/**
 * Client-side invoice PDF: نوع محصول · عدد · قیمت · عکس
 * Site palette + KikoMiko wordmark linked to kikomiko.ir
 */

const PALETTE = {
  ink: "#22191a",
  background: "#fffcfb",
  soft: "#f8f1ef",
  blush: "#f4e4e0",
  berry: "#9a3d4f",
  muted: "#8a7874",
  gold: "#c4a07a",
  cardBorder: "#eaddd8",
  white: "#ffffff",
};

const SITE_URL = "https://kikomiko.ir/";
const SITE_HOST = "kikomiko.ir";

function formatFaInt(n) {
  return new Intl.NumberFormat("fa-IR", { maximumFractionDigits: 0 }).format(n);
}

function loadImage(src) {
  return new Promise((resolve) => {
    if (!src) {
      resolve(null);
      return;
    }
    const img = new Image();
    img.decoding = "async";
    img.onload = () => resolve(img);
    img.onerror = () => resolve(null);
    img.src = src;
  });
}

function wrapText(ctx, text, maxWidth) {
  const words = String(text || "").split(/\s+/).filter(Boolean);
  if (!words.length) return [""];
  const lines = [];
  let line = words[0];
  for (let i = 1; i < words.length; i++) {
    const test = `${line} ${words[i]}`;
    if (ctx.measureText(test).width <= maxWidth) line = test;
    else {
      lines.push(line);
      line = words[i];
    }
  }
  lines.push(line);
  return lines;
}

async function ensureInvoiceFonts() {
  try {
    if (document.fonts?.load) {
      await Promise.all([
        document.fonts.load('700 28px "Yekan Bakh"'),
        document.fonts.load('300 28px "Yekan Bakh"'),
        document.fonts.load('400 13px "Yekan Bakh"'),
      ]);
    }
  } catch {
    /* fallback fonts below */
  }
}

/**
 * Draw site wordmark (Kiko bold berry + Miko light ink) + kikomiko.ir under it.
 * @returns {{ x: number; y: number; w: number; h: number }} hit area for PDF link
 */
function drawBrandLogo(ctx, fontFamily, rightX, topY) {
  const mark = "Kiko";
  const tail = "Miko";
  ctx.save();
  ctx.direction = "ltr";
  ctx.textAlign = "left";
  ctx.textBaseline = "top";

  ctx.font = `700 26px ${fontFamily}`;
  const markW = ctx.measureText(mark).width;
  ctx.font = `300 26px ${fontFamily}`;
  const tailW = ctx.measureText(tail).width;
  const logoW = markW + tailW;
  const logoX = rightX - logoW;

  ctx.font = `700 26px ${fontFamily}`;
  ctx.fillStyle = PALETTE.berry;
  ctx.fillText(mark, logoX, topY);

  ctx.font = `300 26px ${fontFamily}`;
  ctx.fillStyle = PALETTE.ink;
  ctx.fillText(tail, logoX + markW, topY);

  ctx.font = `500 11px ${fontFamily}`;
  ctx.fillStyle = PALETTE.berry;
  const urlW = ctx.measureText(SITE_HOST).width;
  ctx.fillText(SITE_HOST, rightX - urlW, topY + 32);

  ctx.strokeStyle = PALETTE.gold;
  ctx.lineWidth = 1;
  ctx.beginPath();
  ctx.moveTo(rightX - urlW, topY + 45);
  ctx.lineTo(rightX, topY + 45);
  ctx.stroke();

  ctx.restore();
  return {
    x: Math.min(logoX, rightX - urlW),
    y: topY,
    w: Math.max(logoW, urlW),
    h: 48,
  };
}

