const std = @import("std");
const drm = @import("drm/card.zig");

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    const allocator = gpa.allocator();

    var card = try drm.Card.open("card0", allocator);
    defer card.close();

    var resources = try card.resources();
    defer resources.deinit();

    var connector = try card.connector(resources.connector_ids[0]);
    defer connector.deinit();

    std.debug.print("connector = {}\n", .{ connector.id });

    const mode = connector.modes[0];

    std.debug.print("mode = {s}@{d}Hz\n", .{ mode.name, mode.frame_rate() });

    var crtc = try crtc: {
        for (connector.encoder_ids) |encoder_id| {
            var encoder = try card.encoder(encoder_id);
            defer encoder.deinit();

            for (resources.crtc_ids, 0..) |crtc_id, index| {
                if ((encoder.possible_crtcs & (@as(u32, 1) << @intCast(index))) != 0) {
                    break :crtc card.crtc(crtc_id);
                }
            }
        }

        break :crtc error.CrtcNotFound;
    };
    defer crtc.detach();

    std.debug.print("crtc = {}\n", .{ crtc.id });

    var framebuffer = try card.create_frame_buffer(mode.horizontal.size, mode.vertical.size, 32);
    defer framebuffer.deinit();

    std.debug.print("framebuffer = {}, {}\n", .{ framebuffer.id, framebuffer.canvas_size });

    try crtc.attach(&framebuffer, &connector, mode);

    var frame: u24 = 0;

    while (true) {
        for (0..framebuffer.width) |x| {
            for (0..framebuffer.height) |y| {
                const raster_x = (frame + x) / 100 * 100;
                const raster_y = y / 100 * 100;
                const color = ((raster_x + raster_y) + 0x129453) * 0x329120;
                framebuffer.set(@intCast(x), @intCast(y), .{
                    .red = @intCast(color & 0xff),
                    .green = @intCast((color >> 8) & 0xff),
                    .blue = @intCast((color >> 16) & 0xff),
                });
            }
        }

        frame, _ = @addWithOverflow(frame, 1);

        try crtc.attach(&framebuffer, &connector, mode);

        std.time.sleep(@intFromFloat(1000000000 / mode.frame_rate()));
    }

    while (true) { std.time.sleep(5000000000); }
}