package domain

import (
	"errors"
	"fmt"
	"net"
	"net/url"
	"path/filepath"
	"strconv"
	"strings"
	"time"
)

type BrowserKind string

const (
	BrowserChrome BrowserKind = "chrome"
	BrowserEdge   BrowserKind = "edge"

	DefaultRemoteDebugPort = 9666
	MinRemoteDebugPort     = 1024
	MaxRemoteDebugPort     = 65535
)

func (k BrowserKind) Valid() bool { return k == BrowserChrome || k == BrowserEdge }

type InstanceStatus string

const (
	StatusCreated  InstanceStatus = "created"
	StatusStarting InstanceStatus = "starting"
	StatusRunning  InstanceStatus = "running"
	StatusStopping InstanceStatus = "stopping"
	StatusExited   InstanceStatus = "exited"
	StatusFailed   InstanceStatus = "failed"
	StatusUnknown  InstanceStatus = "unknown"
)

type LaunchSpec struct {
	Kind             BrowserKind
	Executable       string
	UserDataDir      string
	ProfileDirectory string
	RemoteDebugPort  int
	TargetURL        string
	ProxyServer      string
	Headless         bool
	ExtraArgs        []string
}

func (s LaunchSpec) Normalize() (LaunchSpec, error) {
	if !s.Kind.Valid() {
		return LaunchSpec{}, fmt.Errorf("%w: unsupported browser kind", ErrInvalidLaunchSpec)
	}
	userDataDir := strings.TrimSpace(s.UserDataDir)
	if userDataDir == "" || !filepath.IsAbs(userDataDir) {
		return LaunchSpec{}, fmt.Errorf("%w: user data dir must be absolute", ErrInvalidLaunchSpec)
	}
	if s.RemoteDebugPort != 0 && !ValidRemoteDebugPort(s.RemoteDebugPort) {
		return LaunchSpec{}, fmt.Errorf("%w: remote debugging port must be between %d and %d", ErrInvalidLaunchSpec, MinRemoteDebugPort, MaxRemoteDebugPort)
	}
	target := strings.TrimSpace(s.TargetURL)
	if target != "" {
		parsed, err := url.Parse(target)
		if err != nil || parsed.Host == "" || parsed.User != nil || (parsed.Scheme != "http" && parsed.Scheme != "https") {
			return LaunchSpec{}, fmt.Errorf("%w: target URL must be absolute http or https", ErrInvalidLaunchSpec)
		}
		target = parsed.String()
	}
	normalized := s
	normalized.Executable = strings.TrimSpace(s.Executable)
	normalized.UserDataDir = filepath.Clean(userDataDir)
	normalized.ProfileDirectory = strings.TrimSpace(s.ProfileDirectory)
	normalized.TargetURL = target
	proxy, err := NormalizeProxyServer(s.ProxyServer)
	if err != nil {
		return LaunchSpec{}, err
	}
	normalized.ProxyServer = proxy
	normalized.ExtraArgs = append([]string(nil), s.ExtraArgs...)
	return normalized, nil
}

// NormalizeProxyServer accepts only non-authenticated Chromium proxy endpoints.
// Keeping this validation in domain makes configuration and process launch share
// the same security boundary: no proxy userinfo can reach disk or command args.
func NormalizeProxyServer(value string) (string, error) {
	proxy := strings.TrimSpace(value)
	if proxy == "" {
		return "", nil
	}
	parsed, err := url.Parse(proxy)
	if err != nil || parsed.User != nil || parsed.Hostname() == "" || parsed.Port() == "" || parsed.Path != "" || parsed.RawQuery != "" || parsed.Fragment != "" {
		return "", fmt.Errorf("%w: proxy must be scheme://host:port without credentials", ErrInvalidLaunchSpec)
	}
	scheme := strings.ToLower(parsed.Scheme)
	if scheme != "http" && scheme != "https" && scheme != "socks4" && scheme != "socks5" {
		return "", fmt.Errorf("%w: unsupported proxy scheme", ErrInvalidLaunchSpec)
	}
	port, err := strconv.Atoi(parsed.Port())
	if err != nil || port < 1 || port > 65535 {
		return "", fmt.Errorf("%w: proxy port out of range", ErrInvalidLaunchSpec)
	}
	return scheme + "://" + net.JoinHostPort(strings.ToLower(parsed.Hostname()), strconv.Itoa(port)), nil
}

func ValidRemoteDebugPort(port int) bool {
	return port >= MinRemoteDebugPort && port <= MaxRemoteDebugPort
}

type InstanceView struct {
	ID              string
	Kind            BrowserKind
	Executable      string
	PID             int
	RemoteDebugPort int
	UserDataDir     string
	Profile         string
	TargetURL       string
	Status          InstanceStatus
	ExitCode        *int
	StartedAt       time.Time
	ChangedAt       time.Time
	IdentityNote    string
}

type EventKind string

const (
	EventBrowserStarted       EventKind = "browser.started"
	EventBrowserStatusChanged EventKind = "browser.status.changed"
	EventBrowserExited        EventKind = "browser.exited"
)

type BrowserEvent struct {
	Kind       EventKind
	InstanceID string
	Status     InstanceStatus
	PID        int
	ExitCode   *int
	ErrorCode  ErrorCode
	At         time.Time
}

type ErrorCode string

const (
	ErrorInvalidLaunchSpec  ErrorCode = "invalid_launch_spec"
	ErrorProfileOccupied    ErrorCode = "profile_occupied"
	ErrorExecutableNotFound ErrorCode = "executable_not_found"
	ErrorInstanceNotFound   ErrorCode = "instance_not_found"
	ErrorIdentityMismatch   ErrorCode = "identity_mismatch"
	ErrorProcessPermission  ErrorCode = "process_permission"
	ErrorProcessStart       ErrorCode = "process_start_failed"
)

var (
	ErrInvalidLaunchSpec = errors.New("invalid browser launch specification")
	ErrProfileOccupied   = errors.New("browser user data dir is occupied")
	ErrInstanceNotFound  = errors.New("browser instance was not found")
	ErrIdentityMismatch  = errors.New("browser process identity mismatch")
)