// Framework-neutral print-CSS base for the shared HTML -> PDF pipeline.
//
// Report (OPL-2598) and invoice (OPL-2602) templates render HTML for on-screen
// display first, then lazily produce a PDF from the SAME HTML on download. To
// keep both surfaces visually identical in print, every template should include
// this base CSS (e.g. inside a <style> tag in the document <head>) and rely on
// the page-break utility classes below for editorial pagination control.
//
// The rules here intentionally avoid any framework/runtime coupling — it is a
// plain string so it can be inlined by React (web hub) and by string templates
// (desktop) alike.

export type PaperSize = "Letter" | "A4";

/** Margin can be a single CSS length applied to all sides, or per-side. */
export type PageMargin =
  | string
  | {
      top?: string;
      right?: string;
      bottom?: string;
      left?: string;
    };

/**
 * The static, parameter-free portion of the print base: color fidelity,
 * orphans/widows defaults, and page-break utility classes. Page size and
 * margins are layered on by {@link buildPrintCss} via the `@page` rule (and by
 * Playwright's `page.pdf()` options) so this constant stays size-agnostic.
 */
export const PRINT_BASE_CSS = `
/* Preserve background colors/images in print (Chromium strips them otherwise). */
*,
*::before,
*::after {
  -webkit-print-color-adjust: exact;
  print-color-adjust: exact;
}

/* Sensible editorial defaults: never strand a single line across a page break. */
p,
li,
blockquote {
  orphans: 3;
  widows: 3;
}

/* Headings should stay attached to the content that follows them. */
h1,
h2,
h3,
h4,
h5,
h6 {
  break-after: avoid;
  break-inside: avoid;
}

/* Tables and figures should not be split mid-element where avoidable. */
thead {
  display: table-header-group;
}
tr,
img,
figure,
pre {
  break-inside: avoid;
}

/* Page-break utility classes (framework-neutral; include in template markup). */
.break-before {
  break-before: page;
}
.break-after {
  break-after: page;
}
.break-inside-avoid,
.no-break {
  break-inside: avoid;
}

@media print {
  a {
    color: inherit;
    text-decoration: none;
  }
}
`.trim();

function normalizeMargin(margin: PageMargin): string {
  if (typeof margin === "string") {
    return margin;
  }
  const top = margin.top ?? "0";
  const right = margin.right ?? "0";
  const bottom = margin.bottom ?? "0";
  const left = margin.left ?? "0";
  return `${top} ${right} ${bottom} ${left}`;
}

export interface BuildPrintCssOptions {
  /** Paper size for the `@page` rule. Defaults to "Letter". */
  paperSize?: PaperSize;
  /** Page margin for the `@page` rule. Defaults to "0.5in" on all sides. */
  margin?: PageMargin;
}

/**
 * Build the full print stylesheet: an `@page` rule (size + margin) followed by
 * {@link PRINT_BASE_CSS}. Templates that set their own `@page` rule can use
 * {@link PRINT_BASE_CSS} directly instead.
 */
export function buildPrintCss(options: BuildPrintCssOptions = {}): string {
  const paperSize = options.paperSize ?? "Letter";
  const margin = normalizeMargin(options.margin ?? "0.5in");
  const size = paperSize === "A4" ? "A4" : "letter";
  return `@page {\n  size: ${size};\n  margin: ${margin};\n}\n\n${PRINT_BASE_CSS}`;
}