package crypto

import (
	"sync"
)

// BatchDecryptResult 批量解密结果
type BatchDecryptResult struct {
	Index     int
	Plaintext []byte
	Error     error
}

// BatchDecrypt 批量并行解密
// workerCount 指定并行工作数，如果 <= 0 则使用 CPU 核数
func (e *MessageEncryptor) BatchDecrypt(ciphertexts []string, workerCount int) [][]byte {
	if e == nil || len(ciphertexts) == 0 {
		return nil
	}

	results := make([][]byte, len(ciphertexts))

	// 小批量直接串行处理
	if len(ciphertexts) <= 10 {
		for i, ct := range ciphertexts {
			if ct == "" {
				continue
			}
			plaintext, err := e.Decrypt(ct)
			if err == nil {
				results[i] = plaintext
			}
		}
		return results
	}

	// 并行处理
	jobs := make(chan int, len(ciphertexts))
	var wg sync.WaitGroup

	// 确定工作数
	if workerCount <= 0 {
		workerCount = 4 // 默认4个并行
	}
	if workerCount > len(ciphertexts) {
		workerCount = len(ciphertexts)
	}

	// 启动 worker
	for w := 0; w < workerCount; w++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for i := range jobs {
				ct := ciphertexts[i]
				if ct == "" {
					continue
				}
				plaintext, err := e.Decrypt(ct)
				if err == nil {
					results[i] = plaintext
				}
			}
		}()
	}

	// 分发任务
	for i := range ciphertexts {
		jobs <- i
	}
	close(jobs)

	wg.Wait()
	return results
}