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// @ts-ignore
import { Fr } from '@aztec/bb.js';
// @ts-ignore -- no types
export async function pedersenLeftRight(
barretenberg: any,
left: string,
right: string) {
let leftBuffer = Fr.fromBufferReduce(Buffer.from(left.slice(2), 'hex'));
let rightBuffer = Fr.fromBufferReduce(Buffer.from(right.slice(2), 'hex'));
let hashRes = await barretenberg.pedersenPlookupCompressFields(leftBuffer, rightBuffer);
return hashRes.toString()
}
export class MerkleTree {
zeroValue = "0xf35fcb490b7ea67c3ac26ed530fa5d8dfe8be344e7177ebb63fe02723fb6f725"; // sha256("Momiji")
levels: number;
defaultLeaves: string[]
hashLeftRight: any;
storage: Map<string, string>;
zeros: string[];
totalLeaves: number;
barretenberg: any;
constructor(
levels,
barretenberg,
defaultLeaves = [],
hashLeftRight = pedersenLeftRight) {
this.levels = levels;
this.hashLeftRight = hashLeftRight;
this.storage = new Map();
this.zeros = [];
this.totalLeaves = 0;
this.barretenberg = barretenberg;
this.defaultLeaves = defaultLeaves
}
async init() {
// build zeros depends on tree levels
let currentZero = this.zeroValue;
this.zeros.push(currentZero);
for (let i = 0; i < this.levels; i++) {
currentZero = await this.hashLeftRight(this.barretenberg, currentZero, currentZero);
this.zeros.push(currentZero);
}
if (this.defaultLeaves.length > 0) {
this.totalLeaves = this.defaultLeaves.length;
// store leaves with key value pair
let level = 0;
this.defaultLeaves.forEach((leaf, index) => {
this.storage.set(MerkleTree.indexToKey(level, index), leaf);
});
// build tree with initial leaves
level++;
let numberOfNodesInLevel = Math.ceil(this.totalLeaves / 2);
for (level; level <= this.levels; level++) {
for (let i = 0; i < numberOfNodesInLevel; i++) {
const leftKey = MerkleTree.indexToKey(level - 1, 2 * i);
const rightKey = MerkleTree.indexToKey(level - 1, 2 * i + 1);
const left = this.storage.get(leftKey);
const right = this.storage.get(rightKey) || this.zeros[level - 1];
if (!left) throw new Error("leftKey not found");
const node = await this.hashLeftRight(this.barretenberg, left, right);
this.storage.set(MerkleTree.indexToKey(level, i), node);
}
numberOfNodesInLevel = Math.ceil(numberOfNodesInLevel / 2);
}
}
}
static indexToKey(level, index) {
return `${level}-${index}`;
}
getIndex(leaf) {
for (const [key, value] of this.storage) {
if (value === leaf) {
return Number(key.split("-")[1]);
}
}
return -1;
}
root() {
return this.storage.get(MerkleTree.indexToKey(this.levels, 0)) || this.zeros[this.levels];
}
proof(indexOfLeaf) {
let pathElements: string[] = [];
let pathIndices: number[] = [];
const leaf = this.storage.get(MerkleTree.indexToKey(0, indexOfLeaf));
if (!leaf) throw new Error("leaf not found");
// store sibling into pathElements and target's indices into pathIndices
const handleIndex = (level, currentIndex, siblingIndex) => {
const siblingValue = this.storage.get(MerkleTree.indexToKey(level, siblingIndex)) || this.zeros[level];
pathElements.push(siblingValue);
pathIndices.push(currentIndex % 2);
};
this.traverse(indexOfLeaf, handleIndex);
return {
root: this.root(),
pathElements,
pathIndices,
leaf: leaf,
};
}
async insert(leaf) {
const index = this.totalLeaves;
await this.update(index, leaf, true);
this.totalLeaves++;
}
async update(index, newLeaf, isInsert = false) {
if (!isInsert && index >= this.totalLeaves) {
throw Error("Use insert method for new elements.");
} else if (isInsert && index < this.totalLeaves) {
throw Error("Use update method for existing elements.");
}
let keyValueToStore: any[] = [];
let currentElement = newLeaf;
const handleIndex = async (level, currentIndex, siblingIndex) => {
const siblingElement = this.storage.get(MerkleTree.indexToKey(level, siblingIndex)) || this.zeros[level];
let left;
let right;
if (currentIndex % 2 === 0) {
left = currentElement;
right = siblingElement;
} else {
left = siblingElement;
right = currentElement;
}
keyValueToStore.push({
key: MerkleTree.indexToKey(level, currentIndex),
value: currentElement,
});
currentElement = await this.hashLeftRight(this.barretenberg, left, right);
};
await this.traverse(index, handleIndex);
// push root to the end
keyValueToStore.push({
key: MerkleTree.indexToKey(this.levels, 0),
value: currentElement,
});
keyValueToStore.forEach(o => {
this.storage.set(o.key, o.value);
});
}
// traverse from leaf to root with handler for target node and sibling node
async traverse(indexOfLeaf, handler) {
let currentIndex = indexOfLeaf;
for (let i = 0; i < this.levels; i++) {
let siblingIndex;
if (currentIndex % 2 === 0) {
siblingIndex = currentIndex + 1;
} else {
siblingIndex = currentIndex - 1;
}
await handler(i, currentIndex, siblingIndex);
currentIndex = Math.floor(currentIndex / 2);
}
}
}