Implement support for local filtering

Author: gpunto

stream-android-core/src/main/java/io/getstream/android/core/api/filter/Filter.kt

@@ -17,32 +17,69 @@ package io.getstream.android.core.api.filter
 
 import io.getstream.android.core.annotations.StreamInternalApi
 import io.getstream.android.core.annotations.StreamPublishedApi
-import io.getstream.android.core.internal.filter.FilterOperator
+import io.getstream.android.core.internal.filter.BinaryOperator
+import io.getstream.android.core.internal.filter.CollectionOperator
+import io.getstream.android.core.internal.filter.FilterOperations
 
 /**
  * Base interface for filters used in Stream API operations.
  *
  * Filters are used to specify criteria for querying and retrieving data from Stream services. Each
  * filter implementation defines specific matching logic for different comparison operations.
  */
-@StreamPublishedApi public sealed interface Filter<F : FilterField>
+@StreamPublishedApi public sealed interface Filter<M, F : FilterField<M>>
 
-internal data class BinaryOperationFilter<F : FilterField, V : Any>(
-    val operator: FilterOperator,
+internal data class BinaryOperationFilter<M, F : FilterField<M>>(
+    val operator: BinaryOperator,
     val field: F,
-    val value: V,
-) : Filter<F>
+    val value: Any,
+) : Filter<M, F>
 
-internal data class CollectionOperationFilter<F : FilterField>(
-    internal val operator: FilterOperator,
-    val filters: Set<Filter<F>>,
-) : Filter<F>
+internal data class CollectionOperationFilter<M, F : FilterField<M>>(
+    internal val operator: CollectionOperator,
+    val filters: Set<Filter<M, F>>,
+) : Filter<M, F>
 
 /** Converts a [Filter] instance to a request map suitable for API queries. */
 @StreamInternalApi
-public fun Filter<*>.toRequest(): Map<String, Any> =
+public fun Filter<*, *>.toRequest(): Map<String, Any> =
     when (this) {
         is BinaryOperationFilter<*, *> -> mapOf(field.remote to mapOf(operator.remote to value))
-        is CollectionOperationFilter<*> ->
-            mapOf(operator.remote to filters.map(Filter<*>::toRequest))
+        is CollectionOperationFilter<*, *> ->
+            mapOf(operator.remote to filters.map(Filter<*, *>::toRequest))
+    }
+
+/** Checks if this filter matches the given item. */
+@StreamInternalApi
+public infix fun <M, F : FilterField<M>> Filter<M, F>.matches(item: M): Boolean =
+    when (this) {
+        is BinaryOperationFilter<M, F> -> {
+            val fieldValue = field.localValue(item)
+            val filterValue = value
+            val notNull = fieldValue != null
+
+            with(FilterOperations) {
+                when (operator) {
+                    BinaryOperator.EQUAL -> notNull && fieldValue == filterValue
+                    BinaryOperator.GREATER -> notNull && fieldValue greater filterValue
+                    BinaryOperator.LESS -> notNull && fieldValue less filterValue
+                    BinaryOperator.GREATER_OR_EQUAL ->
+                        notNull && fieldValue greaterOrEqual filterValue
+                    BinaryOperator.LESS_OR_EQUAL -> notNull && fieldValue lessOrEqual filterValue
+                    BinaryOperator.IN -> notNull && fieldValue `in` filterValue
+                    BinaryOperator.QUERY -> notNull && search(filterValue, where = fieldValue)
+                    BinaryOperator.AUTOCOMPLETE -> notNull && fieldValue autocompletes filterValue
+                    BinaryOperator.EXISTS -> fieldValue exists filterValue
+                    BinaryOperator.CONTAINS -> notNull && fieldValue contains filterValue
+                    BinaryOperator.PATH_EXISTS -> notNull && fieldValue containsPath filterValue
+                }
+            }
+        }
+
+        is CollectionOperationFilter<M, F> -> {
+            when (operator) {
+                CollectionOperator.AND -> filters.all { it.matches(item) }
+                CollectionOperator.OR -> filters.any { it.matches(item) }
+            }
+        }
     }

stream-android-core/src/main/java/io/getstream/android/core/api/filter/FilterField.kt

@@ -19,9 +19,13 @@ package io.getstream.android.core.api.filter
  * Interface representing a field that can be used in filters for querying data from the Stream API.
  *
  * Implementations of this interface should provide [remote], which is the name of the field as
- * expected by the Stream API.
+ * expected by the Stream API, and [localValue], a function to extract the field's value from a
+ * model instance.
  */
-public interface FilterField {
+public interface FilterField<M> {
     /** The name of this field as expected by the Stream API. */
     public val remote: String
+
+    /** Function to extract the field's value from a model instance. */
+    public val localValue: (M) -> Any?
 }

stream-android-core/src/main/java/io/getstream/android/core/api/filter/Filters.kt

