const CONTENT_LIMIT = 2000;
const SNIPPET_LEN = 80;
const LABEL_LEN = 50;
const REF_CONTENT_LIMIT = 200;

const CLICKABLE_SELECTOR =
  "p, h1, h2, h3, h4, li, figure, figcaption, blockquote, .case-callout, .case-media, .case-media-gallery__item, .case-block, section";

const MEDIA_ANCESTOR_SELECTOR = "figure, .case-media, .case-media-gallery__item";

const IGNORE_SELECTOR =
  "header, footer, nav, .fab-stack, .content-edit-fab-stack, .content-edit-dock, button, video, input, textarea, select, a, [data-hero-rotator], [data-content-edit-ui]";

export function getMainRoot() {
  return document.querySelector("main#case-main") || document.querySelector("main#main") || document.querySelector("main");
}

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

function escapeCssIdent(value) {
  if (typeof CSS !== "undefined" && CSS.escape) return CSS.escape(value);
  return value.replace(/([!"#$%&'()*+,./:;<=>?@[\\\]^`{|}~])/g, "\\$1");
}

function segmentForElement(el) {
  if (el.id) return `#${escapeCssIdent(el.id)}`;

  const tag = el.tagName.toLowerCase();
  const parent = el.parentElement;
  if (!parent) return tag;

  const preferred = Array.from(el.classList).filter(
    (c) => c.startsWith("case-") || c.startsWith("section__") || c.startsWith("hero__")
  );
  let seg = tag;
  if (preferred.length) {
    seg += preferred.slice(0, 2).map((c) => `.${escapeCssIdent(c)}`).join("");
  }

  const sameTag = Array.from(parent.children).filter((c) => c.tagName === el.tagName);
  if (sameTag.length > 1) {
    const index = sameTag.indexOf(el) + 1;
    seg += `:nth-of-type(${index})`;
  }
  return seg;
}

export function buildSelector(el, main) {
  const segments = [];
  let current = el;

  while (current && current !== main) {
    segments.unshift(segmentForElement(current));
    current = current.parentElement;
  }

  const mainSeg = main.id ? `main#${escapeCssIdent(main.id)}` : "main";
  let selector = `${mainSeg} ${segments.join(" > ")}`;

  let matches = main.querySelectorAll(selector);
  if (matches.length === 1) return selector;

  segments.length = 0;
  current = el;
  while (current && current !== main) {
    segments.unshift(segmentForElement(current));
    current = current.parentElement;
    const trySel = `${mainSeg} ${segments.join(" > ")}`;
    matches = main.querySelectorAll(trySel);
    if (matches.length === 1) return trySel;
  }

  return selector;
}

export function getAnchorId(el, main) {
  let node = el;
  while (node && node !== main && node !== document.body) {
    if (node.id) return node.id;
    node = node.parentElement;
  }
  return main.id || "main";
}

function mediaFileName(el) {
  const img = el.tagName === "IMG" ? el : el.querySelector("img");
  if (!img) return "";
  const src = img.getAttribute("src") || img.currentSrc || "";
  const file = src.split("/").pop()?.split("?")[0] || "";
  return file;
}

function mediaLabel(el) {
  const tag = el.tagName.toLowerCase();
  const file = mediaFileName(el);
  if (file) return `Изображение: ${file}`;
  if (tag === "figure" || tag === "img" || el.classList.contains("case-media")) return "Изображение";
  if (el.classList.contains("case-media-gallery__item")) return "Элемент галереи";
  return "";
}

export function extractContent(el) {
  const tag = el.tagName.toLowerCase();

  if (tag === "figure" || tag === "img" || el.classList.contains("case-media-gallery__item")) {
    const cap = el.querySelector("figcaption");
    const img = el.tagName === "IMG" ? el : el.querySelector("img");
    const parts = [];
    if (cap) parts.push(normalizeText(cap.textContent));
    if (img?.getAttribute("alt")) parts.push(normalizeText(img.getAttribute("alt")));
    const file = mediaFileName(el);
    if (file) parts.push(file);
    const joined = parts.filter(Boolean).join(" — ");
    if (joined) return joined.slice(0, CONTENT_LIMIT);
    return mediaLabel(el).slice(0, CONTENT_LIMIT);
  }

  const text = normalizeText(el.textContent);
  if (text) return text.slice(0, CONTENT_LIMIT);

  const childText = normalizeText(
    Array.from(el.querySelectorAll("p, figcaption, h1, h2, h3, li"))
      .map((n) => n.textContent)
      .join(" ")
  );
  return childText.slice(0, CONTENT_LIMIT);
}

export function makeSnippet(content) {
  const s = normalizeText(content);
  if (s.length <= SNIPPET_LEN) return s;
  return `${s.slice(0, SNIPPET_LEN)}…`;
}

function truncateWithEllipsis(text, maxLen) {
  const s = normalizeText(text);
  if (s.length <= maxLen) return s;
  return `${s.slice(0, maxLen)}…`;
}

