package model

import (
	"errors"
	"fmt"
	"io/ioutil"
	"strings"

	"gopkg.in/yaml.v3"
)

var (
	ErrConfigBirthdayFileEmpty                   = errors.New("birthday file cannot be empty")
	ErrLoggerConfigBadLevel                      = errors.New("logger level needs to be one of debug, info, warn, error, fatal or left empty")
	ErrTelegramNotificationsConfigEmptyBotToken  = errors.New("bot token cannot be empty")
	ErrTelegramNotificationsConfigEmptyChannelID = errors.New("channel ID cannot be empty")
)

type Config struct {
	BirthdayFile          string                       `yaml:"birthday_file"`
	Logger                *LoggerConfig                `yaml:"logger"`
	TelegramNotifications *TelegramNotificationsConfig `yaml:"telegram_notifications"`
}

// ToDo: to be implemented
func (c *Config) IsValid() error {
	if c.BirthdayFile == "" {
		return ErrConfigBirthdayFileEmpty
	}

	if err := c.Logger.IsValid(); err != nil {
		return fmt.Errorf("invalid logger config: %w", err)
	}

	if c.TelegramNotifications != nil {
		if err := c.TelegramNotifications.IsValid(); err != nil {
			return fmt.Errorf("invalid telegram notifications config: %w", err)
		}
	}

	return nil
}

func (c *Config) SetDefaults() {
	if c.Logger == nil {
		c.Logger = &LoggerConfig{}
	}

	c.Logger.SetDefaults()

	if c.TelegramNotifications != nil {
		c.TelegramNotifications.SetDefaults()
	}
}

type LoggerConfig struct {
	Level        string `yaml:"level"`
	ReportCaller bool   `yaml:"report_caller"`
}

func (lc *LoggerConfig) SetDefaults() {}

func (lc *LoggerConfig) IsValid() error {
	level := strings.TrimSpace(strings.ToLower(lc.Level))

	found := false
	for _, ll := range []string{"debug", "info", "warn", "error", "fatal", ""} {
		if level == ll {
			found = true
			break
		}
	}

	if !found {
		return ErrLoggerConfigBadLevel
	}

	return nil
}

type TelegramNotificationsConfig struct {
	BotToken  string `yaml:"bot_token"`
	ChannelID string `yaml:"channel_id"`
}

func (tnc *TelegramNotificationsConfig) SetDefaults() {}

func (tnc *TelegramNotificationsConfig) IsValid() error {
	if tnc.BotToken == "" {
		return ErrTelegramNotificationsConfigEmptyBotToken
	}

	if tnc.ChannelID == "" {
		return ErrTelegramNotificationsConfigEmptyChannelID
	}

	return nil
}

func ReadConfig(path string) (*Config, error) {
	fileBytes, err := ioutil.ReadFile(path)
	if err != nil {
		return nil, err
	}

	var config *Config
	if err := yaml.Unmarshal(fileBytes, &config); err != nil {
		return nil, err
	}

	config.SetDefaults()

	return config, nil
}