ag.import("std")

td = {mx = 0, my = 0, picking = false, pick_x = 0, pick_y = 0}

function init_event()
    ground = std.createPlanePointNormal(0, 0, 0, 0, 0, 1)
    ground:setColor(0, 1, 0)

    grid_texture = ag.loadTexture("grid.png")

    grid = ag.createQuad(0, 0, 0, 8, 0, 0, 0, 8, 0)
    grid:setTexture(grid_texture)
    grid:setOffset(1)

    grid_selector = ag.createQuad(0, 0, 0, 0.5, 0, 0, 0, 0.5, 0)
    grid_selector:setVisible(false)
    grid_selector:setColor(0, 0, 1, 0.5)
    grid_selector:setBlending(true)
    grid_selector:setOffset(2)

    ag.setCamera(2, -12, 10)

    ag.setCursorVisible(true)
end

function key_down_event(k)
    if (k == "q") then
        ag.exit()
    end
end

function update_event()
    hit = ag.pickOne(td.mx, td.my, ground)
    if (hit) then
        local px = ground.pick_pos[1]
        local py = ground.pick_pos[2]
        local x_coord = math.floor(px + 8)
        local y_coord = math.floor(py + 8)
        td.picking = (x_coord >= 0 and x_coord <= 15 and y_coord >= 0 and y_coord <= 15)
        if (td.picking) then
            grid_selector:setPosition(x_coord - 7.5, y_coord - 7.5, 0)
            td.pick_x = x_coord
            td.pick_y = y_coord
        end
    end
    grid_selector:setVisible(td.picking)
end

function mouse_motion_event(x, y)
    td.mx = x
    td.my = y
end

function mousebutton_down_event(button, x, y)
    if (button == 1) then
        if td.picking then
            local s = ag.createSphere(0.48)
            s:setColor(math.random(), math.random(), math.random())
            s:setPosition(td.pick_x - 7.5, td.pick_y - 7.5, 0.6)
        end
    end
end