import { readFile } from "node:fs/promises";
import path from "node:path";
import { getAdminPocketBase } from "./server/pocketbase-admin";
import type { BaseRecord } from "./types";

/**
 * Letterhead — server-side read model for a row in `letterhead_settings`.
 *
 * Each company (CNL, ISHERWOOD) has exactly one row (enforced by the
 * `idx_letterhead_settings_one_per_company` unique index). The PDF
 * generator fetches this row fresh on every render so edits in the
 * PB admin UI (logo swap, bank detail fix, terms tweak, accent color
 * change) propagate to the next quote without a code deploy.
 */
export type LetterheadCode = "CNL" | "ISHERWOOD";

export const LETTERHEAD_CODES: readonly LetterheadCode[] = ["CNL", "ISHERWOOD"] as const;

export interface Letterhead extends BaseRecord {
  display_name: string;
  address: string;
  phone: string;
  email: string;
  vat_number: string;
  registration_number: string;
  bank_name: string;
  bank_account_number: string;
  bank_branch_code: string;
  terms: string;
  default_markup_percent: number;
  footer_text: string;
  /** PB file token (filename) — combine with `letterheadLogoUrl` for a usable URL. */
  logo: string;
  is_active: boolean;
  company: string;
  /** Hex like "#738224". Set per-company so the PDF table header + accents differ. */
  accent_color: string;
}

/**
 * Look up the letterhead row for a given company code.
 *
 * Matches on the `display_name` field (e.g. "CNL Mining Supplies" matches
 * the `CNL` code). Throws if no row matches — that's a config bug, not a
 * user error, so it surfaces as a 500 in the API.
 */
export async function fetchLetterhead(code: LetterheadCode): Promise<Letterhead> {
  if (!LETTERHEAD_CODES.includes(code)) {
    throw new Error(`Unknown letterhead code: ${code}`);
  }
  const pb = await getAdminPocketBase();
  const rows = await pb.collection("letterhead_settings").getFullList<Letterhead>({
    filter: `display_name ~ "${code}"`,
  });
  if (rows.length === 0) {
    throw new Error(
      `No letterhead_settings row matching code ${code}. ` +
        `Seed one in the PB admin UI (Settings → Collections → letterhead_settings).`
    );
  }
  return rows[0];
}

/**
 * Public file URL for the logo. PB's `/api/files/{collection}/{record}/{filename}`
 * endpoint serves without auth, so the PDF renderer can fetch this directly
 * — though we still inline as data URI in the API route to avoid extra
 * round trips during render and to keep the document component pure.
 */
export function letterheadLogoUrl(row: Letterhead): string | null {
  if (!row.logo) return null;
  const base = process.env.NEXT_PUBLIC_POCKETBASE_URL || "http://127.0.0.1:8090";
  return `${base}/api/files/${row.collectionId}/${row.id}/${row.logo}`;
}

/** Default accent for a code if the row has no `accent_color` set. */
export function defaultAccentFor(code: LetterheadCode): string {
  return code === "CNL" ? "#738224" : "#7ed957";
}

/**
 * Load the company logo SVG from `public/letterhead/<code>.svg` and
 * return it as a `data:image/svg+xml;base64,...` URI suitable for
 * `<Image src={...}>` in @react-pdf.
 *
 * We embed SVG instead of the original raster (PNG/JPEG) logos because
 * @react-pdf/renderer v4.5.1 has a confirmed byte-corruption bug that
 * replaces every byte ≥ 0x80 in raster image data with `0xFD`. SVG is
 * text-based, so it sidesteps that code path — @react-pdf parses the
 * SVG XML and embeds vector primitives directly into the PDF stream.
 *
 * **Base64, not URL-encoded.** The bundled PDFKit only matches
 * `^data:.+?;base64,(.*)$` when decoding inline data URIs (see
 * `PDFImage.open` in `@react-pdf/pdfkit/lib/pdfkit.js`). A
 * `;charset=utf-8,<urlencoded>` URI is treated as a filesystem path
 * and silently dropped. Base64 it is — yes, the data URI is ~33%
 * bigger than URL-encoded, but for a 1x-per-quote render that's
 * a non-issue.
 *
 * Returns `null` if the file is missing or unreadable — that's a
 * non-fatal degradation (the PDF still renders, just without a logo),
 * so callers should treat it as best-effort.
 */
export async function loadLetterheadLogoDataUri(
  code: LetterheadCode
): Promise<string | null> {
  try {
    const filePath = path.join(
      process.cwd(),
      "public",
      "letterhead",
      `${code.toLowerCase()}.svg`
    );
    const raw = await readFile(filePath);
    return `data:image/svg+xml;base64,${raw.toString("base64")}`;
  } catch (err) {
    console.warn(`[letterhead] could not load logo for ${code}:`, err);
    return null;
  }
}