// A small incremental SHA-256 implementation for model downloads. Web Crypto only
// exposes one-shot digest(), which would require retaining a several-hundred-MiB
// model file in memory before it could be admitted to Cache Storage.
const INITIAL = [0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19];
const ROUND = [
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
    0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
    0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
    0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
    0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
    0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
];
export class StreamingSha256 {
    state = new Uint32Array(INITIAL);
    block = new Uint8Array(64);
    buffered = 0;
    bytes = 0;
    update(value) {
        this.bytes += value.byteLength;
        let offset = 0;
        if (this.buffered > 0) {
            const take = Math.min(64 - this.buffered, value.byteLength);
            this.block.set(value.subarray(0, take), this.buffered);
            this.buffered += take;
            offset = take;
            if (this.buffered === 64) {
                this.compress(this.block);
                this.buffered = 0;
            }
        }
        while (offset + 64 <= value.byteLength) {
            this.compress(value.subarray(offset, offset + 64));
            offset += 64;
        }
        if (offset < value.byteLength) {
            this.block.set(value.subarray(offset));
            this.buffered = value.byteLength - offset;
        }
    }
    hexDigest() {
        const final = new StreamingSha256();
        final.state.set(this.state);
        final.block.set(this.block);
        final.buffered = this.buffered;
        final.bytes = this.bytes;
        const bitLength = BigInt(final.bytes) * 8n;
        const padding = new Uint8Array(final.buffered < 56 ? 64 - final.buffered : 128 - final.buffered);
        padding[0] = 0x80;
        for (let index = 0; index < 8; index += 1)
            padding[padding.length - 1 - index] = Number((bitLength >> BigInt(index * 8)) & 0xffn);
        final.updateWithoutLength(padding);
        const output = new Uint8Array(32);
        for (let index = 0; index < 8; index += 1) {
            const word = final.state[index];
            output[index * 4] = word >>> 24;
            output[index * 4 + 1] = word >>> 16;
            output[index * 4 + 2] = word >>> 8;
            output[index * 4 + 3] = word;
        }
        return Array.from(output, (part) => part.toString(16).padStart(2, "0")).join("");
    }
    updateWithoutLength(value) {
        let offset = 0;
        if (this.buffered > 0) {
            const take = Math.min(64 - this.buffered, value.byteLength);
            this.block.set(value.subarray(0, take), this.buffered);
            this.buffered += take;
            offset = take;
            if (this.buffered === 64) {
                this.compress(this.block);
                this.buffered = 0;
            }
        }
        while (offset + 64 <= value.byteLength) {
            this.compress(value.subarray(offset, offset + 64));
            offset += 64;
        }
        if (offset < value.byteLength) {
            this.block.set(value.subarray(offset));
            this.buffered = value.byteLength - offset;
        }
    }
    compress(block) {
        const words = new Uint32Array(64);
        for (let index = 0; index < 16; index += 1)
            words[index] = ((block[index * 4] << 24) | (block[index * 4 + 1] << 16) | (block[index * 4 + 2] << 8) | block[index * 4 + 3]) >>> 0;
        for (let index = 16; index < 64; index += 1) {
            const x = words[index - 15];
            const y = words[index - 2];
            words[index] = (small0(x) + words[index - 7] + small1(y) + words[index - 16]) >>> 0;
        }
        let [a, b, c, d, e, f, g, h] = this.state;
        for (let index = 0; index < 64; index += 1) {
            const next1 = (h + big1(e) + choose(e, f, g) + ROUND[index] + words[index]) >>> 0;
            const next2 = (big0(a) + majority(a, b, c)) >>> 0;
            h = g;
            g = f;
            f = e;
            e = (d + next1) >>> 0;
            d = c;
            c = b;
            b = a;
            a = (next1 + next2) >>> 0;
        }
        this.state[0] = (this.state[0] + a) >>> 0;
        this.state[1] = (this.state[1] + b) >>> 0;
        this.state[2] = (this.state[2] + c) >>> 0;
        this.state[3] = (this.state[3] + d) >>> 0;
        this.state[4] = (this.state[4] + e) >>> 0;
        this.state[5] = (this.state[5] + f) >>> 0;
        this.state[6] = (this.state[6] + g) >>> 0;
        this.state[7] = (this.state[7] + h) >>> 0;
    }
}
function rotr(value, amount) { return (value >>> amount) | (value << (32 - amount)); }
function choose(x, y, z) { return (x & y) ^ (~x & z); }
function majority(x, y, z) { return (x & y) ^ (x & z) ^ (y & z); }
function big0(value) { return rotr(value, 2) ^ rotr(value, 13) ^ rotr(value, 22); }
function big1(value) { return rotr(value, 6) ^ rotr(value, 11) ^ rotr(value, 25); }
function small0(value) { return rotr(value, 7) ^ rotr(value, 18) ^ (value >>> 3); }
function small1(value) { return rotr(value, 17) ^ rotr(value, 19) ^ (value >>> 10); }
