/*
 * 719_signed_data_emit — corpus-coverage-blind sentinel for #19.
 *
 * Confirms each cstage / wwstage `.s` for a top-level `let` of signed
 * integer type contains a `DATAW <sym>(SB),"..."` row, *and* that the
 * inline literal bytes encode the value's two's complement at the
 * declared element width. Pre-fix:
 *   - cstage emit_lets dropped the row entirely on `let x: i8 = -1i8;`
 *     (link failed, no DATAW); the array arm dropped the whole row.
 *   - wwstage emitletdataw silently emitted zero bytes where the
 *     negative literal should have produced 0xFF... (link succeeded;
 *     runtime read 0). The array arm hit the same gap.
 *
 * Both 923_signed_data_emit_run and the broader bootstrap byte-id
 * (995_self_rebuild) would catch a future regression, but this row
 * pins the *asm shape* itself — a future cgen refactor that emits
 * the slot via a different directive (e.g. via DATA + DATAR rather
 * than DATAW) would silently divergent even with green semantics.
 *
 * Plus a cstage-vs-wwstage byte-id diff per row, mirroring 707's
 * pattern.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>

static int
runwait(const char *cmd)
{
	int rc = system(cmd);
	if (rc == -1) return -1;
	if (WIFEXITED(rc)) return WEXITSTATUS(rc);
	return -1;
}

struct row {
	const char *label;
	const char *src;
	const char *sym;
	const char *want_bytes;	/* exact byte-payload inside the DATAW */
};

/* The .s emits each byte either as a printable ASCII glyph (b is 0x20-
 * 0x7e and not '"'/'\\') or as `\xNN`. emit_data_byte's rules: 0x22 + 0x5c
 * → `\"` / `\\`; printable → raw; everything else → `\xNN`. For the
 * sign-extended pads we'll see `\xff` × N as a contiguous run. */
static const struct row rows[] = {
	/* Scalar i8 = -1 → low byte 0xff, then 7 bytes of sign-extension. */
	{ "i8_neg",  "let x: i8 = -1i8;\n"
	             "fn main() i32 = { return 0; };\n",
	  "x",
	  "\\xff\\xff\\xff\\xff\\xff\\xff\\xff\\xff" },
	/* Scalar i16 = -2 → 0xfe 0xff then 6 byte sign extension. */
	{ "i16_neg", "let x: i16 = -2i16;\n"
	             "fn main() i32 = { return 0; };\n",
	  "x",
	  "\\xfe\\xff\\xff\\xff\\xff\\xff\\xff\\xff" },
	/* Scalar i32 = -100 → 0x9C 0xFF 0xFF 0xFF then 4 byte sign extension. */
	{ "i32_neg", "let x: i32 = -100i32;\n"
	             "fn main() i32 = { return 0; };\n",
	  "x",
	  "\\x9c\\xff\\xff\\xff\\xff\\xff\\xff\\xff" },
	/* Scalar i64 = -1000 → 0xfffffffffffffc18 little-endian. */
	{ "i64_neg", "let x: i64 = -1000i64;\n"
	             "fn main() i32 = { return 0; };\n",
	  "x",
	  "\\x18\\xfc\\xff\\xff\\xff\\xff\\xff\\xff" },
	/* Array [4]i8 = [1, -2, 3, -4] → 0x01 0xfe 0x03 0xfc. */
	{ "i8_arr",  "let a: [4]i8 = [1i8, -2i8, 3i8, -4i8];\n"
	             "fn main() i32 = { return 0; };\n",
	  "a",
	  "\\x01\\xfe\\x03\\xfc" },
	/* Array [4]i16 = [1, -2, 3, -4] → LE16 each. */
	{ "i16_arr", "let a: [4]i16 = [1i16, -2i16, 3i16, -4i16];\n"
	             "fn main() i32 = { return 0; };\n",
	  "a",
	  "\\x01\\x00\\xfe\\xff\\x03\\x00\\xfc\\xff" },
	/* Array [3]i32 = [10, -20, 30] → LE32 each. */
	{ "i32_arr", "let a: [3]i32 = [10i32, -20i32, 30i32];\n"
	             "fn main() i32 = { return 0; };\n",
	  "a",
	  "\\x0a\\x00\\x00\\x00\\xec\\xff\\xff\\xff\\x1e\\x00\\x00\\x00" },
	/* Array [2]i64 = [100, -200] → LE64 each. Note 100 == 'd' and
	 * 56 == '8' are printable ASCII so emit_data_byte writes them
	 * raw rather than as `\xNN`. */
	{ "i64_arr", "let a: [2]i64 = [100i64, -200i64];\n"
	             "fn main() i32 = { return 0; };\n",
	  "a",
	  "d\\x00\\x00\\x00\\x00\\x00\\x00\\x00"
	  "8\\xff\\xff\\xff\\xff\\xff\\xff\\xff" },
};

static int
slurp(const char *path, char *buf, size_t cap)
{
	FILE *f = fopen(path, "rb");
	if (!f) return -1;
	size_t n = fread(buf, 1, cap - 1, f);
	fclose(f);
	buf[n] = '\0';
	return (int)n;
}

