package snowflake

import (
	"fmt"
	"sync"
	"time"

	"github.com/bwmarrin/snowflake"
)

var mu sync.Mutex

// Snowflake provides a way to NewNode for Generate UID.
type Snowflake struct {
	machineNodeID int64

	startTime time.Time
}

// Option is the options type to configure Snowflake.
type Option func(*Snowflake)

// New returns a new Snowflake instance with the provided options.
func New(opts ...Option) *Snowflake {
	s := &Snowflake{
		// default machine 1
		machineNodeID: 1,
	}

	for _, opt := range opts {
		opt(s)
	}

	return s
}

// WithMachineNodeID adds machineID total 10bit = 1024 machine number.
func WithMachineNodeID(machineNodeID int64) Option {
	return func(snowflake *Snowflake) {
		snowflake.machineNodeID = machineNodeID
	}
}

// WithStartTime adds snowflake start timestamp in milliseconds.
func WithStartTime(startTime time.Time) Option {
	return func(snowflake *Snowflake) {
		snowflake.startTime = startTime
	}
}

// GetNowDate return nowTodayDate e.g. 2023-07-20 00:00:00 +0000 UTC.
func GetNowDate() (time.Time, error) {
	startTime := time.Now().UTC().Format(time.DateOnly)

	st, err := time.Parse(time.DateOnly, startTime)
	if err != nil {
		return time.Time{}, fmt.Errorf("time.Parse failed :%w", err)
	}

	return st, nil
}

// NewNode return snowflake node use Generate UID.
func (s *Snowflake) NewNode() (*snowflake.Node, error) {
	mu.Lock()
	defer mu.Unlock()

	snowflake.Epoch = s.startTime.UnixMilli()

	node, err := snowflake.NewNode(s.machineNodeID)
	if err != nil {
		return nil, fmt.Errorf("snowflake.NewNode, failed :%w",
			&NewNodeError{
				machineNodeID: s.machineNodeID,
				startTime:     s.startTime,
				Err:           err,
			})
	}

	return node, nil
}