aconfig: Add codegen for java

Add codegen for java skeleton

Bug: 279485059
Test: atest aconfig.test
Change-Id: Ia0481cec9c2e137e88e9a77d1b82412529b64adc

tools/aconfig/src/codegen_java.rs

@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * 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.
+ */
+
+use anyhow::Result;
+use serde::Serialize;
+use tinytemplate::TinyTemplate;
+
+use crate::aconfig::{FlagState, Permission};
+use crate::cache::{Cache, Item};
+
+pub struct GeneratedFile {
+    pub file_content: String,
+    pub file_name: String,
+}
+
+pub fn generate_java_code(cache: &Cache) -> Result<GeneratedFile> {
+    let class_elements: Vec<ClassElement> = cache.iter().map(create_class_element).collect();
+    let readwrite = class_elements.iter().any(|item| item.readwrite);
+    let namespace = uppercase_first_letter(
+        cache.iter().find(|item| !item.namespace.is_empty()).unwrap().namespace.as_str(),
+    );
+    let context = Context { namespace: namespace.clone(), readwrite, class_elements };
+    let mut template = TinyTemplate::new();
+    template.add_template("java_code_gen", include_str!("../templates/java.template"))?;
+    let file_content = template.render("java_code_gen", &context)?;
+    Ok(GeneratedFile { file_content, file_name: format!("{}.java", namespace) })
+}
+
+#[derive(Serialize)]
+struct Context {
+    pub namespace: String,
+    pub readwrite: bool,
+    pub class_elements: Vec<ClassElement>,
+}
+
+#[derive(Serialize)]
+struct ClassElement {
+    pub method_name: String,
+    pub readwrite: bool,
+    pub default_value: String,
+    pub feature_name: String,
+    pub flag_name: String,
+}
+
+fn create_class_element(item: &Item) -> ClassElement {
+    ClassElement {
+        method_name: item.name.clone(),
+        readwrite: item.permission == Permission::ReadWrite,
+        default_value: if item.state == FlagState::Enabled {
+            "true".to_string()
+        } else {
+            "false".to_string()
+        },
+        feature_name: item.name.clone(),
+        flag_name: item.name.clone(),
+    }
+}
+
+fn uppercase_first_letter(s: &str) -> String {
+    s.chars()
+        .enumerate()
+        .map(
+            |(index, ch)| {
+                if index == 0 {
+                    ch.to_ascii_uppercase()
+                } else {
+                    ch.to_ascii_lowercase()
+                }
+            },
+        )
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::aconfig::{Flag, Value};
+    use crate::commands::Source;
+
+    #[test]
+    fn test_generate_java_code() {
+        let namespace = "TeSTFlaG";
+        let mut cache = Cache::new(1, namespace.to_string());
+        cache
+            .add_flag(
+                Source::File("test.txt".to_string()),
+                Flag {
+                    name: "test".to_string(),
+                    description: "buildtime enable".to_string(),
+                    values: vec![Value::default(FlagState::Enabled, Permission::ReadOnly)],
+                },
+            )
+            .unwrap();
+        cache
+            .add_flag(
+                Source::File("test2.txt".to_string()),
+                Flag {
+                    name: "test2".to_string(),
+                    description: "runtime disable".to_string(),
+                    values: vec![Value::default(FlagState::Disabled, Permission::ReadWrite)],
+                },
+            )
+            .unwrap();
+        let expect_content = "package com.android.aconfig;
+
+        import android.provider.DeviceConfig;
+
+        public final class Testflag {
+
+            public static boolean test() {
+                return true;
+            }
+
+            public static boolean test2() {
+                return DeviceConfig.getBoolean(
+                    \"Testflag\",
+                    \"test2__test2\",
+                    false
+                );
+            }
+
+        }
+        ";
+        let expected_file_name = format!("{}.java", uppercase_first_letter(namespace));
+        let generated_file = generate_java_code(&cache).unwrap();
+        assert_eq!(expected_file_name, generated_file.file_name);
+        assert_eq!(expect_content.replace(' ', ""), generated_file.file_content.replace(' ', ""));
+    }
+}