class MerkleTree {
    constructor(arr, concat) {
        this.arr = arr
        this.concat = concat
    }
    getProof(index, tempArr = this.arr, proof = []) {
        if (tempArr.length === 1) {
            return proof;
        }
        let newArr = [];
        for (let i = 0; i < tempArr.length; i += 2) {
            let left = tempArr[i];
            let right = tempArr[i + 1];
            if(index === i || index === i + 1) {
                // is the index referring to one of these two nodes
                const isLeft = !(index === i);
                const data = isLeft ? left : right;
                if (data) {
                    proof.push({
                        left: isLeft,
                        data
                    });
                }
            }
            if (right) {
                newArr.push(this.concat(left, right))
            } else {
                newArr.push(left);
            }
        }
        return this.getProof(Math.floor(index/2), newArr, proof);
    }
    getRoot(tempArr = this.arr, newArr = []) {
        if (tempArr.length === 1) return tempArr[0];
        for (let i = 0; i < tempArr.length; i += 2) {
            if (tempArr[i + 1]) {
                newArr.push(this.concat(tempArr[i], tempArr[i + 1]))
            } else {
                newArr.push(tempArr[i])
            }
        }
        return this.getRoot(newArr)
    }
}
module.exports = MerkleTree;