package harness

import (
	"errors"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"
)

// Options 控制测试进程启动。
type Options struct {
	// Listen 写入配置的 listen，默认 127.0.0.1:0。
	Listen string
	// AdminListen 可选；非空时写入 admin_listen，并读取 admin.addr。
	AdminListen string
	// AdminInit 可选；nil 时用 CLIAdminInit。不支持时忽略并继续启动。
	AdminInit AdminInitializer
	// KeepDir 为 true 时 Stop 不删除数据目录（命令行启动器在清理前可读）。
	KeepDir bool
}

// Server 是一次集成测试用的真实 nixmsg 进程。
type Server struct {
	BinPath       string
	ConfigPath    string
	DataDir       string
	Addr          string // 来自 listen.addr，形如 127.0.0.1:12345
	AdminAddr     string // 来自 admin.addr（若有）
	AdminPassword string
	HTTPBase      string
	AdminHTTPBase string

	cmd     *exec.Cmd
	keepDir bool
	stopped bool
}

// Start 编译（如需）并启动服务：临时目录、listen 端口 0、读 listen.addr。
func Start(opts Options) (*Server, error) {
	bin, err := Binary()
	if err != nil {
		return nil, err
	}
	dataDir, err := os.MkdirTemp("", "nixmsg-harness-*")
	if err != nil {
		return nil, err
	}
	listen := opts.Listen
	if listen == "" {
		listen = "127.0.0.1:0"
	}
	cfgPath := filepath.Join(dataDir, "config.yaml")
	cfg := fmt.Sprintf("listen: %q\ndata_dir: %q\n", listen, filepath.ToSlash(dataDir))
	if opts.AdminListen != "" {
		cfg += fmt.Sprintf("admin_listen: %q\n", opts.AdminListen)
	}
	if err = os.WriteFile(cfgPath, []byte(cfg), 0o644); err != nil {
		_ = os.RemoveAll(dataDir)
		return nil, err
	}

	adminInit := opts.AdminInit
	if adminInit == nil {
		adminInit = CLIAdminInit{}
	}
	password, initErr := adminInit.Init(bin, cfgPath)
	if initErr != nil && !errors.Is(initErr, ErrAdminInitUnsupported) {
		_ = os.RemoveAll(dataDir)
		return nil, initErr
	}
	if errors.Is(initErr, ErrAdminInitUnsupported) {
		password = ""
	}

	cmd := exec.Command(bin, "serve")
	cmd.Env = append(os.Environ(), "NIXMSG_CONFIG="+cfgPath)
	cmd.Stdout = os.Stderr
	cmd.Stderr = os.Stderr
	if err = cmd.Start(); err != nil {
		_ = os.RemoveAll(dataDir)
		return nil, fmt.Errorf("start serve: %w", err)
	}

	s := &Server{
		BinPath:       bin,
		ConfigPath:    cfgPath,
		DataDir:       dataDir,
		AdminPassword: password,
		cmd:           cmd,
		keepDir:       opts.KeepDir,
	}

	addr, err := waitAddrFile(filepath.Join(dataDir, "listen.addr"), 10*time.Second)
	if err != nil {
		_ = s.Stop()
		return nil, fmt.Errorf("wait listen.addr: %w", err)
	}
	s.Addr = addr
	s.HTTPBase = "http://" + addr

	if opts.AdminListen != "" {
		adminAddr, adminErr := waitAddrFile(filepath.Join(dataDir, "admin.addr"), 10*time.Second)
		if adminErr == nil {
			s.AdminAddr = adminAddr
			s.AdminHTTPBase = "http://" + adminAddr
		}
	}
	if s.AdminHTTPBase == "" {
		s.AdminHTTPBase = s.HTTPBase
	}
	return s, nil
}

// AdminClient 返回指向管理接口的 HTTP 客户端。
func (s *Server) AdminClient() (*AdminClient, error) {
	base := s.AdminHTTPBase
	if base == "" {
		base = s.HTTPBase
	}
	return NewAdminClient(base)
}

// Stop 结束进程并删除临时目录（除非 KeepDir）。
func (s *Server) Stop() error {
	if s == nil || s.stopped {
		return nil
	}
	s.stopped = true
	var stopErr error
	if s.cmd != nil && s.cmd.Process != nil {
		_ = s.cmd.Process.Kill()
		_, _ = s.cmd.Process.Wait()
	}
	if !s.keepDir && s.DataDir != "" {
		if err := os.RemoveAll(s.DataDir); err != nil {
			stopErr = err
		}
	}
	return stopErr
}

func waitAddrFile(path string, timeout time.Duration) (string, error) {
	deadline := time.Now().Add(timeout)
	var lastErr error
	for time.Now().Before(deadline) {
		b, err := os.ReadFile(path)
		if err == nil {
			addr := strings.TrimSpace(string(b))
			if addr != "" {
				return addr, nil
			}
			lastErr = fmt.Errorf("empty addr file")
		} else {
			lastErr = err
		}
		time.Sleep(20 * time.Millisecond)
	}
	return "", lastErr
}