ccLightSim

--[[ This program is a simple simulation of light.
     It's not supposed to have a special purpose.
     It was made for other people to use in their programs. ]]

os.unloadAPI(shell.resolveProgram("redirect"))
os.loadAPI(shell.resolveProgram("redirect"))

local map = {{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},{1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}}

local scrWidth,scrHeight = term.getSize()
local buffer = redirect.createRedirectBuffer(scrWidth, scrHeight)

local args = { ... }

if #args >= 1 then
    local mapFile = args[1]

    if fs.exists(mapFile) then
        map = paintutils.loadImage(shell.resolve(mapFile))
    end

    for y=1,#map do
        for x=1,#map[y] do
            if map[y][x] == colours.black or map[y][x] == 0 then
                map[y][x] = 0
            elseif map[y][x] == colours.white then
                map[y][x] = 1
            elseif map[y][x] == colours.purple then
                map[y][x] = 2
            end
        end
    end
end

local function canMoveTo(x, y)
    if x > #map[1] or x < 1 or y > #map or y < 1 then return false end
    return map[y][x] == 0
end

local function isReflective(x, y)
    return (not canMoveTo(x, y)) and map[y][x] == 2
end

local function swap(a, b)
    local temp = b
    b = a
    a = temp
    return a, b
end

--[[ A modified version of paintutils's drawLine. ]]
local function line(startX, startY, endX, endY)
    local points = {}

    startX = math.floor(startX)
    startY = math.floor(startY)
    endX = math.floor(endX)
    endY = math.floor(endY)

    if startX == endX and startY == endY then
        points[#points + 1] = { posX = startX, posY = startY }
        return points
    end

    local minX = math.min(startX, endX)
    local minY, maxX, maxY

    if minX == startX then
        minY = startY
        maxX = endX
        maxY = endY
    else
        minY = endY
        maxX = startX
        maxY = startY
    end

    local xDiff = maxX - minX
    local yDiff = maxY - minY

    if xDiff > math.abs(yDiff) then
        local y = minY
        local dy = yDiff / xDiff

        for x=minX,maxX do
            points[#points + 1] = { posX = x, posY = math.floor(y + 0.5) }
            y = y + dy
        end
    else
        local x = minX
        local dx = xDiff / yDiff

        if maxY >= minY then
            for y=minY, maxY do
                points[#points + 1] = { posX = math.floor(x + 0.5), posY = y }
                x = x + dx
            end
        else
            for y=minY,maxY,-1 do
                points[#points + 1] = { posX = math.floor(x + 0.5), posY = y }
                x = x - dx
            end
        end
    end

    return points
end

local lineBuffer = {}

local function addToLineBuffer(pt)
    if pt == nil or pt.x0 == nil or pt.x1 == nil or
        pt.y0 == nil or pt.y1 == nil then return end

    for _,v in ipairs(lineBuffer) do
        if v.x0 == pt.x0 and v.y0 == pt.y0 and
            v.x1 == pt.x1 and v.y1 == pt.y1 then
            return
        end
    end

    lineBuffer[#lineBuffer + 1] = pt
end

local function calculateDirectionalAngles(x, y, dirX, dirY, coneAngle)
    local angle = math.deg(math.atan2(dirY - y, dirX - x))
    local startAngle = angle - coneAngle / 2
    local endAngle = angle + coneAngle / 2
    return startAngle, endAngle
end

--[[

WIP!
function reflect(x, y, angle, length)
    local refAngle = 0

    if (angle <= 90 and angle > -90) or (angle <= 360 and angle > 270) then
        refAngle = angle - 90
    elseif (angle <= 180 and angle > 90) or (angle <= 270 and angle > 180) then
        refAngle = angle + 90
    end

    local _x0, _y0, _x1, _y1 = calculateLightRay(x, y, refAngle, length, true)
    addToLineBuffer({ x0 = _x0, y0 = _y0, x1 = _x1, y1 = _y1 })
end

]]

function calculateLightRay(x, y, angle, length, fromReflect)
    if fromReflect == nil then fromReflect = false end

    local tx = x + math.cos(math.rad(angle)) * length
    local ty = y + math.sin(math.rad(angle)) * length

    local pts = line(x, y, tx, ty)

    if angle == 0 then return nil end

    if (angle > -89 and angle <= 90) or angle > 270 then
        for i=1,#pts do
            if i + 1 < #pts and not canMoveTo(pts[i + 1].posX, pts[i + 1].posY) then
                --[[if (not fromReflect) and isReflective(pts[i + 1].posX, pts[i + 1].posY) then
                    reflect(pts[i].posX, pts[i].posY, angle, length)
                end]]
                return x, y, pts[i].posX, pts[i].posY
            end
        end
    end

