/*
 * 845_tuple_trailing_comma_reject (catB-92) — cstage and wwstage
 * LOUD-REJECT a single-element trailing-comma tuple `(a,)`.
 *
 * A trailing comma is legal ONLY after >=2 tuple elements; `(a,)` is a
 * parse error, `(a, b)` and `(a, b,)` are 2-tuples. cstage parse.c:552-
 * 558 parses each element BEFORE the RPAREN-break, so `(a,)` errors at
 * the next parseexpr (it sees `)`). wwstage's lib/ww/parse/expr.ww tuple
 * loop checked the RPAREN-break at the TOP, so `(a,)` parsed as a
 * 1-element N_TUPLE and reached cgen — a silent wrong-accept. The fix
 * mirrors cstage's loop order (break sits AFTER accept(COMMA)).
 *
 * The reject row is `let t = (5,);` — an INFERRED-type 1-tuple, the
 * context the old wwstage built rc=0 and codegen'd (a 2-tuple-DECLARED
 * `(5,)` already errored on arity downstream, masking the parse bug;
 * the inferred form is the clean discriminator). Pre-fix wwstage built
 * it rc=0; cstage rejected it. Post-fix both reject at parse.
 *
 *   row        | shape           | expect
 *   -----------+-----------------+--------
 *   one_comma  | let t = (5,);   | REJECT (parse)
 *   two_elem   | (3, 4)          | BUILD, run 7
 *   two_comma  | (3, 4,)         | BUILD, run 7  (trailing OK after >=2)
 */
#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;
}

/* outbin — derive the driver's default binary name from a *.ww source
 * (strip dir + the .ww suffix), placed in tmpdir. */
static void
outbin(char *dst, size_t n, const char *tmpdir, const char *src)
{
	const char *base = strrchr(src, '/');
	base = base ? base + 1 : src;
	snprintf(dst, n, "%s/%s", tmpdir, base);
	char *dot = strrchr(dst, '.');
	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
}

static int
filehas(const char *path, const char *needle)
{
	char buf[8192];
	FILE *f = fopen(path, "rb");
	if (!f) return 0;
	size_t n = fread(buf, 1, sizeof buf - 1, f);
	fclose(f);
	buf[n] = '\0';
	return strstr(buf, needle) != NULL;
}

/* build_should_fail — returns 0 when the build FAILS *and* the stage's
 * own parse diagnostic appears; a crash wraps as a nonzero "w6c failed"
 * with no diagnostic, so the substring distinguishes it (#20). The two
 * stages' parse messages diverge with no common core (cstage "unexpected
 * token in expression"/"expected ), got ;" vs wwstage "parse: expected
 * expression"/"parse: expected ')' in tuple"), so `diag` is passed
 * per-stage by the caller (a real fidelity gap, filed under #20). */
static int
build_should_fail(const char *driver, const char *label, const char *src,
    const char *diag, int i)
{
	char s[128], tmpdir[64], cmd[1024], bin[128], errf[128], rmcmd[160];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/tuptc_%d_d_%d", getpid(), i);
	mkdir(tmpdir, 0755);
	snprintf(s, sizeof s, "%s/tuptc_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(errf, sizeof errf, "%s/tuptc_%d_e_%d.txt", tmpdir, getpid(), i);
	snprintf(rmcmd, sizeof rmcmd, "rm -rf %s", tmpdir);
	FILE *f = fopen(s, "wb");
	if (!f) { runwait(rmcmd); return -1; }
	fputs(src, f);
	fclose(f);
	/* explicit -o INSIDE tmpdir so the binary AND its <stem>.sepwork land
	 * under tmpdir and die with rm -rf; a reject leaks the mkdir'd scratch
	 * too, so clean on every exit path. */
	outbin(bin, sizeof bin, tmpdir, s);
	snprintf(cmd, sizeof cmd, "%s build -o %s %s >/dev/null 2>%s",
	    driver, bin, s, errf);
	int rc = runwait(cmd);
	int hasmsg = filehas(errf, diag);
	runwait(rmcmd);
	if (rc == 0) {
		fprintf(stderr, "tuptc[%s][%s]: built ok, expected a reject\n",
		    driver, label);
		return -1;
	}
	if (!hasmsg) {
		fprintf(stderr, "tuptc[%s][%s]: nonzero exit but missing "
		    "diagnostic \"%s\" (a crash, not a clean reject)\n",
		    driver, label, diag);
		return -1;
	}
	return 0;
}

/* run_build — build a program that MUST compile, run it, return exit. */
static int
run_build(const char *driver, const char *label, const char *src, int i)
{
	char s[128], tmpdir[64], cmd[1024], bin[128], rmcmd[160];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/tuptc_ok_%d_d_%d", getpid(), i);
	mkdir(tmpdir, 0755);
	snprintf(s, sizeof s, "%s/tuptc_ok_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(bin, sizeof bin, "%s/tuptc_ok_%d_%d", tmpdir, getpid(), i);
	snprintf(rmcmd, sizeof rmcmd, "rm -rf %s", tmpdir);
	FILE *f = fopen(s, "wb");
	if (!f) { runwait(rmcmd); return -1; }
	fputs(src, f);
	fclose(f);
	snprintf(cmd, sizeof cmd, "%s build -o %s %s 2>/dev/null",
	    driver, bin, s);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "tuptc[%s][%s]: build failed (a valid tuple "
		    "must compile)\n", driver, label);
		runwait(rmcmd);
		return -1;
	}
	int got = runwait(bin);
	runwait(rmcmd);
	return got;
}

struct rejrow {
	const char *label;
	const char *src;
	const char *cdiag;	/* cstage diagnostic body substring */
	const char *wdiag;	/* wwstage diagnostic body substring (#20 gap) */
};

static const struct rejrow reject_rows[] = {
	{ "one_comma",
	  "package main;\n"
	  "fn main() i32 = { let t = (5,); return 0; };\n",
	  "unexpected token in expression", "expected expression" },
};

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

static const struct okrow ok_rows[] = {
	{ "two_elem",
	  "package main;\n"
	  "fn pair() (i32, i32) = { return (3, 4); };\n"
	  "fn main() i32 = { let a, b = pair(); return a + b; };\n", 7 },

	{ "two_comma",
	  "package main;\n"
	  "fn pair() (i32, i32) = { return (3, 4,); };\n"
	  "fn main() i32 = { let a, b = pair(); return a + b; };\n", 7 },
};

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);

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

	int nrej = (int)(sizeof reject_rows / sizeof reject_rows[0]);
	int nok = (int)(sizeof ok_rows / sizeof ok_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, "tuptc: skip %s (no %s)\n",
			    drivers[d].name, drivers[d].path);
			continue;
		}
		for (int i = 0; i < nrej; i++) {
			total++;
			if (build_should_fail(drivers[d].path,
			    reject_rows[i].label, reject_rows[i].src,
			    drivers[d].gated ? reject_rows[i].wdiag
			    : reject_rows[i].cdiag, d * 100 + i) != 0)
				fail++;
		}
		for (int i = 0; i < nok; i++) {
			total++;
			int got = run_build(drivers[d].path, ok_rows[i].label,
			    ok_rows[i].src, d * 100 + i);
			if (got != ok_rows[i].want) {
				fprintf(stderr, "tuptc[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, ok_rows[i].label,
				    got, ok_rows[i].want);
				fail++;
			}
		}
	}

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