local modem = peripheral.wrap("top")
local rChan = 7321
local sChan = 7322
local map = {}
local dir = 0
local location = {x = 0, y = 0}
local w, h = term.getSize()
local running = true

term.clear()

local charPos = {
    x = math.floor(w/2),
    y = math.floor(h/2)
}

if modem.isWireless() == false then
    printError("A wireless modem is required.")
    return
end

if not term.isColor() then
    printError("A terminal supporting color is required.")
    return
end

modem.open(rChan)

local tDirs = {
    [0] = '^',
    [1] = '>',
    [2] = 'V',
    [3] = '<'
}

local invColorMappings = {
    [1] = colors.red,
    [2] = colors.green,
    [3] = colors.yellow,
    [4] = colors.blue,
    [5] = colors.magenta,
    [6] = colors.cyan,
    [7] = colors.pink,
    [8] = colors.lime
}

-- TODO: Handle messages that are too long with -- More --
local function displayMessage(msg)
    term.setCursorPos(1, 1)
    term.clearLine()
    write(msg)
end

local function updateMap(x, y)
    local sY = location.y - charPos.y + 2
    local eY = location.y + (h - charPos.y)
    local sX = location.x - charPos.x + 1
    local eX = location.x + (w - charPos.x)

    term.setCursorPos(1, 2)
    for i=sY,eY do
        if map[i] ~= nil then
            for j=sX,eX do
                if map[i][j] == nil then
                    term.write(" ")
                else
                    local c = map[i][j]
                    if c == -1 then
                        term.setBackgroundColour(colors.black)
                        term.setTextColor(colors.lightGray)
                        term.write('.')
                    elseif c == 0 then
                        term.setBackgroundColor(colors.lightGray)
                        term.write(' ')
                    else
                        term.setBackgroundColor(invColorMappings[c - 8])
                        term.write(' ')
                    end
                end
                term.setBackgroundColor(colors.black)
                term.setTextColor(colors.white)
            end
        else
            term.clearLine()
        end
        local tw, th = term.getCursorPos()
        term.setCursorPos(1, th + 1)
    end
end

local function updateChar()
    term.setCursorPos(charPos.x, charPos.y)
    term.write(tDirs[dir])
end

local function split(str)
    local ret = {}
    for i in string.gmatch(str, "%S+") do
        table.insert(ret, i)
    end
    return ret
end

local function getTarget()
    local d = {
        [0] = { 0, -1},
        [1] = { 1, 0},
        [2] = { 0, 1},
        [3] = { -1, 0}
    }

    return location.x + d[dir][1], location.y + d[dir][2]
end

local function getBlock(x, y)
    if map[y] == nil or map[y][x] == nil then
        return -2
    end
    return map[y][x]
end

local function setBlock(x, y, type)
    if map[y] == nil then map[y] = {} end
    map[y][x] = tonumber(type)
end

local function updateMapAndChar()
    updateMap()
    updateChar()
end

updateMap()
updateChar()

local function displayChoices(msg, options)
    displayMessage(msg)
    write(" (")
    for _, v in pairs(options) do
        write(v)
    end
    write(") ")
end

local function doItemSelection(msg, options)
    while true do
        displayChoices(msg, options)
        term.setCursorBlink(true)
        local ev, char = os.pullEvent("char")
        term.setCursorBlink(false)
        if ev == "char" then
            if char == "q" then
                displayMessage("Never mind.")
                return false
            end
            for _, v in pairs(options) do
                if v == char then
                    term.setCursorPos(1, 1)
                    term.clearLine()
                    return char
                end
            end
            displayMessage("Unknown choice.")
            sleep(1)
        end
    end
end

local function confirm(msg, allowQuit)
    -- FIXME: allowQuit does nothing right now.
    while true do
        displayMessage(msg)
        write(" [yn] ")

        term.setCursorBlink(true)
        local ev, char = os.pullEvent("char")
        term.setCursorBlink(false)
        if char == 'y' then
            return true
        elseif char == 'n' then
            return false
        else
            displayMessage("Unknown option.")
            sleep(1)
        end
    end
end

local commands = {
    right = function()
        dir = dir + 1
        if dir == 4 then dir = 0 end
        updateChar()
    end,
    left = function()
        dir = dir - 1
        if dir == -1 then dir = 3 end
        updateChar()
    end,
    forward = function()
        local tx, ty = getTarget()
        location.x = tx
        location.y = ty
        updateMapAndChar()
    end,
    block = function(args)
        local facingX, facingY = getTarget()
        local there = tonumber(args[2])
        local blockThere = getBlock(facingX, facingY)
        if there ~= -1 and blockThere < 0 then
            setBlock(facingX, facingY, there)
        elseif there == -1 then
            setBlock(facingX, facingY, -1)
        end
        updateMap()
        updateChar()
    end,
    iblock = function(args)
        local facingX, facingY = getTarget()
        local there = tonumber(args[2])
        if there ~= -1 then
            setBlock(facingX, facingY, there)
        else
            setBlock(facingX, facingY, -1)
        end
        updateMap()
        updateChar()
    end,
    mine = function(args)
        displayMessage("Put in #" .. args[2] .. " (Has " .. args[3] .. " blocks).")
    end,
    cantmine = function(args)
        displayMessage("Unable to mine.")
    end,
    nospace = function()
        displayMessage("No remaining inventory space.")
    end,
    emptyslot = function()
        displayMessage("No items in slot.")
    end,
    cantplace = function()
        displayMessage("Can't place this here.")
    end
}

local keyHandlers = {
    h = 'left',
    j = 'down',
    k = 'up',
    l = 'right',
    s = 'search',
    S = 'isearch',
    a = 'mine',
    p = function()
        local choice = doItemSelection("Place what?", {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'})
        if choice == false then
            return
        end
        local choices = {a = 9, b = 10, c = 11, d = 12, e = 13, f = 14, g = 15, h = 16}
        choice = choices[choice]
        modem.transmit(sChan, rChan, "place " .. choice)
    end,
    q = function()
        local choice = confirm("Really quit", false)
        if choice == true then
            running = false
            term.clear()
            term.setCursorPos(1, 1)
        end
    end
}

while running do
    local ev, modemSide, channel, replyChannel, message, senderDistance = os.pullEvent()
    if ev == 'modem_message' then
        local smsg = split(message)
        if commands[smsg[1]] ~= nil then
            commands[smsg[1]](smsg)
        end
    elseif ev == 'char' then
        term.setCursorPos(1, 1)
        term.clearLine()
        local key = modemSide
        if keyHandlers[key] ~= nil then
            if type(keyHandlers[key]) == 'function' then
                keyHandlers[key]()
            else
                modem.transmit(sChan, rChan, keyHandlers[key])
            end
        end
    end
end