package chatgpt

import (
	"context"
	"crypto/tls"
	"fmt"
	"net"
	"net/http"
	"net/url"
	"time"

	"golang.org/x/net/proxy"
)

const (
	oaiClientVersion = "prod-eddc2f6ff65fee2d0d6439e379eab94fe3047f72"
	userAgent        = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36"
	openaiClientID   = "app_EMoamEEZ73f0CkXaXp7hrann"
)

// Client wraps HTTP operations with common headers and optional proxy.
type Client struct {
	httpClient *http.Client
	proxyURL   string
}

// NewClient creates a ChatGPT API client with optional proxy support.
func NewClient(proxyURL string) *Client {
	c := &Client{proxyURL: proxyURL}
	c.httpClient = c.buildHTTPClient()
	return c
}

func (c *Client) buildHTTPClient() *http.Client {
	transport := &http.Transport{
		TLSClientConfig: &tls.Config{MinVersion: tls.VersionTLS12},
		IdleConnTimeout: 90 * time.Second,
	}

	if c.proxyURL != "" {
		parsed, err := url.Parse(c.proxyURL)
		if err == nil {
			scheme := parsed.Scheme
			if scheme == "socks5" || scheme == "socks5h" {
				var auth *proxy.Auth
				if parsed.User != nil {
					pass, _ := parsed.User.Password()
					auth = &proxy.Auth{
						User:     parsed.User.Username(),
						Password: pass,
					}
				}
				dialer, dErr := proxy.SOCKS5("tcp", parsed.Host, auth, proxy.Direct)
				if dErr == nil {
					if ctxDialer, ok := dialer.(proxy.ContextDialer); ok {
						transport.DialContext = ctxDialer.DialContext
					} else {
						transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
							return dialer.Dial(network, addr)
						}
					}
				}
			} else {
				transport.Proxy = http.ProxyURL(parsed)
			}
		}
	}

	return &http.Client{
		Transport: transport,
		Timeout:   60 * time.Second,
	}
}

// buildHeaders returns common headers for ChatGPT backend API calls.
func buildHeaders(token, chatgptAccountID string) http.Header {
	h := http.Header{}
	h.Set("Accept", "*/*")
	h.Set("Accept-Language", "zh-CN,zh;q=0.9")
	h.Set("Authorization", fmt.Sprintf("Bearer %s", token))
	h.Set("Chatgpt-Account-Id", chatgptAccountID)
	h.Set("Oai-Client-Version", oaiClientVersion)
	h.Set("Oai-Language", "zh-CN")
	h.Set("User-Agent", userAgent)
	h.Set("Origin", "https://chatgpt.com")
	h.Set("Referer", "https://chatgpt.com/admin/members")
	return h
}