address PR comments

Author: Kimblebee

app/src/main/java/com/google/jetpackcamera/JcaFilePathGenerator.kt

@@ -17,6 +17,7 @@ package com.google.jetpackcamera
 
 import android.os.Environment
 import com.google.jetpackcamera.core.common.FilePathGenerator
+import com.google.jetpackcamera.core.common.FilePathGenerator.Companion.constructFilename
 import java.io.File
 import java.util.Date
 
@@ -32,26 +33,24 @@ class JcaFilePathGenerator : FilePathGenerator {
         get() = Environment.getExternalStoragePublicDirectory(
             Environment.DIRECTORY_MOVIES
         )?.path ?: ""
-    private fun createTimestamp() = Date().time
 
-    private fun generateFilename(
-        prefix: String,
-        suffixText: String?,
-        fileExtension: String?
-    ): String {
-        val timestamp = createTimestamp()
-        return buildString {
-            append("$prefix-$timestamp")
-            suffixText?.let { append("-$it") }
-            fileExtension?.let { append(it) }
-        }
-    }
+    private fun createTimestamp() = Date().time
 
     override fun generateImageFilename(suffixText: String?, fileExtension: String?): String {
-        return generateFilename("JCA-photo", suffixText, fileExtension)
+        return constructFilename(
+            "JCA-photo",
+            createTimestamp().toString(),
+            suffixText,
+            fileExtension
+        )
     }
 
     override fun generateVideoFilename(suffixText: String?, fileExtension: String?): String {
-        return generateFilename("JCA-recording", suffixText, fileExtension)
+        return constructFilename(
+            "JCA-recording",
+            createTimestamp().toString(),
+            suffixText,
+            fileExtension
+        )
     }
 }

core/common/src/main/java/com/google/jetpackcamera/core/common/FakeFilePathGenerator.kt

@@ -16,6 +16,7 @@
 package com.google.jetpackcamera.core.common
 
 import android.os.Environment
+import com.google.jetpackcamera.core.common.FilePathGenerator.Companion.constructFilename
 import java.io.File
 import java.util.Date
 
@@ -34,24 +35,21 @@ class FakeFilePathGenerator : FilePathGenerator {
 
     private fun createTimestamp() = Date().time
 
-    private fun generateFilename(
-        prefix: String,
-        suffixText: String?,
-        fileExtension: String?
-    ): String {
-        val timestamp = createTimestamp()
-        return buildString {
-            append("$prefix-$timestamp")
-            suffixText?.let { append("-$it") }
-            fileExtension?.let { append(it) }
-        }
-    }
-
     override fun generateImageFilename(suffixText: String?, fileExtension: String?): String {
-        return generateFilename("JCA-test-photo", suffixText, fileExtension)
+        return constructFilename(
+            "JCA-test-photo",
+            createTimestamp().toString(),
+            suffixText,
+            fileExtension
+        )
     }
 
     override fun generateVideoFilename(suffixText: String?, fileExtension: String?): String {
-        return generateFilename("JCA-test-recording", suffixText, fileExtension)
+        return constructFilename(
+            "JCA-test-recording",
+            createTimestamp().toString(),
+            suffixText,
+            fileExtension
+        )
     }
 }

core/common/src/main/java/com/google/jetpackcamera/core/common/FilePathGenerator.kt

@@ -56,4 +56,29 @@ interface FilePathGenerator {
      * @param fileExtension the extension to be appended at the end of the generated filename
      */
     fun generateVideoFilename(suffixText: String? = null, fileExtension: String? = ".mp4"): String
+
+    companion object {
+        /**
+         * constructs a filename based on the provided values
+         *
+         * @param prefix the first portion of the filename's text
+         * @param timestamp a unique string to prevent subsequently created files from overwriting
+         * each other. i.e. a timestamp
+         * @param suffixText additional text to append to the end of the generated filename, before
+         * the file extension.
+         * @param fileExtension the extension to be appended at the end of the generated filename (i.e. `.mp4``.jpg`)
+         */
+        fun constructFilename(
+            prefix: String,
+            timestamp: String,
+            suffixText: String?,
+            fileExtension: String?
+        ): String {
+            return buildString {
+                append("$prefix-$timestamp")
+                suffixText?.let { append("-$it") }
+                fileExtension?.let { append(it) }
+            }
+        }
+    }
 }