fix: Handle null properties in `Attachment.Focus` (#449)

The `x` and `y` properties in `Attachment.Focus` may be null (not
documented as such, but observed in the wild).

Provide a `DefaultIfNull` adapter that can be applied to these to
replace null values with a sensible default.

app/src/test/java/app/pachli/StatusComparisonTest.kt

@@ -2,6 +2,7 @@ package app.pachli
 
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import app.pachli.core.database.model.TranslationState
+import app.pachli.core.network.json.DefaultIfNullAdapter.Companion.DefaultIfNullAdapterFactory
 import app.pachli.core.network.json.GuardedAdapter.Companion.GuardedAdapterFactory
 import app.pachli.core.network.model.Status
 import app.pachli.viewdata.StatusViewData
@@ -18,7 +19,9 @@ import org.junit.runner.RunWith
 class StatusComparisonTest {
     private val moshi = Moshi.Builder()
         .add(Date::class.java, Rfc3339DateJsonAdapter())
-        .add(GuardedAdapterFactory()).build()
+        .add(GuardedAdapterFactory())
+        .add(DefaultIfNullAdapterFactory())
+        .build()
 
     @Test
     fun `two equal statuses - should be equal`() {

app/src/test/java/app/pachli/components/timeline/CachedTimelineRemoteMediatorTest.kt

@@ -20,6 +20,7 @@ import app.pachli.core.database.model.AccountEntity
 import app.pachli.core.database.model.RemoteKeyEntity
 import app.pachli.core.database.model.RemoteKeyKind
 import app.pachli.core.database.model.TimelineStatusWithAccount
+import app.pachli.core.network.json.DefaultIfNullAdapter.Companion.DefaultIfNullAdapterFactory
 import app.pachli.core.network.json.GuardedAdapter.Companion.GuardedAdapterFactory
 import com.google.common.truth.Truth.assertThat
 import com.squareup.moshi.Moshi
@@ -66,6 +67,7 @@ class CachedTimelineRemoteMediatorTest {
     private val moshi: Moshi = Moshi.Builder()
         .add(Date::class.java, Rfc3339DateJsonAdapter())
         .add(GuardedAdapterFactory())
+        .add(DefaultIfNullAdapterFactory())
         .build()
 
     @Before

app/src/test/java/app/pachli/components/timeline/StatusMocker.kt

@@ -5,6 +5,7 @@ import app.pachli.core.database.model.TimelineAccountEntity
 import app.pachli.core.database.model.TimelineStatusEntity
 import app.pachli.core.database.model.TimelineStatusWithAccount
 import app.pachli.core.database.model.TranslationState
+import app.pachli.core.network.json.DefaultIfNullAdapter.Companion.DefaultIfNullAdapterFactory
 import app.pachli.core.network.json.GuardedAdapter.Companion.GuardedAdapterFactory
 import app.pachli.core.network.model.Status
 import app.pachli.core.network.model.TimelineAccount
@@ -101,6 +102,7 @@ fun mockStatusEntityWithAccount(
     val moshi = Moshi.Builder()
         .add(Date::class.java, Rfc3339DateJsonAdapter())
         .add(GuardedAdapterFactory())
+        .add(DefaultIfNullAdapterFactory())
         .build()
 
     return TimelineStatusWithAccount(

core/network/src/main/kotlin/app/pachli/core/network/di/NetworkModule.kt

@@ -22,6 +22,7 @@ import android.os.Build
 import app.pachli.core.common.util.versionName
 import app.pachli.core.mastodon.model.MediaUploadApi
 import app.pachli.core.network.BuildConfig
+import app.pachli.core.network.json.DefaultIfNullAdapter.Companion.DefaultIfNullAdapterFactory
 import app.pachli.core.network.json.GuardedAdapter.Companion.GuardedAdapterFactory
 import app.pachli.core.network.retrofit.InstanceSwitchAuthInterceptor
 import app.pachli.core.network.retrofit.MastodonApi
@@ -63,6 +64,7 @@ object NetworkModule {
     fun providesMoshi(): Moshi = Moshi.Builder()
         .add(Date::class.java, Rfc3339DateJsonAdapter())
         .add(GuardedAdapterFactory())
+        .add(DefaultIfNullAdapterFactory())
         .build()
 
     @Provides

core/network/src/main/kotlin/app/pachli/core/network/json/DefaultIfNullAdapter.kt

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2024 Pachli Association
+ *
+ * This file is a part of Pachli.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Pachli; if not,
+ * see <http://www.gnu.org/licenses>.
+ */
+
+package app.pachli.core.network.json
+
+import com.squareup.moshi.JsonAdapter
+import com.squareup.moshi.JsonQualifier
+import com.squareup.moshi.JsonReader
+import com.squareup.moshi.JsonWriter
+import com.squareup.moshi.Moshi
+import com.squareup.moshi.Types
+import java.lang.reflect.Type
+
+@Retention(AnnotationRetention.RUNTIME)
+@JsonQualifier
+annotation class DefaultIfNull
+
+class DefaultIfNullAdapter(private val delegate: JsonAdapter<Any>) : JsonAdapter<Any>() {
+    override fun fromJson(reader: JsonReader): Any? {
+        val value = reader.readJsonValue()
+        if (value is Map<*, *>) {
+            val withoutNulls = value.filterValues { it != null }
+            return delegate.fromJsonValue(withoutNulls)
+        }
+        return delegate.fromJsonValue(value)
+    }
+
+    override fun toJson(writer: JsonWriter, value: Any?) {
+        return delegate.toJson(writer, value)
+    }
+
+    companion object {
+        class DefaultIfNullAdapterFactory : Factory {
+            override fun create(
+                type: Type,
+                annotations: MutableSet<out Annotation>,
+                moshi: Moshi,
+            ): JsonAdapter<*>? {
+                val delegateAnnotations = Types.nextAnnotations(
+                    annotations,
+                    DefaultIfNull::class.java,
+                ) ?: return null
+                val delegate = moshi.nextAdapter<Any>(
+                    this,
+                    type,
+                    delegateAnnotations,
+                )
+                return DefaultIfNullAdapter(delegate)
+            }
+        }
+    }
+}

