package core

import (
	"net"
	"sync"
	"time"
)

// PingResult contains the result of a ping to a server.
type PingResult struct {
	Ms    int64 // round-trip time in ms, -1 if failed
	Color string
}

// PingAddress pings a single address using TCP connect (ICMP requires elevated privileges).
// Returns round-trip time in ms or -1 on failure.
func PingAddress(address string, timeout time.Duration) int64 {
	if timeout == 0 {
		timeout = 3 * time.Second
	}

	start := time.Now()
	conn, err := net.DialTimeout("tcp", address+":443", timeout)
	if err != nil {
		return -1
	}
	conn.Close()
	return time.Since(start).Milliseconds()
}

// PingConfig pings a VPN config and returns the result.
func PingConfig(config *VpnConfig) PingResult {
	link := TryParseLink(config.Link)
	if link == nil {
		return PingResult{Ms: -1, Color: "#666"}
	}

	ms := PingAddress(link.Address, 3*time.Second)
	if ms < 0 {
		return PingResult{Ms: -1, Color: "#666"}
	}
	return PingResult{Ms: ms, Color: GetPingColor(ms)}
}

// PingAllConfigs pings all configs concurrently.
func PingAllConfigs(configs []VpnConfig) []PingResult {
	results := make([]PingResult, len(configs))
	var wg sync.WaitGroup

	for i := range configs {
		wg.Add(1)
		go func(idx int) {
			defer wg.Done()
			results[idx] = PingConfig(&configs[idx])
		}(i)
	}

	wg.Wait()
	return results
}

// GetPingColor returns a color hex code based on ping latency.
func GetPingColor(ms int64) string {
	switch {
	case ms < 50:
		return "#4CAF50" // green
	case ms < 100:
		return "#8BC34A" // light green
	case ms < 150:
		return "#CDDC39" // lime
	case ms < 200:
		return "#FFC107" // amber
	case ms < 300:
		return "#FF9800" // orange
	default:
		return "#E53935" // red
	}
}