/*
 * 989_defercap_run (#40, F13 c1) — the defer stack must fail loud at its cap
 * in BOTH stages, not silently drop the overflowing deferred call.
 *
 * THE BUG (cat-A, both stages diverged AND both wrong at their cap): wwstage
 * cgstmt N_DEFER pushed only while defertop < DEFER_MAX where DEFER_MAX was 16
 * (cgen.ww), so a function with 17 defers silently dropped the 17th — the
 * counter reached 16, exit 1, while cstage (DEFER_MAX 32) emitted all 17.
 * cstage in turn silently dropped its own 33rd defer. The runtime-correct
 * target (CAP-SEMANTICS rule: cstage silent at its own cap => loud both):
 * the cap is the shared 32, and a function exceeding it is a hard compile
 * error in BOTH stages (cgenstmt.ww N_DEFER + cgen.c N_DEFER fatal).
 *
 *   row         | ndefers | shape                         | result (cs==ww)
 *   ------------+---------+-------------------------------+----------------
 *   seventeen   | 17      | original repro (>old ww 16)   | exit 0
 *   at_cap_32   | 32      | exactly the shared cap        | exit 0
 *   over_cap_33 | 33      | one past the cap              | build FAILS loud
 *
 * seventeen was RED pre-c1 on wwstage (counter 16, exit 1 vs cstage exit 0).
 * over_cap_33 was RED pre-c1 on BOTH stages (silent rc=0 accept dropping the
 * overflowing defer). at_cap_32 pins the boundary stays accepted byte-id.
 */
#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; int ndefers; int want_build_fail; int want_exit; };

static const struct row rows[] = {
	{ "seventeen",   17, 0, 0 },
	{ "at_cap_32",   32, 0, 0 },
	{ "over_cap_33", 33, 1, 0 },
};

/* Emit `package main` with a doit() carrying ndefers `defer bump();` and a
 * main() that checks the global counter equals ndefers. */
static int
write_src(const char *path, int ndefers)
{
	FILE *f = fopen(path, "wb");
	if (!f) return -1;
	fputs("package main;\n"
	      "let cnt: i32 = 0;\n"
	      "fn bump() void = { cnt = cnt + 1; };\n"
	      "fn doit() void = {\n", f);
	for (int i = 0; i < ndefers; i++)
		fputs("\tdefer bump();\n", f);
	fprintf(f,
	      "};\n"
	      "export fn main() i32 = {\n"
	      "\tdoit();\n"
	      "\tif (cnt == %d) { return 0; };\n"
	      "\treturn 1;\n"
	      "};\n", ndefers);
	fclose(f);
	return 0;
}

/* Returns the build rc in *brc; the run exit code (or -1) as the value. */
static int
build_run(const char *driver, const struct row *r, int i, int *brc)
{
	char src[64], tmpdir[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/dcap_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/dcap_%d_d_%d", getpid(), i);

	if (write_src(src, r->ndefers) != 0) { *brc = -1; return -1; }

	mkdir(tmpdir, 0755);
	snprintf(cmd, sizeof cmd, "cd %s && %s build %s 2>/dev/null",
	    tmpdir, driver, src);
	*brc = runwait(cmd);

	const char *base = strrchr(src, '/');
	base = base ? base + 1 : src;
	char outbin[128];
	snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
	char *dot = strrchr(outbin, '.');
	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';

	int got = -1;
	if (*brc == 0) got = runwait(outbin);

	unlink(src); unlink(outbin); rmdir(tmpdir);
	return got;
}

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char absbin[1024];
	if (bin[0] != '/') {
		char cwd[1024];
		if (getcwd(cwd, sizeof cwd) == NULL) return 1;
		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
		bin = absbin;
	}

	char cdrv[1024], wdrv[1024];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);
	int have_ww = (access(wdrv, X_OK) == 0);

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

	for (int i = 0; i < n; i++) {
		total++;
		int cbrc, gc = build_run(cdrv, &rows[i], i, &cbrc);

		if (rows[i].want_build_fail) {
			if (cbrc == 0) {
				fprintf(stderr, "defercap[cstage][%s]: built rc=0, "
				    "expected loud build failure (#40)\n", rows[i].label);
				fail++;
			}
		} else {
			if (cbrc != 0 || gc != rows[i].want_exit) {
				fprintf(stderr, "defercap[cstage][%s]: brc=%d exit=%d "
				    "want_exit=%d\n", rows[i].label, cbrc, gc,
				    rows[i].want_exit);
				fail++;
			}
		}

		if (!have_ww) {
			fprintf(stderr, "defercap: skip wwstage (no %s)\n", wdrv);
			continue;
		}
		int wbrc, gw = build_run(wdrv, &rows[i], i, &wbrc);

		if (rows[i].want_build_fail) {
			if (wbrc == 0) {
				fprintf(stderr, "defercap[wwstage][%s]: built rc=0, "
				    "expected loud build failure (#40)\n", rows[i].label);
				fail++;
			}
			/* both-fail is the rule-10 agreement here */
			if ((cbrc == 0) != (wbrc == 0)) {
				fprintf(stderr, "defercap[%s]: build-fail divergence "
				    "cs_rc=%d ww_rc=%d (#40)\n", rows[i].label, cbrc, wbrc);
				fail++;
			}
		} else {
			if (wbrc != 0 || gw != rows[i].want_exit) {
				fprintf(stderr, "defercap[wwstage][%s]: brc=%d exit=%d "
				    "want_exit=%d\n", rows[i].label, wbrc, gw,
				    rows[i].want_exit);
				fail++;
			}
			if (gw != gc) {
				fprintf(stderr, "defercap[%s]: cs=%d != ww=%d "
				    "(defer-cap divergence — #40)\n", rows[i].label, gc, gw);
				fail++;
			}
		}
	}

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