FileSizeUtils.kt

package ando.file.core

import ando.file.core.FileOperator.getContext
import android.content.Context
import android.database.Cursor
import android.net.Uri
import android.os.Build
import android.provider.OpenableColumns
import ando.file.core.FileSizeUtils.FileSizeType.*
import ando.file.core.FileLogger.e
import ando.file.core.FileLogger.i
import ando.file.core.FileUri.getPathByUri
import java.io.File
import java.math.BigDecimal

/**
 * # FileSizeUtils
 *
 * - 1.计算文件大小: BigDecimal
 *
 * - 2.获取文件大小的方法只有两种(There are only two ways to get the file size):
 *
 *      - File.length
 *      - ContentResolver.query()
 */
object FileSizeUtils {

    enum class FileSizeType(val id: Int, val unit: String) {
        SIZE_TYPE_B(1, "B"),
        SIZE_TYPE_KB(2, "KB"),
        SIZE_TYPE_MB(3, "M"),
        SIZE_TYPE_GB(4, "GB"),
        SIZE_TYPE_TB(5, "TB")
    }

    // File/Dir Size
    //-----------------------------------------------------------------------

    /**
     * 获取指定 `文件/文件夹` 大小
     *
     * Get the size of the specified `file folder`
     */
    @Throws(Exception::class)
    fun getFolderSize(file: File?): Long {
        var size = 0L
        if (file == null || !file.exists()) return size
        val files = file.listFiles()
        if (files.isNullOrEmpty()) return size

        for (i in files.indices) {
            size += if (files[i].isDirectory) getFolderSize(files[i]) else getFileSize(files[i])
        }
        return size
    }

    /**
     * 计算`文件/文件夹`的大小 (Calculate the size of `file folder`)
     *
     * @param path 文件/文件夹的路径
     * @param sizeType 指定要转换的单位类型
     * @return 大小 double
     */
    fun calculateFileOrDirSize(path: String?, scale: Int = 2, sizeType: FileSizeType): Double {
        if (path.isNullOrBlank()) return 0.00
        return formatSizeByTypeWithoutUnit(calculateFileOrDirSize(path).toBigDecimal(), scale, sizeType).toDouble()
    }

    /**
     * 计算`文件/文件夹`的大小 (Calculate the size of `file folder`)
     *
     * @param path 文件/文件夹的路径
     * @return Size
     */
    fun calculateFileOrDirSize(path: String?): Long {
        if (path.isNullOrBlank()) return 0L

        val file = File(path)
        var blockSize = 0L
        try {
            blockSize = if (file.isDirectory) getFolderSize(file) else getFileSize(file)
        } catch (e: Exception) {
            e("Failed to get file size = $e")
        }
        i("Get file size = $blockSize")
        return blockSize
    }

    /**
     * 自动计算指定文件或指定文件夹的大小 (Automatically calculate the size of the specified file or specified folder)
     *
     * @param path 文件路径
     * @return 带 B、KB、M、GB、TB 单位的字符串
     */
    fun getFileOrDirSizeFormatted(path: String?): String = formatFileSize(calculateFileOrDirSize(path))

    /**
     * 获取文件大小
     */
    fun getFileSize(file: File?): Long = if (file?.exists() == true) file.length() else 0L

    fun getFileSize(uri: Uri?): Long = getFileSize(getContext(), uri) ?: 0L

    /**
     * ContentResolver.query 获取 `文件/文件夹` 大小 (Get the size of `file folder`)
     *
     * @return File Size, Unit Byte
     */
    private fun getFileSize(context: Context, uri: Uri?): Long? =
        uri?.use {
            val zero = 0L
            val uriScheme = uri.scheme
            val cursor: Cursor? = context.contentResolver.query(uri, null, null, null, null)
            return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q || "content".equals(uriScheme, true)) {
                cursor?.use { c ->
                    val sizeIndex: Int = c.getColumnIndex(OpenableColumns.SIZE)
                    // 1.Technically the column stores an int, but cursor.getString() will do the conversion automatically.
                    // it.getString(sizeIndex)
                    // 2.it.moveToFirst() -> Caused by: android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 1
                    if (c.moveToFirst() && !c.isNull(sizeIndex)) c.getLong(sizeIndex) else zero
                }
            } else if ("file".equals(uriScheme, true)) File(getPathByUri(uri) ?: return zero).length() else zero
        }
    // format size
    //-----------------------------------------------------------------------

    /**
     * 保留两位小数, 不带单位 (Keep two decimal places, no unit)
     */
    fun formatFileSize(size: Long): String = formatFileSize(size, 2, true)

