/*
 * 940_mixed_scalar_tuple_sret_run — project #240: an over-cap tuple whose
 * elements mix a scalar with slices/str (e.g. `(int, []u8, str)`) must lay
 * out IDENTICALLY in both stages and round-trip through an sret return.
 *
 * Two SILENT, gate-blind (no bootstrap mixed-scalar tuple) cs!=ww
 * divergences met here:
 *
 *  (a) callee SEND (cstage cgen.c N_RETURN over-cap-tuple arm): the packed
 *      element offset advanced by the LITERAL expression's type size, not
 *      the declared return-type element size. A bare int literal element is
 *      stamped TY_UNTYPED_INT (size 0), so `foff += e->type->size` added 0
 *      for a leading scalar — the next element clobbered it at offset 0 and
 *      every trailing element packed 8 bytes low. wwstage already walked the
 *      return-type tuple (c.fnret.list) for the size, so the stages diverged
 *      on the callee frame's store offsets. Fix: size foff from cg_ret_type's
 *      tuple params (rule-13 type table), mirroring wwstage.
 *
 *  (b) caller RECEIVE (wwstage cgenstmt.ww cglet N_TTUPLE arm): the register
 *      tuple-receive branch (designed for in-cap 16/32B tuples) had NO
 *      capacity gate, so a 56B over-cap tuple was received via AX/DX/CX/R8
 *      (+ R8 fill) instead of from the sret dest the callee actually wrote.
 *      cstage gates that branch on `sz == 16 || sz == 32` and falls an
 *      over-cap tuple through to the sret receive. Fix: add the same size
 *      gate to wwstage.
 *
 * Each program assigns DISTINCT, checkable values to every element (a scalar
 * read directly, a slice/str via len()), and returns 0 only when all read
 * back correctly — so a wrong offset (either bug) yields a nonzero exit.
 * Both an annotated and an inferred `let t` are covered (same receive path).
 *
 * All K_RUN: build+run exit 0 on BOTH drivers AND cs==ww byte-identical.
 * NNN<950, self-contained (/tmp, no imports), so rule-14's selfhost-sibling
 * race does not apply (903/940/945 precedent).
 */
#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;
}

static int
slurp_eq(const char *a, const char *b)
{
	FILE *fa = fopen(a, "rb");
	FILE *fb = fopen(b, "rb");
	if (!fa || !fb) { if (fa) fclose(fa); if (fb) fclose(fb); return -1; }
	int rc = 0;
	for (;;) {
		int ca = fgetc(fa), cb = fgetc(fb);
		if (ca != cb) { rc = -1; break; }
		if (ca == EOF) break;
	}
	fclose(fa); fclose(fb);
	return rc;
}

struct row { const char *label; const char *src; int want; };

static const struct row rows[] = {
	/* leading scalar (the canonical #240 case), annotated let. */
	{ "int_slice_str",
	  "package main;\n"
	  "fn mk() (int, []u8, str) = {\n"
	  "	let b: []u8; b.len = 5; b.cap = 9;\n"
	  "	let s: str = \"abcd\";\n"
	  "	return (42, b, s);\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "	let t: (int, []u8, str) = mk();\n"
	  "	if (t.0 != 42) { return 1; };\n"
	  "	if (len(t.1) != 5) { return 2; };\n"
	  "	if (len(t.2) != 4) { return 3; };\n"
	  "	return 0;\n"
	  "};\n", 0 },
	/* same shape, inferred `let t = mk();` — exercises the receive
	 * path that picks up the type from the callee return. */
	{ "int_slice_str_inferred",
	  "package main;\n"
	  "fn mk() (int, []u8, str) = {\n"
	  "	let b: []u8; b.len = 6; b.cap = 8;\n"
	  "	let s: str = \"xyz\";\n"
	  "	return (17, b, s);\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "	let t = mk();\n"
	  "	if (t.0 != 17) { return 1; };\n"
	  "	if (len(t.1) != 6) { return 2; };\n"
	  "	if (len(t.2) != 3) { return 3; };\n"
	  "	return 0;\n"
	  "};\n", 0 },
	/* trailing scalar: foff must reach the last element's offset. */
	{ "slice_str_int",
	  "package main;\n"
	  "fn mk() ([]u8, str, int) = {\n"
	  "	let b: []u8; b.len = 7; b.cap = 9;\n"
	  "	let s: str = \"hello\";\n"
	  "	return (b, s, 99);\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "	let t: ([]u8, str, int) = mk();\n"
	  "	if (len(t.0) != 7) { return 1; };\n"
	  "	if (len(t.1) != 5) { return 2; };\n"
	  "	if (t.2 != 99) { return 3; };\n"
	  "	return 0;\n"
	  "};\n", 0 },
	/* scalar in the middle. */
	{ "str_int_slice",
	  "package main;\n"
	  "fn mk() (str, int, []u8) = {\n"
	  "	let s: str = \"abcde\";\n"
	  "	let b: []u8; b.len = 3; b.cap = 4;\n"
	  "	return (s, 77, b);\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "	let t: (str, int, []u8) = mk();\n"
	  "	if (len(t.0) != 5) { return 1; };\n"
	  "	if (t.1 != 77) { return 2; };\n"
	  "	if (len(t.2) != 3) { return 3; };\n"
	  "	return 0;\n"
	  "};\n", 0 },
};

