use std::os::unix::fs::FileTypeExt;
use std::{fs, io, process};
use zellij_utils::{
    consts::ZELLIJ_SOCK_DIR,
    interprocess::local_socket::LocalSocketStream,
    ipc::{ClientToServerMsg, IpcSenderWithContext},
};

pub(crate) fn get_sessions() -> Result<Vec<String>, io::ErrorKind> {
    match fs::read_dir(&*ZELLIJ_SOCK_DIR) {
        Ok(files) => {
            let mut sessions = Vec::new();
            files.for_each(|file| {
                let file = file.unwrap();
                let file_name = file.file_name().into_string().unwrap();
                if file.file_type().unwrap().is_socket() && assert_socket(&file_name) {
                    sessions.push(file_name);
                }
            });
            Ok(sessions)
        }
        Err(err) => {
            if let io::ErrorKind::NotFound = err.kind() {
                Ok(Vec::with_capacity(0))
            } else {
                Err(err.kind())
            }
        }
    }
}

fn assert_socket(name: &str) -> bool {
    let path = &*ZELLIJ_SOCK_DIR.join(name);
    match LocalSocketStream::connect(path) {
        Ok(stream) => {
            IpcSenderWithContext::new(stream).send(ClientToServerMsg::ClientExited);
            true
        }
        Err(e) => {
            if e.kind() == io::ErrorKind::ConnectionRefused {
                drop(fs::remove_file(path));
                false
            } else {
                true
            }
        }
    }
}

pub(crate) fn print_sessions(sessions: Vec<String>) {
    let curr_session = std::env::var("ZELLIJ_SESSION_NAME").unwrap_or_else(|_| "".into());
    sessions.iter().for_each(|session| {
        let suffix = if curr_session == *session {
            " (current)"
        } else {
            ""
        };
        println!("{}{}", session, suffix);
    })
}

pub(crate) enum ActiveSession {
    None,
    One(String),
    Many,
}

pub(crate) fn get_active_session() -> ActiveSession {
    match get_sessions() {
        Ok(mut sessions) => {
            if sessions.len() == 1 {
                return ActiveSession::One(sessions.pop().unwrap());
            }
            if sessions.is_empty() {
                ActiveSession::None
            } else {
                ActiveSession::Many
            }
        }
        Err(e) => {
            eprintln!("Error occured: {:?}", e);
            process::exit(1);
        }
    }
}

pub(crate) fn list_sessions() {
    let exit_code = match get_sessions() {
        Ok(sessions) => {
            if sessions.is_empty() {
                println!("No active zellij sessions found.");
            } else {
                print_sessions(sessions);
            }
            0
        }
        Err(e) => {
            eprintln!("Error occured: {:?}", e);
            1
        }
    };
    process::exit(exit_code);
}

pub(crate) fn session_exists(name: &str) -> Result<bool, io::ErrorKind> {
    return match get_sessions() {
        Ok(sessions) => {
            if sessions.iter().any(|s| s == name) {
                return Ok(true);
            }
            Ok(false)
        }
        Err(e) => Err(e),
    };
}

pub(crate) fn assert_session(name: &str) {
    match session_exists(name) {
        Ok(result) => {
            if result {
                return;
            } else {
                println!("No session named {:?} found.", name);
            }
        }
        Err(e) => {
            eprintln!("Error occured: {:?}", e);
        }
    };
    process::exit(1);
}

pub(crate) fn assert_session_ne(name: &str) {
    match get_sessions() {
        Ok(sessions) => {
            if sessions.iter().all(|s| s != name) {
                return;
            }
            println!("Session with name {:?} aleady exists. Use attach command to connect to it or specify a different name.", name);
        }
        Err(e) => eprintln!("Error occured: {:?}", e),
    };
    process::exit(1);
}