Add URI as inline classes

* Added Album, Artist, Playlist, Track and User
* Added test for them

Author: molikuner

build.gradle

@@ -63,6 +63,9 @@ test {
 
 compileKotlin {
     kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions {
+        freeCompilerArgs = ["-XXLanguage:+InlineClasses"]
+    }
 }
 compileTestKotlin {
     kotlinOptions.jvmTarget = "1.8"

src/main/kotlin/com/adamratzman/spotify/utils/SpotifyUris.kt

@@ -0,0 +1,61 @@
+package com.adamratzman.spotify.utils
+
+private fun String.add(type: String, length: Int = 22): String {
+    val match = "^(?:$type:)?(.{$length})(?::.*)?$".toRegex().matchEntire(this)
+    match?.groupValues?.get(1)?.also {
+        return "$type:$it"
+    }
+    throw IllegalArgumentException("$this isn't convertible to $type uri")
+}
+
+private fun String.remove(type: String, length: Int = 22): String {
+    val match = "^(?:$type:)?(.{$length})(?::.*)?$".toRegex().matchEntire(this)
+    match?.groupValues?.get(1)?.also {
+        return it
+    }
+    throw IllegalArgumentException("'$this' isn't convertible to '$type' id")
+}
+
+
+inline class AlbumURI(private val input: String) {
+    val uri: String
+        get() = input.add("spotify:album")
+    val id: String
+        get() = input.remove("spotify:album")
+}
+
+inline class ArtistURI(private val input: String) {
+    val uri: String
+        get() = input.add("spotify:artist")
+    val id: String
+        get() = input.remove("spotify:artist")
+}
+
+inline class TrackURI(private val input: String) {
+    val uri: String
+        get() = input.add("spotify:track")
+    val id: String
+        get() = input.remove("spotify:track")
+}
+
+inline class UserURI(private val input: String) {
+    val uri: String
+        get() = input.add("spotify:user", 25)
+    val id: String
+        get() = input.remove("spotify:user", 25)
+
+    // inline is not supported as non-top-level-class
+    inner /*inline*/ class PlaylistURI(private val input: String) {
+        val uri: String
+            get() = input.add("${this@UserURI.uri}:playlist")
+        val id: String
+            get() = input.remove("${this@UserURI.uri}:playlist")
+    }
+
+    companion object {
+        @Suppress("FunctionName") // "static" constructor
+        fun PlaylistURI(input: String): PlaylistURI {
+            return UserURI(input).PlaylistURI(input).also { it.uri /*check format*/ }
+        }
+    }
+}