Add file logger

app/src/debug/java/org/tasks/BuildSetup.kt

@@ -14,6 +14,7 @@ import com.facebook.soloader.SoLoader
 import com.todoroo.andlib.utility.AndroidUtilities.atLeastOreo
 import com.todoroo.andlib.utility.AndroidUtilities.atLeastQ
 import leakcanary.AppWatcher
+import org.tasks.logging.FileLogger
 import org.tasks.preferences.Preferences
 import timber.log.Timber
 import timber.log.Timber.DebugTree
@@ -21,10 +22,11 @@ import javax.inject.Inject
 
 class BuildSetup @Inject constructor(
         private val context: Application,
-        private val preferences: Preferences) {
-
+        private val preferences: Preferences
+) {
     fun setup() {
         Timber.plant(DebugTree())
+        Timber.plant(FileLogger(context))
         SoLoader.init(context, false)
         if (preferences.getBoolean(R.string.p_leakcanary, false)) {
             AppWatcher.manualInstall(context)
@@ -63,4 +65,4 @@ class BuildSetup @Inject constructor(
             StrictMode.setVmPolicy(builder.build())
         }
     }
-}
+}

app/src/main/java/org/tasks/logging/FileLogger.kt

@@ -0,0 +1,67 @@
+package org.tasks.logging
+
+import android.content.Context
+import android.os.Process
+import android.util.Log
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.launch
+import org.tasks.logging.LogFormatter.Companion.LINE_SEPARATOR
+import timber.log.Timber
+import java.io.File
+import java.util.logging.FileHandler
+import java.util.logging.Logger
+
+class FileLogger(
+    context: Context,
+) : Timber.DebugTree() {
+    val logDirectory = File(context.cacheDir, "logs").apply { mkdirs() }
+    private val scope = CoroutineScope(SupervisorJob() + Dispatchers.IO)
+    private val fileHandler: FileHandler = FileHandler(
+        "${logDirectory.absolutePath}/log.%g.txt",
+        20 * 1024 * 1024,
+        10
+    )
+    private val logger = Logger.getLogger(context.packageName)
+
+    init {
+        fileHandler.formatter = LogFormatter()
+        logger.addHandler(fileHandler)
+    }
+
+    override fun log(priority: Int, tag: String?, message: String, t: Throwable?) {
+        if (priority < Log.DEBUG) {
+            return
+        }
+        val threadId = Process.myTid()
+        scope.launch {
+            t?.let { logger.info(it.stackTrace.joinToString(LINE_SEPARATOR)) }
+            logger.info("${Process.myPid()}-${threadId} ${(tag ?: "").truncateOrPad()} ${levels[priority] ?: priority} $message")
+        }
+    }
+
+    fun flush() {
+        fileHandler.flush()
+    }
+
+    companion object {
+        private const val MAX_LENGTH = 23
+        private const val TAG_PART = (MAX_LENGTH - 3) / 2
+
+        private val levels = mapOf(
+            Log.VERBOSE to "V",
+            Log.DEBUG to "D",
+            Log.INFO to "I",
+            Log.WARN to "W",
+            Log.ERROR to "E",
+        )
+
+        private fun String.truncateOrPad(): String =
+            when {
+                length == MAX_LENGTH -> this
+                length < MAX_LENGTH -> padEnd(MAX_LENGTH, ' ')
+                else -> "${substring(0, TAG_PART)}...${substring(length - TAG_PART)}"
+            }
+    }
+}

app/src/main/java/org/tasks/logging/LogFormatter.kt

@@ -0,0 +1,20 @@
+package org.tasks.logging
+
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.util.Locale
+import java.util.TimeZone
+import java.util.logging.Formatter
+import java.util.logging.LogRecord
+
+class LogFormatter : Formatter() {
+
+    override fun format(r: LogRecord): String =
+        "${DATE_FORMAT.format(Date(r.millis))}Z ${r.message}$LINE_SEPARATOR${r.thrown?.stackTrace?.joinToString(LINE_SEPARATOR) ?: ""}"
+
+    companion object {
+        val LINE_SEPARATOR = System.lineSeparator() ?: "\n"
+        private val DATE_FORMAT = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS", Locale.US)
+            .apply { timeZone = TimeZone.getTimeZone("UTC") }
+    }
+}

app/src/release/java/org/tasks/BuildSetup.kt

@@ -1,12 +1,19 @@
 package org.tasks
 
 import android.annotation.SuppressLint
+import android.app.Application
 import android.util.Log
+import org.tasks.logging.FileLogger
 import timber.log.Timber
 import javax.inject.Inject
 
-class BuildSetup @Inject constructor() {
-    fun setup() = Timber.plant(ErrorReportingTree())
+class BuildSetup @Inject constructor(
+    private val context: Application,
+) {
+    fun setup() {
+        Timber.plant(ErrorReportingTree())
+        Timber.plant(FileLogger(context))
+    }
 
     private class ErrorReportingTree : Timber.Tree() {
         @SuppressLint("LogNotTimber")