/**
 * thermal-print.ts
 *
 * Generates a self-contained 80 mm HTML document and fires it through a
 * hidden <iframe> so the browser's OS print spooler routes the job to the
 * default printer (e.g. Atom A300 USB driver).
 *
 * Why iframe instead of window.print() on the main page?
 *   – The iframe document contains ONLY the receipt, so @page height = content
 *     height. No blank A4 tail after the receipt.
 *   – `html { direction: rtl }` is set unconditionally inside the iframe.
 *     The main app's dir attribute never bleeds in.
 *   – No `visibility: hidden` tricks needed — the print area IS the document.
 */

export type ThermalLine = {
  name: string;
  quantity: number;
  price?: string;
  notes?: string;
};

export type ThermalTotals = {
  subtotal?: string;
  discount?: string;
  tax?: string;
  total: string;
  payments?: { method: string; amount: string }[];
};

export type ThermalSlipData = {
  cafeName: string;
  /** "فیش آشپزخانه" or "صورتحساب مشتری" */
  title: string;
  date: string;
  /** Pre-formatted row, e.g. "میز: ۳ | سفارش: #۱۰۵" */
  metaRow?: string;
  lines: ThermalLine[];
  totals?: ThermalTotals;
  footer?: string;
  /** 'fa' (default) → RTL, 'en' → LTR */
  locale?: string;
  /** Optional café logo URL — rendered centered above the name for branding. */
  logoUrl?: string;
  /** Optional tagline / address line under the café name. */
  tagline?: string;
  /** Optional custom header note (from branch print settings) shown under the name. */
  header?: string;
  /** Optional WiFi password line printed near the footer. */
  wifi?: string;
  /** Paper width in mm — 58 or 80 (default 80). Controls page width + scale. */
  paperWidthMm?: number;
};

/** Absolute URL to the bundled Vazirmatn web-font (same origin). */
function vazirmatnFontUrl(): string {
  const origin =
    typeof window !== "undefined" ? window.location.origin : "";
  return `${origin}/fonts/Vazirmatn-Variable.woff2`;
}

// ─────────────────────────────────────────────────────────────────────────────
// Helpers
// ─────────────────────────────────────────────────────────────────────────────

/** Escapes a string for safe injection into an HTML template. */
function esc(str: string): string {
  return str
    .replace(/&/g, "&amp;")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;");
}

// ─────────────────────────────────────────────────────────────────────────────
// Document builder
// ─────────────────────────────────────────────────────────────────────────────

export function buildThermalDocument(data: ThermalSlipData): string {
  const isRtl = (data.locale ?? "fa") !== "en";
  const dir = isRtl ? "rtl" : "ltr";
  const lang = data.locale ?? "fa";

  const linesHtml = data.lines
    .map((l) => {
      const notePart = l.notes ? ` (${esc(l.notes)})` : "";
      return `<div class="row">
        <span>${esc(l.name)} × ${l.quantity}${notePart}</span>
        ${l.price ? `<span class="price">${esc(l.price)}</span>` : ""}
      </div>`;
    })
    .join("\n");

  let totalsHtml = "";
  if (data.totals) {
    const tt = data.totals;
    const subtotalLabel = isRtl ? "جمع اقلام" : "Subtotal";
    const discountLabel = isRtl ? "تخفیف" : "Discount";
    const taxLabel = isRtl ? "مالیات (۹٪)" : "Tax (9%)";
    const totalLabel = isRtl ? "مجموع" : "Total";
    totalsHtml = `
      <hr class="dashed">
      ${tt.subtotal ? `<div class="row sm"><span>${subtotalLabel}</span><span>${esc(tt.subtotal)}</span></div>` : ""}
      ${tt.discount ? `<div class="row sm"><span>${discountLabel}</span><span>- ${esc(tt.discount)}</span></div>` : ""}
      ${tt.tax ? `<div class="row sm"><span>${taxLabel}</span><span>${esc(tt.tax)}</span></div>` : ""}
      <div class="row total"><span>${totalLabel}</span><span>${esc(tt.total)}</span></div>
      ${(tt.payments ?? [])
        .map((p) => `<div class="row sm mt1"><span>${esc(p.method)}</span><span>${esc(p.amount)}</span></div>`)
        .join("")}
    `;
  }

