/*
 * Copyright (C) 2026 Mateusz Gruszczynski @linuxiarz.pl
 * Source-Available Code / Dual-Licensed.
 *
 * Free for non-commercial and evaluation use under terms of BSL/GPLv3.
 * Commercial or production use requires a valid paid license.
 * See LICENSE file in repository root for details.
 */

import { t } from "@rustpad/i18n";
import { toast } from "@rustpad/toast";
import { loadHighlight } from "@rustpad/vendor-libs";

const STORAGE_PREFIX = "rustpad:pdf-export:";

const PAGE_FORMATS = Object.freeze({
  "a4-portrait": { cssSize: "A4 portrait", widthMm: 210, heightMm: 297 },
  "a4-landscape": { cssSize: "A4 landscape", widthMm: 297, heightMm: 210 },
  "a3-portrait": { cssSize: "A3 portrait", widthMm: 297, heightMm: 420 },
  "a3-landscape": { cssSize: "A3 landscape", widthMm: 420, heightMm: 297 },
  "a5-portrait": { cssSize: "A5 portrait", widthMm: 148, heightMm: 210 },
  "letter-portrait": { cssSize: "letter portrait", widthMm: 215.9, heightMm: 279.4 },
  "letter-landscape": { cssSize: "letter landscape", widthMm: 279.4, heightMm: 215.9 },
  "screen-16-9": { cssSize: "338.667mm 190.5mm", widthMm: 338.667, heightMm: 190.5 },
  "screen-4-3": { cssSize: "254mm 190.5mm", widthMm: 254, heightMm: 190.5 },
});

function escapeHtml(value) {
  return String(value ?? "")
    .replaceAll("&", "&")
    .replaceAll("<", "&lt;")
    .replaceAll(">", "&gt;")
    .replaceAll('"', "&quot;")
    .replaceAll("'", "&#39;");
}

function saved(key, fallback) {
  try { return localStorage.getItem(`${STORAGE_PREFIX}${key}`) || fallback; } catch { return fallback; }
}

function save(key, value) {
  try { localStorage.setItem(`${STORAGE_PREFIX}${key}`, String(value)); } catch { /* optional preference */ }
}

function stylesheetLinks() {
  return [...document.querySelectorAll('link[rel="stylesheet"][href]')]
    .map(link => `<link rel="stylesheet" href="${escapeHtml(link.href)}">`)
    .join("");
}

async function ensureSyntaxHighlight(root) {
  const nodes = [...root.querySelectorAll('pre code[class*="language-"]:not(.language-mermaid)')];
  if (!nodes.length) return;

  let hljs;
  try { hljs = await loadHighlight(); } catch { return; }

  const highlightText = (text, language) => {
    try {
      return language
        ? hljs.highlight(text, { language, ignoreIllegals: true }).value
        : hljs.highlightAuto(text).value;
    } catch {
      return hljs.highlightAuto(text).value;
    }
  };

  nodes.forEach(node => {
    const language = [...node.classList].find(name => name.startsWith("language-"))?.slice(9);
    const lines = [...node.querySelectorAll(".code-line")];

    if (lines.length) {
      lines.forEach(line => {
        if (line.querySelector('[class*="hljs-"]')) return;
        line.innerHTML = highlightText(line.textContent || "", language);
      });
      node.classList.add("hljs");
      return;
    }

    if (!node.querySelector('[class*="hljs-"]')) {
      node.innerHTML = highlightText(node.textContent || "", language);
    }
    node.classList.add("hljs");
  });
}

function mmToPx(doc) {
  const probe = doc.createElement("div");
  probe.style.cssText = "position:absolute;visibility:hidden;pointer-events:none;width:100mm;height:100mm;";
  doc.body.appendChild(probe);
  const pxPerMm = probe.getBoundingClientRect().height / 100;
  probe.remove();
  return pxPerMm;
}

function alignFooterToLastPage(doc, pageHeightMm, marginMm) {
  const documentRoot = doc.querySelector(".pdf-document");
  const spacer = doc.querySelector(".pdf-footer-spacer");
  const footer = doc.querySelector(".pdf-generated-footer");
  if (!documentRoot || !spacer || !footer) return;

  spacer.style.height = "0px";

