// SHA-256 streaming-equivalence + file hashing for `modules/std/hash.sx`.
//
// The chunk boundary must not affect the result: feeding the same bytes
// one-shot, one byte at a time, split mid-block, and split exactly on a
// 64-byte block boundary all yield the same digest, anchored to a pinned
// value. Then `sha256_file` of a written temp file must equal the
// in-memory digest of the same bytes — the streaming file path agrees
// with the buffered path.
//
// All comparisons go through `string` views over the zero-heap `[64]u8`
// digests; the byte/split updates view directly into the input buffer
// (no `substr`, no copies).

#import "modules/std.sx";
#import "modules/std/hash.sx";
#import "modules/std/fs.sx";

// 112-byte NIST multi-block vector — long enough that a 64-byte split is
// a genuine block boundary and a 30-byte split lands mid-block.
MSG :: "abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu";
PIN :: "cf5b16a778af8380036ce59e7b0492370b249b11e8f07a51afac45037afee9d1";

check :: (label: string, got: [64]u8, want: string) {
    view := string.{ ptr = @got[0], len = 64 };
    if view == want {
        print("{}: ok\n", label);
    } else {
        print("{}: FAIL got {} want {}\n", label, view, want);
    }
}

report :: (label: string, ok: bool) {
    if ok { print("{}: ok\n", label); } else { print("{}: FAIL\n", label); }
}

// Absorb `data` one byte at a time (views of length 1 into the buffer).
stream_by_byte :: (data: string) -> [64]u8 {
    h := init();
    i := 0;
    while i < data.len {
        h.update(string.{ ptr = @data[i], len = 1 });
        i += 1;
    }
    h.final()
}

// Absorb `data` as two updates split at `at` (views into the buffer).
stream_split :: (data: string, at: s64) -> [64]u8 {
    h := init();
    h.update(string.{ ptr = @data[0],  len = at });
    h.update(string.{ ptr = @data[at], len = data.len - at });
    h.final()
}

main :: () {
    check("oneshot-pinned",    sha256_hex(MSG), PIN);
    check("byte-at-a-time",    stream_by_byte(MSG), PIN);
    check("split-mid-block",   stream_split(MSG, 30), PIN);   // 30: mid first block
    check("split-on-boundary", stream_split(MSG, 64), PIN);   // 64: exact block edge

    // sha256_file (streaming) must equal the in-memory digest.
    if !create_dir_all(".sx-tmp") { print("mkdir: FAIL\n"); return; }
    path := ".sx-tmp/sx_0712_stream.bin";
    if !write_file(path, MSG) { print("file-write: FAIL\n"); return; }

    maybe := sha256_file(path);
    if maybe == null { print("file-eq-memory: FAIL (open)\n"); return; }
    file_digest := maybe!;
    mem_digest := sha256_hex(MSG);

    fv := string.{ ptr = @file_digest[0], len = 64 };
    mv := string.{ ptr = @mem_digest[0],  len = 64 };
    report("file-eq-memory", fv == mv);
    check("file-pinned", file_digest, PIN);

    delete_file(path);
}