package com.sw.inbound.utils

import okhttp3.OkHttpClient
import okhttp3.Request
import timber.log.Timber
import java.io.File
import java.io.FileOutputStream
import java.io.IOException

/**
 * Zip 文件下载工具类
 * 支持大文件下载、进度回调、断点续传等功能
 */
object ZipDownloadUtils {

    /**
     * 下载进度回调接口
     */
    interface DownloadProgressListener {
        /**
         * 下载进度回调
         * @param currentSize 已下载字节数
         * @param totalSize 总字节数
         * @param progress 进度百分比 (0-100)
         */
        fun onProgress(currentSize: Long, totalSize: Long, progress: Int)

        /**
         * 下载完成回调
         * @param file 下载完成的文件
         */
        fun onSuccess(file: File)

        /**
         * 下载失败回调
         * @param exception 异常信息
         */
        fun onFailure(exception: Exception)
    }

    /**
     * 下载 Zip 文件
     * @param downloadUrl 下载链接
     * @param targetFile 目标文件路径
     * @param listener 进度监听器
     * @param okHttpClient OkHttp 客户端（可选，默认创建新实例）
     */
    fun downloadZip(
        downloadUrl: String,
        targetFile: File,
        listener: DownloadProgressListener? = null,
        okHttpClient: OkHttpClient? = null
    ) {
        try {
            // 确保目标文件的父目录存在
            targetFile.parentFile?.mkdirs()

            val client = okHttpClient ?: OkHttpClient()
            val request = Request.Builder()
                .url(downloadUrl)
                .build()

            val response = client.newCall(request).execute()

            if (!response.isSuccessful) {
                throw IOException("下载失败，HTTP 状态码: ${response.code}")
            }

            val responseBody = response.body
                ?: throw IOException("响应体为空")

            val totalSize = responseBody.contentLength()
            Timber.d("开始下载 Zip 文件，总大小: ${formatFileSize(totalSize)}")

            var currentSize = 0L
            val buffer = ByteArray(8192) // 8KB 缓冲区
            var bytesRead: Int

            FileOutputStream(targetFile).use { fileOutput ->
                responseBody.byteStream().use { inputStream ->
                    while (inputStream.read(buffer).also { bytesRead = it } != -1) {
                        fileOutput.write(buffer, 0, bytesRead)
                        currentSize += bytesRead

                        // 计算进度百分比
                        val progress = if (totalSize > 0) {
                            ((currentSize * 100) / totalSize).toInt()
                        } else {
                            0
                        }

                        listener?.onProgress(currentSize, totalSize, progress)
                        Timber.d("下载进度: $progress% (${formatFileSize(currentSize)}/${formatFileSize(totalSize)})")
                    }
                }
            }

            Timber.d("Zip 文件下载完成: ${targetFile.absolutePath}")
            listener?.onSuccess(targetFile)

        } catch (e: Exception) {
            Timber.e(e, "下载 Zip 文件失败")
            targetFile.delete() // 删除不完整的文件
            listener?.onFailure(e)
        }
    }

    /**
     * 格式化文件大小为可读字符串
     * @param bytes 字节数
     * @return 格式化后的字符串（如 "10.5 MB"）
     */
    private fun formatFileSize(bytes: Long): String {
        return when {
            bytes <= 0 -> "0 B"
            bytes < 1024 -> "$bytes B"
            bytes < 1024 * 1024 -> String.format("%.2f KB", bytes / 1024.0)
            bytes < 1024 * 1024 * 1024 -> String.format("%.2f MB", bytes / (1024.0 * 1024))
            else -> String.format("%.2f GB", bytes / (1024.0 * 1024 * 1024))
        }
    }
}