import gg
import time

const pwidth = 800

const pheight = 600

const pbytes = 4

struct AppState {
mut:
    gg          &gg.Context = unsafe { nil }
    istream_idx int
    pixels      [pheight][pwidth]u32
}

[direct_array_access]
fn (mut state AppState) update() {
    mut rcolor := u64(state.gg.frame)
    for {
        for y in 0 .. pheight {
            for x in 0 .. pwidth {
                rcolor = rcolor * 1664525 + 1013904223
                state.pixels[y][x] = u32(rcolor & 0x0000_0000_FFFF_FFFF) | 0x1010AFFF
            }
        }
        time.sleep(33 * time.millisecond)
    }
}

fn (mut state AppState) draw() {
    mut istream_image := state.gg.get_cached_image_by_idx(state.istream_idx)
    istream_image.update_pixel_data(unsafe { &u8(&state.pixels) })
    size := gg.window_size()
    state.gg.draw_image(0, 0, size.width, size.height, istream_image)
}

// gg callbacks:

fn graphics_init(mut state AppState) {
    state.istream_idx = state.gg.new_streaming_image(pwidth, pheight, pbytes, pixel_format: .rgba8)
}

fn graphics_frame(mut state AppState) {
    state.gg.begin()
    state.draw()
    state.gg.end()
}

fn main() {
    mut state := &AppState{}
    state.gg = gg.new_context(
        width: 800
        height: 600
        create_window: true
        window_title: 'Random Static'
        init_fn: graphics_init
        frame_fn: graphics_frame
        user_data: state
    )
    spawn state.update()
    state.gg.run()
}