-- Learn to Program with Singe -- Lesson 7: A Game

dofile("Singe/Framework.singe")

local PLAYER_WIDTH  = 40
local PLAYER_HEIGHT = 8
local PLAYER_SPEED  = 4
local PLAYER_MARGIN = 4
local BLOCK_SIZE    = 12
local BLOCK_SPEED   = 1.5
local BLOCK_FASTER  = 0.05
local SPAWN_FRAMES  = 40
local START_LIVES   = 3
local TEXT_COLUMNS  = overlayGetWidth() // overlayGetFontWidth()

local screenWidth  = overlayGetWidth()
local screenHeight = overlayGetHeight()
local playerY      = screenHeight - PLAYER_HEIGHT - PLAYER_MARGIN

local playerX    = (screenWidth - PLAYER_WIDTH) / 2
local goingLeft  = false
local goingRight = false
local blocks     = {}
local blockSpeed = BLOCK_SPEED
local spawnTimer = 0
local score      = 0
local lives      = START_LIVES
local state      = "waiting"


function drawGame()
    colorForeground(80, 255, 160)
    overlayBox(playerX, playerY, playerX + PLAYER_WIDTH - 1, playerY + PLAYER_HEIGHT - 1)
    colorForeground(255, 90, 90)
    for i, block in ipairs(blocks) do
        overlayBox(block.x, block.y, block.x + BLOCK_SIZE - 1, block.y + BLOCK_SIZE - 1)
    end
    overlayPrint(1, 1, "SCORE " .. score .. "    LIVES " .. lives)
end


function drawOverText()
    printCentered(7, "GAME OVER")
    printCentered(9, "PRESS SPACE TO PLAY AGAIN")
end


function drawWaitingText()
    printCentered(6, "DODGE THE BLOCKS")
    printCentered(8, "ARROW KEYS TO MOVE")
    printCentered(10, "PRESS SPACE TO START")
end


function printCentered(row, text)
    overlayPrint(math.floor((TEXT_COLUMNS - #text) / 2), row, text)
end


function spawnBlock()
    local block = {}
    block.x = math.random(0, screenWidth - BLOCK_SIZE)
    block.y = -BLOCK_SIZE
    table.insert(blocks, block)
end


function startGame()
    playerX    = (screenWidth - PLAYER_WIDTH) / 2
    blocks     = {}
    blockSpeed = BLOCK_SPEED
    spawnTimer = 0
    score      = 0
    lives      = START_LIVES
    state      = "playing"
end


function updatePlaying()
    if goingLeft then
        playerX = playerX - PLAYER_SPEED
    end
    if goingRight then
        playerX = playerX + PLAYER_SPEED
    end
    if playerX < 0 then
        playerX = 0
    elseif playerX > screenWidth - PLAYER_WIDTH then
        playerX = screenWidth - PLAYER_WIDTH
    end

    spawnTimer = spawnTimer - 1
    if spawnTimer <= 0 then
        spawnBlock()
        spawnTimer = SPAWN_FRAMES
    end

    for i = #blocks, 1, -1 do
        local block = blocks[i]
        block.y = block.y + blockSpeed
        if collideRects(block.x, block.y, BLOCK_SIZE, BLOCK_SIZE, playerX, playerY, PLAYER_WIDTH, PLAYER_HEIGHT) then
            table.remove(blocks, i)
            lives = lives - 1
            if lives == 0 then
                state = "over"
            end
        elseif block.y > screenHeight then
            table.remove(blocks, i)
            score      = score + 1
            blockSpeed = blockSpeed + BLOCK_FASTER
        end
    end
end


function onInputPressed(what)
    if what == SWITCH_LEFT then
        goingLeft = true
    elseif what == SWITCH_RIGHT then
        goingRight = true
    elseif what == SWITCH_BUTTON1 and state ~= "playing" then
        startGame()
    end
end


function onInputReleased(what)
    if what == SWITCH_LEFT then
        goingLeft = false
    elseif what == SWITCH_RIGHT then
        goingRight = false
    end
end


function onOverlayUpdate()
    if state == "playing" then
        updatePlaying()
    end

    overlayClear()
    drawGame()
    if state == "waiting" then
        drawWaitingText()
    elseif state == "over" then
        drawOverText()
    end

    return OVERLAY_UPDATED
end