/*
 * 989_modresetadj_run — BUG-A (#9) regression pin: the lexer must NOT
 * leave a stale TK_MODPATH pending past a `//ww:module-reset`.
 *
 * THE BUG: `//ww:module <p>` and `//ww:module-reset` are both recognized
 * inside skipws() in SOURCE ORDER, each setting a sticky lexer flag;
 * lexnext() drains them in a FIXED order (modreset first, modpath second).
 * When the two land in the SAME skipws run with no real token between them
 * — i.e. `//ww:module e` directly followed by `//ww:module-reset`, which the
 * sep driver emits for an empty / export-less inlined module body — the
 * modreset drained first, then the STALE TK_MODPATH=e surfaced PAST the
 * reset boundary, re-binding pathmod=e. The root `package main` was then
 * validated against import path "e" → "package main does not match import
 * path e" → HARD REJECT (cmd/wcc/parse.c:1437, both stages).
 *
 * THE FIX (cmd/wcc/lex.c + lib/ww/syntax/lex.ww, skipws): a reset
 * recognized in source clears any modpath set earlier in the same skipws
 * run. In the NORMAL non-empty boundary (reset THEN the next module's path)
 * the clear is a no-op — the path is set after the reset and legitimately
 * survives (the 990-997 byte-id gates cover that case).
 *
 * WHY a direct-frontend pin and not a `ww build` dir-fixture: the driver
 * materializes an empty module's interface (`.wwi`) BEFORE composing the
 * root unit, and wwi_emit defaults a decl-less module's package line to the
 * literal "main" (task #11, a SEPARATE bug) — so a natural empty-module dir
 * import never produces the directive ADJACENCY this bug needs; it trips #11
 * first. The pin therefore feeds the composed unit (with the adjacency)
 * straight to w6c / w6c_ww, immune to #11.
 *
 * Three legs (the teeth): (1) w6c accepts the adjacency unit (pre-fix it
 * REJECTS — the BUG-A teeth); (2) w6c_ww accepts it (rule-10 twin);
 * (3) the two `.s` are byte-identical (rule-10 stage symmetry) and the
 * assembled+linked program runs to its return value (the emitted code is
 * valid, not just parse-clean).
 *
 * Light wwstage-driver test (CLAUDE.md rule 14): every intermediate is
 * `-o`-redirected to /tmp, so it is phase-1 parallel-safe and never lands
 * next to a source. Models 989_declns_sep + 994_w6c_ww conventions; 989
 * prefix per the sep-gate precedent (the 7xx range is exhausted).
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.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 const char *
absbin(void)
{
	const char *b = getenv("BIN");
	if (!b) b = "out/bin";
	if (b[0] == '/') return b;
	static char buf[2048];
	char cwd[1024];
	if (getcwd(cwd, sizeof cwd) == NULL) return NULL;
	snprintf(buf, sizeof buf, "%s/%s", cwd, b);
	return buf;
}

static int
slurp(const char *path, char **outbuf, size_t *outlen)
{
	FILE *f = fopen(path, "rb");
	if (!f) return -1;
	fseek(f, 0, SEEK_END);
	long n = ftell(f);
	fseek(f, 0, SEEK_SET);
	if (n < 0) { fclose(f); return -1; }
	char *b = malloc((size_t)n + 1);
	if (!b) { fclose(f); return -1; }
	if (fread(b, 1, (size_t)n, f) != (size_t)n) { free(b); fclose(f); return -1; }
	b[n] = '\0';
	fclose(f);
	*outbuf = b;
	*outlen = (size_t)n;
	return 0;
}

static int
files_eq(const char *a, const char *b)
{
	char *ba = NULL, *bb = NULL;
	size_t na = 0, nb = 0;
	if (slurp(a, &ba, &na) < 0 || slurp(b, &bb, &nb) < 0) {
		free(ba); free(bb);
		return -1;
	}
	int eq = (na == nb && memcmp(ba, bb, na) == 0);
	free(ba); free(bb);
	return eq ? 0 : 1;
}

static int
write_file(const char *path, const char *content)
{
	FILE *f = fopen(path, "wb");
	if (!f) return -1;
	fputs(content, f);
	fclose(f);
	return 0;
}

