;
          } else {
            found = preferShotTarget(el);
          }
          return;
        }
      }
      if (el.tagName === "A") {
        const href = el.getAttribute("href") || "";
        if (href.includes(`/${bare}`) || href.includes(full) || href.includes(`t1_${bare}`)) {
          found = preferShotTarget(el);
        }
      }
    });
    return found;
  }

  function preferShotTarget(el) {
    if (!el) return null;
    // Prefer a comment-sized container over a tiny permalink icon/link.
    let best = el;
    let node = el;
    for (let depth = 0; depth < 10 && node; depth += 1) {
      const rect = node.getBoundingClientRect ? node.getBoundingClientRect() : null;
      if (rect && rect.height >= 48 && rect.width >= 120) {
        best = node;
        // Prefer shreddit-comment host when available.
        if ((node.tagName || "").toLowerCase() === "shreddit-comment") break;
      }
      node = node.parentElement;
    }
    return best;
  }

  function walkDom(root, visit) {
    const stack = [root];
    while (stack.length) {
      const node = stack.pop();
      if (!node) continue;
      visit(node);
      if (node.shadowRoot) stack.push(node.shadowRoot);
      const children = node.children;
      if (children) {
        for (let i = 0; i < children.length; i += 1) {
          stack.push(children[i]);
        }
      }
    }
  }

  function scrapeNewComments(post) {
    const selector = [
      "shreddit-comment",
      "[thingid^='t1_']",
      "[id^='t1_']",
      'div[data-testid="comment"]',
      "faceplate-tracker[noun='comment']",
    ].join(", ");
    const nodes = queryAllDeep(document, selector);
    const comments = [];
    const seen = new Set();

    nodes.forEach((node) => {
      let id =
        node.getAttribute("thingid") ||
        node.getAttribute("comment-id") ||
        node.getAttribute("id") ||
        "";
      // Some wrappers put the id on a child.
      if (!id || (!id.startsWith("t1_") && !/^t1_/.test(id))) {
        const nested = node.querySelector("[thingid^='t1_'], [id^='t1_']");
        if (nested) {
          id = nested.getAttribute("thingid") || nested.id || id;
        }
      }
      id = normalizeThingId(id, "comment");
      if (!id || !id.startsWith("t1_") || seen.has(id)) return;
      seen.add(id);

      const authorName =
        node.getAttribute("author") ||
        cleanText((node.querySelector('a[href*="/user/"]') || {}).textContent) ||
        "[deleted]";

      const bodyEl =
        node.querySelector('[slot="comment"], .md, [id$="-post-rtjson-content"], [data-testid="comment"]') ||
        node.querySelector("p");

      const permalinkAttr = node.getAttribute("permalink");
      const permalinkLink = node.querySelector('a[href*="/comments/"]');
      const permalink =
        absoluteUrl(permalinkAttr) ||
        absoluteUrl(permalinkLink && permalinkLink.getAttribute("href")) ||
        "";

      comments.push({
        reddit_comment_id: id,
        body: bodyEl ? bodyEl.innerText.trim() : cleanText(node.innerText).slice(0, 5000),
        author_id: node.getAttribute("author-id") || "",
        author_name: authorName,
        reddit_post_id: post ? post.reddit_post_id : "",
        post_title: post ? post.title : "",
        post_body: post ? post.body : "",
        post_author_id: post ? post.author_id : "",
        post_author_name: post ? post.author_name : "",
        post_permalink: post ? post.permalink : "",
        subreddit: post ? post.subreddit : "",
        permalink,
        element: node,
      });
    });
    return comments;
  }

  function walkListingComments(children, out) {
    if (!Array.isArray(children)) return;
    children.forEach((child) => {
      if (!child || child.kind !== "t1" || !child.data) return;
      const d = child.data;
      const id = normalizeThingId(d.name || d.id, "comment");
      if (!id) return;
      out.push({
        reddit_comment_id: id,
        body: d.body || "",
        author_id: d.author_fullname || "",
        author_name: d.author || "[deleted]",
        permalink: absoluteUrl(d.permalink),
        subreddit: d.subreddit || "",
      });
      if (d.replies && d.replies.data && d.replies.data.children) {
        walkListingComments(d.replies.data.children, out);
      }
    });
  }

