package checker

import (
	"fmt"
	"net"
	"strings"
	"time"

	"github.com/intodns/backend/internal/resolver"
	"github.com/miekg/dns"
)

// checkWWW runs the 2 WWW checks.
func checkWWW(domain string, r *resolver.Resolver) Category {
	cat := Category{Name: "www", Title: "WWW"}

	domain = dns.Fqdn(domain)
	wwwName := "www." + domain

	// 1. www-a-record
	cat.Checks = append(cat.Checks, checkWWWARecord(wwwName, r))

	// 2. www-cname
	cat.Checks = append(cat.Checks, checkWWWCNAME(wwwName, r))

	return cat
}

func checkWWWARecord(wwwName string, r *resolver.Resolver) CheckResult {
	start := time.Now()
	res := CheckResult{ID: "www-a-record", Title: "WWW A Record"}
	defer func() { res.DurationMs = measureDuration(start) }()

	resp, err := r.Query(wwwName, "8.8.8.8", dns.TypeA)
	if err != nil {
		res.Status = StatusWarn
		res.Message = fmt.Sprintf("Failed to query A record for %s: %v", wwwName, err)
		return res
	}

	var ips []string
	for _, rr := range resp.Answer {
		if a, ok := rr.(*dns.A); ok {
			ips = append(ips, a.A.String())
		}
	}

	if len(ips) == 0 {
		res.Status = StatusInfo
		res.Message = fmt.Sprintf("No A record found for %s", wwwName)
		return res
	}

	allPublic := true
	for _, ipStr := range ips {
		ip := net.ParseIP(ipStr)
		if isPublicIP(ip) {
			res.Details = append(res.Details, fmt.Sprintf("%s -> %s (public)", wwwName, ipStr))
		} else {
			allPublic = false
			res.Details = append(res.Details, fmt.Sprintf("%s -> %s (NOT public)", wwwName, ipStr))
		}
	}

	if allPublic {
		res.Status = StatusPass
		res.Message = fmt.Sprintf("%s has A record(s) with public IP(s)", wwwName)
	} else {
		res.Status = StatusWarn
		res.Message = fmt.Sprintf("%s has A record(s) but some IPs are not public", wwwName)
	}
	return res
}

func checkWWWCNAME(wwwName string, r *resolver.Resolver) CheckResult {
	start := time.Now()
	res := CheckResult{ID: "www-cname", Title: "WWW CNAME"}
	defer func() { res.DurationMs = measureDuration(start) }()

	resp, err := r.Query(wwwName, "8.8.8.8", dns.TypeCNAME)
	if err != nil {
		res.Status = StatusInfo
		res.Message = fmt.Sprintf("Could not check CNAME for %s", wwwName)
		return res
	}

	var targets []string
	for _, rr := range resp.Answer {
		if cname, ok := rr.(*dns.CNAME); ok {
			targets = append(targets, cname.Target)
		}
	}

	if len(targets) > 0 {
		res.Status = StatusInfo
		res.Message = fmt.Sprintf("%s is a CNAME to %s", wwwName, strings.Join(targets, ", "))
		for _, t := range targets {
			res.Details = append(res.Details, fmt.Sprintf("CNAME target: %s", t))
		}
	} else {
		res.Status = StatusInfo
		res.Message = fmt.Sprintf("%s is not a CNAME (direct A/AAAA record)", wwwName)
	}
	return res
}