import Foundation

/// OpenAI服务异常
public class OpenAIError: Error {
    let message: String
    
    init(_ message: String) {
        self.message = message
    }
}

/// 工具调用信息
private class ToolCallInfo {
    var id: String = ""
    var name: String = ""
    var arguments: String = ""
    
    var isValid: Bool {
        return !id.isEmpty && !name.isEmpty
    }
}

/// OpenAI服务iOS原生实现
public class OpenAIService {
    private let TAG = "OpenAIService"
    private var baseUrl = "https://api.openai.com/v1/chat/completions"
    private var apiKey: String = ""
    private var isInitialized = false
    private var model: String = "doubao-1-5-lite-32k-250115" // 默认模型
    
    // 用于存储注册的函数
    private var registeredFunctions: [[String: Any]] = []
    
    // URL会话
    private let session: URLSession
    
    public init() {
        // 创建URL会话配置
        let config = URLSessionConfiguration.default
        config.timeoutIntervalForRequest = 30.0
        config.timeoutIntervalForResource = 30.0
        session = URLSession(configuration: config)
    }
    
    /// 创建用户消息
    public func createUserMessage(content: String) -> [String: Any] {
        return ["role": "user", "content": content]
    }
    
    /// 创建助手消息
    public func createAssistantMessage(content: String) -> [String: Any] {
        return ["role": "assistant", "content": content]
    }

    /// 初始化OpenAI服务
    public func initialize(apiKey: String, baseUrl: String = "", model: String = "") -> Bool {
        self.apiKey = apiKey
        if !baseUrl.isEmpty {
            self.baseUrl = baseUrl
        }
        if !model.isEmpty {
            self.model = model
        }
        isInitialized = !apiKey.isEmpty
        return isInitialized
    }
    
    /// 注册函数
    public func registerFunction(name: String, description: String, parameters: [String: Any]) -> Bool {
        do {
            let function: [String: Any] = [
                "name": name,
                "description": description,
                "parameters": parameters
            ]
            
            // 检查是否已存在相同名称的函数
            if let existingIndex = registeredFunctions.firstIndex(where: { ($0["name"] as? String) == name }) {
                // 如果已存在，则替换
                registeredFunctions[existingIndex] = function
            } else {
                // 如果不存在，则添加
                registeredFunctions.append(function)
            }
            
            return true
        } catch {
            return false
        }
    }
    
    /// 发送消息（非流式输出）
    public func sendMessage(messages: [[String: Any]], systemPrompt: String) throws -> String {
        guard isInitialized, !apiKey.isEmpty else {
            throw OpenAIError("OpenAI服务未初始化")
        }
        
        // 构建完整消息，添加系统提示
        var fullMessages: [[String: Any]] = [
            ["role": "system", "content": systemPrompt]
        ]
        fullMessages.append(contentsOf: messages)
        
        // 构建请求体
        var requestDict: [String: Any] = [
            "model": model,
            "messages": fullMessages,
            "temperature": 0.7,
            "max_tokens": 2000,
            "stream": false
        ]
        
        // 如果有注册的函数，添加到请求中
        if !registeredFunctions.isEmpty {
            var tools: [[String: Any]] = []
            for function in registeredFunctions {
                let tool: [String: Any] = [
                    "type": "function",
                    "function": function
                ]
                tools.append(tool)
            }
            requestDict["tools"] = tools
        }
        
        // 将请求数据转换为JSON数据
        guard let jsonData = try? JSONSerialization.data(withJSONObject: requestDict) else {
            throw OpenAIError("无法序列化请求数据")
        }
        
        // 创建URL请求
        guard let url = URL(string: baseUrl) else {
            throw OpenAIError("无效的URL")
        }
        
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
        request.addValue("Bearer \(apiKey)", forHTTPHeaderField: "Authorization")
        request.httpBody = jsonData
        
        // 创建信号量用于同步请求
        let semaphore = DispatchSemaphore(value: 0)
        var responseResult: Result<String, Error> = .failure(OpenAIError("未收到响应"))
        
        // 执行请求
        let task = session.dataTask(with: request) { data, response, error in
            if let error = error {
                responseResult = .failure(OpenAIError("请求失败: \(error.localizedDescription)"))
                semaphore.signal()
                return
            }
            
            guard let httpResponse = response as? HTTPURLResponse else {
                responseResult = .failure(OpenAIError("无效的HTTP响应"))
                semaphore.signal()
                return
            }
            
            guard httpResponse.statusCode == 200 else {
                responseResult = .failure(OpenAIError("API调用失败: \(httpResponse.statusCode)"))
                semaphore.signal()
                return
            }
            
            guard let data = data else {
                responseResult = .failure(OpenAIError("响应数据为空"))
                semaphore.signal()
                return
            }
            
            do {
                // 解析JSON响应
                guard let jsonResponse = try JSONSerialization.jsonObject(with: data) as? [String: Any] else {
                    responseResult = .failure(OpenAIError("无法解析JSON响应"))
                    semaphore.signal()
                    return
                }
                
