/**
 * DMP-04 — `kind:'bitset'` payload via @suaveplan/bitpacker-compressed.
 *
 * Property-based round-trip across random bit densities, plus the
 * "1000-chunk file with 3 needed chunks fits in <40 bytes" example
 * from the spec.
 */

import { describe, expect, it } from "@suaveplan/testing/runner";
import fc from "fast-check";
import {
    BITSET_HEADER_SIZE,
    chunkIdsToRawBitset,
    decodeFramedBitset,
    encodeFramedBitset,
    rawBitsetToChunkIds,
} from "../src/index.js";

describe("DMP-04 — bitset round-trip", () => {
    it("bitset roundtrip preserves bit positions for random densities", {
        timeout: 10000,
    }, () => {
        fc.assert(
            fc.property(
                fc
                    .array(fc.integer({ min: 0, max: 9999 }), {
                        minLength: 1,
                        maxLength: 200,
                    })
                    .map((arr) => Array.from(new Set(arr))),
                (input) => {
                    const sorted = [...input].sort((a, b) => a - b);
                    const max = sorted[sorted.length - 1] as number;
                    const bitLength = max + 1;
                    const raw = chunkIdsToRawBitset(sorted, bitLength);
                    const framed = encodeFramedBitset(raw, bitLength);
                    const decoded = decodeFramedBitset(framed);
                    expect(decoded.bitLength).toBe(bitLength);
                    const recovered = rawBitsetToChunkIds(
                        decoded.raw,
                        decoded.bitLength
                    );
                    expect(recovered).toEqual(sorted);
                }
            ),
            { numRuns: 50 }
        );
    });

    it("1000-chunk file with 3 needed chunks fits in <165 bytes", {
        timeout: 5000,
    }, () => {
        const needed = [100, 105, 200];
        const bitLength = 1000;
        const raw = chunkIdsToRawBitset(needed, bitLength);
        const framed = encodeFramedBitset(raw, bitLength);
        // header + 125 bytes raw bitset = ~137 bytes; well under 165.
        expect(framed.length).toBeLessThan(BITSET_HEADER_SIZE + 200);
        const back = rawBitsetToChunkIds(raw, bitLength);
        expect(back).toEqual(needed);
    });
});