package config

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

	"gopkg.in/yaml.v3"
)

type Config struct {
	Mode                 string                     `yaml:"mode"`
	ExternalIPProvider   ExternalIpProviderConfig   `yaml:"ip_provider"`
	DNSProvider          DNSProviderConfig          `yaml:"dns_provider"`
	NotificationProvider NotificationProviderConfig `yaml:"notification_provider,omitempty"`
	Domains              []DomainConfig             `yaml:"domains"`
	CheckInterval        string                     `yaml:"check_interval"`
	LogLevel             string                     `yaml:"log_level"`
}

const (
	RunOnceMode   = "RunOnce"
	ScheduledMode = "Scheduled"
)

var LogLevelMap = map[string]slog.Level{
	"debug": slog.LevelDebug,
	"info":  slog.LevelInfo,
	"warn":  slog.LevelWarn,
	"error": slog.LevelError,
}

func isValidLogLevel(level string) bool {
	_, ok := LogLevelMap[strings.ToLower(level)]
	return ok
}

type DomainConfig struct {
	TLD        string   `yaml:"tld"`
	Subdomains []string `yaml:"subdomains"`
}

type ExternalIpProviderConfig struct {
	Type           string    `yaml:"type"`
	ProviderConfig yaml.Node `yaml:"config"`
}

type DNSProviderConfig struct {
	Type           string    `yaml:"type"`
	ProviderConfig yaml.Node `yaml:"config"`
}

type NotificationProviderConfig struct {
	Type           string    `yaml:"type"`
	ProviderConfig yaml.Node `yaml:"config"`
}

func (c *Config) Load(filePath string) error {
	inputConfig, err := os.ReadFile(filePath)
	if err != nil {
		return fmt.Errorf("failed to read config file: %w", err)
	}

	if err := yaml.Unmarshal(inputConfig, c); err != nil {
		return fmt.Errorf("failed to unmarshal config file: %w", err)
	}

	if err := c.validate(); err != nil {
		return fmt.Errorf("failed to validate config: %w", err)
	}

	return nil
}

func (c *Config) validate() error {
	if c.Mode != RunOnceMode && c.Mode != ScheduledMode {
		return errors.New("mode must be one of 'RunOnce' or 'Scheduled'")
	}

	if c.Mode == ScheduledMode && c.CheckInterval == "" {
		return errors.New("check interval must be set when mode is 'Scheduled'")
	}

	if c.LogLevel != "" && !isValidLogLevel(c.LogLevel) {
		return fmt.Errorf("log level must be one of 'debug', 'info', 'warn', 'error', but got %s", c.LogLevel)
	}

	return nil
}