Coreless Station V2

--Station Program
--  Author: Andrew Lalis, all rights reserved.
--  This program is not to be distributed without
--  express permission from the author, by any means.

--Constants
local configFile = "station_config"
local pastebinURL = "YZtchLvt"
local VERSION = "1.0"

--Protocol for broadcasting station metadata.
local metadataProt = "STATION_META"
--Protocol for requesting metadata from all stations.
local metadataRequestProt = "STATION_META_REQUEST"
--Protocol for requesting a train to be dispatched from a station.
local trainDispatchProt = "TRAIN_DISPATCH"
--Protocol for train admin commands.
local trainAdminProt = "TRAIN_ADMIN"

--Config table containing all station information.
local stationConfig

--Offset if the user has scrolled on the stations list.
local stationsOffset = 0

--Peripherals.
local ticketMachine
local noteBlock
local monitor

--Timers
-- Prompt on monitor screen.
local promptTimer
local inPrompt = false
-- Requesting train from another station.
local requestTimer

--Returns the number of items in a table.
function tableSize(tbl)
    local count = 0
    for i in pairs(tbl) do count = count + 1 end
    return count
end

--Logging function to make output more pretty.
function logMsg(t, msg)
    local c = colors.white
    if (t == "ERROR") then
        c = colors.red
    elseif (t == "INFO") then
        c = colors.blue
    elseif (t == "INFO_DETAIL") then
        c = colors.lightBlue
        term.write("  ")
    elseif (t == "INFO_HIGH") then
        c = colors.magenta
    elseif (t == "WARNING") then
        c = colors.orange
    end
    term.setTextColor(c)
    print("["..t.."]: "..msg)
end

--Saves the current station config to a file.
function saveConfig()
    local f = fs.open(configFile, "w")
    f.write(textutils.serialize(stationConfig))
    f.close()
    --logMsg("INFO_DETAIL", "Station config saved.")
end

--Wraps a string into a table.
function wrap(str, limit)
  limit = limit or 72
  local here = 1
  local buf = ""
  local t = {}
  str:gsub("(%s*)()(%S+)()",
  function(sp, st, word, fi)
        if fi-here > limit then
           --# Break the line
           here = st
           table.insert(t, buf)
           buf = word
        else
           buf = buf..sp..word  --# Append
        end
  end)
  --# Tack on any leftovers
  if(buf ~= "") then
        table.insert(t, buf)
  end
  return t
end

--Gets the cosmetic name of a station, given the destination name.
function getCosmeticName(dest)
    for i,v in ipairs(stationConfig.otherStations) do
        if (v[1] == dest) then
            return v[2]
        end
    end
    return nil
end

--Draws a horizontal line across the screen.
function drawLine(y, c)
    local sizeX,sizeY = monitor.getSize()
    monitor.setTextColor(colors.black)
    monitor.setBackgroundColor(c)
    for i=1,sizeX do
        monitor.setCursorPos(i,y)
        monitor.write(" ")
    end
end

--Draws a box of a color
function drawBox(x, y, width, height, bc)
    monitor.setBackgroundColor(bc)
    for i=x,width+x do
        for k=y,height+y do
            monitor.setCursorPos(i,k)
            monitor.write(" ")
        end
    end
end

--Writes to the screen with a certain color, background color, and other parameters.
function writeToScreen(text, x, y, tc, bc)
    monitor.setCursorPos(x,y)
    monitor.setTextColor(tc)
    monitor.setBackgroundColor(bc)
    monitor.write(text)
end

--Writes to the screen centered at some x coordinate.
function writeCentered(text, x, y, tc, bc)
    monitor.setTextColor(tc)
    monitor.setBackgroundColor(bc)
    monitor.setCursorPos((x - (string.len(text)/2)),y)
    monitor.write(text)
end

