package dnsmasq

import (
	"fmt"
	"log/slog"
	"os/exec"
	"strings"

	"github.com/wild-cloud/wild-central/internal/config"
	"github.com/wild-cloud/wild-central/internal/network"
)

// GenerateMainConfig creates the main dnsmasq configuration with global settings
// and a conf-dir directive to include per-domain configs
func (g *ConfigGenerator) GenerateMainConfig(cfg *config.State) string {
	// Get the Wild Central IP address
	dnsIP, err := network.GetWildCentralIP()
	if err != nil {
		slog.Error("failed to detect Wild Central IP", "component", "dnsmasq", "error", err)
		dnsIP = ""
	}

	var sb strings.Builder

	fmt.Fprintf(&sb, `# Wild Cloud DNS Configuration (Main)
# This file contains global settings. Domain-specific DNS entries are
# generated by reconciliation into the monolithic config.

# Basic Settings
listen-address=%s
bind-interfaces
domain-needed
bogus-priv
no-resolv

# Upstream DNS servers
server=1.1.1.1
server=8.8.8.8

# Logging
log-queries
log-dhcp
`, dnsIP)

	// DHCP section (only when explicitly enabled)
	if cfg != nil && cfg.Cloud.Dnsmasq.DHCP.Enabled {
		dhcp := cfg.Cloud.Dnsmasq.DHCP
		sb.WriteString("\n# DHCP Configuration\n")

		leaseTime := dhcp.LeaseTime
		if leaseTime == "" {
			leaseTime = "24h"
		}
		fmt.Fprintf(&sb, "dhcp-range=%s,%s,%s\n", dhcp.RangeStart, dhcp.RangeEnd, leaseTime)

		gateway := dhcp.Gateway
		if gateway != "" {
			fmt.Fprintf(&sb, "dhcp-option=3,%s\n", gateway) // default gateway
		}
		if dnsIP != "" {
			fmt.Fprintf(&sb, "dhcp-option=6,%s\n", dnsIP) // DNS server
		}

		for _, lease := range dhcp.StaticLeases {
			if lease.Hostname != "" {
				fmt.Fprintf(&sb, "dhcp-host=%s,%s,%s\n", lease.MAC, lease.IP, lease.Hostname)
			} else {
				fmt.Fprintf(&sb, "dhcp-host=%s,%s\n", lease.MAC, lease.IP)
			}
		}
	}

	return sb.String()
}

// ValidateConfig tests a dnsmasq configuration file for syntax errors
func (g *ConfigGenerator) ValidateConfig(configPath string) error {
	// Use dnsmasq --test to validate the configuration
	cmd := exec.Command("dnsmasq", "--test", "-C", configPath)
	output, err := cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("config validation failed: %w (output: %s)", err, string(output))
	}

	// Check if output contains "syntax check OK"
	if !strings.Contains(string(output), "syntax check OK") {
		return fmt.Errorf("config validation did not report OK: %s", string(output))
	}

	return nil
}

// ReloadService sends a SIGHUP to dnsmasq to reload configuration
// This is lighter weight than a full restart
func (g *ConfigGenerator) ReloadService() error {
	// Use systemctl reload which sends SIGHUP
	cmd := exec.Command("systemctl", "reload", "dnsmasq.service")
	_, err := cmd.CombinedOutput()
	if err != nil {
		// If reload fails, try restart as fallback
		slog.Error("reload failed, attempting restart", "component", "dnsmasq", "error", err)
		return g.RestartService()
	}
	slog.Info("dnsmasq service reloaded", "component", "dnsmasq")
	return nil
}