import {
  Body,
  Controller,
  Get,
  HttpCode,
  Post,
  UnauthorizedException,
} from '@nestjs/common';
import {
  ApiBody,
  ApiConsumes,
  ApiOkResponse,
  ApiOperation,
  ApiProperty,
  ApiTags,
  ApiUnauthorizedResponse,
} from '@nestjs/swagger';
import {
  IdentityService,
  InvalidCredentialsError,
} from '@task-stream/api/identity/application';
import {
  AuthorizationConfig,
  TokenGrant,
  TokenSet,
} from '@task-stream/api/identity/domain';
import { Public } from '../auth/auth.decorators';
import { IssueTokenDto } from './dto/issue-token.dto';

export class AuthorizationConfigDto {
  @ApiProperty({ example: 'https://oauth.pireon.dev/oauth/authorize' })
  authorizeUrl!: string;
  @ApiProperty({
    type: String,
    nullable: true,
    description:
      'Public id of the authorization_code client ("Sign in with Pireon"); null when only email + password is configured',
  })
  clientId!: string | null;
  @ApiProperty({ type: [String], example: ['users:read'] })
  scopes!: string[];
  @ApiProperty({ description: 'Whether email + password sign-in is allowed' })
  passwordGrant!: boolean;
}

export class TokenResponseDto {
  @ApiProperty() access_token!: string;
  @ApiProperty({ type: String, nullable: true }) refresh_token!: string | null;
  @ApiProperty({ description: 'Seconds' }) expires_in!: number;
  @ApiProperty({ example: 'Bearer' }) token_type!: string;
}

/**
 * Sign-in for browsers. Pireon's /oauth/token has no CORS and the client
 * secret must stay server-side, so the web app goes through here.
 */
@ApiTags('Auth')
@Controller('auth')
export class AuthController {
  constructor(private readonly identity: IdentityService) {}

  /** What the web app needs to start Authorization Code + PKCE (null = not configured). */
  @Public()
  @Get('config')
  @ApiOperation({
    summary: 'How to sign in with Pireon (null when not configured)',
  })
  @ApiOkResponse({ type: AuthorizationConfigDto })
  config(): Promise<AuthorizationConfig | null> {
    return this.identity.authorizationConfig();
  }

  @Public()
  @Post('token')
  @HttpCode(200)
  @ApiOperation({
    summary:
      'Exchange a grant for Pireon tokens (proxy of Pireon /oauth/token)',
    description:
      'For browsers (Pireon has no CORS) and Swagger UI: adds the client secret ' +
      'server-side. Apps with their own Pireon OAuth client can get tokens from ' +
      'Pireon directly; any valid Pireon access token is accepted by this API.',
  })
  @ApiConsumes('application/json', 'application/x-www-form-urlencoded')
  @ApiBody({ type: IssueTokenDto })
  @ApiOkResponse({ type: TokenResponseDto })
  @ApiUnauthorizedResponse({ description: 'Pireon rejected the grant' })
  async token(@Body() dto: IssueTokenDto) {
    try {
      return toResponse(await this.identity.issueToken(toGrant(dto)));
    } catch (error) {
      if (error instanceof InvalidCredentialsError)
        throw new UnauthorizedException(error.message);
      throw error;
    }
  }
}

function toGrant(dto: IssueTokenDto): TokenGrant {
  switch (dto.grant_type) {
    case 'authorization_code':
      return {
        type: 'authorization_code',
        code: dto.code as string,
        codeVerifier: dto.code_verifier as string,
        redirectUri: dto.redirect_uri as string,
      };
    case 'password':
      return {
        type: 'password',
        username: dto.username as string,
        password: dto.password as string,
      };
    case 'refresh_token':
      return {
        type: 'refresh_token',
        refreshToken: dto.refresh_token as string,
      };
  }
}

/** Standard OAuth2 token response. */
function toResponse(token: TokenSet) {
  return {
    access_token: token.accessToken,
    refresh_token: token.refreshToken,
    expires_in: token.expiresIn,
    token_type: token.tokenType,
  };
}