def unknown(mud, command, id):
    mud.send_message(id, "Unknown command '{}'"
                     .format(command))


def help(mud, id):
    mud.send_message(id, '''This are the currently available commands:
    * say <message>: Says something to everyone in the room.
    * go <exit>: Enters an exit.
    * look: Gives a description of the room. Use it in a players to see info
    about them. Use 'me' to see info about you.
    * open <exit> <room>: (Only available for the builders of the room) creates
    an exit to another room.
    * build <room> <return> <description>: Creates a room. The return param is
    the name of an exit to come back to the current room.
    * me <action>: Emotes action. Example, 'me chuckles'. Visible to everyone
    in the room.
''')


def say(mud, id, players, params):
    for pid, pl in players.items():
        if players[pid]["room"] == players[id]["room"]:
            mud.send_message(pid, "{} says: {}"
                             .format(players[id]["name"], params))


def go(mud, id, players, rooms, params):
    old_room = players[id]["room"]
    params_list = params.split()
    if len(params_list) != 1:
        mud.send_message(id, "Invalid params.")
        return
    exit = params_list[0]
    room = rooms[players[id]["room"]]
    if exit in room["exits"]:
        if room["exits"][exit] not in rooms:
            mud.send_message(id, "Room '{}' not found."
                             .format(room["exits"][exit]))
            return
        for pid, pl in players.items():
            if pl["room"] == players[id]["room"] and pid != id:
                mud.send_message(pid, "{} left via exit '{}'."
                                 .format(players[id]["name"], exit))
        players[id]["room"] = room["exits"][exit]
        mud.send_message(id, "You arrive at '{}'.".format(players[id]["room"]))

        for pid, pl in players.items():
            if pl["room"] == players[id]["room"] and pid != id:
                mud.send_message(pid, "{} arrived from '{}' via exit '{}'."
                                 .format(players[id]["name"], old_room, exit))
    else:
        mud.send_message(id, "Unknown exit '{}'".format(exit))


def look(mud, id, players, rooms, params):
    params_list = params.split()
    if len(params_list) > 1:
        mud.send_message(id, "Invalid params.")
        return
    if len(params_list) == 1:
        for pid, pl in players.items():
            if params_list[0] == "me":
                mud.send_message(id, players[id]["description"])
                mud.send_message(id, "species: {}"
                                 .format(players[id]["species"]))
                break
            elif params_list[0] == pl["name"]:
                mud.send_message(id, pl["description"])
                mud.send_message(id, "species: {}"
                                 .format(players[pid]["species"]))
        return
    room = rooms[players[id]["room"]]
    mud.send_message(id, room["description"])

    room_players = []

    for pid, pl in players.items():
        if pl["room"] != players[id]["room"]:
            continue
        room_players.append(pl["name"])

    mud.send_message(id, "Players here: {}.".format(", ".join(room_players)))
    mud.send_message(id, "Exits are: {}.".format(", ".join(room["exits"])))


def open(mud, id, players, rooms, params):
    params_list = params.split()
    if len(params_list) != 2:
        mud.send_message(id, "Invalid params.")
        return
    if not players[id]["name"] in rooms[players[id]["room"]]["builders"]:
        mud.send_message(id, "You don't have the rights of building here.")
        return
    rooms[players[id]["room"]]["exits"][params_list[0]] = params_list[1]
    mud.send_message(id, "You open the exit '{}' to '{}'."
                     .format(params_list[0], params_list[1]))


def build(mud, id, players, rooms, params):
    params_list = params.split()
    if len(params_list) < 3:
        mud.send_message(id, "Invalid params.")
        return
    params_list = [params_list[0], params_list[1],  " ".join(params_list[2:])]
    room = params_list[0]
    if room in rooms:
        mud.send_message("Room '{}' already exits."
                         .format(room))
        return
    rooms[room] = {
        "description": params_list[2],
        "exits": {params_list[1]: players[id]["room"]},
        "owner": players[id]["name"],
        "builders": [players[id]["name"]]
    }


def me(mud, id, players, rooms, params):
    if not params:
        mud.send_message(id, "Invalid params.")
        return
    for pid, pl in players.items():
        if pl["room"] == players[id]["room"]:
            mud.send_message(pid, "{} {}"
                             .format(players[id]["name"], params))