module io.base;

import std.socket;

import io.events;

R delegate(T) makeDelegate(R, T)(R function(T) f) {
	struct delegateClass {
		R function(T) m_f;
		
		R callback(T t) { return m_f(t); }
	}

	delegateClass* o = new delegateClass;
	o.m_f = f;
	return &o.callback;
}

private extern (C) int iobase_write(int fd, void *buf, int len);
private extern (C) int iobase_read(int fd, void *buf, int len);

class BufferedSocket {
	private Socket m_socket;
	private IOWatcher m_watcher;
	private void delegate(void[] buf) m_readcb;
	private void delegate() m_eofcb, m_closecb;
	
	private bool m_closed, m_eof, m_sendeof;

	private class chunk {
		chunk next;
		void[] buf;
		this(void[] b) { buf = b.dup; }
	}
	private chunk m_cfirst, m_clast;

	final void delegate(void[] buf) readcb() { return m_readcb; }
	final void delegate(void[] buf) readcb(void delegate(void[] buf) r) {
		m_readcb = r;
		if (m_readcb is null || m_eof || m_closed) {
			m_watcher.events = m_watcher.events & ~Event.READ;
		} else {
			m_watcher.events = m_watcher.events | Event.READ;
		}
		return m_readcb;
	}
	
	final void delegate() eofcb() { return m_eofcb; }
	final void delegate() eofcb(void delegate() f) { return m_eofcb = f; }

	final void delegate() closecb() { return m_closecb; }
	final void delegate() closecb(void delegate() f) { return m_closecb = f; }

	this(Loop loop, Socket sock, void delegate(void[] buf) readcb = null) {
		m_socket = sock;
		m_readcb = readcb;

		m_watcher = new IOWatcher();
		m_watcher.socket = m_socket;
		m_watcher.events = Event.READ;
		m_watcher.read = &this.handleread;
		m_watcher.write = &this.handlewrite;
		m_watcher.start(loop);
	}
	
	~this() {
		m_cfirst = m_clast = null;
		shutdown();
		delete m_watcher;
		delete m_socket;
	}

	void write(void[] buf) {
		if (m_closed || m_sendeof || 0 == buf.length) return;
		chunk c = new chunk(buf);
		if (m_clast !is null) {
			m_clast.next = c;
			m_clast = c;
		} else {
			m_cfirst = m_clast = c;
		}
		m_watcher.events = m_watcher.events | Event.WRITE;
	}
	
	void shutdown() {
		if (m_closed || m_sendeof) return;
		m_sendeof = true;
		if (m_cfirst is null) {
			m_socket.shutdown(SocketShutdown.SEND);
		}
	}
	
	/* may destroy object */
	private final void handleeof() {
		m_eof = true;
		m_watcher.events = m_watcher.events & ~Event.READ;
		if (m_eofcb !is null) {
			m_eofcb();
		} else {
			delete this;
		}
	}
	
	/* may destroy object */
	private final void handleclose() {
		m_closed = true;
		m_watcher.events = Event.NONE;
		if (m_closecb !is null) {
			m_closecb();
		} else {
			delete this;
		}
	}
	
	private final void handleread() {
		if (m_readcb is null) {
			m_watcher.events = m_watcher.events & ~Event.READ;
			return;
		}
		ubyte buf[4096];
		int res = iobase_read(m_socket.handle, buf.ptr, buf.length);
		if (res == 0) {
			handleeof();
		} else if (res > 0) {
			m_readcb(buf[0 .. res]);
		} else if (res != -1) {
			handleclose();
		}
	}
	private final void handlewrite() {
		while (m_cfirst !is null) {
			chunk c = m_cfirst;
			int res = iobase_write(m_socket.handle, c.buf.ptr, c.buf.length);
			if (res > 0) {
				if (res == c.buf.length) {
					m_cfirst = c.next;
				} else {
					c.buf = c.buf[res .. $];
					return;
				}
			} else if (res == -1) {
				return;
			} else {
				handleclose();
				return;
			}
		}
		if (m_sendeof) {
			m_socket.shutdown(SocketShutdown.SEND);
		}
		m_clast = null;
		m_watcher.events = m_watcher.events & ~Event.WRITE;
	}
}

class TcpServer {
	private Socket m_socket;
	private IOWatcher m_watcher;
	private void delegate(Socket con) m_accept_cb;
	
	public final Socket socket() { return m_socket; }
	
	this(Loop loop, Address bind, void delegate(Socket con) accept) {
		m_accept_cb = accept;

		m_socket = new TcpSocket(bind.addressFamily);
		m_socket.blocking = false;
		m_socket.setOption(SocketOptionLevel.SOCKET, SocketOption.REUSEADDR, 1);
// 		m_socket.setOption(SocketOptionLevel.IPV6, SocketOption.IPV6_V6ONLY, 1);
		m_socket.bind(bind);
		m_socket.listen(1024);

		m_watcher = new IOWatcher();
		m_watcher.socket = m_socket;
		m_watcher.events = Event.READ;
		m_watcher.read = &this.acceptcb;
		m_watcher.start(loop);
	}
	
	private final void acceptcb() {
		Socket con = m_socket.accept();
		if (con !is null) m_accept_cb(con);
	}
}

class EchoConnection {
	protected int m_idx = -1;
	protected EchoServer m_srv;
	protected Socket m_socket;
	protected BufferedSocket m_bufsock;

	this(Socket s) {
		m_socket = s;
		m_bufsock = new BufferedSocket(Loop.defaultloop, s, &this.handleread);
	}

	~this() {
		if (m_srv !is null) m_srv.delCon(this);
	}

	private final void handleread(void[] buf) {
		m_bufsock.write(buf);
	}
};

class EchoServer {
	private EchoConnection m_con[];
	private Loop m_loop;
	private TcpServer m_server;

	this(Loop loop, Address address) {
		m_loop = loop;
		m_server = new TcpServer(m_loop, address, &this.accept);
		m_con = new EchoConnection[0];
	}

	protected final void addCon(EchoConnection con) {
		con.m_srv = this;
		con.m_idx = m_con.length;
		m_con.length = m_con.length + 1;
		m_con[con.m_idx] = con;
	}
	
	protected final void delCon(EchoConnection con) {
		if (con.m_srv !is this) return;
		m_con[con.m_idx] = m_con[m_con.length - 1];
		m_con.length = m_con.length - 1;
		con.m_srv = null;
		con.m_idx = -1;
	}
	
	private final void accept(Socket s) {
		auto con = new EchoConnection(s);
		addCon(con);
	}
};

void main(string args[]) {
	Loop loop = Loop.defaultloop;
	EchoServer srv = new EchoServer(loop, new InternetAddress(8080));
	Loop.defaultloop.run();
}