amethyst/app/src/main/java/com/vitorpamplona/amethyst/ui/actions/ImageSaver.kt

package com.vitorpamplona.amethyst.ui.actions

import android.content.ContentResolver
import android.content.ContentValues
import android.content.Context
import android.content.Intent
import android.os.Build
import android.os.Environment
import android.provider.MediaStore
import androidx.annotation.RequiresApi
import androidx.core.net.toUri
import okhttp3.*
import okio.BufferedSource
import okio.IOException
import okio.sink
import java.io.File

object ImageSaver {
    /**
     * Saves the image to the gallery.
     * May require a storage permission.
     *
     * @see PICTURES_SUBDIRECTORY
     */
    fun saveImage(
        url: String,
        context: Context,
        onSuccess: () -> Any?,
        onError: (Throwable) -> Any?
    ) {
        val client = OkHttpClient.Builder().build()

        val request = Request.Builder()
            .header("User-Agent", "Amethyst")
            .get()
            .url(url)
            .build()

        client.newCall(request).enqueue(object : Callback {
            override fun onFailure(call: Call, e: IOException) {
                e.printStackTrace()
                onError(e)
            }

            override fun onResponse(call: Call, response: Response) {
                try {
                    check(response.isSuccessful)

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
                        val contentType = response.header("Content-Type")
                        checkNotNull(contentType) {
                            "Can't find out the content type"
                        }

                        saveContentQ(
                            displayName = File(url).nameWithoutExtension,
                            contentType = contentType,
                            contentSource = response.body.source(),
                            contentResolver = context.contentResolver
                        )
                    } else {
                        saveContentDefault(
                            fileName = File(url).name,
                            contentSource = response.body.source(),
                            context = context
                        )
                    }
                    onSuccess()
                } catch (e: Exception) {
                    e.printStackTrace()
                    onError(e)
                }
            }
        })
    }

    @RequiresApi(Build.VERSION_CODES.Q)
    private fun saveContentQ(
        displayName: String,
        contentType: String,
        contentSource: BufferedSource,
        contentResolver: ContentResolver
    ) {
        val contentValues = ContentValues().apply {
            put(MediaStore.MediaColumns.DISPLAY_NAME, displayName)
            put(MediaStore.MediaColumns.MIME_TYPE, contentType)
            put(
                MediaStore.MediaColumns.RELATIVE_PATH,
                Environment.DIRECTORY_PICTURES + File.separatorChar + PICTURES_SUBDIRECTORY
            )
        }

        val uri =
            contentResolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, contentValues)
        checkNotNull(uri) {
            "Can't insert the new content"
        }

        try {
            val outputStream = contentResolver.openOutputStream(uri)
            checkNotNull(outputStream) {
                "Can't open the content output stream"
            }

            outputStream.use {
                contentSource.readAll(it.sink())
            }
        } catch (e: Exception) {
            contentResolver.delete(uri, null, null)
            throw e
        }
    }

    private fun saveContentDefault(
        fileName: String,
        contentSource: BufferedSource,
        context: Context
    ) {
        val subdirectory = File(
            Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
            PICTURES_SUBDIRECTORY
        )

        if (!subdirectory.exists()) {
            subdirectory.mkdirs()
        }

        val outputFile = File(subdirectory, fileName)

        outputFile
            .outputStream()
            .use {
                contentSource.readAll(it.sink())
            }

        // Call the media scanner manually, so the image
        // appears in the gallery faster.
        context.sendBroadcast(
            Intent(
                Intent.ACTION_MEDIA_SCANNER_SCAN_FILE,
                outputFile.toUri()
            )
        )
    }

    private const val PICTURES_SUBDIRECTORY = "Amethyst"
}