package cache

import (
	"errors"
	"github.com/patrickmn/go-cache"
	"reflect"
	"time"
)

var (
	ErrMemoryCacheNotExists    = errors.New("item does not exist")
	ErrMemoryCacheNotSupported = errors.New("memory cache does not support retrieving items without a destination pointer")
)

type MemoryCache struct {
	c *cache.Cache
}

func NewMemoryCache(cleanupTime time.Duration) (CacheInterface, error) {
	c := cache.New(1*time.Minute, cleanupTime)

	return &MemoryCache{c: c}, nil
}

func (mc *MemoryCache) Has(key string) bool {
	_, exists := mc.c.Get(key)

	return exists
}

func (mc *MemoryCache) Get(key string, dst ...interface{}) ([]byte, error) {
	item, exists := mc.c.Get(key)

	if !exists {
		return nil, ErrMemoryCacheNotExists
	}

	if len(dst) == 0 {
		return nil, ErrMemoryCacheNotSupported
	}

	v := dst[0]

	switch v := v.(type) {
	case *string:
		if v != nil {
			*v = item.(string)
			return nil, nil
		}
	case *[]byte:
		if v != nil {
			*v = item.([]byte)
			return nil, nil
		}
	case *int:
		if v != nil {
			*v = item.(int)
			return nil, nil
		}
	case *int8:
		if v != nil {
			*v = item.(int8)
			return nil, nil
		}
	case *int16:
		if v != nil {
			*v = item.(int16)
			return nil, nil
		}
	case *int32:
		if v != nil {
			*v = item.(int32)
			return nil, nil
		}
	case *int64:
		if v != nil {
			*v = item.(int64)
			return nil, nil
		}
	case *uint:
		if v != nil {
			*v = item.(uint)
			return nil, nil
		}
	case *uint8:
		if v != nil {
			*v = item.(uint8)
			return nil, nil
		}
	case *uint16:
		if v != nil {
			*v = item.(uint16)
			return nil, nil
		}
	case *uint32:
		if v != nil {
			*v = item.(uint32)
			return nil, nil
		}
	case *uint64:
		if v != nil {
			*v = item.(uint64)
			return nil, nil
		}
	case *bool:
		if v != nil {
			*v = item.(bool)
			return nil, nil
		}
	case *float32:
		if v != nil {
			*v = item.(float32)
			return nil, nil
		}
	case *float64:
		if v != nil {
			*v = item.(float64)
			return nil, nil
		}
	case *[]string:
		*v = item.([]string)
		return nil, nil
	case *map[string]string:
		*v = item.(map[string]string)
		return nil, nil
	case *map[string]interface{}:
		*v = item.(map[string]interface{})
		return nil, nil
	case *time.Duration:
		if v != nil {
			*v = item.(time.Duration)
			return nil, nil
		}
	case *time.Time:
		if v != nil {
			*v = item.(time.Time)
			return nil, nil
		}
	}

	vv := reflect.ValueOf(dst[0])

	if !vv.IsValid() {
		return nil, errors.New("dst pointer is not valid")
	}

	if vv.Kind() != reflect.Ptr {
		return nil, errors.New("dst pointer is not a pointer")
	}

	vv = vv.Elem()

	if !vv.IsValid() {
		return nil, errors.New("dst pointer is not a valid element")
	}

	vv.Set(reflect.ValueOf(item))

	return nil, nil
}

func (mc *MemoryCache) Set(key string, val interface{}, ttl time.Duration) error {
	mc.c.Set(key, val, ttl)
	return nil
}

func (mc *MemoryCache) Del(key string) error {
	mc.c.Delete(key)
	return nil
}