@@ -15,7 +15,8 @@
  */
 package io.getstream.android.core.api.filter
 
-import io.getstream.android.core.internal.filter.FilterOperator
+import io.getstream.android.core.internal.filter.BinaryOperator
+import io.getstream.android.core.internal.filter.CollectionOperator
 
 /** Utility class for building filters. */
 public object Filters {
@@ -25,17 +26,17 @@ public object Filters {
      * @param filters The filters to combine.
      * @return A filter that matches when all provided filters match.
      */
-    public fun <F : FilterField> and(vararg filters: Filter<F>): Filter<F> =
-        CollectionOperationFilter(FilterOperator.AND, filters.toSet())
+    public fun <M, F : FilterField<M>> and(vararg filters: Filter<M, F>): Filter<M, F> =
+        CollectionOperationFilter(CollectionOperator.AND, filters.toSet())
 
     /**
      * Creates a filter that combines multiple filters with a logical OR operation.
      *
      * @param filters The filters to combine.
      * @return A filter that matches when any of the specified filters match.
      */
-    public fun <F : FilterField> or(vararg filters: Filter<F>): Filter<F> =
-        CollectionOperationFilter(FilterOperator.OR, filters.toSet())
+    public fun <M, F : FilterField<M>> or(vararg filters: Filter<M, F>): Filter<M, F> =
+        CollectionOperationFilter(CollectionOperator.OR, filters.toSet())
 }
 
 /**
@@ -44,111 +45,111 @@ public object Filters {
  * @param value The value to check equality against.
  * @return A filter that matches when this field equals the specified value.
  */
-public fun <F : FilterField> F.equal(value: Any): Filter<F> =
-    BinaryOperationFilter(FilterOperator.EQUAL, this, value)
+public fun <M, F : FilterField<M>> F.equal(value: Any): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.EQUAL, this, value)
 
 /**
  * Creates a filter that checks if this field is greater than a specific value.
  *
  * @param value The value to check against.
  * @return A filter that matches when this field is greater than the specified value.
  */
-public fun <F : FilterField> F.greater(value: Any): Filter<F> =
-    BinaryOperationFilter(FilterOperator.GREATER, this, value)
+public fun <M, F : FilterField<M>> F.greater(value: Any): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.GREATER, this, value)
 
 /**
  * Creates a filter that checks if this field is greater than or equal to a specific value.
  *
  * @param value The value to check against.
  * @return A filter that matches when this field is greater than or equal to the specified value.
  */
-public fun <F : FilterField> F.greaterOrEqual(value: Any): Filter<F> =
-    BinaryOperationFilter(FilterOperator.GREATER_OR_EQUAL, this, value)
+public fun <M, F : FilterField<M>> F.greaterOrEqual(value: Any): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.GREATER_OR_EQUAL, this, value)
 
 /**
  * Creates a filter that checks if this field is less than a specific value.
  *
  * @param value The value to check against.
  * @return A filter that matches when this field is less than the specified value.
  */
-public fun <F : FilterField> F.less(value: Any): Filter<F> =
-    BinaryOperationFilter(FilterOperator.LESS, this, value)
+public fun <M, F : FilterField<M>> F.less(value: Any): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.LESS, this, value)
 
 /**
  * Creates a filter that checks if this field is less than or equal to a specific value.
  *
  * @param value The value to check against.
  * @return A filter that matches when this field is less than or equal to the specified value.
  */
-public fun <F : FilterField> F.lessOrEqual(value: Any): Filter<F> =
-    BinaryOperationFilter(FilterOperator.LESS_OR_EQUAL, this, value)
+public fun <M, F : FilterField<M>> F.lessOrEqual(value: Any): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.LESS_OR_EQUAL, this, value)
 
 /**
  * Creates a filter that checks if this field's value is in a specific list of values.
  *
  * @param values The list of values to check against.
  * @return A filter that matches when this field's value is in the specified list.
  */
-public fun <F : FilterField> F.`in`(values: List<Any>): Filter<F> =
-    BinaryOperationFilter(FilterOperator.IN, this, values.toSet())
+public fun <M, F : FilterField<M>> F.`in`(values: List<Any>): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.IN, this, values.toSet())
 
 /**
  * Creates a filter that checks if this field's value is in a specific set of values.
  *
  * @param values The values to check against.
  * @return A filter that matches when this field's value is in the specified values.
  */
-public fun <F : FilterField> F.`in`(vararg values: Any): Filter<F> =
-    BinaryOperationFilter(FilterOperator.IN, this, values.toSet())
+public fun <M, F : FilterField<M>> F.`in`(vararg values: Any): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.IN, this, values.toSet())
 
 /**
  * Creates a filter that performs a full-text query on this field.
  *
  * @param value The query string to search for.
  * @return A filter that matches based on the full-text query.
  */
-public fun <F : FilterField> F.query(value: String): Filter<F> =
-    BinaryOperationFilter(FilterOperator.QUERY, this, value)
+public fun <M, F : FilterField<M>> F.query(value: String): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.QUERY, this, value)
 
