package app

import (
	"context"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/http/httptest"
	"net/url"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
	"time"

	"golang.org/x/net/proxy"
	"gopkg.in/yaml.v3"
)

func freePort(t *testing.T) int {
	t.Helper()
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	port := listener.Addr().(*net.TCPAddr).Port
	listener.Close()
	return port
}

// This test starts a real core with TUN disabled and routes test traffic through local HTTP proxy nodes.
// It never modifies the development machine's routes, forwarding, DNS, or DHCP.
func TestRealMihomoProxyAndNodeSelection(t *testing.T) {
	binary := os.Getenv("CLASHWEB_TEST_MIHOMO_BIN")
	rulesDir := os.Getenv("CLASHWEB_TEST_RULES_DIR")
	if binary == "" || rulesDir == "" {
		t.Skip("set CLASHWEB_TEST_MIHOMO_BIN and CLASHWEB_TEST_RULES_DIR to run real-core integration")
	}
	binary, _ = filepath.Abs(binary)
	dir := t.TempDir()
	os.MkdirAll(filepath.Join(dir, "rules"), 0750)
	for _, file := range []string{"cn-domain.mrs", "cn-ip.mrs"} {
		data, err := os.ReadFile(filepath.Join(rulesDir, file))
		if err != nil {
			t.Fatal(err)
		}
		os.WriteFile(filepath.Join(dir, "rules", file), data, 0640)
	}
	makeProxy := func(label string) *httptest.Server {
		return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			if r.Method != http.MethodConnect {
				fmt.Fprint(w, label)
				return
			}
			connection, buffer, err := w.(http.Hijacker).Hijack()
			if err != nil {
				return
			}
			defer connection.Close()
			io.WriteString(buffer, "HTTP/1.1 200 Connection Established\r\n\r\n")
			buffer.Flush()
			request, err := http.ReadRequest(buffer.Reader)
			if err != nil {
				return
			}
			request.Body.Close()
			time.Sleep(30 * time.Millisecond)
			fmt.Fprintf(buffer, "HTTP/1.1 200 OK\r\nContent-Length: %d\r\nConnection: close\r\n\r\n%s", len(label), label)
			buffer.Flush()
		}))
	}
	nodeA, nodeB := makeProxy("node-a"), makeProxy("node-b")
	defer nodeA.Close()
	defer nodeB.Close()
	makeNode := func(name string, server *httptest.Server) map[string]any {
		u, _ := url.Parse(server.URL)
		_, p, _ := net.SplitHostPort(u.Host)
		port, _ := strconv.Atoi(p)
		return map[string]any{"name": name, "type": "http", "server": "127.0.0.1", "port": port}
	}
	s := defaultState()
	s.Settings.SelectedNode = "node-A"
	s.Settings.MixedPort = freePort(t)
	s.Settings.DNSPort = freePort(t)
	s.Subscriptions = []Subscription{{Enabled: true, Nodes: []map[string]any{makeNode("node-A", nodeA), makeNode("node-B", nodeB)}}}
	data, _ := compileConfig(s, "integration-secret")
	var config map[string]any
	yaml.Unmarshal(data, &config)
	controller := freePort(t)
	config["external-controller"] = fmt.Sprintf("127.0.0.1:%d", controller)
	data, _ = yaml.Marshal(config)
	core := Core{Binary: binary, Dir: dir, URL: fmt.Sprintf("http://127.0.0.1:%d", controller), Secret: "integration-secret", HTTP: &http.Client{Timeout: 3 * time.Second}}
	if err := core.Validate(context.Background(), data); err != nil {
		t.Fatal(err)
	}
	if err := atomicWrite(filepath.Join(dir, "config.yaml"), data); err != nil {
		t.Fatal(err)
	}
	command := exec.Command(binary, "-d", dir, "-f", filepath.Join(dir, "config.yaml"))
	var output strings.Builder
	command.Stdout = &output
	command.Stderr = &output
	if err := command.Start(); err != nil {
		t.Fatal(err)
	}
	defer func() {
		command.Process.Signal(os.Interrupt)
		command.Wait()
		if t.Failed() {
			t.Log(output.String())
		}
	}()
	ready := false
	for i := 0; i < 50; i++ {
		var version map[string]any
		if core.Request(context.Background(), "GET", "/version", nil, &version) == nil {
			ready = true
			break
		}
		time.Sleep(100 * time.Millisecond)
	}
	if !ready {
		t.Fatal("core did not start")
	}
	var latency struct {
		Delay int `json:"delay"`
	}
	if err := core.Request(context.Background(), "GET", "/proxies/node-A/delay?url="+url.QueryEscape("http://198.51.100.42/health")+"&timeout=2000", nil, &latency); err != nil || latency.Delay <= 0 {
		t.Fatalf("node latency check failed: delay=%d err=%v", latency.Delay, err)
	}
	u, _ := url.Parse(fmt.Sprintf("http://127.0.0.1:%d", s.Settings.MixedPort))
	client := &http.Client{Transport: &http.Transport{Proxy: http.ProxyURL(u)}, Timeout: 5 * time.Second}
	get := func(target, want string) {
		t.Helper()
		resp, err := client.Get(target)
		if err != nil {
			t.Fatal(err)
		}
		defer resp.Body.Close()
		b, _ := io.ReadAll(resp.Body)
		if string(b) != want {
			t.Fatalf("got %q, want %q", b, want)
		}
	}
	get("http://198.51.100.42/test", "node-a")
	if err := core.Request(context.Background(), "PUT", "/proxies/"+ProxyGroup, map[string]string{"name": "node-B"}, nil); err != nil {
		t.Fatal(err)
	}
	get("http://198.51.100.42/test", "node-b")
	direct := makeProxy("direct-lan")
	defer direct.Close()
	get(direct.URL, "direct-lan")
	dialer, err := proxy.SOCKS5("tcp", fmt.Sprintf("127.0.0.1:%d", s.Settings.MixedPort), nil, proxy.Direct)
	if err != nil {
		t.Fatal(err)
	}
	socksClient := &http.Client{Transport: &http.Transport{DialContext: func(ctx context.Context, network, address string) (net.Conn, error) {
		return dialer.(proxy.ContextDialer).DialContext(ctx, network, address)
	}}, Timeout: 5 * time.Second}
	resp, err := socksClient.Get("http://198.51.100.42/socks")
	if err != nil {
		t.Fatal(err)
	}
	b, _ := io.ReadAll(resp.Body)
	resp.Body.Close()
	if string(b) != "node-b" {
		t.Fatal("SOCKS selection not applied", string(b))
	}
	if err := core.Request(context.Background(), "PUT", "/proxies/"+ProxyGroup, map[string]string{"name": "REJECT"}, nil); err != nil {
		t.Fatal(err)
	}
	resp, err = client.Get("http://198.51.100.42/reject")
	if err == nil {
		resp.Body.Close()
		if resp.StatusCode < 400 {
			t.Fatal("REJECT fell back to a different node")
		}
	}
	get(direct.URL, "direct-lan")
}