/** Короткая метка для вставки в instruction (~50 символов). */
export function buildShortLabel(el) {
  const tag = el.tagName.toLowerCase();

  if (tag === "figcaption") {
    return truncateWithEllipsis(el.textContent, LABEL_LEN);
  }

  const cap = el.querySelector?.("figcaption");
  if (cap && (tag === "figure" || el.classList.contains("case-media"))) {
    const capText = normalizeText(cap.textContent);
    if (capText) return truncateWithEllipsis(capText, LABEL_LEN);
  }

  if (tag === "figure" || tag === "img" || el.classList.contains("case-media-gallery__item")) {
    const file = mediaFileName(el);
    if (file) return truncateWithEllipsis(`Изображение: ${file}`, LABEL_LEN);
    const img = el.tagName === "IMG" ? el : el.querySelector("img");
    const alt = normalizeText(img?.getAttribute("alt") || "");
    if (alt) return truncateWithEllipsis(alt, LABEL_LEN);
    return truncateWithEllipsis(mediaLabel(el), LABEL_LEN);
  }

  const text = normalizeText(el.textContent);
  if (text) return truncateWithEllipsis(text, LABEL_LEN);

  return truncateWithEllipsis(mediaLabel(el) || "Блок", LABEL_LEN);
}

/** Ref для Shift+клика: короткий content (~200), не полный extractContent. */
export function buildRefTarget(el, main) {
  const fullContent = extractContent(el);
  const content = truncateWithEllipsis(fullContent, REF_CONTENT_LIMIT);
  const mediaRef = mediaFileName(el);
  const label = buildShortLabel(el);

  return {
    label,
    target: {
      selector: buildSelector(el, main),
      anchorId: getAnchorId(el, main),
      tag: el.tagName.toLowerCase(),
      content,
      snippet: makeSnippet(fullContent) || mediaLabel(el),
      mediaRef: mediaRef || undefined,
    },
  };
}

export function buildTarget(el, main) {
  const selector = buildSelector(el, main);
  const content = extractContent(el);
  const mediaRef = mediaFileName(el);
  return {
    selector,
    anchorId: getAnchorId(el, main),
    tag: el.tagName.toLowerCase(),
    content,
    snippet: makeSnippet(content) || mediaLabel(el),
    mediaRef: mediaRef || undefined,
  };
}

export function normalizeForMatch(text) {
  return normalizeText(text).toLowerCase();
}

export function findClickableTarget(event, main) {
  if (!main) return null;

  let el = event.target;
  if (!(el instanceof Element)) return null;
  if (el.closest(IGNORE_SELECTOR)) return null;
  if (!main.contains(el)) return null;

  let hit = el.closest(CLICKABLE_SELECTOR);

  if (!hit && el.closest("img")) {
    hit = el.closest(MEDIA_ANCESTOR_SELECTOR);
  }

  if (!hit || !main.contains(hit)) return null;
  if (hit.closest(IGNORE_SELECTOR)) return null;

  if (hit.matches("a") && !hit.closest(".case-article, .case-callout__content, main")) return null;

  return hit;
}

export function resolveElement(target, main) {
  if (!target?.selector) return null;
  try {
    const el = main.querySelector(target.selector);
    if (el) return el;
  } catch {
    /* invalid selector */
  }

  if (target.mediaRef) {
    const imgs = main.querySelectorAll("img");
    for (const img of imgs) {
      const file = mediaFileName(img);
      if (file && file === target.mediaRef) {
        return img.closest(MEDIA_ANCESTOR_SELECTOR) || img;
      }
    }
  }

  if (!target.content) return null;
  const needle = normalizeForMatch(target.content);
  if (!needle) return null;

  const candidates = main.querySelectorAll(CLICKABLE_SELECTOR);
  for (const el of candidates) {
    if (normalizeForMatch(extractContent(el)) === needle) return el;
    if (normalizeForMatch(extractContent(el)).includes(needle.slice(0, 40))) return el;
  }
  return null;
}

export function findItemBySelector(items, selector) {
  return items.find((item) => item.target?.selector === selector) ?? null;
}

export const PAGE_EDIT_SCOPE = "page";

export function isPageScopeItem(item) {
  if (item?.target?.scope === PAGE_EDIT_SCOPE) return true;
  const t = item?.target;
  return t?.tag === "main" && t?.snippet === "Общая правка страницы";
}

export function getItemKey(item) {
  if (!item?.target) return "";
  if (isPageScopeItem(item)) return PAGE_EDIT_SCOPE;
  return item.target.selector || "";
}

export function buildPageTarget(main) {
  const mainId = main.id || "main";
  return {
    scope: PAGE_EDIT_SCOPE,
    selector: main.id ? `main#${main.id}` : "main",
    anchorId: mainId,
    tag: "main",
    content: "Общая правка страницы",
    snippet: "Общая правка страницы",
  };
}

export function findPageEditItem(items) {
  return items.find((item) => isPageScopeItem(item)) ?? null;
}