  let jsonCache = { postId: "", at: 0, comments: [], error: "" };

  async function fetchThreadCommentsJson(post) {
    if (!post || !post.reddit_post_id) return [];
    const now = Date.now();
    if (jsonCache.postId === post.reddit_post_id && now - jsonCache.at < 15000) {
      if (jsonCache.error) throw new Error(jsonCache.error);
      return jsonCache.comments.map((c) => ({
        ...c,
        element: findCommentElement(c.reddit_comment_id),
      }));
    }
    const bare = post.reddit_post_id.replace(/^t3_/, "");
    try {
      const response = await chrome.runtime.sendMessage({
        type: "rcs.redditJson",
        path: `/comments/${bare}.json?limit=500&raw_json=1`,
      });
      if (!response || !response.ok) {
        throw new Error((response && response.error) || "reddit json failed");
      }
      const listing = response.data;
      const comments = [];
      if (Array.isArray(listing) && listing[1] && listing[1].data) {
        walkListingComments(listing[1].data.children, comments);
      }
      const mapped = comments.map((c) => ({
        ...c,
        reddit_post_id: post.reddit_post_id,
        post_title: post.title,
        post_body: post.body,
        post_author_id: post.author_id,
        post_author_name: post.author_name,
        post_permalink: post.permalink,
        subreddit: c.subreddit || post.subreddit,
      }));
      jsonCache = { postId: post.reddit_post_id, at: now, comments: mapped, error: "" };
      return mapped.map((c) => ({
        ...c,
        element: findCommentElement(c.reddit_comment_id),
      }));
    } catch (err) {
      jsonCache = {
        postId: post.reddit_post_id,
        at: now,
        comments: [],
        error: String(err && err.message ? err.message : err),
      };
      throw err;
    }
  }

  function mergeComments(domComments, jsonComments) {
    const byId = new Map();
    domComments.forEach((c) => byId.set(c.reddit_comment_id, c));
    jsonComments.forEach((c) => {
      const existing = byId.get(c.reddit_comment_id);
      if (!existing) {
        byId.set(c.reddit_comment_id, c);
        return;
      }
      // Prefer non-empty body / author from JSON when DOM is empty.
      if (!existing.body && c.body) existing.body = c.body;
      if ((!existing.author_name || existing.author_name === "[deleted]") && c.author_name) {
        existing.author_name = c.author_name;
      }
      if (!existing.permalink && c.permalink) existing.permalink = c.permalink;
      if (!existing.element && c.element) existing.element = c.element;
    });
    return [...byId.values()];
  }

  function scrapePage() {
    const classic = isOldReddit();
    const post = classic ? scrapeOldPost() : scrapeNewPost();
    const comments = classic ? scrapeOldComments(post) : scrapeNewComments(post);
    return { post, comments, isOld: classic, isShreddit: !classic && isShreddit() };
  }

  async function scrapePageAsync() {
    const base = scrapePage();
    if (base.isOld) return base;
    try {
      const jsonComments = await fetchThreadCommentsJson(base.post);
      return {
        ...base,
        comments: mergeComments(base.comments, jsonComments),
        jsonCount: jsonComments.length,
        domCount: base.comments.length,
      };
    } catch (err) {
      return {
        ...base,
        jsonError: String(err && err.message ? err.message : err),
        jsonCount: 0,
        domCount: base.comments.length,
      };
    }
  }

  function isElementMostlyVisible(el) {
    if (!el) return false;
    const rect = el.getBoundingClientRect();
    if (rect.width < 2 || rect.height < 2) return false;
    const vh = window.innerHeight || document.documentElement.clientHeight;
    return rect.bottom > 0 && rect.top < vh;
  }

  global.RCSScrape = {
    scrapePage,
    scrapePageAsync,
    isElementMostlyVisible,
    isOldReddit,
    debugDomHints,
    findCommentElement,
  };
})(typeof window !== "undefined" ? window : self);