CC Task Thing

-- Read map
-- Save tiles in a Cartesian plane, such that the top left corner is (0, 0).
-- Locate starting position via the 'K'
-- Walls are #
-- Whitespace is open.
-- GOAL:
--      Figure out if all spaces are accessible.
--      Pick a target, then iterate through all possible paths until
--      we find one that works, then set that tile as checked.

-- Have a base map table
-- Have a checked map table

local map           = {}
local spacesChecked = {} -- Is 2D table in which spacesChecked[y][x] is a whitespace tile that has or has not been checked.

local function loadMap(path)
    local fileHandle = fs.open(path, 'r')

    if not fileHandle then
        error("Could not open map at " .. path)
    end

    local height, width = fileHandle.readLine():match("(%d+)%s(%d+)")
    print("Map Dimensions: [w = " .. width .. ", h = " .. height .. "]")

    local spacesChecked = {}
    local map           = {}
    local line          = ""

    for y = 1, height do
        map[y] = {}
        line = fileHandle.readLine()

        for x = 1, width do
            local tile = line:sub(x, x)

            map[y][x] = tile
            if tile == " " then
                if not spacesChecked[y] then
                    spacesChecked[y] = {}
                end

                spacesChecked[y][x] = { checked = false, accessible = false }
            elseif tile == "K" then
                map.start = { x = x, y = y }
            end
        end
    end

    return map, spacesChecked
end

local function printMap(map, spacesChecked)
    for y, line in ipairs(map) do
        for x, char in ipairs(line) do
            if spacesChecked[y] and spacesChecked[y][x] then
                write(".")
            else
                write(char)
            end
        end
        print("")
    end
end

local function distanceTo(fromX, fromY, x, y)
    return math.sqrt((x - fromX)^2 + (y - fromY)^2)
end

local function getSurroundingFreeSpace(map, x, y, destX, destY)
    local freeSpace = {}

    for _y = y - 1, y + 1 do
        for _x = x - 1, x + 1 do
            if not (_x == x and _y == y) and map[_y][_x] == " " then
                table.insert(freeSpace, { x = _x, y = _y, d = distanceTo(_x, _y, destX, destY) })
            end
        end
    end

    return freeSpace
end

local function getTrueSize(_table)
    local size = 0

    for _, __ in pairs(_table) do
        size = size + 1
    end

    return size
end

local function isSpaceAccessible(map, fromX, fromY, spaceX, spaceY)
    if fromX == spaceX and fromY == spaceY then
        return true
    end

    -- Gather surrounding free-space.
    local freeSpace = getSurroundingFreeSpace(map, fromX, fromY, spaceX, spaceY)

    -- Select the space which will get us closest to the space.
    if getTrueSize(freeSpace) < 1 then
        error("Trapped at " .. fromX .. ", " .. fromY)
    end

    local closestSpace = freeSpace[1]
    for _, space in ipairs(freeSpace) do
        if space.d < closestSpace.d then
            closestSpace = space
        end
    end

    print("Destination: (" .. spaceX .. ", " .. spaceY .. ")\n     (" .. fromX .. ", " .. fromY .. "; " .. distanceTo(fromX, fromY, spaceX, spaceY) .. ") -> (" .. closestSpace.x .. ", " .. closestSpace.y .. "; " .. closestSpace.d .. ")")

    -- Shouldn't this prevent getting stuck?
    if distanceTo(fromX, fromY, spaceX, spaceY) <= closestSpace.d then
        return false
    end

    -- Shit's gonna get stuck going back and forth between two spaces.
    return isSpaceAccessible(map, closestSpace.x, closestSpace.y, spaceX, spaceY)
end

map, spacesChecked = loadMap("/map")

local function checkSpaces(map, spacesChecked)
    for y, set in pairs(spacesChecked) do
        for x, space in pairs(set) do
            space.checked = true
            space.accessible = isSpaceAccessible(map, map.start.x, map.start.y, x, y)
        end
    end
end

printMap(map, spacesChecked)
checkSpaces(map, spacesChecked)
for y, set in pairs(spacesChecked) do
    for x, space in pairs(set) do
        print("[" .. x .. ", " .. y .. "] = Checked: " .. tostring(space.checked) .. "; Accessible: " .. tostring(space.accessible))
        sleep(0.05)
    end
end