/* build+run via a driver (ww / ww_ww); returns 0 pass, nonzero fail. */
static int
run_driver(const char *driver, const struct row *r, int i)
{
	char src[96], tmpdir[96], errf[96], cmd[1024];
	snprintf(src, sizeof src, "/tmp/mxst_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/mxst_%d_d_%d", getpid(), i);
	snprintf(errf, sizeof errf, "/tmp/mxst_%d_e_%d", getpid(), i);

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

	mkdir(tmpdir, 0755);
	snprintf(cmd, sizeof cmd, "cd %s && %s build %s >/dev/null 2>%s",
	    tmpdir, driver, src, errf);
	int brc = runwait(cmd);
	if (brc != 0) {
		fprintf(stderr, "row[%s]: build via %s failed\n",
		    r->label, driver);
		unlink(src); unlink(errf); rmdir(tmpdir);
		return -1;
	}

	const char *base = strrchr(src, '/');
	base = base ? base + 1 : src;
	char outbin[256];
	snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
	char *dot = strrchr(outbin, '.');
	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
	int got = runwait(outbin);

	unlink(src); unlink(outbin); unlink(errf); rmdir(tmpdir);
	if (got != r->want) {
		fprintf(stderr, "row[%s]: %s exit %d, want %d\n",
		    r->label, driver, got, r->want);
		return 1;
	}
	return 0;
}

/* cs==ww .s byte-id (rule 10). */
static int
byteid(const char *w6c, const char *w6c_ww, const struct row *r, int i)
{
	char src[96], cs_s[96], ws_s[96], cmd[1024];
	snprintf(src, sizeof src, "/tmp/mxst_bi_%d_%d.ww", getpid(), i);
	snprintf(cs_s, sizeof cs_s, "/tmp/mxst_bi_%d_%d_cs.s", getpid(), i);
	snprintf(ws_s, sizeof ws_s, "/tmp/mxst_bi_%d_%d_ww.s", getpid(), i);

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

	int rc = 0;
	snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null", w6c, cs_s, src);
	if (runwait(cmd) != 0) { fprintf(stderr, "row[%s]: w6c failed\n", r->label); rc = 1; }
	else {
		snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null", w6c_ww, ws_s, src);
		if (runwait(cmd) != 0) { fprintf(stderr, "row[%s]: w6c_ww failed\n", r->label); rc = 1; }
		else if (slurp_eq(cs_s, ws_s) != 0) {
			fprintf(stderr, "row[%s]: cstage/wwstage .s DIFFER "
			    "(#240 mixed-scalar tuple sret-layout regression)\n",
			    r->label);
			rc = 1;
		}
	}
	unlink(src); unlink(cs_s); unlink(ws_s);
	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 cdrv[640], wdrv[640], w6c[640], w6c_ww[640];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);
	snprintf(w6c, sizeof w6c, "%s/w6c", bin);
	snprintf(w6c_ww, sizeof w6c_ww, "%s/w6c_ww", bin);

	struct { const char *name; const char *path; int gated; }
	drivers[] = {
		{ "cstage",  cdrv, 0 },
		{ "wwstage", wdrv, 1 },
		{ NULL, NULL, 0 },
	};

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

	for (int d = 0; drivers[d].name; d++) {
		if (drivers[d].gated && access(drivers[d].path, X_OK) != 0) {
			fprintf(stderr, "mixed_scalar_tuple_sret: skip %s (no %s)\n",
			    drivers[d].name, drivers[d].path);
			continue;
		}
		for (int i = 0; i < n; i++) {
			total++;
			if (run_driver(drivers[d].path, &rows[i], i) != 0) fail++;
		}
	}

	if (access(w6c_ww, X_OK) == 0) {
		for (int i = 0; i < n; i++) {
			total++;
			if (byteid(w6c, w6c_ww, &rows[i], i) != 0) fail++;
		}
	}

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