fn main() {}

use std::ffi::OsStr;
use std::fs;
use std::io::{self, Write};
use std::path::{Path, PathBuf};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // 推荐下面的方式生成grpc rust代码
    // 完成下面的步骤后，在main.rs中添加 mod rust_grpc;
    // 1.读取proto目录下的*.proto
    let proto_dir: PathBuf = "proto".into(); // proto文件所在目录
    let mut file_list = Vec::new(); // 存放proto文件名
    let lists = proto_dir.read_dir().expect("read proto dir failed");
    for entry_path in lists {
        if entry_path.as_ref().unwrap().path().is_file() {
            file_list.push(entry_path.unwrap().path())
        }
    }

    let out_dir = Path::new("src/rust_grpc"); // 存放grpc rust代码生成的目录
    // let _ = fs::remove_dir_all(out_dir); // 删除原来的pb目录，可以根据实际情况打开注释
    let _ = fs::create_dir(out_dir); // 创建目录

    // grpc reflection 描述信息这是一个二进制文件
    let descriptor_path = out_dir.join("rpc_descriptor.bin");

    // 2.生成rust grpc代码
    // 指定rust grpc 代码生成的目录
    tonic_prost_build::configure()
        .file_descriptor_set_path(&descriptor_path)
        .out_dir(out_dir)
        .compile_protos(&file_list, &[proto_dir])?;

    // 3.生成mod.rs文件
    // 用下面的rust方式生成mod.rs
    // 拓展名是proto的文件名写入mod.rs中，作为pub mod xxx;导出模块
    // 先清空crates/pb/src/lib.rs文件内容
    let mod_file = out_dir.join("mod.rs");
    let _ = fs::remove_file(mod_file);

    let ext: Option<&OsStr> = Some(&OsStr::new("proto"));
    let mut mod_file = fs::OpenOptions::new()
        .write(true)
        .create(true)
        .open(out_dir.join("mod.rs"))
        .expect("create mod.rs failed");

    let header = String::from("// @generated by tonic-build.Do not edit it!!!\n");
    let _ = mod_file.write(header.as_bytes());
    for file in file_list.iter() {
        if file.extension().eq(&ext) {
            if let Some(file) = file.file_name() {
                let f = file.to_str().unwrap();
                let filename = f.replace(".proto", "");
                println!("current filename: {}", f);
                let _ = mod_file.write(format!("pub mod {};\n", filename).as_bytes());

                // 实现message serde encode/decode
                let filename = out_dir.join(f.replace(".proto", ".rs"));
                let mut buffer = fs::read_to_string(&filename).unwrap();
                buffer = buffer.replace(
                    "prost::Message",
                    "prost::Message, serde::Serialize, serde::Deserialize",
                );
                fs::write(&filename, buffer).expect("write file content failed");
            }
        }
    }

    // 将生成的代码放在rust gateway目录中
    let gateway_dir = Path::new("gateway/rust_grpc");
    fs::create_dir_all(gateway_dir)?; // 创建gateway目录
    copy_dir_to(out_dir, gateway_dir)?;
    fs::remove_file(gateway_dir.join("rpc_descriptor.bin"))?;

    Ok(())
}

/// Copy the existing directory `src` to the target path `dst`.
fn copy_dir_to(src: &Path, dst: &Path) -> io::Result<()> {
    if !dst.is_dir() {
        fs::create_dir(dst)?;
    }
    for entry_result in src.read_dir()? {
        let entry = entry_result?;
        let file_type = entry.file_type()?;
        copy_to(&entry.path(), &file_type, &dst.join(entry.file_name()))?;
    }
    Ok(())
}

/// Copy whatever is at `src` to the target path `dst`.
fn copy_to(src: &Path, src_type: &fs::FileType, dst: &Path) -> io::Result<()> {
    if src_type.is_file() {
        fs::copy(src, dst)?;
    } else if src_type.is_dir() {
        copy_dir_to(src, dst)?;
    } else {
        return Err(io::Error::new(
            io::ErrorKind::Other,
            format!("don't know how to copy: {}", src.display()),
        ));
    }

    Ok(())
}

use autometrics::autometrics;
use infras::metrics::prometheus_init;
use rust_grpc::hello::greeter_service_server::{GreeterService, GreeterServiceServer};
use rust_grpc::hello::{HelloReply, HelloReq};
use std::net::SocketAddr;
use std::time::Duration;
use tonic::{transport::Server, Request, Response, Status};

mod infras;
/// 定义grpc代码生成的包名
mod rust_grpc;

// 这个file descriptor文件是build.rs中定义的descriptor_path路径
// 读取proto file descriptor bin二进制文件
pub(crate) const PROTO_FILE_DESCRIPTOR_SET: &[u8] = include_bytes!("rust_grpc/rpc_descriptor.bin");

/// 实现hello.proto 接口服务
#[derive(Debug, Default)]
pub struct GreeterImpl {}

#[async_trait::async_trait]
impl GreeterService for GreeterImpl {
    // 实现async_hello方法
    #[autometrics]
    async fn say_hello(&self, request: Request<HelloReq>) -> Result<Response<HelloReply>, Status> {
        // 获取request pb message
        let req = &request.into_inner();
        println!("got request.id:{}", req.id);
        println!("got request.name:{}", req.name);
        let reply = HelloReply {
            message: format!("hello,{}", req.name),
            name: format!("{}", req.name).into(),
        };

        Ok(Response::new(reply))
    }
}

/// 采用 tokio 运行时来跑grpc server
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let address: SocketAddr = "0.0.0.0:50051".parse()?;
    println!("grpc server run on:{}", address);

    // grpc reflection服务
    let reflection_service = tonic_reflection::server::Builder::configure()
        .register_encoded_file_descriptor_set(PROTO_FILE_DESCRIPTOR_SET)
        .build_v1()
        .unwrap();

    // create http /metrics endpoint
    let metrics_server = prometheus_init(8090);
    let metrics_handler = tokio::spawn(metrics_server);

    // create grpc server
    let greeter = GreeterImpl::default();
    let grpc_handler = tokio::spawn(async move {
        Server::builder()
            .add_service(reflection_service)
            .add_service(GreeterServiceServer::new(greeter))
            .serve_with_shutdown(
                address,
                infras::shutdown::graceful_shutdown(Duration::from_secs(3)),
            )
            .await
            .expect("failed to start grpc server");
    });

    // run async tasks by tokio try_join macro
    let _ = tokio::try_join!(metrics_handler, grpc_handler);
    Ok(())
}

// create http /metrics endpoint
let metrics_server = prometheus_init(8091);
let metrics_handler = tokio::spawn(metrics_server);

// create grpc server
let greeter = GreeterImpl::default ();
let grpc_handler = tokio::spawn( async move {
Server::builder()
.add_service(reflection_service)
.add_service(GreeterServiceServer::new(greeter))
.serve_with_shutdown(
address,
infras::shutdown::graceful_shutdown(Duration::from_secs(3)),
)
.await
.expect("failed to start grpc server");
});

// run async tasks by tokio try_join macro
let _ = tokio::try_join!(metrics_handler, grpc_handler);
Ok(())