--Function to draw station monitor with a given offset for the stations list.
function drawMonitor()
    local sizeX,sizeY = monitor.getSize()
    monitor.setBackgroundColor(colors.black)
    monitor.clear()
    --Draw Station Name.
    drawLine(1, colors.blue)
    writeCentered(stationConfig.name, sizeX/2, 1, colors.white, colors.blue)
    --Draw help button.
    writeToScreen("Help",sizeX-3,1,colors.yellow,colors.lightBlue)
    --Draw list of stations, as found in the station config.
    local index = 0
    for i=1,tableSize(stationConfig.otherStations) do
        local bc = colors.gray
        if (i % 2 == 0) then
            bc = colors.lightGray
        end
        drawLine(i+1, bc)
        writeToScreen(stationConfig.otherStations[i][2], 2, i+1, colors.white, bc)
    end
end

--Draws wrapped text.
function drawWrappedText(text, x, y, width, height, tc, bc)
    drawBox(x,y,width,height,bc)
    local t = wrap(text, width)
    if (tableSize(t) > height) then
        logMsg("WARNING", "Text is too large to wrap in given bounds.")
    end
    for i,line in ipairs(t) do
        writeToScreen(line, x, y + i - 1, tc, bc)
    end
end

--Draws an alert which disappears in a small time.
function prompt(text, delay, tc, bc)
    local sizeX, sizeY = monitor.getSize()
    drawBox(3,3,sizeX-6,sizeY-1, bc)
    drawWrappedText(text,4,4,sizeX-8,sizeY-2, tc, bc)
    promptTimer = os.startTimer(delay)
    inPrompt = true
end

--Beep the noteblock to indicate the track on which a train is being dispatched.
function beep(count)
    for i=1,count do
        noteBlock.triggerNote()
        os.sleep(0.5)
    end
end

--Updates the station file from pastebin.
function updateStationFile()
    prompt("Updating station software. Please wait while the system restarts. Thank you.",
    5,
    colors.yellow,
    colors.white)
    logMsg("INFO", "Fetching update from pastebin.")
    fs.delete("station")
    shell.run("pastebin", "get", pastebinURL, "station")
    logMsg("INFO", "System will now reboot.")
    --Send a message to the train admin.
    rednet.broadcast(stationConfig.dest.." has updated.", trainAdminProt)
    os.sleep(3)
    os.reboot()
end

--Request a train from a station which has more than 1 train.
function requestTrain()
    for i=1,tableSize(stationConfig.otherStations) do
        if (stationConfig.otherStations[i][3] > 1) then
            rednet.send(stationConfig.otherStations[i][4], stationConfig.dest, trainDispatchProt)
            logMsg("INFO", "Sent request to "..stationConfig.otherStations[i][1].." for a train.")
            return
        end
    end
    logMsg("WARNING", "Unable to find a station with an extra train, waiting 1 min before next attempt.")
    requestTimer = os.startTimer(60)
end

--Dispatches a train from a track, by sending a ticket to it.
function dispatchTrain(destination, trainCountAtDest, isPlayer)
    --Iterate until an occupied track is found.
    for i=1,tableSize(stationConfig.tracks) do
        if (stationConfig.tracks[i][1]) then
            local success = ticketMachine.createTicket(destination,1)
            if (not success) then
                logMsg("ERROR", "Unable to create ticket.")
                prompt("Unable to create ticket. Please check that the ticket machine has ink and paper.",
                5,
                colors.red,
                colors.white)
                return false
            end
            logMsg("INFO_HIGH", "Train on track "..i.." will be dispatched to "..destination..".")
            if (isPlayer) then
                prompt("Train to "..getCosmeticName(destination).." leaves on track "..i..". Have a pleasant journey!",
                    5,
                    colors.green,
                    colors.white)
            end
            beep(i)
            redstone.setBundledOutput("top", stationConfig.tracks[i][2])
            os.sleep(2)
            redstone.setBundledOutput("top", 0)
            return true
        end
    end
    logMsg("ERROR", "Unable to find train to dispatch.")
    prompt("Error, unable to find train to dispatch. Please ensure that the system has n+1 trains, where n = number of stations.",
        5,
        colors.red,
        colors.white)
    return false
end

