import { EVENT } from './enums';

export function create(size) {
    const buffer = new ArrayBuffer(size);
    return {
        'offset': 0,
        'size': size,
        'buffer': buffer,
        'view': new DataView(buffer),
        'strview': new Uint8Array(buffer),
    };
}

export function u8(s, value) {
    s.view.setUint8(s.offset, value);
    s.offset += 1;
}

export function u16(s, value) {
    s.view.setUint16(s.offset, value, true);
    s.offset += 2;
}

export function f32(s, value) {
    s.view.setFloat32(s.offset, value, true);
    s.offset += 4;
}

export function u32(s, value) {
    s.view.setUint32(s.offset, value, true);
    s.offset += 4;
}

export function s32(s, value) {
    s.view.setInt32(s.offset, value, true);
    s.offset += 4;
}

export function bytes(s, bytes) {
    s.strview.set(new Uint8Array(bytes.buffer, bytes.byteOffset, bytes.byteLength), s.offset);
    s.offset += bytes.byteLength;
}

export function align(s, to) {
    // TODO: non-stupid version of this
    while (s.offset % to != 0) {
        s.offset++;
    }
}

export function event(s, event) {
    u32(s, event.type); // for alignment reasons
    u32(s, event.user_id);

    switch (event.type) {
        case EVENT.PREDRAW: {
            f32(s, event.x);
            f32(s, event.y);
            break;
        }

        case EVENT.MOVE_CURSOR: {
            f32(s, event.x);
            f32(s, event.y);
            break;
        }

        case EVENT.MOVE_CANVAS: {
            u32(s, event.offset_x);
            u32(s, event.offset_y);
            s32(s, event.zoom_level);
            break;
        }

        case EVENT.ZOOM_CANVAS: {
            s32(s, event.zoom_level);
            f32(s, event.zoom_cx);
            f32(s, event.zoom_cy);
            break;
        }

        case EVENT.USER_JOINED:
        case EVENT.LEAVE:
        case EVENT.CLEAR: {
            break;
        }

        case EVENT.SET_COLOR: {
            u32(s, event.color);
            break;
        }

        case EVENT.SET_WIDTH: {
            u16(s, event.width);
            break;
        }

        case EVENT.STROKE: {
            const points_bytes = event.points;
            const pressures_bytes = event.pressures;
            u32(s, event.stroke_id);
            u16(s, points_bytes.byteLength / 2 / 4); // each point is 2 * f32
            u16(s, event.width);
            u32(s, event.color);
            bytes(s, points_bytes);
            bytes(s, pressures_bytes);
            align(s, 4);
            break;
        }

        case EVENT.IMAGE: 
        case EVENT.IMAGE_MOVE: {
            u32(s, event.image_id);
            f32(s, event.x);
            f32(s, event.y);
            break;
        }

        case EVENT.UNDO:
        case EVENT.REDO: {
            break;
        }

        case EVENT.ERASER: {
            u32(s, event.stroke_id);
            break;
        }

        default: {
            console.error('fuck');
            console.trace();
            process.exit(1);
        }
    }
}