package ai

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"time"
)

// SiliconFlowClient 硅基流动API客户端
type SiliconFlowClient struct {
	apiKey     string
	baseURL    string
	model      string
	timeout    time.Duration
	maxRetries int
}

// Config AI配置
type Config struct {
	Endpoint   string `yaml:"endpoint"`
	Model      string `yaml:"model"`
	Timeout    int    `yaml:"timeout"`
	MaxRetries int    `yaml:"max_retries"`
	ApiKey string `yaml:"api_key"`
}

// ChatMessage 聊天消息
type ChatMessage struct {
	Role    string `json:"role"`
	Content string `json:"content"`
}

// ChatRequest 聊天请求
type ChatRequest struct {
	Model       string        `json:"model"`
	Messages    []ChatMessage `json:"messages"`
	Temperature float64       `json:"temperature"`
	Stream      bool          `json:"stream"`
}

// ChatResponse 聊天响应
type ChatResponse struct {
	ID      string   `json:"id"`
	Object  string   `json:"object"`
	Created int64    `json:"created"`
	Model   string   `json:"model"`
	Choices []Choice `json:"choices"`
	Usage   Usage    `json:"usage"`
}

// Choice 选择项
type Choice struct {
	Index        int         `json:"index"`
	Message      ChatMessage `json:"message"`
	FinishReason string      `json:"finish_reason"`
}

// Usage 使用情况
type Usage struct {
	PromptTokens     int `json:"prompt_tokens"`
	CompletionTokens int `json:"completion_tokens"`
	TotalTokens      int `json:"total_tokens"`
}

// NewClient 创建新的AI客户端
func NewClient(config Config) *SiliconFlowClient {
	return &SiliconFlowClient{
		apiKey:     config.ApiKey,
		baseURL:    config.Endpoint,
		model:      config.Model,
		timeout:    time.Duration(config.Timeout) * time.Second,
		maxRetries: config.MaxRetries,
	}
}

// Generate 生成内容
func (c *SiliconFlowClient) Generate(prompt string) (string, error) {
	reqBody := ChatRequest{
		Model: c.model,
		Messages: []ChatMessage{
			{
				Role:    "user",
				Content: prompt,
			},
		},
		Temperature: 0.7,
		Stream:      false,
	}

	reqJSON, err := json.Marshal(reqBody)
	if err != nil {
		return "", fmt.Errorf("failed to marshal request: %w", err)
	}

	var lastErr error
	for attempt := 0; attempt < c.maxRetries; attempt++ {
		result, err := c.sendRequest(reqJSON)
		if err == nil {
			return result, nil
		}

		lastErr = err

		if attempt < c.maxRetries-1 {
			time.Sleep(time.Duration(attempt+1) * time.Second)
		}
	}

	return "", fmt.Errorf("failed after %d attempts: %w", c.maxRetries, lastErr)
}

func (c *SiliconFlowClient) sendRequest(reqJSON []byte) (string, error) {
	url := c.baseURL + "/chat/completions"

	req, err := http.NewRequest("POST", url, bytes.NewReader(reqJSON))
	if err != nil {
		return "", fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("Authorization", "Bearer "+c.apiKey)
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{
		Timeout: c.timeout,
	}

	resp, err := client.Do(req)
	if err != nil {
		return "", fmt.Errorf("failed to send request: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", fmt.Errorf("failed to read response: %w", err)
	}

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("API returned status code %d: %s", resp.StatusCode, string(body))
	}

	var chatResp ChatResponse
	if err := json.Unmarshal(body, &chatResp); err != nil {
		return "", fmt.Errorf("failed to unmarshal response: %w", err)
	}

	if len(chatResp.Choices) == 0 {
		return "", fmt.Errorf("no choices in response")
	}

	return chatResp.Choices[0].Message.Content, nil
}