package com.suno.android.common_data.media.usecase

import android.content.ContentResolver
import android.net.Uri
import java.io.DataOutputStream
import javax.inject.Inject
import kotlin.time.Duration

class TrimWavUseCase @Inject constructor(
    private val contentResolver: ContentResolver,
) {

    operator fun invoke(
        inputFile: Uri,
        outputFile: Uri,
        trimTime: ClosedRange<Duration>,
    ): Result<Unit> =
        runCatching {
            // Read WAV file header and data
            val inputStream = contentResolver.openInputStream(inputFile) ?: error("could not open input")

            // Read WAV header (44 bytes)
            val header = ByteArray(44)
            inputStream.read(header)

            // Calculate bytes per sample and number of channels from header
            val bitsPerSample = ((header[35].toInt() and 0xFF) shl 8) or (header[34].toInt() and 0xFF)
            val bytesPerSample = bitsPerSample / 8
            val numChannels = ((header[23].toInt() and 0xFF) shl 8) or (header[22].toInt() and 0xFF)
            val sampleRate =
                ((header[27].toInt() and 0xFF) shl 24) or ((header[26].toInt() and 0xFF) shl 16) or
                    ((header[25].toInt() and 0xFF) shl 8) or
                    (header[24].toInt() and 0xFF)

            // Calculate start and end positions in bytes
            val startByte =
                ((trimTime.start.inWholeMilliseconds * sampleRate) / 1000) * bytesPerSample * numChannels + 44
            val endByte =
                ((trimTime.endInclusive.inWholeMilliseconds * sampleRate) / 1000) * bytesPerSample * numChannels + 44
            val trimmedSize = endByte - startByte

            // Update data size in header
            val newDataSize = trimmedSize
            header[40] = (newDataSize and 0xFF).toByte()
            header[41] = ((newDataSize shr 8) and 0xFF).toByte()
            header[42] = ((newDataSize shr 16) and 0xFF).toByte()
            header[43] = ((newDataSize shr 24) and 0xFF).toByte()

            // Write trimmed WAV file
            val outputStream =
                DataOutputStream(contentResolver.openOutputStream(outputFile) ?: error("could not open output"))

            // Write header
            outputStream.write(header)

            // Skip to start position
            inputStream.skip(startByte - 44)

            // Copy trimmed portion
            val buffer = ByteArray(8192)
            var bytesRemaining = trimmedSize
            while (bytesRemaining > 0) {
                val bytesToRead = minOf(buffer.size.toLong(), bytesRemaining).toInt()
                val bytesRead = inputStream.read(buffer, 0, bytesToRead)
                if (bytesRead == -1) break
                outputStream.write(buffer, 0, bytesRead)
                bytesRemaining -= bytesRead
            }

            inputStream.close()
            outputStream.close()
        }
}