package common

import (
	"flag"
	"log/slog"
	"net"
	"os"
	"strconv"

	"github.com/pion/webrtc/v4"
)

var globalFlags *Flags

type Flags struct {
	RegenIdentity   bool   // Remove old identity on startup and regenerate it
	Verbose         bool   // Log everything to console
	Debug           bool   // Enable debug mode, implies Verbose
	EndpointPort    int    // Port for HTTP/S and WS/S endpoint (TCP)
	WebRTCUDPStart  int    // WebRTC UDP port range start - ignored if UDPMuxPort is set
	WebRTCUDPEnd    int    // WebRTC UDP port range end - ignored if UDPMuxPort is set
	STUNServer      string // WebRTC STUN server
	UDPMuxPort      int    // WebRTC UDP mux port - if set, overrides UDP port range
	AutoAddLocalIP  bool   // Automatically add local IP to NAT 1 to 1 IPs
	NAT11IP         string // WebRTC NAT 1 to 1 IP - allows specifying IP of relay if behind NAT
	PersistDir      string // Directory to save persistent data to
	Metrics         bool   // Enable metrics endpoint
	MetricsPort     int    // Port for metrics endpoint
	PlayoutDelayMin int    // UNSTABLE: Minimum playout latency
	PlayoutDelayMax int    // UNSTABLE: Maximum playout latency
	FlexFEC         bool   // UNSTABLE: Enable/disable FlexFEC for video streams
}

func (flags *Flags) DebugLog() {
	slog.Debug("Relay flags",
		"regenIdentity", flags.RegenIdentity,
		"verbose", flags.Verbose,
		"debug", flags.Debug,
		"endpointPort", flags.EndpointPort,
		"webrtcUDPStart", flags.WebRTCUDPStart,
		"webrtcUDPEnd", flags.WebRTCUDPEnd,
		"stunServer", flags.STUNServer,
		"webrtcUDPMux", flags.UDPMuxPort,
		"autoAddLocalIP", flags.AutoAddLocalIP,
		"webrtcNAT11IPs", flags.NAT11IP,
		"persistDir", flags.PersistDir,
		"metrics", flags.Metrics,
		"metricsPort", flags.MetricsPort,
		"playoutDelayMin", flags.PlayoutDelayMin,
		"playoutDelayMax", flags.PlayoutDelayMax,
		"flexFEC", flags.FlexFEC,
	)
}

func getEnvAsInt(name string, defaultVal int) int {
	valueStr := os.Getenv(name)
	if value, err := strconv.Atoi(valueStr); err != nil {
		return defaultVal
	} else {
		return value
	}
}

func getEnvAsBool(name string, defaultVal bool) bool {
	valueStr := os.Getenv(name)
	val, err := strconv.ParseBool(valueStr)
	if err != nil {
		return defaultVal
	}
	return val
}

func getEnvAsString(name string, defaultVal string) string {
	valueStr := os.Getenv(name)
	if len(valueStr) == 0 {
		return defaultVal
	}
	return valueStr
}

func InitFlags() {
	// Create Flags struct
	globalFlags = &Flags{}
	// Get flags
	flag.BoolVar(&globalFlags.RegenIdentity, "regenIdentity", getEnvAsBool("REGEN_IDENTITY", false), "Regenerate identity on startup")
	flag.BoolVar(&globalFlags.Verbose, "verbose", getEnvAsBool("VERBOSE", false), "Verbose mode")
	flag.BoolVar(&globalFlags.Debug, "debug", getEnvAsBool("DEBUG", false), "Debug mode")
	flag.IntVar(&globalFlags.EndpointPort, "endpointPort", getEnvAsInt("ENDPOINT_PORT", 8088), "HTTP endpoint port")
	flag.IntVar(&globalFlags.WebRTCUDPStart, "webrtcUDPStart", getEnvAsInt("WEBRTC_UDP_START", 0), "WebRTC UDP port range start")
	flag.IntVar(&globalFlags.WebRTCUDPEnd, "webrtcUDPEnd", getEnvAsInt("WEBRTC_UDP_END", 0), "WebRTC UDP port range end")
	flag.StringVar(&globalFlags.STUNServer, "stunServer", getEnvAsString("STUN_SERVER", "stun.l.google.com:19302"), "WebRTC STUN server")
	flag.IntVar(&globalFlags.UDPMuxPort, "webrtcUDPMux", getEnvAsInt("WEBRTC_UDP_MUX", 9099), "WebRTC UDP mux port")
	flag.BoolVar(&globalFlags.AutoAddLocalIP, "autoAddLocalIP", getEnvAsBool("AUTO_ADD_LOCAL_IP", false), "Automatically add local IP to NAT 1 to 1 IPs")
	// String with comma separated IPs
	nat11IP := ""
	flag.StringVar(&nat11IP, "webrtcNAT11IP", getEnvAsString("WEBRTC_NAT_IP", ""), "WebRTC NAT 1 to 1 IP")
	flag.StringVar(&globalFlags.PersistDir, "persistDir", getEnvAsString("PERSIST_DIR", "./persist-data"), "Directory to save persistent data to")
	flag.BoolVar(&globalFlags.Metrics, "metrics", getEnvAsBool("METRICS", false), "Enable metrics endpoint")
	flag.IntVar(&globalFlags.MetricsPort, "metricsPort", getEnvAsInt("METRICS_PORT", 3030), "Port for metrics endpoint")
	flag.IntVar(&globalFlags.PlayoutDelayMin, "playoutDelayMin", getEnvAsInt("PLAYOUTDELAY_MIN", 0), "Minimum playout delay")
	flag.IntVar(&globalFlags.PlayoutDelayMin, "playoutDelayMax", getEnvAsInt("PLAYOUTDELAY_MAX", 0), "Maximum playout delay")
	flag.BoolVar(&globalFlags.FlexFEC, "flexFEC", getEnvAsBool("FLEXFEC", true), "Enable FlexFEC for video streams")
	// Parse flags
	flag.Parse()

	// If debug is enabled, verbose is also enabled
	if globalFlags.Debug {
		globalFlags.Verbose = true
	}

	// ICE STUN servers
	globalWebRTCConfig.ICEServers = []webrtc.ICEServer{
		{
			URLs: []string{"stun:" + globalFlags.STUNServer},
		},
	}

	// Parse NAT 1 to 1 IPs from string
	if len(nat11IP) > 0 {
		globalFlags.NAT11IP = nat11IP
	} else if globalFlags.AutoAddLocalIP {
		globalFlags.NAT11IP = getLocalIP()
	}
}

func GetFlags() *Flags {
	return globalFlags
}

// getLocalIP returns local IP, be it either IPv4 or IPv6, skips loopback addresses
func getLocalIP() string {
	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return ""
	}
	for _, address := range addrs {
		if ipnet, ok := address.(*net.IPNet); ok && !ipnet.IP.IsLoopback() && !ipnet.IP.IsPrivate() && !ipnet.IP.IsUnspecified() {
			if ipnet.IP.To4() != nil || ipnet.IP != nil {
				return ipnet.IP.String()
			}
		}
	}
	return ""
}