use std::{
    collections::HashMap,
    fs,
    io::{self, BufRead, BufReader, Write},
    os::unix::net::UnixListener,
    path::Path,
    sync::{atomic::AtomicU32, Arc, RwLock},
    thread,
};

use crate::{energy::ProcessInfo, Pid};

pub struct LoggingSocketService {
    path: String,
    power_limit: Arc<AtomicU32>,
    process_info: Arc<RwLock<HashMap<Pid, ProcessInfo>>>,
}

impl LoggingSocketService {
    pub fn new(
        path: &str,
        process_info: Arc<RwLock<HashMap<Pid, ProcessInfo>>>,
        power_limit: Arc<AtomicU32>,
    ) -> Self {
        LoggingSocketService {
            path: path.to_string(),
            process_info,
            power_limit,
        }
    }

    pub fn run(self) {
        thread::spawn(move || {
            let listener = UnixListener::bind(self.path.clone()).unwrap();
            for stream in listener.incoming() {
                let mut socket = stream.unwrap();
                let mut reader = BufReader::new(socket.try_clone().unwrap());
                let mut line = String::new();
                while let Ok(bytes_read) = reader.read_line(&mut line) {
                    if bytes_read == 0 {
                        break;
                    }
                    let (command, args) = line.split_once(' ').unwrap_or((line.trim(), ""));
                    let output = match command {
                        "pid" => self.get_process(args.trim().parse().unwrap_or_default()),
                        "list" => self.list_processes(),
                        "limit" => self.set_power_limit(args),
                        _ => "Unrecognized command#".into(),
                    };
                    socket.write_all(output.as_bytes()).unwrap();
                    line.clear();
                }
            }
        });
    }
    fn list_processes(&self) -> String {
        let mut output = String::new();
        use std::fmt::Write;
        for (pid, info) in self.process_info.read().unwrap().iter() {
            writeln!(
                &mut output,
                "{pid},{},{}",
                info.energy_j, info.tree_energy_j
            )
            .unwrap();
        }
        writeln!(&mut output, "#",).unwrap();
        output
    }

    fn set_power_limit(&self, args: &str) -> String {
        if let Ok(power_limit) = args.trim().parse() {
            self.power_limit
                .store(power_limit, std::sync::atomic::Ordering::Relaxed);
            "#".into()
        } else {
            format!("failed to parse {args} as energy limit#")
        }
    }

    fn get_process(&self, pid: i32) -> String {
        if let Some(info) = self.process_info.read().unwrap().get(&pid) {
            format!(
                "pid: {pid} process: {}J process tree: {}J\n",
                info.energy_j, info.tree_energy_j
            )
        } else {
            format!("Unknown pid: {pid}\n")
        }
    }
}

pub fn start_logging_socket_service(
    path: &str,
    process_info: Arc<RwLock<HashMap<Pid, ProcessInfo>>>,
) -> io::Result<Arc<AtomicU32>> {
    if Path::new(path).exists() {
        fs::remove_file(path)?;
    }
    let arc = Arc::new(AtomicU32::new(50));
    let socket = LoggingSocketService::new(path, process_info, arc.clone());
    socket.run();
    Ok(arc)
}