/**
 * Embed JPEG page images into a PDF (A4). Optional link rects in JPEG pixel space (top-left origin).
 * @param {Array<{ bytes: Uint8Array; w: number; h: number; links?: Array<{ x: number; y: number; w: number; h: number; url: string }> }>} pages
 */
function jpegsToPdfBlob(pages) {
  const pageW = 595.28;
  const pageH = 841.89;
  const margin = 18;
  const encoder = new TextEncoder();
  const objects = [];

  function addObj(body) {
    objects.push(body);
    return objects.length;
  }

  function pdfEscape(s) {
    return String(s).replace(/\\/g, "\\\\").replace(/\(/g, "\\(").replace(/\)/g, "\\)");
  }

  const fontId = addObj(`<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>`);
  const pageIds = [];

  for (const page of pages) {
    const maxW = pageW - margin * 2;
    const maxH = pageH - margin * 2;
    const fit = Math.min(maxW / page.w, maxH / page.h, 1);
    const dw = page.w * fit;
    const dh = page.h * fit;
    const x = (pageW - dw) / 2;
    const y = pageH - margin - dh;

    const annotIds = [];
    for (const link of page.links || []) {
      const sx = dw / page.w;
      const sy = dh / page.h;
      const left = x + link.x * sx;
      const bottom = y + (page.h - link.y - link.h) * sy;
      const right = left + link.w * sx;
      const top = bottom + link.h * sy;
      const annotId = addObj(
        `<< /Type /Annot /Subtype /Link /Rect [${left.toFixed(2)} ${bottom.toFixed(2)} ${right.toFixed(2)} ${top.toFixed(2)}] /Border [0 0 0] /A << /S /URI /URI (${pdfEscape(link.url)}) >> >>`
      );
      annotIds.push(annotId);
    }

    const imgId = addObj("IMG");
    const contentStream = `q\n${dw.toFixed(2)} 0 0 ${dh.toFixed(2)} ${x.toFixed(2)} ${y.toFixed(2)} cm\n/Im0 Do\nQ\n`;
    const contentId = addObj(
      `<< /Length ${encoder.encode(contentStream).length} >>\nstream\n${contentStream}\nendstream`
    );
    const annots =
      annotIds.length > 0
        ? ` /Annots [${annotIds.map((id) => `${id} 0 R`).join(" ")}]`
        : "";
    const pageId = addObj(
      `<< /Type /Page /Parent 0 0 R /MediaBox [0 0 ${pageW} ${pageH}] /Contents ${contentId} 0 R /Resources << /XObject << /Im0 ${imgId} 0 R >> /Font << /F1 ${fontId} 0 R >> >>${annots} >>`
    );
    pageIds.push({ pageId, imgId, jpeg: page.bytes, imgW: page.w, imgH: page.h });
  }

  const kids = pageIds.map((p) => `${p.pageId} 0 R`).join(" ");
  const pagesId = addObj(`<< /Type /Pages /Kids [${kids}] /Count ${pageIds.length} >>`);
  const catalogId = addObj(`<< /Type /Catalog /Pages ${pagesId} 0 R >>`);

  for (const p of pageIds) {
    objects[p.pageId - 1] = objects[p.pageId - 1].replace(
      "/Parent 0 0 R",
      `/Parent ${pagesId} 0 R`
    );
  }

  const imgIdSet = new Map(pageIds.map((p) => [p.imgId, p]));
  const parts = [];
  const offsets = [0];
  let offset = 0;

  function pushStr(s) {
    const b = typeof s === "string" ? encoder.encode(s) : s;
    parts.push(b);
    offset += b.length;
  }

  pushStr("%PDF-1.4\n");

  for (let i = 0; i < objects.length; i++) {
    offsets.push(offset);
    const n = i + 1;
    const imgPage = imgIdSet.get(n);
    if (imgPage) {
      const jpeg = imgPage.jpeg;
      pushStr(`${n} 0 obj\n`);
      pushStr(
        `<< /Type /XObject /Subtype /Image /Width ${imgPage.imgW} /Height ${imgPage.imgH} /ColorSpace /DeviceRGB /BitsPerComponent 8 /Filter /DCTDecode /Length ${jpeg.length} >>\nstream\n`
      );
      parts.push(jpeg);
      offset += jpeg.length;
      pushStr("\nendstream\nendobj\n");
    } else {
      pushStr(`${n} 0 obj\n${objects[i]}\nendobj\n`);
    }
  }

  const xrefStart = offset;
  pushStr(`xref\n0 ${objects.length + 1}\n`);
  pushStr("0000000000 65535 f \n");
  for (let i = 1; i <= objects.length; i++) {
    pushStr(`${String(offsets[i]).padStart(10, "0")} 00000 n \n`);
  }
  pushStr(
    `trailer\n<< /Size ${objects.length + 1} /Root ${catalogId} 0 R >>\nstartxref\n${xrefStart}\n%%EOF\n`
  );