  const wifiLabel = isRtl ? "وای‌فای" : "WiFi";
  const footerInner = [
    data.wifi ? `<div class="center sm">${wifiLabel}: ${esc(data.wifi)}</div>` : "",
    data.footer ? `<div class="center sm muted">${esc(data.footer)}</div>` : "",
  ]
    .filter(Boolean)
    .join("");
  const footerHtml = footerInner ? `<hr class="dashed">${footerInner}` : "";

  const logoHtml = data.logoUrl
    ? `<img class="logo" src="${esc(data.logoUrl)}" alt="">`
    : "";
  const taglineHtml = data.tagline
    ? `<div class="center tagline">${esc(data.tagline)}</div>`
    : "";
  const headerHtml = data.header
    ? `<div class="center header-note">${esc(data.header)}</div>`
    : "";

  // Paper width: 58 mm or 80 mm. Narrower paper gets a slightly smaller base
  // font so lines don't wrap awkwardly.
  const widthMm = data.paperWidthMm === 58 ? 58 : 80;
  const baseFontPt = widthMm === 58 ? 10 : 11.5;
  const wrapPadMm = widthMm === 58 ? "3mm 3mm 5mm" : "4mm 4.5mm 6mm";

  const fontUrl = vazirmatnFontUrl();

  return `<!DOCTYPE html>
<html dir="${dir}" lang="${lang}">
<head>
<meta charset="utf-8">
<style>
/* ── Web-font: bundled Vazirmatn variable ─────────────────── */
@font-face {
  font-family: 'Vazirmatn';
  src: url('${fontUrl}') format('woff2');
  font-weight: 100 900;
  font-style: normal;
  font-display: block;
}
/* ── Page ─────────────────────────────────────────────────── */
@page {
  /* width tracks the configured paper; height tracks content — no blank tail */
  size: ${widthMm}mm auto;
  margin: 0;
}
/* ── Reset ────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
/* ── Root ─────────────────────────────────────────────────── */
html, body {
  width: ${widthMm}mm;
  direction: ${dir};
  font-family: 'Vazirmatn', 'Tahoma', 'Arial', sans-serif;
  font-size: ${baseFontPt}pt;
  font-weight: 500;
  line-height: 1.55;
  color: #000;
  background: #fff;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
/* ── Wrapper ──────────────────────────────────────────────── */
.wrap { padding: ${wrapPadMm}; }
/* ── Branding header ──────────────────────────────────────── */
.logo {
  display: block;
  max-width: 36mm;
  max-height: 18mm;
  margin: 0 auto 1.5mm;
  object-fit: contain;
}
.cafe-name {
  text-align: center;
  font-size: 16pt;
  font-weight: 800;
  letter-spacing: -0.2px;
  line-height: 1.25;
}
.tagline {
  font-size: 8.5pt;
  font-weight: 500;
  color: #444;
  margin-top: 0.5mm;
}
.header-note {
  font-size: 9pt;
  font-weight: 600;
  color: #222;
  margin-top: 1mm;
  white-space: pre-line;
}
.doc-title {
  text-align: center;
  font-size: 10pt;
  font-weight: 700;
  margin-top: 1.5mm;
  padding: 0.8mm 0;
  border-top: 1px solid #000;
  border-bottom: 1px solid #000;
}
.date {
  text-align: center;
  font-size: 8.5pt;
  color: #444;
  margin-top: 1.5mm;
}
.meta {
  font-size: 9pt;
  font-weight: 600;
  margin-top: 1.5mm;
  text-align: center;
  color: #222;
}
/* ── Text helpers ─────────────────────────────────────────── */
.center  { text-align: center; }
.bold    { font-weight: 700; }
.sm      { font-size: 9.5pt; }
.muted   { color: #555; }
.mt1     { margin-top: 1mm; }
.mt2     { margin-top: 2mm; }
/* ── Divider ──────────────────────────────────────────────── */
hr.dashed { border: none; border-top: 1px dashed #000; margin: 2.5mm 0; }
hr.solid  { border: none; border-top: 1px solid  #000; margin: 2.5mm 0; }
/* ── Rows ─────────────────────────────────────────────────── */
.row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 2mm;
  line-height: 1.7;
}
.row > span:first-child { flex: 1; }
.row .price { white-space: nowrap; font-weight: 700; font-variant-numeric: tabular-nums; }
.row.sm { color: #333; }
/* ── Totals ───────────────────────────────────────────────── */
.total {
  font-size: 14pt;
  font-weight: 800;
  margin-top: 1.5mm;
  padding-top: 1.5mm;
  border-top: 2px solid #000;
}
.total .price { font-size: 14pt; }
</style>
</head>
<body>
<div class="wrap">
  ${logoHtml}
  <div class="cafe-name">${esc(data.cafeName)}</div>
  ${taglineHtml}
  ${headerHtml}
  <div class="doc-title">${esc(data.title)}</div>
  <div class="date">${esc(data.date)}</div>
  ${data.metaRow ? `<div class="meta">${esc(data.metaRow)}</div>` : ""}
  <hr class="dashed">
  ${linesHtml}
  ${totalsHtml}
  ${footerHtml}
</div>
</body>
</html>`;
}