  const pxPerMm = mmToPx(doc);
  const pageContentHeight = (Number(pageHeightMm) - (2 * Number(marginMm))) * pxPerMm;
  const footerHeight = footer.getBoundingClientRect().height;
  if (!Number.isFinite(pageContentHeight) || pageContentHeight <= footerHeight || footerHeight <= 0) return;

  const rootTop = documentRoot.getBoundingClientRect().top;
  const footerTop = footer.getBoundingClientRect().top - rootTop;
  const pageBreaks = documentRoot.querySelectorAll(".pdf-page-break");
  const lastPageBreak = pageBreaks.length ? pageBreaks[pageBreaks.length - 1] : null;
  const finalSegmentStart = lastPageBreak
    ? lastPageBreak.getBoundingClientRect().bottom - rootTop
    : 0;

  // A forced break starts a fresh page, so only the final segment determines
  // where the one-time footer lands on the last printed page.
  const finalSegmentHeight = Math.max(0, footerTop - finalSegmentStart);
  const positionOnPage = ((finalSegmentHeight % pageContentHeight) + pageContentHeight) % pageContentHeight;
  let spacerHeight = pageContentHeight - positionOnPage - footerHeight;
  if (spacerHeight < -0.25) spacerHeight += pageContentHeight;
  spacer.style.height = `${Math.max(0, spacerHeight)}px`;
}

function preparePreview(preview) {
  const clone = preview.cloneNode(true);
  clone.removeAttribute("id");
  clone.classList.remove("preview");
  clone.classList.add("pdf-content");

  const computed = getComputedStyle(preview);
  clone.style.fontFamily = computed.fontFamily;
  clone.style.fontSize = computed.fontSize;
  clone.style.lineHeight = computed.lineHeight;

  clone.querySelectorAll('[contenteditable="true"]').forEach(node => node.removeAttribute("contenteditable"));
  clone.querySelectorAll(".image-alias-tools, .image-alias-resize-handle").forEach(node => node.remove());
  clone.querySelectorAll("details").forEach(node => { node.open = true; });
  clone.querySelectorAll("input, button, select, textarea").forEach(node => { node.tabIndex = -1; });

  if (clone.classList.contains("preview--raw")) {
    clone.querySelectorAll(".preview-source-line").forEach(line => {
      if (!/^---+$/.test(line.textContent.trim())) return;
      const pageBreak = document.createElement("div");
      pageBreak.className = "pdf-page-break";
      pageBreak.setAttribute("aria-hidden", "true");
      line.replaceWith(pageBreak);
    });
  }

  clone.querySelectorAll("hr.page-break-marker, hr[data-page-break='true']").forEach(marker => {
    const pageBreak = document.createElement("div");
    pageBreak.className = "pdf-page-break";
    pageBreak.setAttribute("aria-hidden", "true");
    marker.replaceWith(pageBreak);
  });

