package redislock

import (
	"context"
	"fmt"
	"time"

	"github.com/zeromicro/go-zero/core/stores/redis"
)

// Lock is a small Redis lease. Value must uniquely identify the worker that
// owns it; Release uses a Lua compare-and-delete to avoid deleting a renewed
// lease owned by another worker.
type Lock struct {
	client *redis.Redis
	key    string
	owner  string
	ttl    time.Duration
}

func New(conf redis.RedisConf, key, owner string, ttl time.Duration) *Lock {
	return &Lock{client: redis.MustNewRedis(conf), key: key, owner: owner, ttl: ttl}
}

func (l *Lock) Acquire(ctx context.Context) (bool, error) {
	if l == nil || l.client == nil || l.key == "" || l.owner == "" {
		return false, fmt.Errorf("invalid redis lock")
	}
	seconds := int(l.ttl.Seconds())
	if seconds < 1 {
		seconds = 1
	}
	return l.client.SetnxExCtx(ctx, l.key, l.owner, seconds)
}

func (l *Lock) Release(ctx context.Context) error {
	if l == nil || l.client == nil {
		return fmt.Errorf("invalid redis lock")
	}
	_, err := l.client.EvalCtx(ctx, `
if redis.call('GET', KEYS[1]) == ARGV[1] then
  return redis.call('DEL', KEYS[1])
end
return 0
`, []string{l.key}, l.owner)
	return err
}