package internal

import (
	"fmt"
	"log"
	"os"
	"strconv"
	"time"
)

const (
	defaultCheckInterval       = 5 * 60
	envKeyDnsToCheck           = "DNS_NAMES"
	envKeyPublicIpResolverTag  = "PUBLIC_IP_RESOLVER"
	envKeyDNSProviderTag       = "DNS_PROVIDER"
	envKeyPublicDNSServer      = "PUBLIC_DNS_SERVER"
	envKeyCloudflareApiKey     = "CLOUDFLARE_API_KEY"
	envKeyCloudflareZone       = "CLOUDFLARE_ZONE"
	envKeyDirectadminUser      = "DA_USER"
	envKeyDirectadminKey       = "DA_KEY"
	envKeyDirectadminUrl       = "DA_URL"
	envKeyOnChangeComment      = "ON_CHANGE_COMMENT"
	envKeyCheckIntervalSeconds = "CHECK_INTERVAL_SECONDS"
	envKeyNotifiers            = "NOTIFIERS"
)

type Config struct {
	DnsRecordsToCheck         []string
	PublicIpResolverTag       string
	PublicDNSServer           string
	DNSProviderTag            string
	DirectadminUsername       string
	DirectadminKey            string
	DirectadminUrl            string
	ApiToken                  string
	WebhookToken              string
	CloudflareZone            string
	CloudflareOnChangeComment string
	Notifiers                 []string
	CheckInterval             time.Duration
}

func (c Config) Validate() error {
	switch c.DNSProviderTag {
	case "cloudflare":
		if c.ApiToken == "" {
			return fmt.Errorf("empty api token env key %s", envKeyCloudflareApiKey)
		}

	case "directadmin":
		if c.DirectadminUrl == "" {
			return fmt.Errorf("empty DirectAdmin URL env key %s", envKeyDirectadminUrl)
		}

		if c.DirectadminUsername == "" {
			return fmt.Errorf("empty DirectAdmin Username in env key %s", envKeyDirectadminUser)
		}

		if c.DirectadminKey == "" {
			return fmt.Errorf("empty DirectAdmin Login Key in env key %s", envKeyDirectadminKey)
		}
	}

	if len(c.DnsRecordsToCheck) == 0 {
		return fmt.Errorf("no dns to check defined in env key %s", envKeyDnsToCheck)
	}

	return nil
}

func NewConfig() Config {
	checkInterval, err := strconv.ParseInt(os.Getenv(envKeyCheckIntervalSeconds), 10, 64)
	if err != nil {
		log.Printf("wrong or missing `%s` value. Check interval set to default(%ds)", envKeyCheckIntervalSeconds, defaultCheckInterval)
		checkInterval = defaultCheckInterval
	}

	return Config{
		DnsRecordsToCheck:         parseCommaDelimited(os.Getenv(envKeyDnsToCheck)),
		DNSProviderTag:            getEnvDefault(envKeyDNSProviderTag, "cloudflare"),
		PublicIpResolverTag:       getEnvDefault(envKeyPublicIpResolverTag, "icanhazip"),
		ApiToken:                  os.Getenv(envKeyCloudflareApiKey),
		CloudflareZone:            os.Getenv(envKeyCloudflareZone),
		CloudflareOnChangeComment: os.Getenv(envKeyOnChangeComment),
		DirectadminUsername:       os.Getenv(envKeyDirectadminUser),
		DirectadminKey:            os.Getenv(envKeyDirectadminKey),
		DirectadminUrl:            os.Getenv(envKeyDirectadminUrl),
		Notifiers:                 parseCommaDelimited(os.Getenv(envKeyNotifiers)),
		CheckInterval:             time.Duration(checkInterval) * time.Second,
		WebhookToken:              os.Getenv("WEBHOOK_TOKEN"),
	}
}

func getEnvDefault(key, fallback string) string {
	value, exists := os.LookupEnv(key)
	if !exists {
		value = fallback
	}
	return value
}