package starnet

import (
	"net/http"
	"net/url"
	"sync"
	"time"
)

// Transport 自定义 Transport（支持请求级配置）
type Transport struct {
	base *http.Transport
	mu   sync.RWMutex
}

// RoundTrip 实现 http.RoundTripper 接口
func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
	// 确保 base 已初始化
	if t.base == nil {
		t.mu.Lock()
		if t.base == nil {
			t.base = &http.Transport{
				ForceAttemptHTTP2:     true,
				MaxIdleConns:          100,
				MaxIdleConnsPerHost:   10,
				IdleConnTimeout:       90 * time.Second,
				TLSHandshakeTimeout:   10 * time.Second,
				ExpectContinueTimeout: 1 * time.Second,
			}
		}
		t.mu.Unlock()
	}

	// 提取请求级别的配置
	reqCtx := getRequestContext(req.Context())

	// 优先级1：完全自定义的 transport
	if reqCtx.Transport != nil {
		return reqCtx.Transport.RoundTrip(req)
	}

	// 优先级2：需要动态配置
	if needsDynamicTransport(reqCtx) {
		dynamicTransport := t.buildDynamicTransport(reqCtx)
		return dynamicTransport.RoundTrip(req)
	}

	// 优先级3：使用基础 transport
	t.mu.RLock()
	defer t.mu.RUnlock()
	return t.base.RoundTrip(req)
}

// buildDynamicTransport 构建动态 Transport
func (t *Transport) buildDynamicTransport(rc *RequestContext) *http.Transport {
	t.mu.RLock()
	transport := t.base.Clone()
	t.mu.RUnlock()

	// 应用 TLS 配置（即使为 nil 也要检查 SkipVerify）
	if rc.TLSConfig != nil {
		transport.TLSClientConfig = rc.TLSConfig
	}

	// 应用代理配置
	if rc.Proxy != "" {
		proxyURL, err := url.Parse(rc.Proxy)
		if err == nil {
			transport.Proxy = http.ProxyURL(proxyURL)
		}
	}

	// 应用自定义 Dial 函数
	if rc.DialFn != nil {
		transport.DialContext = rc.DialFn
	} else if len(rc.CustomIP) > 0 || len(rc.CustomDNS) > 0 || rc.DialTimeout > 0 || rc.LookupIPFn != nil {
		// 使用默认 Dial 函数（会从 context 读取配置）
		transport.DialContext = defaultDialFunc
		transport.DialTLSContext = defaultDialTLSFunc
	}

	return transport
}

// Base 获取基础 Transport
func (t *Transport) Base() *http.Transport {
	t.mu.RLock()
	defer t.mu.RUnlock()
	return t.base
}

// SetBase 设置基础 Transport
func (t *Transport) SetBase(base *http.Transport) {
	t.mu.Lock()
	t.base = base
	t.mu.Unlock()
}