/*
 * 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 std::path::PathBuf;
use tinytemplate::TinyTemplate;

use crate::aconfig::{FlagState, Permission};
use crate::cache::{Cache, Item};
use crate::codegen;
use crate::commands::OutputFile;

pub fn generate_java_code(cache: &Cache) -> Result<OutputFile> {
    let package = cache.package();
    let class_elements: Vec<ClassElement> =
        cache.iter().map(|item| create_class_element(package, item)).collect();
    let readwrite = class_elements.iter().any(|item| item.readwrite);
    let context = Context { package: package.to_string(), readwrite, class_elements };
    let mut template = TinyTemplate::new();
    template.add_template("java_code_gen", include_str!("../templates/java.template"))?;
    let contents = template.render("java_code_gen", &context)?;
    let mut path: PathBuf = package.split('.').collect();
    // TODO: Allow customization of the java class name
    path.push("Flags.java");
    Ok(OutputFile { contents: contents.into(), path })
}

#[derive(Serialize)]
struct Context {
    pub package: 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 device_config_namespace: String,
    pub device_config_flag: String,
}

fn create_class_element(package: &str, item: &Item) -> ClassElement {
    let device_config_flag = codegen::create_device_config_ident(package, &item.name)
        .expect("values checked at cache creation time");
    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()
        },
        device_config_namespace: item.namespace.clone(),
        device_config_flag,
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::aconfig::{FlagDeclaration, FlagValue};
    use crate::cache::CacheBuilder;
    use crate::commands::Source;

    #[test]
    fn test_generate_java_code() {
        let package = "com.example";
        let mut builder = CacheBuilder::new(package.to_string()).unwrap();
        builder
            .add_flag_declaration(
                Source::File("test.txt".to_string()),
                FlagDeclaration {
                    name: "test".to_string(),
                    namespace: "ns".to_string(),
                    description: "buildtime enable".to_string(),
                },
            )
            .unwrap()
            .add_flag_declaration(
                Source::File("test2.txt".to_string()),
                FlagDeclaration {
                    name: "test2".to_string(),
                    namespace: "ns".to_string(),
                    description: "runtime disable".to_string(),
                },
            )
            .unwrap()
            .add_flag_value(
                Source::Memory,
                FlagValue {
                    package: package.to_string(),
                    name: "test".to_string(),
                    state: FlagState::Disabled,
                    permission: Permission::ReadOnly,
                },
            )
            .unwrap();
        let cache = builder.build();
        let expect_content = r#"package com.example;

        import android.provider.DeviceConfig;

        public final class Flags {

            public static boolean test() {
                return false;
            }

            public static boolean test2() {
                return DeviceConfig.getBoolean(
                    "ns",
                    "com.example.test2",
                    false
                );
            }

        }
        "#;
        let file = generate_java_code(&cache).unwrap();
        assert_eq!("com/example/Flags.java", file.path.to_str().unwrap());
        assert_eq!(
            None,
            crate::test::first_significant_code_diff(
                expect_content,
                &String::from_utf8(file.contents).unwrap()
            )
        );
    }
}