                // 检查是否有函数调用
                if let choices = jsonResponse["choices"] as? [[String: Any]], !choices.isEmpty,
                   let choice = choices.first,
                   let message = choice["message"] as? [String: Any] {
                    
                    // 检查是否有工具调用
                    if let toolCalls = message["tool_calls"] as? [[String: Any]], !toolCalls.isEmpty,
                       let toolCall = toolCalls.first,
                       let function = toolCall["function"] as? [String: Any],
                       let name = function["name"] as? String,
                       let arguments = function["arguments"] as? String,
                       let id = toolCall["id"] as? String {
                        
                        let functionCallDict: [String: Any] = [
                            "name": name,
                            "arguments": arguments,
                            "id": id
                        ]
                        
                        // 将函数调用转为JSON字符串
                        if let functionCallData = try? JSONSerialization.data(withJSONObject: functionCallDict),
                           let functionCallString = String(data: functionCallData, encoding: .utf8) {
                            responseResult = .success(functionCallString)
                            semaphore.signal()
                            return
                        }
                    }
                    
                    // 如果没有工具调用，返回消息内容
                    if let content = message["content"] as? String {
                        responseResult = .success(content)
                        semaphore.signal()
                        return
                    }
                }
                
                responseResult = .failure(OpenAIError("无效的响应格式"))
                semaphore.signal()
                
            } catch {
                responseResult = .failure(OpenAIError("解析响应时出错: \(error.localizedDescription)"))
                semaphore.signal()
            }
        }
        
        task.resume()
        
        // 等待响应完成
        _ = semaphore.wait(timeout: .distantFuture)
        
        // 返回结果或抛出错误
        switch responseResult {
        case .success(let result):
            return result
        case .failure(let error):
            throw error
        }
    }
    
    /// 发送消息（流式输出）
    public func sendMessageStream(
        messages: [[String: Any]],
        systemPrompt: String,
        callback: @escaping StreamCallback
    ) {
        guard isInitialized, !apiKey.isEmpty else {
            callback.onError(OpenAIError("OpenAI服务未初始化"))
            return
        }
        
        // 构建请求体
        var requestBody: [String: Any] = [
            "model": model,
            "temperature": 0.7,
            "max_tokens": 2000,
            "stream": true
        ]
        
        // 构建完整消息数组，添加系统提示
        var fullMessages: [[String: Any]] = [
            ["role": "system", "content": systemPrompt]
        ]
        fullMessages.append(contentsOf: messages)
        requestBody["messages"] = fullMessages
        
        // 添加工具列表
        if let toolMaps = mcpClient?.getToolMaps(), !toolMaps.isEmpty {
            var tools: [[String: Any]] = []
            
            for toolMap in toolMaps {
                if let tool = toolMap as? [String: Any] {
                    tools.append(tool)
                }
            }
            
            if !tools.isEmpty {
                requestBody["tools"] = tools
            }
        } else if !registeredFunctions.isEmpty {
            var tools: [[String: Any]] = []
            
            for function in registeredFunctions {
                let tool: [String: Any] = [
                    "type": "function",
                    "function": function
                ]
                tools.append(tool)
            }
            
            if !tools.isEmpty {
                requestBody["tools"] = tools
            }
        }
        
        // 转换为JSON数据
        guard let jsonData = try? JSONSerialization.data(withJSONObject: requestBody) else {
            callback.onError(OpenAIError("无法序列化请求数据"))
            return
        }
        
        // 创建URL请求
        guard let url = URL(string: baseUrl) else {
            callback.onError(OpenAIError("无效的URL"))
            return
        }
        
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
        request.addValue("Bearer \(apiKey)", forHTTPHeaderField: "Authorization")
        request.addValue("text/event-stream", forHTTPHeaderField: "Accept")
        request.httpBody = jsonData
        
        // 创建流式会话任务
        let delegate = SSEStreamDelegate(callback: callback)
        let session = URLSession(configuration: .default, delegate: delegate, delegateQueue: nil)
        let task = session.dataTask(with: request)
        task.resume()
    }
    
    /// 发送函数调用结果
    public func sendFunctionCallResult(
        messages: [[String: Any]],
        systemPrompt: String,
        functionCall: [String: Any],
        functionResult: String,
        callback: @escaping StreamCallback
    ) {
        do {
            // 构建完整消息数组
            var fullMessages: [[String: Any]] = [
                // 添加系统提示
                ["role": "system", "content": systemPrompt]
            ]
            
            // 添加用户消息
            fullMessages.append(contentsOf: messages)
            
            // 获取函数相关信息
            guard let name = functionCall["name"] as? String,
                  let arguments = functionCall["arguments"] as? String else {
                callback.onError(OpenAIError("函数调用信息不完整"))
                return
            }
            
            let id = functionCall["id"] as? String ?? "call_\(Int(Date().timeIntervalSince1970 * 1000))"
            
            // 添加函数调用消息
            fullMessages.append([
                "role": "assistant",
                "content": NSNull(),
                "tool_calls": [
                    [
                        "id": id,
                        "type": "function",
                        "function": [
                            "name": name,
                            "arguments": arguments
                        ]
                    ]
                ]
            ])
            