--Broadcasts the station's name, destination, and train count to all other stations.
function broadcastMetadata()
    rednet.broadcast({stationConfig.dest,stationConfig.name,stationConfig.trainCount}, metadataProt)
    --logMsg("INFO_DETAIL", "Broadcasted metadata.")
end

--Scans redstone inputs from each track.
--  Updates tracks table, and train count, then broadcasts.
function scanTracks()
    local trainCount = 0
    local changed = false
    for i=1,tableSize(stationConfig.tracks) do
        local previous = stationConfig.tracks[i][1]
        stationConfig.tracks[i][1] = colors.test(redstone.getBundledInput("top"), stationConfig.tracks[i][3])
        if (stationConfig.tracks[i][1]) then
            trainCount = trainCount + 1
        end
        if (previous ~= stationConfig.tracks[i][1]) then
            changed = true
        end
        --Test if a train has arrived, and provide a welcome message.
        if (not previous and stationConfig.tracks[i][1]) then
            prompt("Welcome to "..stationConfig.name..". Thank you for using HandieBahn!",
            5,
            colors.blue,
            colors.white)
        end
    end
    stationConfig.trainCount = trainCount
    if (trainCount < 1) then
        requestTrain()
    end
    if (changed) then
        broadcastMetadata()
    end
    saveConfig()
    --logMsg("INFO_DETAIL", "Tracks scanned.")
end

--Determines if occupancy of the tracks is changed according to config.
function tracksChanged()
    for i=1,tableSize(stationConfig.tracks) do
        local previous = stationConfig.tracks[i][1]
        local current = colors.test(redstone.getBundledInput("top"), stationConfig.tracks[i][3])
        if (previous ~= current) then
            --logMsg("INFO_DETAIL", "Track occupancy has changed.")
            return true
        end
    end
    return false
end

--What to do when a redstone event is triggered.
function onRedstoneEvent()
    if (tracksChanged()) then
        scanTracks()
    end
end

--Saves a station's metadata into the stationConfig file.
function saveStation(dest, name, trainCount, compID)
    --First determine if the station already exists in the file.
    local index = 0
    for k,v in pairs(stationConfig.otherStations) do
        if (v[1] == dest) then
            index = k
            break
        end
    end
    if (index ~= 0) then
        stationConfig.otherStations[index] = {dest, name, trainCount, compID}
    else
        table.insert(stationConfig.otherStations, {dest, name, trainCount, compID})
    end
    saveConfig()
end

--What to do when a rednet message is received.
function onRednetMessage(id, msg, prot)
    --If the computer is receiving metadata from another station.
    if (prot == metadataProt or (prot == metadataRequestProt and msg ~= "REQUEST")) then
        saveStation(msg[1], msg[2], msg[3], id)
        logMsg("INFO", "Received metadata from station: "..msg[1])
        if not inPrompt then drawMonitor() end
    --If another computer has requested this computer's metadata.
    elseif (prot == metadataRequestProt and msg == "REQUEST") then
        logMsg("INFO", "Computer "..id.." has requested metadata. Transmitting.")
        rednet.send(id, {stationConfig.dest,stationConfig.name,stationConfig.trainCount}, metadataRequestProt)
    --If another computer has requested a train to be dispatched to a location.
    elseif (prot == trainDispatchProt) then
        logMsg("INFO", "Train requested at: "..msg)
        dispatchTrain(msg, 0, false)
    --If an administrator has sent a message to the station.
    elseif (prot == trainAdminProt) then
        if (msg == "UPDATE") then
            updateStationFile()
        end
    end
end

