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 / brand has exactly one row. 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 / DN / PO without a code deploy.
 */
export type LetterheadCode = "CNL" | "ISHERWOOD" | "WESTSCOTT GROUP OF COMPANIES";

export const LETTERHEAD_CODES: readonly LetterheadCode[] = [
  "CNL",
  "ISHERWOOD",
  "WESTSCOTT GROUP OF COMPANIES",
] as const;

/**
 * Canonical letterhead for ALL delivery-note PDFs, regardless of
 * which subsidiary the customer belongs to. The subsidiary name
 * still appears in the PDF meta block (so the printed document
 * tells the driver which subsidiary the delivery is for) but the
 * letterhead/header is always the Westcott Group one.
 *
 * Centralised here so the delivery-notes service and the invoicing
 * API (which both render delivery-note PDFs) can't drift apart
 * again. If the brand ever needs to change, this is the only
 * constant to touch.
 */
export const DELIVERY_NOTE_LETTERHEAD_CODE: LetterheadCode =
  "WESTSCOTT GROUP OF COMPANIES";

/**
 * Helper that returns the canonical delivery-note letterhead code.
 * Use this anywhere a delivery-note PDF is being rendered so the
 * three-letter `?? "CNL"` fallbacks that used to live in the
 * invoicing API routes stay gone.
 */
export function deliveryNoteLetterheadCode(): LetterheadCode {
  return DELIVERY_NOTE_LETTERHEAD_CODE;
}

/**
 * Letterhead for Repair Request PDFs (the "send to supplier for
 * analysis" document). Always CNL — a repair request is a paper
 * document the office hands to the supplier with the machine, and
 * it identifies the *sender* (the office), not the recipient.
 * Centralised so the service layer + the (future) any-other
 * Repair Request renderer can't drift apart.
 */
export const REPAIR_REQUEST_LETTERHEAD_CODE: LetterheadCode = "CNL";

/**
 * Helper that returns the canonical Repair Request letterhead code.
 * Mirror of `deliveryNoteLetterheadCode()`.
 */
export function repairRequestLetterheadCode(): LetterheadCode {
  return REPAIR_REQUEST_LETTERHEAD_CODE;
}

/**
 * Pick the letterhead code that matches a given company name. The
 * invoice / delivery-note flows don't always carry an explicit
 * letterhead (the operator just hits "Send"), so we infer it from
 * the order's billing company — "ISHERWOOD" or "CNL" in the name
 * wins, otherwise we fall back to `null` and the caller decides
 * (typically defaulting to CNL).
 */
export function letterheadForCompany(companyName: string | undefined | null): LetterheadCode | null {
  const upper = (companyName ?? "").trim().toUpperCase();
  if (!upper) return null;
  if (upper.includes("ISHERWOOD")) return "ISHERWOOD";
  if (upper.includes("CNL")) return "CNL";
  return null;
}

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;
  /** VAT rate the company charges. 15 for VAT-registered, 0 for exempt / below threshold. */
  vat_percent: number;
}

/**
 * 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.
 *
 * The logo is embedded as SVG because `public/letterhead/<code>.svg`
 * IS an SVG source file — @react-pdf parses the XML and embeds vector
 * primitives. (An earlier version of this comment blamed a
 * "@react-pdf byte-corruption bug that replaces every byte ≥ 0x80 with
 * 0xFD" and used SVG as a workaround. The corruption was real but the
 * culprit was this app's own render pipeline — `pdf().toString()`
 * re-encodes the PDF as latin1, so U+FFFD replacement characters
 * truncated to 0xFD. Fixed by using `renderToBuffer()`; see the note
 * at the top of `lib/pdf/render.tsx`. Raster logos work again.)
 *
 * **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;
  }
}