package service

import (
	"encoding/json"
	"fmt"
	"os"
	"time"

	"dario.cat/mergo"
)

type Duration struct {
	time.Duration
}

func (s Duration) MarshalJSON() ([]byte, error) {
	return json.Marshal(s.Duration.String())
}

func (s *Duration) UnmarshalJSON(data []byte) error {
	var str string
	err := json.Unmarshal(data, &str)
	if err != nil {
		return err
	}

	v, err := time.ParseDuration(str)
	if err != nil {
		return err
	}
	*s = Duration{v}

	return nil
}

type Config struct {
	MaxInterval Duration  `json:"max-interval,omitempty"`
	MinInterval Duration  `json:"min-interval,omitempty"`
	Mirrors     []*Mirror `json:"mirrors,omitempty"`
}

var DefaultConfig = Config{
	MaxInterval: Duration{24 * time.Hour},
	MinInterval: Duration{time.Hour},
}

func (c *Config) Apply(arg Config) {
	err := mergo.Merge(c, &arg)
	if err != nil {
		panic(err)
	}
}

// ApplyFileConfig loads the configuration described by the given yaml file.
func ApplyFileConfig(cfg *Config, filePath string) error {
	var ret Config

	f, err := os.Open(filePath)
	if os.IsNotExist(err) {
		return nil
	} else if err != nil {
		return err
	}
	defer f.Close()

	err = json.NewDecoder(f).Decode(&ret)
	if err != nil {
		return fmt.Errorf("loading configuration file: %w", err)
	}

	cfg.Apply(ret)
	return nil
}