package openai

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

// Adapter OpenAI 协议适配器（透传）
type Adapter struct{}

// NewAdapter 创建 OpenAI 适配器
func NewAdapter() *Adapter {
	return &Adapter{}
}

// PrepareRequest 准备发送给供应商的请求（透传）
func (a *Adapter) PrepareRequest(req *ChatCompletionRequest, apiKey, baseURL string) (*http.Request, error) {
	// 序列化请求体
	body, err := json.Marshal(req)
	if err != nil {
		return nil, err
	}

	// 创建 HTTP 请求
	// baseURL 已包含版本路径（如 /v1 或 /v4），只需添加端点路径
	httpReq, err := http.NewRequest("POST", baseURL+"/chat/completions", bytes.NewReader(body))
	if err != nil {
		return nil, err
	}

	// 设置请求头
	httpReq.Header.Set("Content-Type", "application/json")
	httpReq.Header.Set("Authorization", "Bearer "+apiKey)

	return httpReq, nil
}

// ParseResponse 解析供应商响应（透传）
func (a *Adapter) ParseResponse(resp *http.Response) (*ChatCompletionResponse, error) {
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var result ChatCompletionResponse
	err = json.Unmarshal(body, &result)
	if err != nil {
		return nil, err
	}

	return &result, nil
}

// ParseErrorResponse 解析错误响应
func (a *Adapter) ParseErrorResponse(resp *http.Response) (*ErrorResponse, error) {
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var result ErrorResponse
	err = json.Unmarshal(body, &result)
	if err != nil {
		return nil, err
	}

	return &result, nil
}

// ParseStreamChunk 解析流式响应块
func (a *Adapter) ParseStreamChunk(data []byte) (*StreamChunk, error) {
	var chunk StreamChunk
	err := json.Unmarshal(data, &chunk)
	if err != nil {
		return nil, err
	}
	return &chunk, nil
}