/*
 * 847_const_reassign_reject (catB-22) — cstage and wwstage LOUD-REJECT
 * a reassignment of a `const`-declared binding.
 *
 * `const x = 5; x = 6;` mutates an immutable binding — a programmer
 * error. The sym carries an is_const flag (lib/ww/sym.ww), but wwstage
 * never SET it at the let-install nor CONSUMED it at assignment, so the
 * reassignment slipped through silently. The fix mirrors cstage's two
 * sites: set is_const when n.op == TK_CONST at the local let-install
 * (cmd/wcc/check.c:2408) and reject an N_ASSIGN whose lhs ident resolves
 * to an is_const sym (cmd/wcc/check.c:1889-1896). cstage already
 * rejected; this aligns wwstage UP.
 *
 * Both rows annotate `: i32` so the inferred-int default (#34 int/i32
 * cs/ww divergence) does not contaminate the const signal.
 *
 *   row        | shape                          | expect
 *   -----------+--------------------------------+--------
 *   const_set  | const x: i32 = 5; x = 6;       | REJECT
 *   let_set    | let y: i32 = 5; y = 6;         | BUILD, run 6
 */
#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 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;
}

/* A reject row passes only when the build FAILS *and* the stage's clean
 * diagnostic appears; a crash (segfault) wraps as a nonzero "w6c failed"
 * with no diagnostic, so the substring check distinguishes it (#20).
 * cstage "cannot assign to const `x`" and wwstage "cannot assign to const
 * binding" share the "cannot assign to const" core. */
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/creas_%d_d_%d", getpid(), i);
	mkdir(tmpdir, 0755);
	snprintf(s, sizeof s, "%s/creas_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(errf, sizeof errf, "%s/creas_%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);
	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, "creas[%s][%s]: built ok, expected a reject\n",
		    driver, label);
		return -1;
	}
	if (!hasmsg) {
		fprintf(stderr, "creas[%s][%s]: nonzero exit but missing "
		    "diagnostic \"%s\" (a crash, not a clean reject)\n",
		    driver, label, diag);
		return -1;
	}
	return 0;
}

static int
run_build(const char *driver, const char *label, const char *src, int i)
{
	char tmpdir[64], s[128], bin[128], cmd[1024], rmcmd[160];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/creas_ok_%d_d_%d", getpid(), i);
	mkdir(tmpdir, 0755);
	snprintf(s, sizeof s, "%s/creas_ok_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(bin, sizeof bin, "%s/creas_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, "creas[%s][%s]: build failed (a mutable let "
		    "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 *diag; };

static const struct rejrow reject_rows[] = {
	{ "const_set",
	  "package main;\n"
	  "fn main() i32 = { const x: i32 = 5; x = 6; return x; };\n",
	  "cannot assign to const" },
};

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

static const struct okrow ok_rows[] = {
	{ "let_set",
	  "package main;\n"
	  "fn main() i32 = { let y: i32 = 5; y = 6; return y; };\n", 6 },
};

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, "creas: 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,
			    reject_rows[i].diag, 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, "creas[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, ok_rows[i].label,
				    got, ok_rows[i].want);
				fail++;
			}
		}
	}

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