function push_point_xy(s, x, y) {
    ser_f32(s, x);
    ser_f32(s, y);
}

function push_point_xyzrgb(s, x, y, z, r, g, b) {
    ser_f32(s, x);
    ser_f32(s, y);
    ser_f32(s, z);
    ser_u8(s, r);
    ser_u8(s, g);
    ser_u8(s, b);
    ser_align(s, 4);
}

function push_quad_xyzrgb(s, p1x, p1y, p4x, p4y, z, r, g, b) {
    push_point_xyzrgb(s, p1x, p1y, z, r, g, b);
    push_point_xyzrgb(s, p4x, p1y, z, r, g, b);
    push_point_xyzrgb(s, p1x, p4y, z, r, g, b);

    push_point_xyzrgb(s, p4x, p4y, z, r, g, b);
    push_point_xyzrgb(s, p1x, p4y, z, r, g, b);
    push_point_xyzrgb(s, p4x, p1y, z, r, g, b);
}

function push_stroke(context, stroke) {
    const stroke_width = stroke.width;
    const points = stroke.points;
    const color_u32 = stroke.color;

    const r = (color_u32 >> 16) & 0xFF;
    const g = (color_u32 >> 8) & 0xFF;
    const b = color_u32 & 0xFF;

    if (points.length === 0) {
        return;
    }

    const points_from = context.point_serializer.offset / (4 * 2); // 4 is sizeof(f32) btw, just sain'
    const points_to = points_from + points.length;

    ser_u32(context.index_serializer, points_from);
    ser_u32(context.index_serializer, points_to);

    let min_x, min_y, max_x, max_y;

    min_x = Math.floor(points[0].x - stroke_width / 2);
    max_x = Math.ceil(points[0].x + stroke_width / 2);

    min_y = Math.floor(points[0].y - stroke_width / 2);
    max_y = Math.ceil(points[0].y + stroke_width / 2);

    for (const p of points) {
        min_x = Math.min(min_x, Math.floor(p.x - stroke_width / 2));
        min_y = Math.min(min_y, Math.floor(p.y - stroke_width / 2));
        max_x = Math.max(max_x, Math.ceil(p.x + stroke_width / 2));
        max_y = Math.max(max_y, Math.ceil(p.y + stroke_width / 2));
        push_point_xy(context.point_serializer, p.x, p.y);
    }

    push_quad_xyzrgb(context.quad_serializer, min_x, min_y, max_x, max_y, stroke_width / 2, r, g, b);
}

function geometry_prepare_stroke(state) {
    if (!state.online) {
        return null;
    }

    return {
        'color': state.players[state.me].color,
        'width': state.players[state.me].width,
        'points': process_stroke(state, state.players[state.me].points),
        'user_id': state.me,
    };
}

function geometry_add_stroke(state, context, stroke) {
    if (!state.online || !stroke) return;

    const bytes_left = context.point_serializer.size - context.point_serializer.offset;
    const bytes_needed = stroke.points.length * config.bytes_per_point;

    if (bytes_left < bytes_needed) {
        const extend_points_by = Math.ceil((context.point_serializer.size + bytes_needed) * 1.62);
        const extend_indices_by = Math.ceil((context.index_serializer.size + stroke.points.length * 4 * 2) * 1.62); 
        const extend_quads_by = Math.ceil((context.quad_serializer.size + 6 * (4 * 3)) * 1.62);

        context.point_serializer = ser_extend(context.point_serializer, extend_points_by);
        context.index_serializer = ser_extend(context.index_serializer, extend_indices_by);
        context.quad_serializer = ser_extend(context.quad_serializer, extend_quads_by);
    }

    push_stroke(context, stroke);
}

function geometry_delete_stroke(state, context, stroke_index) {
    // NEXT: deleted wrong stroke
    let offset = 0;

    for (let i = 0; i < stroke_index; ++i) {
        const event = state.events[i];
        
        if (event.type === EVENT.STROKE) {
            offset += (event.points.length * 12 + 6) * config.bytes_per_point;
        }   
    }

    const stroke = state.events[stroke_index];

    for (let i = 0; i < stroke.points.length * 12 + 6; ++i) {
        context.static_stroke_serializer.view.setUint8(offset + config.bytes_per_point - 1, 125);
        offset += config.bytes_per_point;
    }
}

function recompute_dynamic_data(state, context) {
    // let bytes_needed = 0;

