/**
 * Dify 服务端 API 模块
 *
 * 提供 Node.js 服务端调用 FastAPI 后端的函数
 * 用于 Remix loader/action 中调用 Dify API
 *
 * 调用链路：
 * Remix Server → FastAPI /dify/* → Dify
 *
 * @module api/dify/client.server
 */

import { API_BASE_URL } from '~/config/api-config';

// ============================================================================
// 配置
// ============================================================================

/**
 * 获取环境变量的服务端函数
 */
const getServerEnvVar = (name: string, defaultValue: string = ''): string => {
    return process.env[name] || defaultValue;
};

/**
 * Dify API 客户端配置
 * 通过 FastAPI 后端的 /dify 路由代理访问 Dify
 */
const DIFY_CONFIG = {
    API_URL: `${API_BASE_URL}/dify`,
    API_KEY: getServerEnvVar('NEXT_PUBLIC_APP_KEY', ''),
    APP_ID: (() => {
        const rawAppId = getServerEnvVar('NEXT_PUBLIC_APP_ID', '');
        const match = rawAppId.match(/\/app\/([a-f0-9-]{36})/);
        return match ? match[1] : rawAppId;
    })(),
};

console.log('🔧 [Dify Server] 配置:', {
    apiUrl: DIFY_CONFIG.API_URL,
    apiBaseUrl: API_BASE_URL,
    appId: DIFY_CONFIG.APP_ID,
    configComplete: !!(DIFY_CONFIG.API_URL && DIFY_CONFIG.APP_ID)
});

// ============================================================================
// 基础请求函数
// ============================================================================

/**
 * Dify API 基础请求函数
 *
 * 使用 JWT 认证通过 FastAPI 代理访问 Dify
 *
 * @param endpoint - API 端点路径
 * @param options - fetch 请求选项
 * @param jwt - JWT 认证令牌
 * @returns Response 对象
 */
async function difyFetch(
    endpoint: string,
    options: RequestInit = {},
    jwt?: string
): Promise<Response> {
    const url = `${DIFY_CONFIG.API_URL}/${endpoint.replace(/^\//, '')}`;

    const headers: HeadersInit = {
        'Content-Type': 'application/json',
        ...options.headers,
    };

    if (jwt) {
        (headers as Record<string, string>)['Authorization'] = `Bearer ${jwt}`;
    } else {
        console.warn('⚠️ [Dify Server] 没有提供 JWT，请求可能失败');
    }

    const response = await fetch(url, {
        ...options,
        headers,
    });

    if (!response.ok) {
        const errorText = await response.text();
        console.error('❌ [Dify Server] Dify API 错误:', {
            status: response.status,
            statusText: response.statusText,
            error: errorText
        });

        if (response.status === 401) {
            throw new Error('JWT认证失败，请重新登录');
        }

        throw new Error(`Dify API Error: ${response.status} ${response.statusText}`);
    }

    return response;
}

// ============================================================================
// Dify API 客户端
// ============================================================================

/**
 * Dify 服务端 API 客户端
 *
 * 所有方法都需要传入 JWT 进行认证
 * user 参数由后端自动从 JWT 中提取
 */
export const difyClient = {
    /**
     * 获取应用参数
     */
    async getApplicationParameters(jwt?: string): Promise<any> {
        const response = await difyFetch('parameters', {
            method: 'GET',
        }, jwt);
        return response.json();
    },

    /**
     * 获取会话列表
     */
    async getConversations(jwt?: string): Promise<any> {
        const params = new URLSearchParams({
            limit: '100',
            first_id: '',
        });

        const response = await difyFetch(`conversations?${params}`, {
            method: 'GET',
        }, jwt);
        return response.json();
    },

    /**
     * 获取会话消息
     */
    async getConversationMessages(conversationId: string, jwt?: string): Promise<any> {
        const params = new URLSearchParams({
            conversation_id: conversationId,
            limit: '20',
            last_id: '',
        });

        const response = await difyFetch(`messages?${params}`, {
            method: 'GET',
        }, jwt);
        return response.json();
    },

    /**
     * 发送聊天消息
     *
     * @param inputs - 输入参数
     * @param query - 用户问题
     * @param responseMode - 响应模式 ('streaming' | 'blocking')
     * @param conversationId - 会话 ID
     * @param files - 附件文件
     * @param jwt - JWT 认证令牌
     * @returns 对于流式响应返回 Response 对象，否则返回 JSON
     */
    async createChatMessage(
        inputs: Record<string, any>,
        query: string,
        responseMode: string = 'streaming',
        conversationId?: string,
        files?: any[],
        jwt?: string
    ): Promise<Response | any> {
        const body = {
            inputs,
            query,
            response_mode: responseMode,
            conversation_id: conversationId,
            files: files || [],
        };
        const response = await difyFetch('chat-messages', {
            method: 'POST',
            body: JSON.stringify(body),
        }, jwt);

        // 对于流式响应，直接返回 Response 对象
        if (responseMode === 'streaming') {
            return response;
        }

        console.log('[Dify Server] 解析 JSON 响应');
        return response.json();
    },

    /**
     * 重命名会话
     */
    async renameConversation(
        conversationId: string,
        name: string,
        autoGenerate: boolean = false,
        jwt?: string
    ): Promise<any> {
        const body = {
            name,
            auto_generate: autoGenerate,
        };

        const response = await difyFetch(`conversations/${conversationId}/name`, {
            method: 'POST',
            body: JSON.stringify(body),
        }, jwt);
        return response.json();
    },

    /**
     * 删除会话
     */
    async deleteConversation(conversationId: string, jwt?: string): Promise<any> {
        console.log('remix后端接收到删除请求,调用fastapi:', conversationId);

        try {
            const response = await difyFetch(`conversations/${conversationId}`, {
                method: 'DELETE',
                body: JSON.stringify({}),
            }, jwt);


            // 对于 204 No Content 响应，直接返回成功
            if (response.status === 204) {
                console.log('删除会话' + conversationId + '成功');
                return { result: 'success' };
            }

            const contentType = response.headers.get('Content-Type');

            if (contentType && contentType.includes('application/json')) {
                const data = await response.json();
                console.log('🗑️ [Dify Server] 删除会话 JSON 响应:', data);
                return data;
            }

            const text = await response.text();
            console.log('🗑️ [Dify Server] 删除会话文本响应:', text);

            return { result: 'success' };
        } catch (error: any) {
            console.warn('⚠️ [Dify Server] 删除会话请求失败，但可能已成功删除:', error.message);
            return { result: 'success' };
        }
    },

    /**
     * 更新消息反馈
     */
    async updateMessageFeedback(
        messageId: string,
        rating: 'like' | 'dislike' | null,
        jwt?: string
    ): Promise<any> {
        const body = {
            rating,
        };

        const response = await difyFetch(`messages/${messageId}/feedbacks`, {
            method: 'POST',
            body: JSON.stringify(body),
        }, jwt);
        return response.json();
    },
};

// ============================================================================
// 工具函数
// ============================================================================

/**
 * Dify 工具函数
 */
export const difyUtils = {
    /**
     * 获取 Dify 配置
     */
    getConfig: () => DIFY_CONFIG,
};