  const total = parts.reduce((n, p) => n + p.length, 0);
  const out = new Uint8Array(total);
  let o = 0;
  for (const p of parts) {
    out.set(p, o);
    o += p.length;
  }
  return new Blob([out], { type: "application/pdf" });
}

function canvasToJpegBytes(canvas, quality = 0.92) {
  return new Promise((resolve, reject) => {
    canvas.toBlob(
      async (blob) => {
        if (!blob) {
          reject(new Error("JPEG encode failed"));
          return;
        }
        resolve(new Uint8Array(await blob.arrayBuffer()));
      },
      "image/jpeg",
      quality
    );
  });
}

/**
 * @param {{
 *   orderId: string;
 *   dateLabel: string;
 *   customerName: string;
 *   customerPhone?: string;
 *   address?: string;
 *   city?: string;
 *   province?: string;
 *   items: Array<{ name: string; category?: string|null; quantity: number; price: number; image?: string|null }>;
 *   totalLabel: string;
 *   formatPrice: (n: number) => string;
 *   eurToTomanRate?: number;
 * }} data
 * @returns {Promise<File>}
 */
export async function generateInvoicePdf(data) {
  await ensureInvoiceFonts();
  const images = await Promise.all(data.items.map((i) => loadImage(i.image)));

  const W = 794;
  const pad = 36;
  const thumbW = 72;
  const thumbH = 96;
  const colQty = 64;
  const colPrice = 130;
  const colImg = 92;
  const colType = W - pad * 2 - colQty - colPrice - colImg;
  const rowPad = 10;
  const font = '"Yekan Bakh",Tahoma,"Segoe UI",Arial,sans-serif';

  const measure = document.createElement("canvas").getContext("2d");
  if (!measure) throw new Error("Canvas unavailable");
  measure.font = `12px ${font}`;

  const rowHeights = data.items.map((item) => {
    const type = item.category || "—";
    const nameLines = wrapText(measure, item.name || "", colType - 16);
    const typeLines = wrapText(measure, type, colType - 16);
    const textH = (typeLines.length + nameLines.length) * 16 + 8;
    return Math.max(thumbH + rowPad * 2, textH + rowPad * 2);
  });

  const headerBandH = 64;
  const infoBlockEstimate = 70;
  const tableHeadH = 36;
  const footerH = 88;
  const tableH = rowHeights.reduce((a, b) => a + b, 0);
  const H = pad + headerBandH + 16 + infoBlockEstimate + tableHeadH + tableH + footerH;

  const scale = 2;
  const canvas = document.createElement("canvas");
  canvas.width = W * scale;
  canvas.height = H * scale;
  const ctx = canvas.getContext("2d");
  if (!ctx) throw new Error("Canvas unavailable");
  ctx.scale(scale, scale);

  ctx.fillStyle = PALETTE.background;
  ctx.fillRect(0, 0, W, H);
  ctx.textBaseline = "top";
  ctx.direction = "rtl";

  let y = 0;

  ctx.fillStyle = PALETTE.soft;
  ctx.fillRect(0, 0, W, headerBandH);
  ctx.fillStyle = PALETTE.berry;
  ctx.fillRect(0, headerBandH - 3, W, 3);

  y = 14;
  const logoHit = drawBrandLogo(ctx, font, W - pad, y);

  ctx.textAlign = "left";
  ctx.direction = "ltr";
  ctx.fillStyle = PALETTE.ink;
  ctx.font = `700 12px ${font}`;
  ctx.fillText(data.orderId, pad, y + 8);
  ctx.font = `400 11px ${font}`;
  ctx.fillStyle = PALETTE.muted;
  ctx.fillText(data.dateLabel, pad, y + 28);
  ctx.direction = "rtl";

  y = headerBandH + 18;

