import { mkdir, readFile, rm, writeFile } from 'node:fs/promises';
import { join } from 'node:path';

import { Injectable } from '@nestjs/common';
import type { FontUploadFormat } from '@dorfteich/shared';

import { AppConfig } from '../config/app-config.service';

/**
 * Filesystem binding for operator-uploaded fonts (issue #303, ADR 0016 §#303).
 *
 * The layout mirrors the baked-in catalog — `<slug>/<slug>-<weight>.woff2` —
 * so the PDF exporter's `@font-face` builder needs no special case beyond
 * choosing the directory.
 *
 * That directory is `CUSTOM_FONTS_DIR`, NOT `FONTS_DIR`: the latter is baked
 * into the image, so anything written there disappears on the next deploy and
 * never reaches a backup. This one is a sibling of the uploads and plugins
 * mounts and travels in the restore set (`apps/backup/src/data-dirs.ts`).
 */
@Injectable()
export class CustomFontStorageService {
  constructor(private readonly config: AppConfig) {}

  private dirFor(slug: string): string {
    return join(this.config.env.CUSTOM_FONTS_DIR, slug);
  }

  fileNameFor(slug: string, weight: number, format: FontUploadFormat): string {
    return `${slug}-${weight}.${format}`;
  }

  pathFor(slug: string, weight: number, format: FontUploadFormat): string {
    return join(this.dirFor(slug), this.fileNameFor(slug, weight, format));
  }

  async save(slug: string, weight: number, format: FontUploadFormat, bytes: Buffer): Promise<void> {
    await mkdir(this.dirFor(slug), { recursive: true });
    await writeFile(this.pathFor(slug, weight, format), bytes);
  }

  read(slug: string, weight: number, format: FontUploadFormat): Promise<Buffer> {
    return readFile(this.pathFor(slug, weight, format));
  }

  /** Removes the family's whole directory. Missing is fine — deletion must
   * stay idempotent so a half-failed upload can still be cleaned up. */
  async deleteFamily(slug: string): Promise<void> {
    await rm(this.dirFor(slug), { recursive: true, force: true });
  }

  async deleteWeight(slug: string, weight: number, format: FontUploadFormat): Promise<void> {
    await rm(this.pathFor(slug, weight, format), { force: true });
  }
}