/**
 * CSPRNG Fisher-Yates shuffle.
 *
 * Only works on lists up to 255 elements.
 */
function cryptoShuffle(l) {
    let out = [];
    for (let i = l.length - 1; i > 0; i--) {
        let value = new Uint8Array([0]);
        crypto.getRandomValues(value);
        while (value[0] > i) {
            crypto.getRandomValues(value);
        }

        let v = l.splice(value[0], 1);
        out.push(v[0]);
    }

    out.push(l[0]);

    return out;
}

window.cryptoShuffle = cryptoShuffle;

const ROUNDS = 24;

function proveRegions(regions) {
    // Construct prover coins
    let coins = [];

    let regionNames = Object.keys(regions);
    for (let x = 0; x < ROUNDS; x++) {
        let psi = cryptoShuffle(structuredClone(regionNames)).join("");
        let newRegions = structuredClone(regions);
        // rearrange keys
        for (let index = 0; index < regionNames.length; index++) {
            let c = regions[psi[index]].clone();
            // re-blind
            c.update(c.pubKey.encrypt(0n));
            newRegions[regionNames[index]] = c;
        }
        coins.push(newRegions);
    }

    // Construct verifier coins
    let hasher = new jsSHA("SHA3-256", "TEXT");
    hasher.update(JSON.stringify(coins));
    let hash = hasher.getHash("UINT8ARRAY");

    let verifierCoins = [];
    for (let i = 0; i < ROUNDS / 8; i++) {
        let v = hash[i];
        for (let j = 0; j < 8; j++) {
            verifierCoins.push(v & 1);
            v >>= 1;
        }
    }

    // Construct prover proofs
    for (let coin of verifierCoins) {
        if (coin === 1) {
            // Reveal bijection and proof for zero
        } else {
            // Reveal proof for plaintext
        }
    }
}

window.proveRegions = proveRegions;