import {
  BadRequestException,
  Body,
  Controller,
  Delete,
  ForbiddenException,
  Get,
  Param,
  Post,
  Put,
  Req,
  UploadedFile,
  UseInterceptors,
} from '@nestjs/common';
import { FileInterceptor } from '@nestjs/platform-express';
import { decodeUploadFilename } from '../accounting/decode-upload-filename';
import type { AuthenticatedRequest, UploadedFileLike } from '../auth/types/auth-user';
import { ModuleManage, UseModule } from '../module-registry/module.guard';
import { HandelswareAccountDto } from './dto/handelsware-account.dto';
import { HandelswareSettingsDto } from './dto/handelsware-settings.dto';
import { HandelswareDatevService } from './handelsware-datev.service';

const MAX_NEW_ACCOUNTS = 10_000;

/**
 * Das Formularfeld `newAccounts` ist ein JSON-Text (Liste der von der Vorschau
 * gemeldeten neuen Konten). Defensiv gelesen: gueltiges JSON, ein Feld, hoechstens
 * 10 000 Eintraege, jeder mit Text-`name` und ganzzahligem `gegenkonto`.
 */
export function parseNewAccountsField(raw: unknown): { name: string; gegenkonto: number }[] {
  const bad = () =>
    new BadRequestException({
      code: 'newAccountsInvalid',
      message: 'Die Angaben zu den neuen Konten sind ungültig.',
    });
  if (raw === undefined || raw === null || raw === '') return [];
  if (typeof raw !== 'string') throw bad();
  let parsed: unknown;
  try {
    parsed = JSON.parse(raw);
  } catch {
    throw bad();
  }
  if (!Array.isArray(parsed) || parsed.length > MAX_NEW_ACCOUNTS) throw bad();
  return parsed.map((entry) => {
    if (
      typeof entry !== 'object' ||
      entry === null ||
      typeof (entry as { name?: unknown }).name !== 'string' ||
      !Number.isInteger((entry as { gegenkonto?: unknown }).gegenkonto)
    ) {
      throw bad();
    }
    const { name, gegenkonto } = entry as { name: string; gegenkonto: number };
    return { name, gegenkonto };
  });
}

/**
 * `@UseModule('handelsware-datev')` auf Klassenebene — Aktivierung UND Freigabe.
 * `tenantId` kommt ausschliesslich aus `req.tenantId`. Die Einstellungen aendern
 * Administratoren und Benutzer mit der Freigabestufe Verwalten
 * (`@ModuleManage`, 261002-icv; T-FM5-02); die Kontenliste pflegen alle Benutzer mit
 * Modulzugriff.
 *
 * REIHENFOLGE: alle statischen Routen (`accounts`, `accounts/export-csv`,
 * `accounts/import-csv`) stehen VOR `accounts/:id` — sonst faengt `:id` sie ab
 * (Unit-Tests sehen das nicht, `handelsware-datev.controller.spec.ts` prueft die
 * Deklarationsreihenfolge).
 */
@Controller('modules/handelsware-datev')
@UseModule('handelsware-datev')
export class HandelswareDatevController {
  constructor(private readonly service: HandelswareDatevService) {}

  private requireTenantId(req: AuthenticatedRequest): string {
    const tenantId = req.tenantId;
    if (!tenantId) {
      throw new ForbiddenException('Kein Mandantenkontext');
    }
    return tenantId;
  }

  @Get('settings')
  async getSettings(@Req() req: AuthenticatedRequest) {
    return this.service.getSettings(this.requireTenantId(req));
  }

  @Put('settings')
  @ModuleManage('handelsware-datev')
  async saveSettings(@Req() req: AuthenticatedRequest, @Body() dto: HandelswareSettingsDto) {
    return this.service.saveSettings(this.requireTenantId(req), dto);
  }

  @Post('preview')
  @UseInterceptors(FileInterceptor('file', { limits: { fileSize: 5 * 1024 * 1024 } }))
  async preview(
    @Req() req: AuthenticatedRequest,
    @UploadedFile() file: UploadedFileLike | undefined,
  ) {
    const tenantId = this.requireTenantId(req);
    if (!file) {
      throw new BadRequestException('Keine Datei hochgeladen');
    }
    return this.service.preview(tenantId, {
      buffer: file.buffer,
      originalname: decodeUploadFilename(file.originalname),
    });
  }

  @Post('export')
  @UseInterceptors(FileInterceptor('file', { limits: { fileSize: 5 * 1024 * 1024 } }))
  async export(
    @Req() req: AuthenticatedRequest,
    @UploadedFile() file: UploadedFileLike | undefined,
    @Body('buchungsdatum') buchungsdatum?: string,
    @Body('newAccounts') newAccounts?: string,
  ) {
    const tenantId = this.requireTenantId(req);
    if (!file) {
      throw new BadRequestException('Keine Datei hochgeladen');
    }
    return this.service.export(
      tenantId,
      { buffer: file.buffer, originalname: decodeUploadFilename(file.originalname) },
      typeof buchungsdatum === 'string' ? buchungsdatum.trim() : '',
      parseNewAccountsField(newAccounts),
    );
  }

  @Get('accounts')
  async listAccounts(@Req() req: AuthenticatedRequest) {
    return this.service.listAccounts(this.requireTenantId(req));
  }

  @Post('accounts')
  async createAccount(@Req() req: AuthenticatedRequest, @Body() dto: HandelswareAccountDto) {
    return this.service.createAccount(this.requireTenantId(req), dto);
  }

  @Get('accounts/export-csv')
  async exportAccountsCsv(@Req() req: AuthenticatedRequest) {
    return this.service.exportAccountsCsv(this.requireTenantId(req));
  }

  @Post('accounts/import-csv')
  @UseInterceptors(FileInterceptor('file', { limits: { fileSize: 1024 * 1024 } }))
  async importAccountsCsv(
    @Req() req: AuthenticatedRequest,
    @UploadedFile() file: UploadedFileLike | undefined,
  ) {
    const tenantId = this.requireTenantId(req);
    if (!file) {
      throw new BadRequestException('Keine Datei hochgeladen');
    }
    return this.service.importAccountsCsv(tenantId, file.buffer);
  }

  @Put('accounts/:id')
  async updateAccount(
    @Req() req: AuthenticatedRequest,
    @Param('id') id: string,
    @Body() dto: HandelswareAccountDto,
  ) {
    return this.service.updateAccount(this.requireTenantId(req), id, dto);
  }

  @Delete('accounts/:id')
  async deleteAccount(@Req() req: AuthenticatedRequest, @Param('id') id: string) {
    return this.service.deleteAccount(this.requireTenantId(req), id);
  }
}