//! tesserasd: daemon with TCP command interface.
//!
//! Manages multiple DHT nodes via a line-oriented TCP
//! protocol.
//!
//! Usage:
//!   cargo run --example tesserasd
//!   cargo run --example tesserasd -- --host 0.0.0.0 --port 8080
//!
//! Then connect with:
//!   nc localhost 12080
//!
//! Commands:
//!   new,NAME,PORT[,global]   Create a node
//!   delete,NAME              Delete a node
//!   set_id,NAME,DATA         Set node ID from data
//!   join,NAME,HOST,PORT      Join network
//!   put,NAME,KEY,VALUE,TTL   Store key-value
//!   get,NAME,KEY             Retrieve value
//!   dump,NAME                Print node state
//!   list                     List all nodes
//!   quit                     Close connection
//!
//! Response codes:
//!   200-205  Success
//!   400-409  Error

use std::collections::HashMap;
use std::io::{BufRead, BufReader, Write};
use std::net::{TcpListener, TcpStream};
use std::time::Duration;

use tesseras_dht::Node;
use tesseras_dht::nat::NatState;

// Response codes
const OK_NEW: &str = "200";
const OK_DELETE: &str = "201";
const OK_JOIN: &str = "202";
const OK_PUT: &str = "203";
const OK_GET: &str = "204";
const OK_SET_ID: &str = "205";

const ERR_UNKNOWN: &str = "400";
const ERR_INVALID: &str = "401";
const ERR_PORT: &str = "402";
const ERR_EXISTS: &str = "403";
const ERR_NO_NODE: &str = "404";

fn main() {
    env_logger::Builder::from_env(
        env_logger::Env::default().default_filter_or("info"),
    )
    .format(|buf, record| {
        use std::io::Write;
        writeln!(
            buf,
            "{} [{}] {}",
            record.level(),
            record.target(),
            record.args()
        )
    })
    .init();

    let mut host = "127.0.0.1".to_string();
    let mut port: u16 = 12080;

    let args: Vec<String> = std::env::args().collect();
    let mut i = 1;
    while i < args.len() {
        match args[i].as_str() {
            "--host" if i + 1 < args.len() => {
                host = args[i + 1].clone();
                i += 2;
            }
            "--port" if i + 1 < args.len() => {
                port = args[i + 1].parse().expect("invalid port");
                i += 2;
            }
            _ => i += 1,
        }
    }

    let listener =
        TcpListener::bind(format!("{host}:{port}")).expect("bind TCP");
    listener.set_nonblocking(true).expect("set_nonblocking");

    println!("tesserasd listening on 127.0.0.1:{port}");
    println!("Connect with: nc localhost {port}");

    let mut nodes: HashMap<String, Node> = HashMap::new();
    let mut clients: Vec<TcpStream> = Vec::new();

    loop {
        // Accept new TCP connections
        if let Ok((stream, addr)) = listener.accept() {
            println!("Client connected: {addr}");
            stream.set_nonblocking(true).expect("set_nonblocking");
            let mut s = stream.try_clone().unwrap();
            let _ = s.write_all(b"tesserasd ready\n");
            clients.push(stream);
        }

        // Process commands from connected clients
        let mut to_remove = Vec::new();
        for (i, client) in clients.iter().enumerate() {
            let mut reader = BufReader::new(client.try_clone().unwrap());
            let mut line = String::new();
            match reader.read_line(&mut line) {
                Ok(0) => to_remove.push(i), // disconnected
                Ok(_) => {
                    let line = line.trim().to_string();
                    if !line.is_empty() {
                        let mut out = client.try_clone().unwrap();
                        let response = handle_command(&line, &mut nodes);
                        let _ = out.write_all(response.as_bytes());
                        let _ = out.write_all(b"\n");

                        if line == "quit" {
                            to_remove.push(i);
                        }
                    }
                }
                Err(ref e) if e.kind() == std::io::ErrorKind::WouldBlock => {
                    // No data yet
                }
                Err(_) => to_remove.push(i),
            }
        }
        // Remove disconnected (reverse order)
        to_remove.sort();
        to_remove.dedup();
        for i in to_remove.into_iter().rev() {
            println!("Client disconnected");
            clients.remove(i);
        }

        // Poll all DHT nodes
        for node in nodes.values_mut() {
            node.poll().ok();
        }

        std::thread::sleep(Duration::from_millis(10));
    }
}

fn handle_command(line: &str, nodes: &mut HashMap<String, Node>) -> String {
    let parts: Vec<&str> = line.split(',').collect();
    if parts.is_empty() {
        return format!("{ERR_UNKNOWN},unknown command");
    }

    match parts[0] {
        "new" => cmd_new(&parts, nodes),
        "delete" => cmd_delete(&parts, nodes),
        "set_id" => cmd_set_id(&parts, nodes),
        "join" => cmd_join(&parts, nodes),
        "put" => cmd_put(&parts, nodes),
        "get" => cmd_get(&parts, nodes),
        "dump" => cmd_dump(&parts, nodes),
        "list" => cmd_list(nodes),
        "quit" => "goodbye".to_string(),
        _ => format!("{ERR_UNKNOWN},unknown command: {}", parts[0]),
    }
}

