import type { IncomingMessage, ServerResponse } from 'node:http';
import { ProjectPluginServiceError } from '../../coding-plugins/project-service';
import { CodingProjectServiceError } from '../../coding-projects/project-service';
import type { HostApiContext } from '../context';
import { parseJsonBody, sendJson } from '../route-utils';
import { CodingProjectPluginServiceError } from '../coding-product-services';

const PLUGIN_ROUTE = /^\/api\/coding\/plugins\/([^/]+)$/u;
const PLUGIN_ID_PATTERN = /^[a-z][a-z0-9.-]{0,127}$/u;

class CodingPluginRouteError extends Error {
  constructor(
    readonly status: 400 | 404 | 503,
    readonly code: string,
    message: string,
  ) {
    super(message);
    this.name = 'CodingPluginRouteError';
  }
}

function requestError(message: string): never {
  throw new CodingPluginRouteError(400, 'plugin_request_invalid', message);
}

function exactProjectId(url: URL): string {
  if ([...url.searchParams.keys()].some((key) => key !== 'projectId')
    || url.searchParams.getAll('projectId').length !== 1) {
    return requestError('GET requires exactly one projectId query parameter');
  }
  const projectId = url.searchParams.get('projectId')?.trim() ?? '';
  if (!projectId || projectId.length > 128) return requestError('projectId is invalid');
  return projectId;
}

function exactPutBody(value: unknown): { projectId: string; enabled: boolean } {
  if (!value || typeof value !== 'object' || Array.isArray(value)) {
    return requestError('Request body must be an object');
  }
  const body = value as Record<string, unknown>;
  const keys = Object.keys(body).sort();
  if (keys.length !== 2 || keys[0] !== 'enabled' || keys[1] !== 'projectId') {
    return requestError('Request body must contain only projectId and enabled');
  }
  if (typeof body.projectId !== 'string' || !body.projectId.trim() || body.projectId.length > 128) {
    return requestError('projectId is invalid');
  }
  if (typeof body.enabled !== 'boolean') return requestError('enabled is invalid');
  return { projectId: body.projectId.trim(), enabled: body.enabled };
}

function routePluginId(value: string): string {
  let id: string;
  try {
    id = decodeURIComponent(value).trim();
  } catch {
    return requestError('plugin id is invalid');
  }
  if (!PLUGIN_ID_PATTERN.test(id)) return requestError('plugin id is invalid');
  return id;
}

function sendError(res: ServerResponse, error: unknown): void {
  if (error instanceof CodingPluginRouteError || error instanceof CodingProjectPluginServiceError) {
    sendJson(res, error.status, { success: false, code: error.code, error: error.message });
    return;
  }
  if (error instanceof CodingProjectServiceError) {
    sendJson(res, error.status, { success: false, code: error.code, error: error.message });
    return;
  }
  if (error instanceof ProjectPluginServiceError) {
    const status = error.code === 'CODING_PLUGIN_UNKNOWN' ? 404
      : error.code === 'CODING_PLUGIN_SELECTION_WRITE_FAILED' ? 500
        : 400;
    const code = error.code === 'CODING_PLUGIN_UNKNOWN' ? 'plugin_not_found'
      : error.code === 'CODING_PLUGIN_SELECTION_WRITE_FAILED' ? 'plugin_selection_write_failed'
        : 'plugin_request_invalid';
    sendJson(res, status, { success: false, code, error: error.message });
    return;
  }
  if (error instanceof SyntaxError) {
    sendJson(res, 400, { success: false, code: 'plugin_request_invalid', error: 'Request body is invalid' });
    return;
  }
  sendJson(res, 503, {
    success: false,
    code: 'plugin_backend_unavailable',
    error: 'Plugin service is temporarily unavailable',
  });
}

export async function handleCodingPluginRoutes(
  req: IncomingMessage,
  res: ServerResponse,
  url: URL,
  ctx: HostApiContext,
): Promise<boolean> {
  if (url.pathname !== '/api/coding/plugins' && !PLUGIN_ROUTE.test(url.pathname)) return false;
  const plugins = ctx.codingProducts?.plugins;
  if (!plugins) {
    sendJson(res, 503, {
      success: false,
      code: 'plugin_backend_unavailable',
      error: 'Plugin service is temporarily unavailable',
    });
    return true;
  }
  try {
    if (url.pathname === '/api/coding/plugins' && req.method === 'GET') {
      sendJson(res, 200, await plugins.list(exactProjectId(url)));
      return true;
    }
    const match = PLUGIN_ROUTE.exec(url.pathname);
    if (match && req.method === 'PUT') {
      if (url.search) requestError('PUT does not accept query parameters');
      const body = exactPutBody(await parseJsonBody<unknown>(req));
      sendJson(res, 200, await plugins.setEnabled(
        body.projectId,
        routePluginId(match[1]),
        body.enabled,
      ));
      return true;
    }
    return false;
  } catch (error) {
    sendError(res, error);
    return true;
  }
}