    /**
     * @param scale 精确到小数点以后几位 (Accurate to a few decimal places)
     */
    fun formatFileSize(size: Long, scale: Int, withUnit: Boolean = false): String {
        val divisor = 1024L
        //ROUND_DOWN 1023 -> 1023B ; ROUND_HALF_UP  1023 -> 1KB
        val kiloByte: BigDecimal = formatSizeByTypeWithDivisor(BigDecimal.valueOf(size), scale, SIZE_TYPE_B, divisor)
        if (kiloByte.toDouble() < 1) {
            return "${kiloByte.toPlainString()}${if (withUnit) SIZE_TYPE_B.unit else ""}"
        }
        //KB
        val megaByte = formatSizeByTypeWithDivisor(kiloByte, scale, SIZE_TYPE_KB, divisor)
        if (megaByte.toDouble() < 1) {
            return "${kiloByte.toPlainString()}${if (withUnit) SIZE_TYPE_KB.unit else ""}"
        }
        //M
        val gigaByte = formatSizeByTypeWithDivisor(megaByte, scale, SIZE_TYPE_MB, divisor)
        if (gigaByte.toDouble() < 1) {
            return "${megaByte.toPlainString()}${if (withUnit) SIZE_TYPE_MB.unit else ""}"
        }
        //GB
        val teraBytes = formatSizeByTypeWithDivisor(gigaByte, scale, SIZE_TYPE_GB, divisor)
        if (teraBytes.toDouble() < 1) {
            return "${gigaByte.toPlainString()}${if (withUnit) SIZE_TYPE_GB.unit else ""}"
        }
        //TB
        return "${teraBytes.toPlainString()}${if (withUnit) SIZE_TYPE_TB.unit else ""}"
    }

    /**
     * ### 转换文件大小不带单位, 注:没有单位,可自定义. 如: sizeType为`FileSizeType.SIZE_TYPE_MB`则返回`2.383`, 即`2.383M`
     *
     *  The converted file size does not have a unit. Note: There is no unit and can be customized.
     *  For example: sizeType is `FileSizeType.SIZE_TYPE_MB` then returns `2.383`, that is, `2.383M`
     *
     * - BigDecimal 实现提供（相对）精确的除法运算。当发生除不尽的情况时(ArithmeticException)，由scale参数指定精度，以后的数字四舍五入
     *
     * - https://www.liaoxuefeng.com/wiki/1252599548343744/1279768011997217
     * https://zhuanlan.zhihu.com/p/75780642
     * <pre>
     *      注: 禁止使用构造方法BigDecimal(double)的方式把double值转化为BigDecimal对象
     *      说明：反编译出的字节码文件显示每次循环都会new出一个StringBuilder对象，然后进行append操作，最后通过toString方法返回String对象，造成内存资源浪费。
     *      BigDecimal result = new BigDecimal(Double.toString(megaByte));
     * </pre>
     *
     * @param size 大小 Byte
     * @param scale 精确到小数点以后几位
     */
    fun formatSizeByTypeWithoutUnit(size: BigDecimal, scale: Int, sizeType: FileSizeType): BigDecimal =
        size.divide(
            BigDecimal.valueOf(
                when (sizeType) {
                    SIZE_TYPE_B -> 1L
                    SIZE_TYPE_KB -> 1024L
                    SIZE_TYPE_MB -> 1024L * 1024L
                    SIZE_TYPE_GB -> 1024L * 1024L * 1024L
                    SIZE_TYPE_TB -> 1024L * 1024L * 1024L * 1024L
                }
            ),
            scale,
            //ROUND_DOWN 1023 -> 1023B ; ROUND_HALF_UP  1023 -> 1KB
            if (sizeType == SIZE_TYPE_B) BigDecimal.ROUND_DOWN else BigDecimal.ROUND_HALF_UP
        )

    fun formatSizeByTypeWithDivisor(size: BigDecimal, scale: Int, sizeType: FileSizeType, divisor: Long): BigDecimal =
        size.divide(
            BigDecimal.valueOf(divisor),
            scale,
            //ROUND_DOWN 1023 -> 1023B ; ROUND_HALF_UP  1023 -> 1KB
            if (sizeType == SIZE_TYPE_B) BigDecimal.ROUND_DOWN else BigDecimal.ROUND_HALF_UP
        )

    /**
     * 转换文件大小带单位, 注:带单位 2.383M
     *
     * Convert file size with unit, note: with unit 2.383M
     */
    fun formatSizeByTypeWithUnit(size: Long, scale: Int, sizeType: FileSizeType): String {
        return "${formatSizeByTypeWithoutUnit(size.toBigDecimal(), scale, sizeType).toPlainString()}${sizeType.unit}"
    }

}