package cache

import (
	"context"
	"strings"
	"time"
)

type l1Cache struct {
	inner Cache
	local Cache
	ttl   time.Duration
}

func newL1Cache(inner Cache, ttl time.Duration) Cache {
	if ttl <= 0 {
		return inner
	}
	return &l1Cache{inner: inner, local: newMemoryCache(), ttl: ttl}
}

func (c *l1Cache) Get(ctx context.Context, key string) ([]byte, error) {
	if isCacheControlKey(key) {
		return c.inner.Get(ctx, key)
	}
	if value, err := c.local.Get(ctx, key); err == nil {
		recordCacheL1("hit")
		return value, nil
	}
	recordCacheL1("miss")

	value, err := c.inner.Get(ctx, key)
	if err != nil {
		return nil, err
	}
	_ = c.local.Set(ctx, key, value, c.ttl)
	return value, nil
}

func (c *l1Cache) GetMulti(ctx context.Context, keys []string) (map[string][]byte, error) {
	if len(keys) == 0 {
		return map[string][]byte{}, nil
	}

	result := make(map[string][]byte, len(keys))
	miss := make([]string, 0, len(keys))
	for _, key := range keys {
		value, err := c.local.Get(ctx, key)
		if err == nil {
			recordCacheL1("hit")
			result[key] = value
			continue
		}
		recordCacheL1("miss")
		miss = append(miss, key)
	}
	if len(miss) == 0 {
		return result, nil
	}

	values, err := c.inner.GetMulti(ctx, miss)
	if err != nil {
		return nil, err
	}
	for key, value := range values {
		result[key] = value
		_ = c.local.Set(ctx, key, value, c.ttl)
	}
	return result, nil
}

func (c *l1Cache) Set(ctx context.Context, key string, value []byte, ttl time.Duration) error {
	if isCacheControlKey(key) {
		return c.inner.Set(ctx, key, value, ttl)
	}
	if err := c.inner.Set(ctx, key, value, ttl); err != nil {
		return err
	}
	return c.local.Set(ctx, key, value, c.l1TTL(ttl))
}

func (c *l1Cache) SetMulti(ctx context.Context, items []Item) error {
	if err := c.inner.SetMulti(ctx, items); err != nil {
		return err
	}
	for _, item := range items {
		_ = c.local.Set(ctx, item.Key, item.Value, c.l1TTL(item.TTL))
	}
	return nil
}

func (c *l1Cache) Delete(ctx context.Context, key string) error {
	_ = c.local.Delete(ctx, key)
	return c.inner.Delete(ctx, key)
}

func (c *l1Cache) DeleteMany(ctx context.Context, keys []string) error {
	_ = c.local.DeleteMany(ctx, keys)
	return c.inner.DeleteMany(ctx, keys)
}

func (c *l1Cache) DeletePrefix(ctx context.Context, prefix string) error {
	_ = c.local.DeletePrefix(ctx, prefix)
	return c.inner.DeletePrefix(ctx, prefix)
}

func (c *l1Cache) l1TTL(ttl time.Duration) time.Duration {
	if ttl > 0 && ttl < c.ttl {
		return ttl
	}
	return c.ttl
}

func isCacheControlKey(key string) bool {
	key = strings.TrimSpace(key)
	return strings.HasPrefix(key, "cache:version:") || strings.Contains(key, ":cache:version:")
}