/**
 * Copyright (c) Whales Corp.
 * All Rights Reserved.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

import { BitString } from "../BitString";
import { Cell } from "../Cell";
import { CellType } from "../CellType";
import { bitsToPaddedBuffer } from "../utils/paddedBits";

export function getRefsDescriptor(
    refs: Cell[],
    levelMask: number,
    type: CellType,
) {
    return (
        refs.length + (type !== CellType.Ordinary ? 1 : 0) * 8 + levelMask * 32
    );
}

export function getBitsDescriptor(bits: BitString) {
    let len = bits.length;
    return Math.ceil(len / 8) + Math.floor(len / 8);
}

export function getRepr(
    originalBits: BitString,
    bits: BitString,
    refs: Cell[],
    level: number,
    levelMask: number,
    type: CellType,
) {
    // Allocate
    const bitsLen = Math.ceil(bits.length / 8);
    const repr = Buffer.alloc(2 + bitsLen + (2 + 32) * refs.length);

    // Write descriptors
    let reprCursor = 0;
    repr[reprCursor++] = getRefsDescriptor(refs, levelMask, type);
    repr[reprCursor++] = getBitsDescriptor(originalBits);

    // Write bits
    bitsToPaddedBuffer(bits).copy(repr, reprCursor);
    reprCursor += bitsLen;

    // Write refs
    for (const c of refs) {
        let childDepth: number;
        if (type == CellType.MerkleProof || type == CellType.MerkleUpdate) {
            childDepth = c.depth(level + 1);
        } else {
            childDepth = c.depth(level);
        }
        repr[reprCursor++] = Math.floor(childDepth / 256);
        repr[reprCursor++] = childDepth % 256;
    }
    for (const c of refs) {
        let childHash: Buffer;
        if (type == CellType.MerkleProof || type == CellType.MerkleUpdate) {
            childHash = c.hash(level + 1);
        } else {
            childHash = c.hash(level);
        }
        childHash.copy(repr, reprCursor);
        reprCursor += 32;
    }

    // Result
    return repr;
}