import { INestApplication } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { DocumentBuilder, OpenAPIObject, SwaggerModule } from '@nestjs/swagger';
import {
  PIREON_BEARER,
  PIREON_OAUTH,
} from '@task-stream/api/identity/presenters';
import { writeFileSync } from 'node:fs';
import { join } from 'node:path';

export const API_VERSION = '1.0.0';

const DESCRIPTION = `
REST API of **Pireon TaskStream** for other apps: projects, tickets (bugs, features,
UI changes, tasks and QA), workflow, comments, relations and releases.

### Authentication
Every endpoint (except \`/auth\`, \`/health\` and the webhook) needs a **Pireon access
token**, so any app or user that consumes it goes through Pireon's OAuth:

- **Authorization Code + PKCE** against \`oauth.pireon.dev/oauth/authorize\`
  (the "Authorize" button here uses it; register \`<api>/api/docs/oauth2-redirect.html\`
  as a redirect URI of the client).
- An app with its own Pireon OAuth client can get tokens from Pireon directly and
  send them as \`Authorization: Bearer <token>\`.

What you can see and change depends on your role in each project.

### Writes are eventually consistent
Commands answer \`{ id, key?, version }\` as soon as the event is stored. Reads come from
a read model that catches up in milliseconds: a \`GET\` right after a write may still
show the previous version (or 404 right after a create).

### Real time
For live updates use the GraphQL subscriptions at \`/graphql\` (graphql-ws).
`.trim();

export interface OpenApiSettings {
  pireonBaseUrl: string;
  scopes: string[];
  passwordGrant: boolean;
}

/** The OpenAPI document of the REST controllers. Needs no database. */
export function buildOpenApiDocument(
  app: INestApplication,
  settings: OpenApiSettings,
): OpenAPIObject {
  const pireon = settings.pireonBaseUrl;
  const scopes = settings.scopes;
  const scopeDocs = Object.fromEntries(
    scopes.map((scope) => [
      scope,
      scope === 'users:read' ? 'Search Pireon users' : scope,
    ]),
  );
  // Token requests go through the API's proxy: Pireon's /oauth/token has no
  // CORS and the client secret stays on the server.
  const tokenUrl = '/api/auth/token';

  const document = SwaggerModule.createDocument(
    app,
    new DocumentBuilder()
      .setTitle('Pireon TaskStream API')
      .setDescription(DESCRIPTION)
      .setVersion(API_VERSION)
      .addServer('/', 'This server (the paths already include /api)')
      .addOAuth2(
        {
          type: 'oauth2',
          description: 'Pireon OAuth2 (Laravel Passport)',
          flows: {
            authorizationCode: {
              authorizationUrl: `${pireon}/oauth/authorize`,
              tokenUrl,
              refreshUrl: tokenUrl,
              scopes: scopeDocs,
            },
            ...(settings.passwordGrant
              ? {
                  password: {
                    tokenUrl,
                    refreshUrl: tokenUrl,
                    scopes: scopeDocs,
                  },
                }
              : {}),
          },
        },
        PIREON_OAUTH,
      )
      .addBearerAuth(
        {
          type: 'http',
          scheme: 'bearer',
          description: 'A Pireon access token obtained elsewhere',
        },
        PIREON_BEARER,
      )
      .addTag('Projects', 'Projects, members, board, stats and activity')
      .addTag(
        'Issues',
        'Tickets: search, create, workflow, relations, comments',
      )
      .addTag('Comments', 'Edit and delete comments')
      .addTag('Releases', 'Versions that group tickets')
      .addTag('Users', 'The signed-in user and the Pireon directory')
      .addTag('Auth', 'Pireon OAuth token proxy')
      .addTag('Health', 'Liveness of the API and its databases')
      .addTag('Webhooks', 'Called by Pireon')
      .build(),
  );

  // Operations without a security requirement are the public ones (@Public():
  // health, auth, webhook). Say so explicitly instead of leaving it undefined.
  for (const path of Object.values(document.paths)) {
    for (const operation of [
      path.get,
      path.post,
      path.put,
      path.patch,
      path.delete,
    ]) {
      if (operation && !operation.security) operation.security = [];
    }
  }

  return document;
}

/**
 * Builds the OpenAPI document from the REST controllers, serves Swagger UI and
 * (in development) writes it to OPENAPI_FILE so other apps can generate clients.
 */
export function setupOpenApi(app: INestApplication): void {
  const config = app.get(ConfigService);
  if (!config.get<boolean>('SWAGGER_ENABLED')) return;

  const scopes = (config.get<string>('PIREON_SCOPES') ?? '')
    .split(/[\s,]+/)
    .filter(Boolean);
  const document = buildOpenApiDocument(app, {
    pireonBaseUrl:
      config.get<string>('PIREON_BASE_URL') ?? 'https://oauth.pireon.dev',
    scopes,
    passwordGrant: !!config.get<boolean>('PIREON_PASSWORD_GRANT'),
  });

  const file = config.get<string>('OPENAPI_FILE');
  if (file) {
    writeFileSync(
      join(process.cwd(), file),
      JSON.stringify(document, null, 2) + '\n',
    );
  }

  SwaggerModule.setup('api/docs', app, document, {
    jsonDocumentUrl: 'api/docs-json',
    yamlDocumentUrl: 'api/docs-yaml',
    customSiteTitle: 'Pireon TaskStream API',
    swaggerOptions: {
      persistAuthorization: true,
      initOAuth: {
        clientId: config.get<string>('PIREON_CLIENT_ID') || undefined,
        scopes,
        usePkceWithAuthorizationCodeGrant: true,
      },
    },
    // The Pireon look, as in the web app.
    customCss: `
      @import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&display=swap');
      .swagger-ui, .swagger-ui .info .title, .swagger-ui .opblock-tag { font-family: Inter, system-ui, sans-serif; }
      .swagger-ui .topbar { display: none; }
      .swagger-ui .info .title { background: linear-gradient(100deg, #a347e1, #1879bf); -webkit-background-clip: text; background-clip: text; color: transparent; }
      .swagger-ui .btn.authorize { color: #a347e1; border-color: #a347e1; }
      .swagger-ui .btn.authorize svg { fill: #a347e1; }
    `,
  });
}