// ─────────────────────────────────────────────────────────────────────────────
// Print trigger
// ─────────────────────────────────────────────────────────────────────────────

const IFRAME_ID = "meezi-thermal-print-frame";

/**
 * Injects (or reuses) a hidden <iframe>, writes the thermal HTML document
 * into it, then calls `iframe.contentWindow.print()`.
 *
 * The iframe is positioned off-screen so it is invisible but still mounted
 * in the DOM — required for Chrome/Edge to render it before printing.
 */
export function printThermal(html: string): void {
  if (typeof window === "undefined") return;

  let frame = document.getElementById(IFRAME_ID) as HTMLIFrameElement | null;

  if (!frame) {
    frame = document.createElement("iframe");
    frame.id = IFRAME_ID;
    frame.setAttribute("aria-hidden", "true");
    frame.setAttribute("tabindex", "-1");
    frame.style.cssText =
      "position:fixed;top:-9999px;left:-9999px;width:80mm;height:1px;" +
      "border:0;opacity:0;pointer-events:none;";
    document.body.appendChild(frame);
  }

  const doc = frame.contentDocument ?? frame.contentWindow?.document;
  if (!doc) return;

  doc.open();
  doc.write(html);
  doc.close();

  const fire = () => {
    try {
      frame!.contentWindow?.focus();
      frame!.contentWindow?.print();
    } catch {
      // Safari throws if the frame was cross-origin — shouldn't happen for
      // same-origin same-page iframes, but guard just in case.
    }
  };

  // Wait for the embedded Vazirmatn web-font to finish loading inside the
  // iframe before printing — otherwise the spooler may rasterise the receipt
  // with a fallback font. `document.fonts.ready` resolves once @font-face
  // loads complete; we cap the wait so a font failure never blocks printing.
  const win = frame.contentWindow;
  const fontSet = win?.document?.fonts;
  if (fontSet) {
    let printed = false;
    const run = () => {
      if (printed) return;
      printed = true;
      requestAnimationFrame(fire);
    };
    fontSet.ready.then(run).catch(run);
    // Safety timeout in case fonts.ready never settles.
    setTimeout(run, 1500);
  } else {
    requestAnimationFrame(fire);
  }
}