--What to do when the monitor is touched.
function onMonitorTouch(x, y)
    local stationIndex = y - 1 + stationsOffset
    local sizeX,sizeY = monitor.getSize()
    --Test first if the user clicks while a prompt is shown, then it will close that.
    if (inPrompt) then
        os.queueEvent("timer", promptTimer)
        return
    end
    --Test if the user clicked on a station's name.
    if (y > 1) then
        --Make sure that a station exists first.
        if (stationIndex <= tableSize(stationConfig.otherStations)) then
            local selectedStation = stationConfig.otherStations[stationIndex]
            --logMsg("INFO", "User selected station: "..selectedStation[1])
            dispatchTrain(selectedStation[1], selectedStation[3], true)
        end
    --The user may have clicked the help button.
    elseif (x >= sizeX-3) then
        --The user has requested help.
        prompt("To use this station, simply click on one of the station names in gray shown below, and a train will be dispatched to that destination.",
        10,
        colors.black,
        colors.white)
    end
end

--What to do when a timer completes.
function onTimerEvent(timerId)
    --If the timer for the pop-up prompt on screen goes off.
    if (timerId == promptTimer) then
        drawMonitor()
        inPrompt = false
    --Timer for checking if it's possible to dispatch a train to a requested destination.
    elseif (timerId == requestTimer) then
        scanTracks()
    end
end

--Handles all incoming events.
function eventHandler()
    local event, p1, p2, p3, p4, p5 = os.pullEvent()
    --If a redstone signal changes, then do something.
    if (event == "redstone") then
        onRedstoneEvent()
    --If the monitor is touched, pass the x and y coordinates to a function.
    elseif (event == "monitor_touch") then
        onMonitorTouch(p2, p3)
    --If a rednet message is received, pass the ID, message, and protocol to a function.
    elseif (event == "rednet_message") then
        onRednetMessage(p1, p2, p3)
    elseif (event == "timer") then
        onTimerEvent(p1)
    end
end

--Sets up the config for the first time, and returns the resulting table.
function firstTimeSetup()
    term.setTextColor(colors.lightBlue)
    logMsg("WARNING", "No config file found. Starting first-time setup...")
    local config = {
        tracks={},
        otherStations={},
    }
    term.setTextColor(colors.white)
    print("  What is the number of the monitor connected to this station?")
    config.monitor_id = "monitor_"..read()
    print("  What is the number of the note block connected to this station?")
    config.note_block_id = "note_block_"..read()
    print("  What is the cosmetic name of this station?")
    config.name = read()
    print("  What is the railcraft destination for this station?")
    config.dest = read()
    print("  How many tracks does this station have?")
    local trackCount = tonumber(read())
    for i=1,trackCount do
        config.tracks[i] = {}
        config.tracks[i][1] = false
        print("    What is track "..i.."'s dispatch decimal color code?")
        config.tracks[i][2] = tonumber(read())
        print("    What is track "..i.."'s detection decimal color code?")
        config.tracks[i][3] = tonumber(read())
    end
    local f = fs.open(configFile, "w")
    f.write(textutils.serialize(config))
    f.close()
    term.setTextColor(colors.lime)
    print("Setup is complete.")
    term.setTextColor(colors.white)
    return config
end

--Loads config from a file, or if there is none, create it from user input.
function loadConfig()
    if (not fs.exists(configFile)) then
        return firstTimeSetup()
    else
        local f = fs.open("station_config", "r")
        local config = textutils.unserialize(f.readAll())
        f.close()
        return config
    end
end

--Perform things before the program begins listening for input.
function setup()
    logMsg("INFO_HIGH", "Station Version: "..VERSION)
    stationConfig = loadConfig()
    --Setup peripherals
    rednet.open("bottom")
    ticketMachine = peripheral.wrap("back")
    noteBlock = peripheral.wrap(stationConfig.note_block_id)
    monitor = peripheral.wrap(stationConfig.monitor_id)
    --Broadcast metadata to all other stations.
    scanTracks()
    --Broadcast a request message to other stations to get their information.
    rednet.broadcast("REQUEST", metadataRequestProt)
    --Draw onto the monitor for the first time.
    drawMonitor()
end

--Main loop
setup()
while (true) do
    eventHandler()
end