/*
 * The composed sep-unit carrying the bug's trigger: `//ww:module e`
 * (opens module e, sets the pending modpath) immediately followed — with
 * no real token between — by `//ww:module-reset` (closes the empty body).
 * Both directives land in ONE skipws run. The primary body then declares
 * `package main` against the reset boundary; pre-fix the stale modpath=e
 * survived and the clause was checked against "e". RET is distinctive so
 * the run leg proves main actually executed.
 */
#define RET 42
static const char UNIT[] =
	"//ww:module e\n"
	"//ww:module-reset\n"
	"package main;\n"
	"import e;\n"
	"export fn main() i32 = { return 42; };\n";

int
main(void)
{
	const char *bin = absbin();
	if (!bin) return 1;
	int pid = (int)getpid();

	char unit[64], scs[64], sww[64], obj[64], prog[64], cmd[4096];
	snprintf(unit, sizeof unit, "/tmp/mradj_%d.unit.ww", pid);
	snprintf(scs, sizeof scs, "/tmp/mradj_%d_cs.s", pid);
	snprintf(sww, sizeof sww, "/tmp/mradj_%d_ww.s", pid);
	snprintf(obj, sizeof obj, "/tmp/mradj_%d.o", pid);
	snprintf(prog, sizeof prog, "/tmp/mradj_%d.bin", pid);

	int fail = 0;

	if (write_file(unit, UNIT) != 0) {
		fprintf(stderr, "modresetadj: cannot write %s\n", unit);
		return 1;
	}

	/* Leg 1 — cstage w6c accepts the adjacency (pre-fix: REJECT). */
	snprintf(cmd, sizeof cmd,
	    "%s/w6c -c -o %s %s 2>/dev/null", bin, scs, unit);
	if (runwait(cmd) != 0) {
		fprintf(stderr,
		    "modresetadj FAIL: w6c rejected the adjacency unit (BUG-A)\n");
		fail++;
	}

	/* Leg 2 — wwstage w6c_ww accepts it (rule-10 twin). */
	snprintf(cmd, sizeof cmd,
	    "%s/w6c_ww -c -o %s %s 2>/dev/null", bin, sww, unit);
	if (runwait(cmd) != 0) {
		fprintf(stderr,
		    "modresetadj FAIL: w6c_ww rejected the adjacency unit (BUG-A)\n");
		fail++;
	}

	/* Leg 3a — the two .s are byte-identical (rule-10 stage symmetry). */
	if (!fail && files_eq(scs, sww) != 0) {
		fprintf(stderr,
		    "modresetadj FAIL: w6c vs w6c_ww .s differ (rule 10)\n");
		fail++;
	}

	/* Leg 3b — the emitted code assembles, links, and runs to RET. */
	if (!fail) {
		snprintf(cmd, sizeof cmd,
		    "%s/w6a -o %s %s 2>/dev/null", bin, obj, scs);
		if (runwait(cmd) != 0) {
			fprintf(stderr, "modresetadj FAIL: w6a errored\n");
			fail++;
		}
	}
	if (!fail) {
		snprintf(cmd, sizeof cmd,
		    "%s/w6l -o %s %s %s/../lib/libwwrt.a 2>/dev/null",
		    bin, prog, obj, bin);
		if (runwait(cmd) != 0) {
			fprintf(stderr, "modresetadj FAIL: w6l errored\n");
			fail++;
		}
	}
	if (!fail) {
		int got = runwait(prog);
		if (got != RET) {
			fprintf(stderr,
			    "modresetadj FAIL: program exit=%d want=%d\n", got, RET);
			fail++;
		}
	}

	unlink(unit); unlink(scs); unlink(sww); unlink(obj); unlink(prog);

	if (fail) return 1;
	printf("modresetadj: w6c/w6c_ww accept the //ww:module + //ww:module-reset "
	    "adjacency, byte-identical .s, program runs to %d (#9)\n", RET);
	return 0;
}