            // 添加函数调用结果
            fullMessages.append([
                "role": "tool",
                "content": functionResult,
                "tool_call_id": id
            ])
            
            // 发送完整对话
            sendMessageStream(messages: fullMessages, systemPrompt: systemPrompt, callback: callback)
            
        } catch {
            callback.onError(OpenAIError("发送函数调用结果失败: \(error.localizedDescription)"))
        }
    }
    
    /// SSE流委托实现
    private class SSEStreamDelegate: NSObject, URLSessionDataDelegate {
        let callback: StreamCallback
        private var buffer = Data()
        private var finalToolCalls: [Int: ToolCallInfo] = [:]
        
        init(callback: @escaping StreamCallback) {
            self.callback = callback
            super.init()
        }
        
        // 接收数据流
        func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
            buffer.append(data)
            
            // 处理可能包含多行的数据
            processBuffer()
        }
        
        // 处理缓冲区数据
        private func processBuffer() {
            // 按行分割
            while let newlineIndex = buffer.firstIndex(of: 10) { // 10是换行符的ASCII码
                let lineData = buffer.prefix(upTo: newlineIndex)
                buffer.removeSubrange(0...newlineIndex) // 移除已处理的行，包括换行符
                
                // 解析行数据
                if let line = String(data: lineData, encoding: .utf8)?.trimmingCharacters(in: .whitespacesAndNewlines) {
                    processLine(line)
                }
            }
        }
        
        // 处理单行数据
        private func processLine(_ line: String) {
            guard !line.isEmpty else { return }
            
            if line.hasPrefix("data: ") {
                let dataContent = line.dropFirst(6)
                
                // 处理[DONE]消息
                if dataContent == "[DONE]" {
                    let hasToolCalls = self.processToolCalls()
                    // 只有在没有工具调用时才认为对话真正完成
                    if !hasToolCalls {
                        callback.onComplete()
                    }
                    return
                }
                
                // 解析JSON数据
                do {
                    if let data = dataContent.data(using: .utf8),
                       let jsonData = try JSONSerialization.jsonObject(with: data) as? [String: Any] {
                        
                        // 处理消息内容
                        if let choices = jsonData["choices"] as? [[String: Any]], !choices.isEmpty,
                           let choice = choices.first {
                            
                            if let delta = choice["delta"] as? [String: Any] {
                                // 处理普通文本内容
                                if let content = delta["content"] as? String {
                                    callback.onToken(content)
                                }
                                
                                // 处理工具调用（函数调用）
                                if let toolCalls = delta["tool_calls"] as? [[String: Any]] {
                                    for toolCall in toolCalls {
                                        if let index = toolCall["index"] as? Int {
                                            // 创建或获取现有的工具调用信息
                                            let toolCallInfo = finalToolCalls[index] ?? ToolCallInfo()
                                            
                                            // 更新ID
                                            if let id = toolCall["id"] as? String {
                                                toolCallInfo.id = id
                                            }
                                            
                                            // 更新函数信息
                                            if let function = toolCall["function"] as? [String: Any] {
                                                if let name = function["name"] as? String {
                                                    toolCallInfo.name = name
                                                }
                                                
                                                if let arguments = function["arguments"] as? String {
                                                    toolCallInfo.arguments += arguments
                                                }
                                            }
                                            
                                            finalToolCalls[index] = toolCallInfo
                                        }
                                    }
                                }
                            }
                        }
                    }
                } catch {
                    NSLog("解析JSON出错: \(error.localizedDescription)")
                    // 忽略解析错误，继续处理其他行
                }
            }
        }
        
        // 处理工具调用
        private func processToolCalls() -> Bool {
            if finalToolCalls.isEmpty { return false }
            
            // 只处理第一个工具调用
            guard let firstToolCall = finalToolCalls.values.first, firstToolCall.isValid else { return false }
            
            // 创建函数调用字典
            let functionCall: [String: Any] = [
                "name": firstToolCall.name,
                "arguments": firstToolCall.arguments,
                "id": firstToolCall.id
            ]
            
            // 回调
            callback.onFunctionCall(functionCall)
            return true
        }
        
        // 处理完成
        func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
            if let error = error {
                callback.onError(OpenAIError("请求失败: \(error.localizedDescription)"))
            }
        }
    }
    
    /// 流式输出回调协议
    public typealias StreamCallback = (onToken: (String) -> Void,
                               onComplete: () -> Void,
                               onError: (Error) -> Void,
                               onFunctionCall: ([String: Any]) -> Void)
    
    /// 处理工具调用（函数调用）并回调
    private func processToolCalls(_ toolCalls: [Int: ToolCallInfo], callback: StreamCallback) -> Bool {
        if toolCalls.isEmpty { return false }
        
        // 只处理第一个工具调用
        guard let firstToolCall = toolCalls.values.first, firstToolCall.isValid else { return false }
        
        // 创建函数调用字典
        let functionCall: [String: Any] = [
            "name": firstToolCall.name,
            "arguments": firstToolCall.arguments,
            "id": firstToolCall.id
        ]
        
        // 回调
        callback.onFunctionCall(functionCall)
        return true
    }
}