  ctx.fillStyle = PALETTE.ink;
  ctx.font = `400 13px ${font}`;
  ctx.textAlign = "right";
  const info = [
    `نام مشتری: ${data.customerName}`,
    data.customerPhone ? `تلفن: ${data.customerPhone}` : "",
    data.address
      ? `آدرس: ${data.address}${data.city ? ` — ${data.city}` : ""}${data.province ? `، ${data.province}` : ""}`
      : "",
  ].filter(Boolean);
  for (const line of info) {
    ctx.fillText(line, W - pad, y);
    y += 20;
  }
  y += 10;

  const cols = [
    { key: "type", w: colType, label: "نوع محصول" },
    { key: "qty", w: colQty, label: "عدد" },
    { key: "price", w: colPrice, label: "قیمت" },
    { key: "img", w: colImg, label: "عکس" },
  ];
  function colXs() {
    let right = W - pad;
    return cols.map((c) => {
      const x0 = right - c.w;
      right = x0;
      return { ...c, x: x0 };
    });
  }

  const headerCols = colXs();
  ctx.fillStyle = PALETTE.blush;
  ctx.fillRect(pad, y, W - pad * 2, tableHeadH);
  ctx.strokeStyle = PALETTE.cardBorder;
  ctx.lineWidth = 1;
  ctx.strokeRect(pad, y, W - pad * 2, tableHeadH);
  ctx.fillStyle = PALETTE.berry;
  ctx.font = `700 12px ${font}`;
  for (const c of headerCols) {
    ctx.strokeRect(c.x, y, c.w, tableHeadH);
    ctx.textAlign = "center";
    ctx.fillText(c.label, c.x + c.w / 2, y + 11);
  }
  y += tableHeadH;

  for (let i = 0; i < data.items.length; i++) {
    const item = data.items[i];
    const rh = rowHeights[i];
    const rowCols = colXs();

    ctx.fillStyle = i % 2 === 0 ? PALETTE.white : PALETTE.soft;
    ctx.fillRect(pad, y, W - pad * 2, rh);
    ctx.strokeStyle = PALETTE.cardBorder;
    ctx.strokeRect(pad, y, W - pad * 2, rh);
    for (const c of rowCols) ctx.strokeRect(c.x, y, c.w, rh);

    const typeCol = rowCols.find((c) => c.key === "type");
    const qtyCol = rowCols.find((c) => c.key === "qty");
    const priceCol = rowCols.find((c) => c.key === "price");
    const imgCol = rowCols.find((c) => c.key === "img");

    ctx.fillStyle = PALETTE.ink;
    ctx.font = `700 12px ${font}`;
    ctx.textAlign = "right";
    const type = item.category || "—";
    let ty = y + rowPad;
    for (const line of wrapText(ctx, type, colType - 16)) {
      ctx.fillText(line, typeCol.x + typeCol.w - 8, ty);
      ty += 16;
    }
    ctx.font = `400 11px ${font}`;
    ctx.fillStyle = PALETTE.muted;
    for (const line of wrapText(ctx, item.name || "", colType - 16)) {
      ctx.fillText(line, typeCol.x + typeCol.w - 8, ty);
      ty += 15;
    }

    ctx.fillStyle = PALETTE.ink;
    ctx.font = `500 13px ${font}`;
    ctx.textAlign = "center";
    ctx.fillText(formatFaInt(item.quantity), qtyCol.x + qtyCol.w / 2, y + rh / 2 - 7);
    ctx.fillText(
      data.formatPrice(item.price * item.quantity),
      priceCol.x + priceCol.w / 2,
      y + rh / 2 - 7
    );

    const img = images[i];
    const ix = imgCol.x + (imgCol.w - thumbW) / 2;
    const iy = y + (rh - thumbH) / 2;
    if (img) {
      ctx.drawImage(img, ix, iy, thumbW, thumbH);
      ctx.strokeStyle = PALETTE.cardBorder;
      ctx.strokeRect(ix, iy, thumbW, thumbH);
    } else {
      ctx.fillStyle = PALETTE.blush;
      ctx.fillRect(ix, iy, thumbW, thumbH);
    }

    y += rh;
  }

  y += 14;
  ctx.strokeStyle = PALETTE.gold;
  ctx.lineWidth = 1.5;
  ctx.beginPath();
  ctx.moveTo(pad, y);
  ctx.lineTo(W - pad, y);
  ctx.stroke();
  y += 14;