core/network/src/main/kotlin/app/pachli/core/network/model/Attachment.kt

@@ -18,6 +18,7 @@
 package app.pachli.core.network.model
 
 import android.os.Parcelable
+import app.pachli.core.network.json.DefaultIfNull
 import com.squareup.moshi.Json
 import com.squareup.moshi.JsonClass
 import kotlinx.parcelize.Parcelize
@@ -58,6 +59,8 @@ data class Attachment(
     @Parcelize
     @JsonClass(generateAdapter = true)
     data class MetaData(
+        // Fields in Focus may be null, see https://github.com/mastodon/mastodon/issues/29222
+        @DefaultIfNull
         val focus: Focus?,
         val duration: Float?,
         val original: Size?,
@@ -73,8 +76,8 @@ data class Attachment(
     @Parcelize
     @JsonClass(generateAdapter = true)
     data class Focus(
-        val x: Float,
+        val x: Float = 0f,
-        val y: Float,
+        val y: Float = 0f,
     ) : Parcelable {
         fun toMastodonApiString(): String = "$x,$y"
     }

core/network/src/test/kotlin/app/pachli/core/network/json/DefaultIfNullTest.kt

@@ -0,0 +1,145 @@
+package app.pachli.core.network.json
+
+import app.pachli.core.network.json.DefaultIfNullAdapter.Companion.DefaultIfNullAdapterFactory
+import com.google.common.truth.Truth.assertThat
+import com.squareup.moshi.JsonClass
+import com.squareup.moshi.Moshi
+import com.squareup.moshi.adapter
+import org.junit.Test
+
+@OptIn(ExperimentalStdlibApi::class)
+class DefaultIfNullTest {
+
+    private val moshi = Moshi.Builder()
+        .add(DefaultIfNullAdapterFactory())
+        .build()
+
+    @JsonClass(generateAdapter = true)
+    data class Wrapper(
+        @DefaultIfNull
+        val data: Data,
+    )
+
+    @JsonClass(generateAdapter = true)
+    data class Data(
+        val x: Int = 1,
+        val y: Float = 2f,
+        val z: String = "hello, world",
+        val nullable: String? = null,
+    )
+
+    @Test
+    fun `null x defaults to 1`() {
+        val jsonInput = """
+            {
+              "data": {
+                "x": null,
+                "y": 3,
+                "z": "foo",
+                "nullable": "bar"
+              }
+            }
+        """.trimIndent()
+        assertThat(moshi.adapter<Wrapper>().fromJson(jsonInput)).isEqualTo(
+            Wrapper(
+                data = Data(
+                    x = 1,
+                    y = 3f,
+                    z = "foo",
+                    nullable = "bar",
+                ),
+            ),
+        )
+    }
+
+    @Test
+    fun `null y defaults to 2f`() {
+        val jsonInput = """
+            {
+              "data": {
+                "x": 1,
+                "y": null,
+                "z": "foo",
+                "nullable": "bar"
+              }
+            }
+        """.trimIndent()
+        assertThat(moshi.adapter<Wrapper>().fromJson(jsonInput)).isEqualTo(
+            Wrapper(
+                data = Data(
+                    x = 1,
+                    y = 2f,
+                    z = "foo",
+                    nullable = "bar",
+                ),
+            ),
+        )
+    }
+
+    @Test
+    fun `null z defaults to "hello, world"`() {
+        val jsonInput = """
+            {
+              "data": {
+                "x": 1,
+                "y": 2,
+                "z": null,
+                "nullable": "bar"
+              }
+            }
+        """.trimIndent()
+        assertThat(moshi.adapter<Wrapper>().fromJson(jsonInput)).isEqualTo(
+            Wrapper(
+                data = Data(
+                    x = 1,
+                    y = 2f,
+                    z = "hello, world",
+                    nullable = "bar",
+                ),
+            ),
+        )
+    }
+
+    @Test
+    fun `nullable remains null`() {
+        val jsonInput = """
+            {
+              "data": {
+                "x": 1,
+                "y": 2,
+                "z": "foo",
+                "nullable": null
+              }
+            }
+        """.trimIndent()
+        assertThat(moshi.adapter<Wrapper>().fromJson(jsonInput)).isEqualTo(
+            Wrapper(
+                data = Data(
+                    x = 1,
+                    y = 2f,
+                    z = "foo",
+                    nullable = null,
+                ),
+            ),
+        )
+    }
+
+    @Test
+    fun `null everything returns default`() {
+        val jsonInput = """
+            {
+              "data": {
+                "x": null,
+                "y": null,
+                "z": null,
+                "nullable": null
+              }
+            }
+        """.trimIndent()
+        assertThat(moshi.adapter<Wrapper>().fromJson(jsonInput)).isEqualTo(
+            Wrapper(
+                data = Data(),
+            ),
+        )
+    }
+}