/* Check that the .s contains a DATAW row for `sym` whose payload
 * matches `want_bytes`. Returns 0 on match. */
static int
check_dataw(const char *spath, const struct row *r)
{
	char buf[1 << 16];
	if (slurp(spath, buf, sizeof buf) < 0) return -1;
	char needle[256];
	snprintf(needle, sizeof needle, "DATAW %s(SB),\"%s\"",
	    r->sym, r->want_bytes);
	return strstr(buf, needle) ? 0 : -1;
}

static int
emit_s(const char *w6c, const struct row *r, int i, char *out_s, size_t cap)
{
	char src[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/sde_asm_%d_%d.ww", getpid(), i);
	snprintf(out_s, cap,      "/tmp/sde_asm_%d_%d_%s.s",
	    getpid(), i, w6c[strlen(w6c) - 1] == 'w' ? "ww" : "c");

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	fputs(r->src, f);
	fclose(f);

	snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null", w6c, out_s, src);
	int rc = runwait(cmd);
	unlink(src);
	return rc;
}

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char absbin[512];
	if (bin[0] != '/') {
		char cwd[256];
		if (getcwd(cwd, sizeof cwd) == NULL) return 1;
		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
		bin = absbin;
	}

	char w6c[640], w6c_ww[640];
	snprintf(w6c,    sizeof w6c,    "%s/w6c", bin);
	snprintf(w6c_ww, sizeof w6c_ww, "%s/w6c_ww", bin);

	int have_ww = (access(w6c_ww, X_OK) == 0);

	int n = (int)(sizeof rows / sizeof rows[0]);
	int total = 0, fail = 0;

	for (int i = 0; i < n; i++) {
		char cs_path[128], ws_path[128];

		/* cstage row: DATAW emit + byte payload. */
		if (emit_s(w6c, &rows[i], i, cs_path, sizeof cs_path) != 0) {
			fprintf(stderr,
			    "signed_data_emit[cstage][%s]: w6c failed\n",
			    rows[i].label);
			fail++; total++; continue;
		}
		total++;
		if (check_dataw(cs_path, &rows[i]) != 0) {
			fprintf(stderr,
			    "signed_data_emit[cstage][%s]: DATAW %s(SB),\"%s\" missing\n",
			    rows[i].label, rows[i].sym, rows[i].want_bytes);
			fail++;
		}

		if (!have_ww) { unlink(cs_path); continue; }

		/* wwstage row: same DATAW emit. */
		if (emit_s(w6c_ww, &rows[i], i, ws_path, sizeof ws_path) != 0) {
			fprintf(stderr,
			    "signed_data_emit[wwstage][%s]: w6c_ww failed\n",
			    rows[i].label);
			fail++; total++;
			unlink(cs_path);
			continue;
		}
		total++;
		if (check_dataw(ws_path, &rows[i]) != 0) {
			fprintf(stderr,
			    "signed_data_emit[wwstage][%s]: DATAW %s(SB),\"%s\" missing\n",
			    rows[i].label, rows[i].sym, rows[i].want_bytes);
			fail++;
		}

		/* Byte-id diff between stages. The bootstrap byte-id covers
		 * cross-stage drift globally; per-row diff here surfaces a
		 * focused regression in the emit_lets / emitletdataw arms. */
		total++;
		char cmd[512];
		snprintf(cmd, sizeof cmd, "cmp -s %s %s", cs_path, ws_path);
		if (runwait(cmd) != 0) {
			fprintf(stderr,
			    "signed_data_emit[%s]: cstage vs wwstage asm differs\n",
			    rows[i].label);
			fail++;
		}

		unlink(cs_path); unlink(ws_path);
	}

	if (fail) {
		fprintf(stderr,
		    "signed_data_emit: %d/%d fixtures failed\n", fail, total);
		return 1;
	}
	printf("signed_data_emit: %d/%d ok\n", total, total);
	return 0;
}