  ctx.fillStyle = PALETTE.berry;
  ctx.font = `700 15px ${font}`;
  ctx.textAlign = "right";
  ctx.fillText("جمع کل", W - pad, y);
  ctx.textAlign = "left";
  ctx.direction = "ltr";
  ctx.fillText(data.totalLabel, pad, y);
  ctx.direction = "rtl";

  const eurRate =
    typeof data.eurToTomanRate === "number" &&
    Number.isFinite(data.eurToTomanRate) &&
    data.eurToTomanRate > 0
      ? data.eurToTomanRate
      : 0;
  if (eurRate > 0) {
    y += 26;
    ctx.fillStyle = PALETTE.muted;
    ctx.font = `400 12px ${font}`;
    ctx.textAlign = "right";
    const rateLabel = `نرخ یورو: ${data.formatPrice(eurRate)}`;
    ctx.fillText(rateLabel, W - pad, y);
  }

  const jpegFull = await canvasToJpegBytes(canvas, 0.92);
  const pageCssH = Math.floor((W * 841.89) / 595.28);
  const pages = [];
  const logoLinkJpeg = {
    x: logoHit.x * scale,
    y: logoHit.y * scale,
    w: logoHit.w * scale,
    h: logoHit.h * scale,
    url: SITE_URL,
  };

  if (H <= pageCssH + 40) {
    pages.push({
      bytes: jpegFull,
      w: canvas.width,
      h: canvas.height,
      links: [logoLinkJpeg],
    });
  } else {
    let sy = 0;
    let pageIndex = 0;
    while (sy < H) {
      const sliceH = Math.min(pageCssH, H - sy);
      const slice = document.createElement("canvas");
      slice.width = canvas.width;
      slice.height = Math.ceil(sliceH * scale);
      const sctx = slice.getContext("2d");
      if (!sctx) break;
      sctx.drawImage(
        canvas,
        0,
        Math.floor(sy * scale),
        canvas.width,
        slice.height,
        0,
        0,
        slice.width,
        slice.height
      );
      const pageLinks =
        pageIndex === 0 && logoHit.y + logoHit.h <= sliceH ? [logoLinkJpeg] : [];
      pages.push({
        bytes: await canvasToJpegBytes(slice, 0.92),
        w: slice.width,
        h: slice.height,
        links: pageLinks,
      });
      sy += sliceH;
      pageIndex += 1;
    }
  }

  const blob = jpegsToPdfBlob(pages);
  return new File([blob], `kikomiko-invoice-${data.orderId}.pdf`, {
    type: "application/pdf",
    lastModified: Date.now(),
  });
}

export function downloadFile(file) {
  const url = URL.createObjectURL(file);
  const a = document.createElement("a");
  a.href = url;
  a.download = file.name;
  a.rel = "noopener";
  document.body.appendChild(a);
  a.click();
  a.remove();
  window.setTimeout(() => URL.revokeObjectURL(url), 60_000);
}

export function whatsappChatUrl(waNumber, text) {
  const digits = String(waNumber || "").replace(/\D/g, "");
  return `https://wa.me/${digits}?text=${encodeURIComponent(text || "")}`;
}

/** Upload PDF to Worker; returns public URL for WhatsApp (no client download). */
export async function uploadInvoicePdf(file) {
  const res = await fetch("/api/invoices", {
    method: "POST",
    headers: { "content-type": "application/pdf" },
    body: file,
  });
  const json = await res.json().catch(() => ({}));
  if (!res.ok || !json.ok || !json.url) {
    throw new Error(json.error || "آپلود فاکتور ناموفق بود");
  }
  return String(json.url);
}

/**
 * Host PDF, open WhatsApp to store with invoice link (no client download).
 */
export async function openWhatsAppWithInvoice(file, waText, waNumber) {
  const pdfUrl = await uploadInvoicePdf(file);
  const note = [waText || "", "", "📄 Invoice PDF:", pdfUrl]
    .filter((line, i, arr) => !(line === "" && arr[i - 1] === ""))
    .join("\n")
    .trim();
  const url = whatsappChatUrl(waNumber, note);
  window.location.href = url;
  return { pdfUrl, waUrl: url };
}