package backends

import (
	"context"
	"sync"

	"github.com/prebid/prebid-cache/utils"
)

// MemoryBackend stores information in the local memory heap. Stored data dissapears upon
// Prebid Cache restart
type MemoryBackend struct {
	db map[string]string
	mu sync.Mutex
}

// Get retrieves from the local memory and uses a mutex lock to aviod data race scenarios
func (b *MemoryBackend) Get(ctx context.Context, key string) (string, error) {
	b.mu.Lock()
	defer b.mu.Unlock()

	v, ok := b.db[key]
	if !ok {
		return "", utils.NewPBCError(utils.KEY_NOT_FOUND)
	}

	return v, nil
}

// Put stores data in local memory and uses a mutex lock to aviod data race scenarios
func (b *MemoryBackend) Put(ctx context.Context, key string, value string, ttlSeconds int) error {
	b.mu.Lock()
	defer b.mu.Unlock()

	// If the record already exists, don't write and throw error
	if _, ok := b.db[key]; ok {
		return utils.NewPBCError(utils.RECORD_EXISTS)
	}

	b.db[key] = value
	return nil
}

// NewMemoryBackend instances a MemoryBackend struct
func NewMemoryBackend() *MemoryBackend {
	return &MemoryBackend{
		db: make(map[string]string),
	}
}