use std::os::unix::fs::FileTypeExt;
use std::time::SystemTime;
use std::{fs, io, process};
use suggest::Suggest;
use zellij_utils::{
    consts::ZELLIJ_SOCK_DIR,
    envs,
    interprocess::local_socket::LocalSocketStream,
    ipc::{ClientToServerMsg, IpcReceiverWithContext, IpcSenderWithContext, ServerToClientMsg},
};

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 io::ErrorKind::NotFound != err.kind() => Err(err.kind()),
        Err(_) => Ok(Vec::with_capacity(0)),
    }
}

pub(crate) fn get_sessions_sorted_by_mtime() -> anyhow::Result<Vec<String>> {
    match fs::read_dir(&*ZELLIJ_SOCK_DIR) {
        Ok(files) => {
            let mut sessions_with_mtime: Vec<(String, SystemTime)> = Vec::new();
            for file in files {
                let file = file?;
                let file_name = file.file_name().into_string().unwrap();
                let file_modified_at = file.metadata()?.modified()?;
                if file.file_type()?.is_socket() && assert_socket(&file_name) {
                    sessions_with_mtime.push((file_name, file_modified_at));
                }
            }
            sessions_with_mtime.sort_by_key(|x| x.1); // the oldest one will be the first

            let sessions = sessions_with_mtime.iter().map(|x| x.0.clone()).collect();
            Ok(sessions)
        },
        Err(err) if io::ErrorKind::NotFound != err.kind() => Err(err.into()),
        Err(_) => Ok(Vec::with_capacity(0)),
    }
}

fn assert_socket(name: &str) -> bool {
    let path = &*ZELLIJ_SOCK_DIR.join(name);
    match LocalSocketStream::connect(path) {
        Ok(stream) => {
            let mut sender = IpcSenderWithContext::new(stream);
            let _ = sender.send(ClientToServerMsg::ConnStatus);
            let mut receiver: IpcReceiverWithContext<ServerToClientMsg> = sender.get_receiver();
            match receiver.recv() {
                Some((ServerToClientMsg::Connected, _)) => true,
                None | Some((_, _)) => false,
            }
        },
        Err(e) if e.kind() == io::ErrorKind::ConnectionRefused => {
            drop(fs::remove_file(path));
            false
        },
        Err(_) => false,
    }
}

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

pub(crate) fn print_sessions_with_index(sessions: Vec<String>) {
    let curr_session = envs::get_session_name().unwrap_or_else(|_| "".into());
    for (i, session) in sessions.iter().enumerate() {
        let suffix = if curr_session == *session {
            " (current)"
        } else {
            ""
        };
        println!("{}: {}{}", i, session, suffix);
    }
}

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

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

pub(crate) fn kill_session(name: &str) {
    let path = &*ZELLIJ_SOCK_DIR.join(name);
    match LocalSocketStream::connect(path) {
        Ok(stream) => {
            let _ = IpcSenderWithContext::new(stream).send(ClientToServerMsg::KillSession);
        },
        Err(e) => {
            eprintln!("Error occurred: {:?}", e);
            process::exit(1);
        },
    };
}

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

#[derive(Debug, Clone)]
pub enum SessionNameMatch {
    AmbiguousPrefix(Vec<String>),
    UniquePrefix(String),
    Exact(String),
    None,
}

pub(crate) fn match_session_name(prefix: &str) -> Result<SessionNameMatch, io::ErrorKind> {
    let sessions = get_sessions()?;

    let filtered_sessions: Vec<_> = sessions.iter().filter(|s| s.starts_with(prefix)).collect();

    if filtered_sessions.iter().any(|s| *s == prefix) {
        return Ok(SessionNameMatch::Exact(prefix.to_string()));
    }

    Ok({
        match &filtered_sessions[..] {
            [] => SessionNameMatch::None,
            [s] => SessionNameMatch::UniquePrefix(s.to_string()),
            _ => {
                SessionNameMatch::AmbiguousPrefix(filtered_sessions.into_iter().cloned().collect())
            },
        }
    })
}

pub(crate) fn session_exists(name: &str) -> Result<bool, io::ErrorKind> {
    match match_session_name(name) {
        Ok(SessionNameMatch::Exact(_)) => Ok(true),
        Ok(_) => 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);
                if let Some(sugg) = get_sessions().unwrap().suggest(name) {
                    println!("  help: Did you mean `{}`?", sugg);
                }
            }
        },
        Err(e) => {
            eprintln!("Error occurred: {:?}", e);
        },
    };
    process::exit(1);
}

pub(crate) fn assert_session_ne(name: &str) {
    if name.trim().is_empty() {
        eprintln!("Session name cannot be empty. Please provide a specific session name.");
        process::exit(1);
    }
    if name == "." || name == ".." {
        eprintln!("Invalid session name: \"{}\".", name);
        process::exit(1);
    }
    if name.contains('/') {
        eprintln!("Session name cannot contains '/'.");
        process::exit(1);
    }

    match session_exists(name) {
        Ok(result) if !result => return,
        Ok(_) => println!("Session with name {:?} already exists. Use attach command to connect to it or specify a different name.", name),
        Err(e) => eprintln!("Error occurred: {:?}", e),
    };
    process::exit(1);
}