// Edge AI Gateway 使用示范 (Go 版本)
//
// 演示 Go 应用如何调用 Edge AI Gateway 的 OpenAI 兼容 API。
//
// 运行：go run examples/demo_usage.go
package main

import (
	"bufio"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
)

const (
	BaseURL = "http://localhost:8080"
	APIKey  = "test-key"
)

func main() {
	// === 1. 非流式对话 ===
	fmt.Println("=== 非流式对话 ===")
	resp := doPost(BaseURL+"/v1/chat/completions", map[string]any{
		"model":    "general-chat",
		"messages": []map[string]string{{"role": "user", "content": "你好，介绍一下你自己"}},
		"stream":   false,
	})
	fmt.Printf("回复: %s\n", resp["choices"].([]any)[0].(map[string]any)["message"].(map[string]any)["content"])
	fmt.Printf("模型: %s\n", resp["actual_model"])
	fmt.Println()

	// === 2. 流式对话 (SSE) ===
	fmt.Println("=== 流式对话 ===")
	doStream(BaseURL+"/v1/chat/completions", map[string]any{
		"model":    "fast-chat",
		"messages": []map[string]string{{"role": "user", "content": "写一个Go hello world"}},
		"stream":   true,
	})
	fmt.Println()

	// === 3. 查看模型列表 ===
	fmt.Println("=== 可用模型 ===")
	resp2 := doGet(BaseURL + "/v1/models")
	for _, m := range resp2["data"].([]any) {
		fmt.Printf("  - %s\n", m.(map[string]any)["id"])
	}
	fmt.Println()

	// === 4. 会话管理 ===
	fmt.Println("=== 会话管理 ===")
	sess := doPost(BaseURL+"/v1/sessions", map[string]any{
		"application_id": "demo-app",
		"user_id":        "user1",
	})
	sessionID := sess["session_id"].(string)
	fmt.Printf("创建会话: %s\n\n", sessionID)

	// === 5. 错误处理 ===
	fmt.Println("=== 错误处理 ===")
	// 无认证
	resp3, _ := http.Get(BaseURL + "/v1/models")
	fmt.Printf("无认证: HTTP %d\n", resp3.StatusCode)
	resp3.Body.Close()
	// 缺少 model
	resp4 := doPost(BaseURL+"/v1/chat/completions", map[string]any{
		"messages": []map[string]string{{"role": "user", "content": "hi"}},
	})
	if err, ok := resp4["error"]; ok {
		fmt.Printf("缺少model: %s\n", err.(map[string]any)["code"])
	}

	fmt.Println("\n✅ 示范完成！")
}

func doPost(url string, body map[string]any) map[string]any {
	b, _ := json.Marshal(body)
	req, _ := http.NewRequest("POST", url, strings.NewReader(string(b)))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "Bearer "+APIKey)
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		fmt.Printf("请求失败: %v\n", err)
		return nil
	}
	defer resp.Body.Close()
	data, _ := io.ReadAll(resp.Body)
	var result map[string]any
	json.Unmarshal(data, &result)
	return result
}

func doGet(url string) map[string]any {
	req, _ := http.NewRequest("GET", url, nil)
	req.Header.Set("Authorization", "Bearer "+APIKey)
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		fmt.Printf("请求失败: %v\n", err)
		return nil
	}
	defer resp.Body.Close()
	data, _ := io.ReadAll(resp.Body)
	var result map[string]any
	json.Unmarshal(data, &result)
	return result
}

func doStream(url string, body map[string]any) {
	b, _ := json.Marshal(body)
	req, _ := http.NewRequest("POST", url, strings.NewReader(string(b)))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "Bearer "+APIKey)
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		fmt.Printf("请求失败: %v\n", err)
		return
	}
	defer resp.Body.Close()
	scanner := bufio.NewScanner(resp.Body)
	for scanner.Scan() {
		line := scanner.Text()
		if !strings.HasPrefix(line, "data: ") {
			continue
		}
		data := strings.TrimPrefix(line, "data: ")
		if data == "[DONE]" {
			return
		}
		var chunk map[string]any
		json.Unmarshal([]byte(data), &chunk)
		choices := chunk["choices"].([]any)
		delta := choices[0].(map[string]any)["delta"].(map[string]any)
		if content, ok := delta["content"]; ok {
			fmt.Print(content.(string))
		}
	}
	if err := scanner.Err(); err != nil {
		fmt.Printf("\nstream error: %v\n", err)
	}
}