import {
  BadRequestException,
  Controller,
  Delete,
  Get,
  HttpCode,
  Param,
  Post,
  Req,
  Res,
  UploadedFiles,
  UseGuards,
  UseInterceptors,
} from '@nestjs/common';
import { AnyFilesInterceptor } from '@nestjs/platform-express';
import {
  CustomFontView,
  FONT_WEIGHTS,
  MAX_FONT_FILE_BYTES,
  createCustomFontInputSchema,
} from '@dorfteich/shared';
import type { Response } from 'express';

import { SiteAdminGuard } from '../admin/site-admin.guard';
import { AuthedRequest, Public } from '../auth/auth.guard';
import { AuthenticatedOnly } from '../permissions/permission.decorators';
import { CustomFontStorageService } from './custom-font-storage.service';
import { CustomFontsService, WeightUpload } from './custom-fonts.service';

/** Multipart field names: `woff2-<weight>` and the optional `woff-<weight>`. */
const FILE_FIELD = /^(woff2|woff)-(\d{3})$/;

function parseUploads(files: Express.Multer.File[] | undefined): WeightUpload[] {
  const byWeight = new Map<number, WeightUpload>();
  for (const file of files ?? []) {
    const match = FILE_FIELD.exec(file.fieldname);
    if (!match) throw new BadRequestException({ code: 'font_unexpected_field' });
    const weight = Number(match[2]);
    if (!(FONT_WEIGHTS as readonly number[]).includes(weight)) {
      throw new BadRequestException({ code: 'font_weight_invalid' });
    }
    const entry = byWeight.get(weight) ?? { weight, woff2: Buffer.alloc(0) };
    if (match[1] === 'woff2') entry.woff2 = file.buffer;
    else entry.woff = file.buffer;
    byWeight.set(weight, entry);
  }
  // A WOFF without its WOFF2 would produce a weight the PDF path cannot
  // embed — the exporter reads WOFF2 only.
  for (const entry of byWeight.values()) {
    if (entry.woff2.length === 0) throw new BadRequestException({ code: 'font_woff2_missing' });
  }
  return [...byWeight.values()].sort((a, b) => a.weight - b.weight);
}

/** Site-Admin management of operator-uploaded fonts (issue #303). */
@Controller('admin/fonts')
@UseGuards(SiteAdminGuard)
export class CustomFontsAdminController {
  constructor(private readonly fonts: CustomFontsService) {}

  @Get()
  list(): Promise<CustomFontView[]> {
    return this.fonts.list();
  }

  @Post()
  @UseInterceptors(AnyFilesInterceptor({ limits: { fileSize: MAX_FONT_FILE_BYTES } }))
  async create(
    @Req() request: AuthedRequest,
    @UploadedFiles() files: Express.Multer.File[] | undefined,
  ): Promise<CustomFontView> {
    // The metadata rides as ordinary multipart fields next to the files.
    const input = createCustomFontInputSchema.parse({
      family: request.body?.family,
      category: request.body?.category,
      licence: request.body?.licence,
      licenceUrl: request.body?.licenceUrl || null,
    });
    return this.fonts.create(request.user!, input, parseUploads(files));
  }

  @Post(':id/weights')
  @UseInterceptors(AnyFilesInterceptor({ limits: { fileSize: MAX_FONT_FILE_BYTES } }))
  async addWeight(
    @Param('id') id: string,
    @Req() request: AuthedRequest,
    @UploadedFiles() files: Express.Multer.File[] | undefined,
  ): Promise<CustomFontView> {
    const uploads = parseUploads(files);
    if (uploads.length !== 1) throw new BadRequestException({ code: 'font_one_weight_expected' });
    return this.fonts.addWeight(request.user!, id, uploads[0]!);
  }

  /** How many live ponds still use the family — shown before deleting. */
  @Get(':id/usage')
  async usage(@Param('id') id: string): Promise<{ pondsAffected: number }> {
    const font = (await this.fonts.list()).find((entry) => entry.id === id);
    if (!font) throw new BadRequestException({ code: 'not_found' });
    return { pondsAffected: await this.fonts.pondsUsing(font.family) };
  }

  @Delete(':id')
  @HttpCode(204)
  async remove(@Param('id') id: string, @Req() request: AuthedRequest): Promise<void> {
    await this.fonts.remove(request.user!, id);
  }
}

/**
 * Reading side of the uploaded fonts: the family list every signed-in user
 * needs, and the bytes themselves.
 *
 * The listing is NOT site-admin-gated (issue #304): every signed-in user picks
 * fonts in their pond's Appearance settings, reads the licence page, and needs
 * the `@font-face` rules injected — the admin list at `/admin/fonts` carries
 * the same data, so gating this one would only force a second, admin-only UI.
 *
 * The file route is unauthenticated on purpose: a font is referenced from CSS,
 * and the login screen carries the pond-independent chrome — an authenticated
 * font URL would simply not load. The bytes are branding, not content.
 */
@Controller('fonts/custom')
export class CustomFontsFileController {
  constructor(
    private readonly storage: CustomFontStorageService,
    private readonly fonts: CustomFontsService,
  ) {}

  // Explicit access declaration, as every route needs (issue #52's fence
  // `route-permissions.e2e.db.test.ts`): a session, no further permission —
  // the list says which families exist, which is what the pickers offer.
  @AuthenticatedOnly()
  @Get()
  list(): Promise<CustomFontView[]> {
    return this.fonts.list();
  }

  @Public()
  @Get(':slug/:file')
  async serve(
    @Param('slug') slug: string,
    @Param('file') file: string,
    @Res() res: Response,
  ): Promise<void> {
    const match = /^([a-z0-9-]+)-(\d{3})\.(woff2|woff)$/.exec(file);
    // The slug must match the file's own prefix, so the path cannot be used
    // to reach a different family's directory.
    if (!match || match[1] !== slug) throw new BadRequestException({ code: 'not_found' });

    const known = (await this.fonts.list()).find((entry) => entry.slug === slug);
    if (!known) throw new BadRequestException({ code: 'not_found' });

    const format = match[3] as 'woff2' | 'woff';
    const bytes = await this.storage
      .read(slug, Number(match[2]), format)
      .catch(() => Promise.reject(new BadRequestException({ code: 'not_found' })));

    res.setHeader('Content-Type', format === 'woff2' ? 'font/woff2' : 'font/woff');
    // Slug + weight + format identify the bytes; a changed family is a new
    // upload under a new id, so a long lifetime is safe.
    res.setHeader('Cache-Control', 'public, max-age=31536000, immutable');
    res.send(bytes);
  }
}