 /**
  * Creates a filter that performs autocomplete matching on this field.
  *
  * @param value The string to autocomplete against.
  * @return A filter that matches based on autocomplete functionality.
  */
-public fun <F : FilterField> F.autocomplete(value: String): Filter<F> =
-    BinaryOperationFilter(FilterOperator.AUTOCOMPLETE, this, value)
+public fun <M, F : FilterField<M>> F.autocomplete(value: String): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.AUTOCOMPLETE, this, value)
 
 /**
  * Creates a filter that checks if this field exists.
  *
  * @return A filter that matches when this field exists.
  */
-public fun <F : FilterField> F.exists(): Filter<F> =
-    BinaryOperationFilter(FilterOperator.EXISTS, this, true)
+public fun <M, F : FilterField<M>> F.exists(): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.EXISTS, this, true)
 
 /**
  * Creates a filter that checks if this field does not exist.
  *
  * @return A filter that matches when this field does not exist.
  */
-public fun <F : FilterField> F.doesNotExist(): Filter<F> =
-    BinaryOperationFilter(FilterOperator.EXISTS, this, false)
+public fun <M, F : FilterField<M>> F.doesNotExist(): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.EXISTS, this, false)
 
 /**
  * Creates a filter that checks if this field contains a specific value.
  *
  * @param value The value to check for within this field.
  * @return A filter that matches when this field contains the specified value.
  */
-public fun <F : FilterField> F.contains(value: Any): Filter<F> =
-    BinaryOperationFilter(FilterOperator.CONTAINS, this, value)
+public fun <M, F : FilterField<M>> F.contains(value: Any): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.CONTAINS, this, value)
 
 /**
  * Creates a filter that checks if a specific path exists within this field.
  *
  * @param value The path to check for existence.
  * @return A filter that matches when the specified path exists in this field.
  */
-public fun <F : FilterField> F.pathExists(value: String): Filter<F> =
-    BinaryOperationFilter(FilterOperator.PATH_EXISTS, this, value)
+public fun <M, F : FilterField<M>> F.pathExists(value: String): Filter<M, F> =
+    BinaryOperationFilter(BinaryOperator.PATH_EXISTS, this, value)

stream-android-core/src/main/java/io/getstream/android/core/internal/filter/FilterOperations.kt

@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2014-2025 Stream.io Inc. All rights reserved.
+ *
+ * Licensed under the Stream License;
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://github.com/GetStream/stream-core-android/blob/main/LICENSE
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.getstream.android.core.internal.filter
+
+internal object FilterOperations {
+    infix fun Any.greater(that: Any) = anyCompare(this, that)?.let { it > 0 } == true
+
+    infix fun Any.greaterOrEqual(that: Any) = anyCompare(this, that)?.let { it >= 0 } == true
+
+    infix fun Any.less(that: Any) = anyCompare(this, that)?.let { it < 0 } == true
+
+    infix fun Any.lessOrEqual(that: Any) = anyCompare(this, that)?.let { it <= 0 } == true
+
+    private fun anyCompare(a: Any, b: Any): Int? {
+        if (a !is Comparable<*>) {
+            return null
+        }
+
+        return try {
+            @Suppress("UNCHECKED_CAST") (a as Comparable<Any>).compareTo(b)
+        } catch (_: ClassCastException) {
+            // The types were not compatible for comparison
+            null
+        }
+    }
+
+    infix fun Any?.exists(that: Any): Boolean = (that is Boolean) && (this != null) == that
+
+    infix fun Any.`in`(that: Any): Boolean =
+        when (that) {
+            is Array<*> -> this in that
+            is Iterable<*> -> this in that
+            else -> false
+        }
+
+    infix fun Any.contains(that: Any): Boolean =
+        when {
+            that `in` this -> true
+
+            this is Map<*, *> && that is Map<*, *> -> {
+                // Partial match: check if all entries in 'that' are present in 'this'
+                that.all { (thatKey, thatValue) ->
+                    val thisValue = this[thatKey]
+
+                    thisValue == thatValue ||
+                        thisValue != null && thatValue != null && thisValue contains thatValue
+                }
+            }
+
+            else -> false
+        }
+
+    infix fun Any.autocompletes(that: Any): Boolean {
+        if (this !is String || that !is String || that.isEmpty()) {
+            return false
+        }
+
+        // Split the text into words using whitespace and punctuation as delimiters
+        return this.split(Regex("[\\s\\p{Punct}]+")).any { word -> word.startsWith(that, true) }
+    }
+
+    fun search(what: Any, where: Any): Boolean =
+        what is String &&
+            where is String &&
+            what.isNotEmpty() &&
+            where.contains(what, ignoreCase = true)
+
+    infix fun Any.containsPath(that: Any): Boolean {
+        if (this !is Map<*, *> || that !is String) return false
+
+        val pathParts = that.split(".")
+        var current: Any? = this
+
+        for (part in pathParts) {
+            when {
+                current !is Map<*, *> -> return false
+                part !in current -> return false
+                else -> current = current[part]
+            }
+        }
+
+        return true
+    }
+}