Add new lint detector

Author: landomen

lint-rules/src/main/java/com/duckduckgo/lint/ui/DaxTextFieldTrailingIconDetector.kt

@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2025 DuckDuckGo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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 com.duckduckgo.lint.ui
+
+import com.android.tools.lint.client.api.UElementHandler
+import com.android.tools.lint.detector.api.Category.Companion.CUSTOM_LINT_CHECKS
+import com.android.tools.lint.detector.api.Detector
+import com.android.tools.lint.detector.api.Implementation
+import com.android.tools.lint.detector.api.Issue
+import com.android.tools.lint.detector.api.JavaContext
+import com.android.tools.lint.detector.api.Scope
+import com.android.tools.lint.detector.api.Severity
+import com.android.tools.lint.detector.api.SourceCodeScanner
+import com.android.tools.lint.detector.api.TextFormat
+import org.jetbrains.uast.UCallExpression
+import org.jetbrains.uast.getParameterForArgument
+import java.util.EnumSet
+
+@Suppress("UnstableApiUsage")
+class DaxTextFieldTrailingIconDetector : Detector(), SourceCodeScanner {
+
+    override fun getApplicableUastTypes() = listOf(UCallExpression::class.java)
+
+    override fun createUastHandler(context: JavaContext): UElementHandler = DaxTextFieldCallHandler(context)
+
+    internal class DaxTextFieldCallHandler(private val context: JavaContext) : UElementHandler() {
+        override fun visitCallExpression(node: UCallExpression) {
+            val methodName = node.methodName
+
+            if (methodName == "DaxTextField") {
+                checkTrailingIconParameter(node)
+            }
+        }
+
+        private fun checkTrailingIconParameter(node: UCallExpression) {
+            // Find the 'trailingIcon' parameter
+            val trailingIconArgument = node.valueArguments.find { arg ->
+                val parameterName = node.getParameterForArgument(arg)?.name
+                parameterName == "trailingIcon"
+            } ?: return // No 'trailingIcon' parameter provided which is fine
+
+            // Check if the trailingIcon uses an invalid composable
+            if (isInvalidComposable(trailingIconArgument)) {
+                reportInvalidComposableUsage(trailingIconArgument)
+            }
+        }
+
+        private fun isInvalidComposable(argument: org.jetbrains.uast.UExpression): Boolean {
+            val source = argument.sourcePsi?.text ?: return false
+
+            if (source.contains("DaxTextFieldTrailingIcon")) {
+                // using the correct 'DaxTextFieldTrailingIcon' composable
+                return false
+            }
+
+            // Check if the source contains invalid Composables (only DaxTextFieldTrailingIcon should be used)
+            // This covers cases like:
+            // - Icon
+            // - IconButton
+            val composablePattern = Regex("""\b(Icon|IconButton|Image|Text|Button|Surface)\s*\(""")
+            return composablePattern.containsMatchIn(source)
+        }
+
+        private fun reportInvalidComposableUsage(arg: org.jetbrains.uast.UExpression) {
+            context.report(
+                issue = INVALID_DAX_TEXT_FIELD_TRAILING_ICON_USAGE,
+                location = context.getLocation(arg),
+                message = INVALID_DAX_TEXT_FIELD_TRAILING_ICON_USAGE.getExplanation(TextFormat.RAW),
+            )
+        }
+    }
+
+    companion object {
+        val INVALID_DAX_TEXT_FIELD_TRAILING_ICON_USAGE = Issue
+            .create(
+                id = "InvalidDaxTextFieldTrailingIconUsage",
+                briefDescription = "DaxTextField trailingIcon parameter should use DaxTextFieldTrailingIcon",
+                explanation = """
+                    Use DaxTextFieldTrailingIcon instead of arbitrary composables for the trailingIcon parameter to maintain design system consistency.
+
+                    Example:
+                    DaxTextField(
+                        state = state,
+                        trailingIcon = {
+                            DaxTextFieldTrailingIcon(
+                                painter = painterResource(R.drawable.ic_copy_24),
+                                contentDescription = stringResource(R.string.icon_description)
+                            )
+                        }
+                    )
+
+                    This ensures consistent styling, spacing, and behavior across all text field icons in the app.
+                """.trimIndent(),
+                moreInfo = "",
+                category = CUSTOM_LINT_CHECKS,
+                priority = 6,
+                severity = Severity.WARNING,
+                androidSpecific = true,
+                implementation = Implementation(
+                    DaxTextFieldTrailingIconDetector::class.java,
+                    EnumSet.of(Scope.JAVA_FILE, Scope.TEST_SOURCES),
+                ),
+            )
+    }
+}