EnderAir - Client

-- This program is the first of a two part system,
-- which enables the player to teleport by selecting a
-- destination in the interface.

-- IMPORTANT:
-- This will require an Enderpearl stasis chamber to work.
-- It is the mechanism this program relies on.

-- This is the list of possible destinations
-- You can extend this in whichever way you like.
-- To add another destination insert a table in the following format:
--
-- {<Destination name>, <Destination Computer ID>}
--
-- for example:
--
-- {"End", 00},
-- {"Home", 01},
-- {"Basement", 03}
--
local dests = {
    {"End", 00},
    {"Home", 01}
}

-- Clears the screen and resets the cursor to the top left corner.
function wipe_screen()
    term.clear()
    term.setCursorPos(1, 1)
end

-- Prints all the possible destinations to the screen.
function print_possible_destinations()
    print("Destination:")
    for i = 1, #dests, 1 do
        print(dests[i][1])
    end
    print("Exit - To end the program")
    print("-------------------------")
    print("Where would you like to go?")
end

-- Handles the processing of the selected destination.
-- Sends RedNet signal to specified target.
function handle_selection(dest_index)
    term.clear()
    term.setCursorPos(1, 1)

    -- Handles the special case, when home is selected.
    if dests[dest_index][1]:lower() == "home" then
        print("Teleporting to", dests[dest_index][1], "sweet", dests[dest_index][1])
    else
        print("Teleporting to", dests[dest_index][1])
    end

    rednet.send(dests[dest_index][2], "tp")
    sleep(2)
    wipe_screen()
end

-- Handles an invalid selection
function handle_invalid_selection()
    term.clear()
    term.setCursorPos(1, 1)
    print("Unknown Destination")
    print("You might want to try this again.")
    sleep(2)
    wipe_screen()
end

-- This function interates through the peripherals of the computer
-- and then returns the side on which a modem is connected.
-- Will terminate if there is none, since this will make the program unusable.
function find_modem()
    devs = peripheral.getNames()
    for i = 1, #devs, 1 do
        if peripheral.getType(devs[i]) == "modem" then
            return devs[i]
        end
    end
    Print("Error: No modem found. Terminating!")
    Print("Connect a modem and try again.")
    return -1
end

function start_interaction()
    while true do
        -- Displaying possible destinations.
        print_possible_destinations()

        -- Awaiting user input
        -- Will store the selected destination
        local tp = io.read()

        -- Locating the side of the device the modem is on.
        -- The program will terminate if there is no terminal.
        local modem_side = find_modem()
        -- Terminating if there is no modem.
        if modem_side == -1 then
            return
        end
        -- Opening the Rednet Channel
        rednet.open(modem_side)

        local valid = false

        -- Iterate over the possible destinations.
        for i = 1, #dests, 1 do
            if tp:lower() == dests[i][1]:lower() then
                handle_selection(i)
                return
            end
        end

        -- In case the input was exit, the program will terminate.
        if tp:lower() == "exit" then
            wipe_screen()
            return
        end

        -- Edge Case
        -- Only used, if the input was invalid
        handle_invalid_selection()
    end
end

function main()
    wipe_screen()
    start_interaction()
end

main()