  return clone;
}

function printStyles(cssSize, pageWidthMm, marginMm, preserveColors) {
  return `
    @page { size: ${cssSize}; margin: ${marginMm}mm; }
    html { color-scheme: light; background: #fff !important; }
    body { width: ${pageWidthMm - (2 * marginMm)}mm; margin: 0 !important; background: #fff !important; color: #16181d !important; }
    .pdf-document { width: ${pageWidthMm - (2 * marginMm)}mm; box-sizing: border-box; }
    .pdf-document-title { margin: 0 0 1.2em; padding: 0 0 .45em; border-bottom: 1px solid #d7dce2; }
    .pdf-document-title h1 { margin: 0; font: 700 1.7rem/1.18 Inter, ui-sans-serif, system-ui, sans-serif; color: #111318; }
    .pdf-footer-spacer {
      display: block;
      width: 100%;
      height: 0;
      margin: 0;
      padding: 0;
      border: 0;
    }
    .pdf-generated-footer {
      box-sizing: border-box;
      margin-top: 8mm;
      padding-top: 1.5mm;
      border-top: .2mm solid #e1e4e8;
      color: #9299a3;
      font: 500 7.5pt/1.2 Inter, ui-sans-serif, system-ui, sans-serif;
      letter-spacing: .01em;
      text-align: center;
      break-inside: avoid;
      page-break-inside: avoid;
    }
    .pdf-content { width: 100%; min-height: 0; margin: 0; padding: 0 !important; overflow: visible !important; color: #16181d !important; box-sizing: border-box; }
    .pdf-content .preview-source-line::before { display: none !important; content: none !important; }
    .pdf-content .preview-source-line { min-height: 0; }
    .pdf-content .preview-editable:hover,
    .pdf-content .preview-editable:focus { background: transparent !important; box-shadow: none !important; }
    .pdf-content a { color: inherit !important; text-decoration: underline; }
    ${preserveColors ? `
    .pdf-document,
    .pdf-document * { print-color-adjust: exact !important; -webkit-print-color-adjust: exact !important; }
    .pdf-content a { color: #5d50a5 !important; }
    .pdf-content code:not(pre code) { background: #eeeaf7 !important; border-color: #bcb2a6 !important; color: #403a33 !important; }
    .pdf-content pre { background: #efeae2 !important; border-color: #e2dcd3 !important; color: #413b34 !important; }
    .pdf-content pre code,
    .pdf-content .hljs { background: transparent !important; color: #403a33 !important; }
    .pdf-content .hljs-keyword,
    .pdf-content .hljs-selector-tag,
    .pdf-content .hljs-literal,
    .pdf-content .hljs-section,
    .pdf-content .hljs-link { color: #7046a5 !important; }
    .pdf-content .hljs-string,
    .pdf-content .hljs-attr,
    .pdf-content .hljs-regexp,
    .pdf-content .hljs-template-tag,
    .pdf-content .hljs-template-variable { color: #36704a !important; }
    .pdf-content .hljs-number,
    .pdf-content .hljs-symbol,
    .pdf-content .hljs-bullet { color: #a54c25 !important; }
    .pdf-content .hljs-title,
    .pdf-content .hljs-title.class_,
    .pdf-content .hljs-title.function_,
    .pdf-content .hljs-built_in,
    .pdf-content .hljs-type { color: #3568b8 !important; }
    .pdf-content .hljs-variable,
    .pdf-content .hljs-selector-id,
    .pdf-content .hljs-selector-class,
    .pdf-content .hljs-property,
    .pdf-content .hljs-attribute { color: #9b3443 !important; }
    .pdf-content .hljs-comment,
    .pdf-content .hljs-quote { color: #756c61 !important; font-style: italic; }
    .pdf-content .hljs-meta { color: #7e5d1d !important; }
    .pdf-content blockquote { border-left-color: #6859b5 !important; color: #625a50 !important; }
    .pdf-content mark { background: #f4e7be !important; color: #624700 !important; }
    .pdf-content th { background: #f5f1ea !important; color: #29251f !important; }
    .pdf-content .markdown-alert--success { border-color: #4c8064 !important; background: rgba(61, 121, 88, .10) !important; }
    .pdf-content .markdown-alert--info { border-color: #56759c !important; background: rgba(68, 103, 148, .09) !important; }
    .pdf-content .markdown-alert--warning { border-color: #a27831 !important; background: rgba(155, 112, 35, .11) !important; }
    .pdf-content .markdown-alert--danger { border-color: #a54b55 !important; background: rgba(155, 52, 67, .09) !important; }
    .pdf-content .task-checkbox { accent-color: #6859b5 !important; }
    ` : ""}
    .pdf-content pre { overflow: visible !important; white-space: pre-wrap !important; break-inside: avoid; page-break-inside: avoid; }
    .pdf-content pre code,
    .pdf-content pre.code-with-lines .code-line { white-space: pre-wrap !important; overflow-wrap: anywhere; word-break: break-word; }
    .pdf-content table,
    .pdf-content img,
    .pdf-content svg,
    .pdf-content blockquote { break-inside: avoid; page-break-inside: avoid; }
    .pdf-content img,
    .pdf-content svg { max-width: 100% !important; height: auto; }
    .pdf-content .table-wrap { overflow: visible !important; }
    .pdf-page-break { display: block; height: 0; margin: 0; padding: 0; border: 0; break-after: page; page-break-after: always; }
  `;
}

function openPrintWindow({ preview, title, formatKey, marginMm, includeTitle, preserveColors }) {
  const format = PAGE_FORMATS[formatKey] || PAGE_FORMATS["a4-portrait"];
  const safeMargin = [8, 12, 20].includes(Number(marginMm)) ? Number(marginMm) : 12;
  const printWindow = window.open("", "_blank");
  if (!printWindow) throw new Error(t("editor.pdfPopupBlocked", {}, "The PDF window was blocked by the browser."));
  try { printWindow.opener = null; } catch { /* same-origin hardening is best effort */ }