    // for (const player_id in state.players) {
    //     const player = state.players[player_id];
    //     if (player.points.length > 0) {
    //         bytes_needed += player.points.length * config.bytes_per_point;
    //     }
    // }

    // if (bytes_needed > context.dynamic_stroke_serializer.size) {
    //     context.dynamic_stroke_serializer = serializer_create(Math.ceil(bytes_needed * 1.62));
    // } else {
    //     context.dynamic_stroke_serializer.offset = 0;
    // }

    // for (const player_id in state.players) {
    //     // player has the same data as their current stroke: points, color, width
    //     const player = state.players[player_id];
    //     if (player.points.length > 0) {
    //         push_stroke(context.dynamic_stroke_serializer, player);
    //     }
    // }
}

function geometry_add_point(state, context, player_id, point) {
    if (!state.online) return;
    state.players[player_id].points.push(point);
    recompute_dynamic_data(state, context);
}

function geometry_clear_player(state, context, player_id) {
    if (!state.online) return;
    state.players[player_id].points.length = 0;
    recompute_dynamic_data(state, context);
}

function add_image(context, image_id, bitmap, p) {
    const x = p.x;
    const y = p.y;
    const gl = context.gl;
    const id = Object.keys(context.textures['image']).length;

    context.textures['image'][id] = {
        'texture': gl.createTexture(),
        'image_id': image_id
    };

    gl.bindTexture(gl.TEXTURE_2D, context.textures[id].texture);
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, bitmap);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);

    context.quad_positions.push(...[
        x,                 y,
        x,                 y + bitmap.height,
        x + bitmap.width,  y + bitmap.height,

        x + bitmap.width,  y,
        x,                 y,
        x + bitmap.width,  y + bitmap.height,
    ]);

    context.quad_texcoords.push(...[
        0, 0,
        0, 1,
        1, 1,
        1, 0,
        0, 0,
        1, 1,
    ]);

    context.quad_positions_f32 = new Float32Array(context.quad_positions);
    context.quad_texcoords_f32 = new Float32Array(context.quad_texcoords);
}

function move_image(context, image_event) {
    const x = image_event.x;
    const y = image_event.y;

    const count = Object.keys(context.textures['image']).length;

    for (let id = 0; id < count; ++id) {
        const image = context.textures['image'][id];
        if (image.image_id === image_event.image_id) {
            context.quad_positions[id * 12 + 0] = x;
            context.quad_positions[id * 12 + 1] = y;
            context.quad_positions[id * 12 + 2] = x;
            context.quad_positions[id * 12 + 3] = y + image_event.height;
            context.quad_positions[id * 12 + 4] = x + image_event.width;
            context.quad_positions[id * 12 + 5] = y + image_event.height;

            context.quad_positions[id * 12 + 6] = x + image_event.width;
            context.quad_positions[id * 12 + 7] = y;
            context.quad_positions[id * 12 + 8] = x;
            context.quad_positions[id * 12 + 9] = y;
            context.quad_positions[id * 12 + 10] = x + image_event.width;
            context.quad_positions[id * 12 + 11] = y + image_event.height;

            context.quad_positions_f32 = new Float32Array(context.quad_positions);

            break;
        }
    }
}

function image_at(state, x, y) {
    for (let i = state.events.length - 1; i >= 0; --i) {
        const event = state.events[i];
        if (event.type === EVENT.IMAGE && !event.deleted) {
            if ('height' in event && 'width' in event) {
                if (event.x <= x && x <= event.x + event.width && event.y <= y && y <= event.y + event.height) {
                    return event;
                }
            }
        }
    }

    return null;
}