// new,NAME,PORT[,global]
fn cmd_new(parts: &[&str], nodes: &mut HashMap<String, Node>) -> String {
    if parts.len() < 3 {
        return format!("{ERR_INVALID},usage: new,NAME,PORT[,global]");
    }
    let name = parts[1];
    let port: u16 = match parts[2].parse() {
        Ok(p) => p,
        Err(_) => return format!("{ERR_INVALID},invalid port"),
    };

    if nodes.contains_key(name) {
        return format!("{ERR_EXISTS},new,{name},{port},already exists");
    }

    let mut node = match Node::bind(port) {
        Ok(n) => n,
        Err(e) => return format!("{ERR_PORT},new,{name},{port},{e}"),
    };

    if parts.len() >= 4 && parts[3] == "global" {
        node.set_nat_state(NatState::Global);
    }

    let id = node.id_hex();
    nodes.insert(name.to_string(), node);
    format!("{OK_NEW},new,{name},{port},{id}")
}

// delete,NAME
fn cmd_delete(parts: &[&str], nodes: &mut HashMap<String, Node>) -> String {
    if parts.len() < 2 {
        return format!("{ERR_INVALID},usage: delete,NAME");
    }
    let name = parts[1];
    if nodes.remove(name).is_some() {
        format!("{OK_DELETE},delete,{name}")
    } else {
        format!("{ERR_NO_NODE},delete,{name},not found")
    }
}

// set_id,NAME,DATA
fn cmd_set_id(parts: &[&str], nodes: &mut HashMap<String, Node>) -> String {
    if parts.len() < 3 {
        return format!("{ERR_INVALID},usage: set_id,NAME,DATA");
    }
    let name = parts[1];
    let data = parts[2];
    match nodes.get_mut(name) {
        Some(node) => {
            node.set_id(data.as_bytes());
            format!("{OK_SET_ID},set_id,{name},{}", node.id_hex())
        }
        None => format!("{ERR_NO_NODE},set_id,{name},not found"),
    }
}

// join,NAME,HOST,PORT
fn cmd_join(parts: &[&str], nodes: &mut HashMap<String, Node>) -> String {
    if parts.len() < 4 {
        return format!("{ERR_INVALID},usage: join,NAME,HOST,PORT");
    }
    let name = parts[1];
    let host = parts[2];
    let port: u16 = match parts[3].parse() {
        Ok(p) => p,
        Err(_) => return format!("{ERR_INVALID},invalid port"),
    };
    match nodes.get_mut(name) {
        Some(node) => match node.join(host, port) {
            Ok(()) => {
                format!("{OK_JOIN},join,{name},{host},{port}")
            }
            Err(e) => format!("{ERR_INVALID},join,{name},{host},{port},{e}"),
        },
        None => {
            format!("{ERR_NO_NODE},join,{name},not found")
        }
    }
}

// put,NAME,KEY,VALUE,TTL
fn cmd_put(parts: &[&str], nodes: &mut HashMap<String, Node>) -> String {
    if parts.len() < 5 {
        return format!("{ERR_INVALID},usage: put,NAME,KEY,VALUE,TTL");
    }
    let name = parts[1];
    let key = parts[2];
    let value = parts[3];
    let ttl: u16 = match parts[4].parse() {
        Ok(t) => t,
        Err(_) => return format!("{ERR_INVALID},invalid TTL"),
    };
    match nodes.get_mut(name) {
        Some(node) => {
            node.put(key.as_bytes(), value.as_bytes(), ttl, false);
            format!("{OK_PUT},put,{name},{key}")
        }
        None => {
            format!("{ERR_NO_NODE},put,{name},not found")
        }
    }
}

// get,NAME,KEY
fn cmd_get(parts: &[&str], nodes: &mut HashMap<String, Node>) -> String {
    if parts.len() < 3 {
        return format!("{ERR_INVALID},usage: get,NAME,KEY");
    }
    let name = parts[1];
    let key = parts[2];
    match nodes.get_mut(name) {
        Some(node) => {
            let vals = node.get(key.as_bytes());
            if vals.is_empty() {
                format!("{OK_GET},get,{name},{key},<not found>")
            } else {
                let values: Vec<String> = vals
                    .iter()
                    .map(|v| String::from_utf8_lossy(v).to_string())
                    .collect();
                format!("{OK_GET},get,{name},{key},{}", values.join(";"))
            }
        }
        None => {
            format!("{ERR_NO_NODE},get,{name},not found")
        }
    }
}

// dump,NAME
fn cmd_dump(parts: &[&str], nodes: &HashMap<String, Node>) -> String {
    if parts.len() < 2 {
        return format!("{ERR_INVALID},usage: dump,NAME");
    }
    let name = parts[1];
    match nodes.get(name) {
        Some(node) => {
            format!(
                "{OK_NEW},dump,{name},id={},nat={:?},\
                 rt={},peers={},storage={}",
                node.id_hex(),
                node.nat_state(),
                node.routing_table_size(),
                node.peer_count(),
                node.storage_count(),
            )
        }
        None => {
            format!("{ERR_NO_NODE},dump,{name},not found")
        }
    }
}

// list
fn cmd_list(nodes: &HashMap<String, Node>) -> String {
    if nodes.is_empty() {
        return format!("{OK_NEW},list,<empty>");
    }
    let mut lines = Vec::new();
    for (name, node) in nodes {
        lines.push(format!(
            "{name}={} rt={} storage={}",
            &node.id_hex()[..8],
            node.routing_table_size(),
            node.storage_count(),
        ));
    }
    format!("{OK_NEW},list,{}", lines.join(";"))
}