  const content = preparePreview(preview);
  const titleBlock = includeTitle && title
    ? `<header class="pdf-document-title"><h1>${escapeHtml(title)}</h1></header>`
    : "";
  const lang = escapeHtml(document.documentElement.lang || "en");
  const base = escapeHtml(`${location.origin}/`);
  const css = printStyles(format.cssSize, format.widthMm, safeMargin, preserveColors);
  const footerText = escapeHtml(t("editor.pdfGeneratedFooter", {}, "Generated by RustPad"));

  return (async () => {
    if (preserveColors) await ensureSyntaxHighlight(content);

    printWindow.document.open();
    printWindow.document.write(`<!doctype html><html lang="${lang}" data-theme="light"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1"><base href="${base}"><title>${escapeHtml(title || "RustPad")}</title>${stylesheetLinks()}<style>${css}</style></head><body><main class="pdf-document">${titleBlock}${content.outerHTML}<div class="pdf-footer-spacer" aria-hidden="true"></div><footer class="pdf-generated-footer" aria-hidden="true">${footerText}</footer></main></body></html>`);
    printWindow.document.close();

    const runPrint = async () => {
      try { await printWindow.document.fonts?.ready; } catch { /* print with available fonts */ }
      await new Promise(resolve => setTimeout(resolve, 120));
      alignFooterToLastPage(printWindow.document, format.heightMm, safeMargin);
      await new Promise(resolve => printWindow.requestAnimationFrame(() => resolve()));
      alignFooterToLastPage(printWindow.document, format.heightMm, safeMargin);
      printWindow.focus();
      printWindow.print();
    };

    printWindow.addEventListener("afterprint", () => printWindow.close(), { once: true });
    if (printWindow.document.readyState === "complete") await runPrint();
    else await new Promise(resolve => {
      printWindow.addEventListener("load", async () => { await runPrint(); resolve(); }, { once: true });
    });
  })().catch(error => {
    try { printWindow.close(); } catch { /* best effort */ }
    throw error;
  });
}

export function bindPdfExport({ button, dialog, form, preview, title }) {
  if (!button || !dialog || !form || !preview) return;
  const formatSelect = form.querySelector("#pdf-page-format");
  const marginSelect = form.querySelector("#pdf-page-margin");
  const includeTitle = form.querySelector("#pdf-include-title");
  const preserveColors = form.querySelector("#pdf-preserve-colors");
  const cancelButtons = form.querySelectorAll("[data-pdf-cancel]");

  const savedFormat = saved("format", "a4-portrait");
  formatSelect.value = Object.hasOwn(PAGE_FORMATS, savedFormat) ? savedFormat : "a4-portrait";
  marginSelect.value = ["8", "12", "20"].includes(saved("margin", "12")) ? saved("margin", "12") : "12";
  includeTitle.checked = saved("include-title", "off") === "on";
  if (preserveColors) preserveColors.checked = saved("preserve-colors", "on") !== "off";

  button.addEventListener("click", () => dialog.showModal());
  cancelButtons.forEach(cancel => cancel.addEventListener("click", () => dialog.close("cancel")));
  dialog.addEventListener("click", event => { if (event.target === dialog) dialog.close("cancel"); });

  form.addEventListener("submit", event => {
    event.preventDefault();
    const formatKey = formatSelect.value;
    const marginMm = Number(marginSelect.value);
    save("format", formatKey);
    save("margin", marginMm);
    save("include-title", includeTitle.checked ? "on" : "off");
    save("preserve-colors", preserveColors?.checked === false ? "off" : "on");
    try {
      const printJob = openPrintWindow({
        preview,
        title: typeof title === "function" ? title() : String(title || ""),
        formatKey,
        marginMm,
        includeTitle: includeTitle.checked,
        preserveColors: preserveColors?.checked !== false,
      });
      dialog.close("confirm");
      void printJob.catch(error => {
        toast.danger(error?.message || t("editor.pdfExportFailed", {}, "Could not prepare the PDF."), {
          title: t("editor.exportPdf", {}, "Export PDF"),
        });
      });
    } catch (error) {
      toast.danger(error?.message || t("editor.pdfExportFailed", {}, "Could not prepare the PDF."), {
        title: t("editor.exportPdf", {}, "Export PDF"),
      });
    }
  });
}