import type { IncomingMessage, ServerResponse } from 'node:http';
import type { HostApiContext } from '../context';
import { sendJson } from '../route-utils';
import { WORKS_SQUARE_CONFIG } from '../works-config';
import { getValidWorksSquareAccessToken } from '../../services/works-square-session';
import { proxyAwareFetch } from '../../utils/proxy-fetch';

const LOCAL_ROOT = '/api/works/image-prompt-museum';
const UPSTREAM_ROOT = '/api/image-prompt-museum';
const LIST_QUERY_KEYS = ['q', 'use_case', 'style', 'subject', 'language', 'model', 'cursor', 'limit'] as const;
const MAX_QUERY_VALUE_LENGTH = 256;

type PromptMuseumRouteDependencies = {
  fetchImpl?: typeof fetch;
  getAccessToken?: typeof getValidWorksSquareAccessToken;
  apiBaseUrl?: string;
};

function isMuseumPath(pathname: string): boolean {
  return pathname === LOCAL_ROOT || /^\/api\/works\/image-prompt-museum\/[^/]+$/.test(pathname);
}

function upstreamPath(pathname: string): string | null {
  if (pathname === LOCAL_ROOT) return UPSTREAM_ROOT;
  const entryId = pathname.slice(`${LOCAL_ROOT}/`.length);
  if (!entryId) return null;
  return `${UPSTREAM_ROOT}/${encodeURIComponent(decodeURIComponent(entryId))}`;
}

function copyAllowedQuery(source: URL): string {
  const query = new URLSearchParams();
  for (const key of LIST_QUERY_KEYS) {
    const value = source.searchParams.get(key)?.trim();
    if (!value || value.length > MAX_QUERY_VALUE_LENGTH) continue;
    query.set(key, value);
  }
  const encoded = query.toString();
  return encoded ? `?${encoded}` : '';
}

async function readPayload(response: Response): Promise<unknown> {
  try {
    return await response.json();
  } catch {
    return null;
  }
}

function errorMessage(payload: unknown, fallback: string): string {
  if (typeof payload === 'object' && payload !== null && !Array.isArray(payload)) {
    const value = (payload as Record<string, unknown>).error;
    if (typeof value === 'string' && value.trim()) return value;
  }
  return fallback;
}

export function createImagePromptMuseumRouteHandler(
  dependencies: PromptMuseumRouteDependencies = {},
) {
  const fetchImpl = dependencies.fetchImpl ?? proxyAwareFetch;
  const getAccessToken = dependencies.getAccessToken ?? getValidWorksSquareAccessToken;
  const apiBaseUrl = (dependencies.apiBaseUrl ?? WORKS_SQUARE_CONFIG.apiBaseUrl).replace(/\/+$/, '');

  return async function handleImagePromptMuseumRoutes(
    req: IncomingMessage,
    res: ServerResponse,
    url: URL,
    _ctx: HostApiContext,
  ): Promise<boolean> {
    if (!isMuseumPath(url.pathname)) return false;
    if (req.method !== 'GET') {
      sendJson(res, 405, {
        success: false,
        code: 'PROMPT_MUSEUM_METHOD_NOT_ALLOWED',
        error: '提示词博物馆只支持读取',
      });
      return true;
    }

    const path = upstreamPath(url.pathname);
    if (!path) {
      sendJson(res, 404, {
        success: false,
        code: 'PROMPT_MUSEUM_NOT_FOUND',
        error: '提示词条目不存在',
      });
      return true;
    }

    try {
      const token = await getAccessToken({ fetchImpl });
      if (!token) {
        sendJson(res, 401, {
          success: false,
          status: 401,
          code: 'PROMPT_MUSEUM_AUTH_REQUIRED',
          error: '请先登录后再获取灵感',
        });
        return true;
      }

      const request = (accessToken: string) => fetchImpl(
        `${apiBaseUrl}${path}${url.pathname === LOCAL_ROOT ? copyAllowedQuery(url) : ''}`,
        {
          method: 'GET',
          headers: {
            Accept: 'application/json',
            Authorization: `Bearer ${accessToken}`,
          },
          redirect: 'manual',
        },
      );

      let response = await request(token);
      if (response.status === 401) {
        await response.body?.cancel().catch(() => undefined);
        const refreshed = await getAccessToken({ fetchImpl, forceRefresh: true });
        if (refreshed) response = await request(refreshed);
      }

      const payload = await readPayload(response);
      if (!response.ok) {
        sendJson(res, response.status, {
          success: false,
          status: response.status,
          code: typeof payload === 'object' && payload !== null && !Array.isArray(payload)
            && typeof (payload as Record<string, unknown>).code === 'string'
            ? (payload as Record<string, unknown>).code
            : response.status === 404 ? 'PROMPT_MUSEUM_NOT_FOUND' : 'PROMPT_MUSEUM_UNAVAILABLE',
          error: errorMessage(payload, '提示词博物馆暂时不可用'),
        });
        return true;
      }

      if (payload === null) {
        sendJson(res, 502, {
          success: false,
          status: 502,
          code: 'PROMPT_MUSEUM_INVALID_RESPONSE',
          error: '提示词博物馆返回了无效数据',
        });
        return true;
      }
      sendJson(res, response.status, payload);
      return true;
    } catch (error) {
      sendJson(res, 502, {
        success: false,
        status: 502,
        code: 'PROMPT_MUSEUM_UNAVAILABLE',
        error: error instanceof Error ? error.message : '提示词博物馆暂时不可用',
      });
      return true;
    }
  };
}

export const handleImagePromptMuseumRoutes = createImagePromptMuseumRouteHandler();