    if (angle < 270 and angle > 90) or angle < -90 then
        for i=#pts,1,-1 do
            if i - 1 > 0 and not canMoveTo(pts[i - 1].posX, pts[i - 1].posY) then
                --[[if (not fromReflect) and isReflective(pts[i - 1].posX, pts[i - 1].posY) then
                    reflect(pts[i].posX, pts[i].posY, angle, length)
                end]]
                return pts[i].posX, pts[i].posY, x, y
            end
        end
    end

    return nil
end

local pointAt = { x = 0, y = 0 }
local lightStartAngle = 0
local lightEndAngle = 360
local lightConeSize = 90

local player = {
    x = 7,
    y = 2,
}

local function drawPixel(x, y, colour)
    buffer.setCursorPos(x, y)
    buffer.setBackgroundColour(colour)
    buffer.write(" ")
end

local function drawLine(x0, y0, x1, y1, colour)
    local ln = line(x0, y0, x1, y1, colour)
    for _,v in ipairs(ln) do
        drawPixel(v.posX, v.posY, colour)
    end
end

local function hasBeenPlaced(t, pt)
    for _,v in ipairs(t) do
        if v.posX == pt.posX and v.posY == pt.posY then
            return true
        end
    end

    return false
end

local function hasBeenPlacedC(t, x, y)
    return hasBeenPlaced(t, { posX = x, posY = y })
end

local function renderLineBuffer()
    for _,v in ipairs(lineBuffer) do
        if v.x0 ~= nil then
            drawLine(v.x0, v.y0, v.x1, v.y1, colours.yellow)
        end
    end
end

local function clearLineBuffer()
    lineBuffer = {}
end

local function render()
    buffer.setBackgroundColour(colours.grey)
    buffer.clear()

    clearLineBuffer()

    for i=lightStartAngle,lightEndAngle do
        local _x0, _y0, _x1, _y1 = calculateLightRay(player.x, player.y, i, #map[1] + 1)
        addToLineBuffer({ x0 = _x0, y0 = _y0, x1 = _x1, y1 = _y1 })
    end

    renderLineBuffer()

    for y=1,#map do
        for x=1,#map[y] do
            if map[y][x] == 1 then
                drawPixel(x, y, colours.white)
            elseif map[y][x] == 2 then
                drawPixel(x, y, colours.purple)
            end
        end
    end

    if pointAt.x > 0 and pointAt.y > 0 and pointAt.x <= scrWidth and pointAt.y <= scrHeight then
        drawPixel(pointAt.x, pointAt.y, colours.green)
    end

    buffer.setBackgroundColour(colours.grey)
    buffer.setTextColour(colours.white)
    buffer.setCursorPos(1, scrHeight - 2)
    buffer.write("Q: Quit")
    buffer.setCursorPos(1, scrHeight - 1)
    buffer.write("Arrow keys: Move light; Cone size: " .. lightConeSize .. "deg (+/-)")
    buffer.setCursorPos(1, scrHeight)
    buffer.write("Middle Mouse: Point to click pos.; R: Reset")

    drawPixel(player.x, player.y, colours.orange)

    buffer.blit(1, 1, 1, 1, scrWidth, scrHeight)
end

local function update(e, p1, p2, p3, p4, p5)
    if e == "key" then
        if p1 == keys.right and canMoveTo(player.x + 1, player.y) then
            player.x = player.x  + 1
        end

        if p1 == keys.left and canMoveTo(player.x - 1, player.y) then
            player.x = player.x - 1
        end

        if p1 == keys.up and canMoveTo(player.x, player.y - 1) then
            player.y = player.y - 1
        end

        if p1 == keys.down and canMoveTo(player.x, player.y + 1) then
            player.y = player.y + 1
        end
    end

    if e == "char" then
        if p1 == 'q' then
            return false
        end

        if p1 == 'r' then
            pointAt.x = 0
            pointAt.y = 0
        end

        if p1 == 'f' then
            fancyGraphics = not fancyGraphics
        end

        if p1 == '+' then
            lightConeSize = lightConeSize + 10

            if lightConeSize >= 360 then
                lightConeSize = 360
                pointAt.x = 0
                pointAt.y = 0
            end
        end

        if p1 == '-' then
            lightConeSize = lightConeSize - 10

            if lightConeSize < 10 then
                lightConeSize = 10
            end
        end
    end

    if e == "mouse_click" then
        if p1 == 3 then
            pointAt.x = p2
            pointAt.y = p3
        end
    end

    if pointAt.x ~= 0 and pointAt.y ~= 0 then
        lightStartAngle, lightEndAngle = calculateDirectionalAngles(player.x, player.y, pointAt.x, pointAt.y, lightConeSize)
    else
        lightStartAngle = 0
        lightEndAngle = 360
    end

    render()
    return true
end

update("init")
while update(os.pullEvent()) do end

term.setBackgroundColour(colours.black)
term.clear()
term.setCursorPos(1, 1)

os.unloadAPI(shell.resolveProgram("redirect"))