/*
 * 706_param_shadow_mod — "value names and module names are disjoint."
 *
 * Pre-fix (task #19): a fn param / local-let named `shadowmod` while
 * the same source carried `use shadowmod;` would compile cleanly and
 * silently miscompile any `shadowmod.X` body lookup — cstage's cexpr
 * N_DOT path resolved the inner ident through the shadow's value
 * bits, then emitted CALL through the str's .ptr field. Symptom in
 * the field was a SIGSEGV inside lib/log's lprintfln (worked around
 * by renaming `fmt: str` → `format: str` at commit 6b6d7dd).
 *
 * Post-fix: cstage check.c (and wwstage check.ww, run by wwdump_ww)
 * refuse the bind at the decl site with a `<kind> '<name>' shadows
 * imported module '<name>'` diagnostic. Same-leaf top-level decls
 * (e.g. `use fnmatch; fn fnmatch(...)`) are exempt — the rule fires
 * only for nested-scope binds whose declaring source file imports
 * the module.
 *
 *   row                  | shape                                | gate
 *   ---------------------+--------------------------------------+--------
 *   neg_param            | `fn p(shadowmod: str)`               | fail
 *   neg_let              | `let shadowmod: i32 = 0;`            | fail
 *   neg_mlet             | `let (shadowmod, x) = pair();`       | fail
 *   neg_forrange_single  | `for (let shadowmod .. s)`           | fail
 *   neg_forrange_tuple   | `for (let (shadowmod, x) .. s)`      | fail
 *   neg_mcase            | `match (r) { case let shadowmod ... }` | fail
 *   pos_rename           | rename param away from `shadowmod`   | exit=42
 *   neg_selfimp          | `package selfimp; import selfimp;`    | fail (both stages)
 *   pos_crossmod         | param named like a CROSS-imported mod | exit=2
 *
 * Fixtures live in test/wcc/data/paramshadowmod/. The shadow-rule rows
 * (the neg_ rows + pos_rename) are cstage-only: wwstage's check.ww runs
 * inside wwdump_ww (diagnostic), and the actual selfhost compile
 * pipeline (994_w6c_ww) doesn't trip because wwstage's cgen takes the
 * module-qualified emit path for any N_DOT-callee bare ident — see
 * STATUS.md's `Wwstage no-checkfile-pass smell` note.
 *
 * neg_selfimp / pos_crossmod (#16): pos_selfimp's old positive scenario
 * (a self-import skipped from the shadow scan so a same-named param
 * doesn't trip) is ABOLISHED — #16 check-(c) hard-rejects self-imports.
 * neg_selfimp converts it: `package selfimp; import selfimp;` must be
 * REJECTED by BOTH w6c and w6c_ww (compile-only, -o /dev/null — rule-14-
 * safe, no wwstage driver) with the "self-import" diagnostic. pos_crossmod
 * preserves the surviving shadow-TOLERANCE in legit form: src_imports
 * filters by the binding's own module, so a param named like a module a
 * SIBLING module imports (not this one) does NOT trip. The now-unreachable
 * self-import-skip arm in check_module_shadow is task #13 (not removed here).
 */
#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
run_neg(const char *driver, const char *fixdir, const char *tag)
{
	char src[64];
	snprintf(src, sizeof src, "neg_%s.ww", tag);
	char cmd[2048];
	/* cd into the fixture dir so the driver's source-dir-first
	 * import search resolves `use shadowmod;`. */
	snprintf(cmd, sizeof cmd,
	    "cd %s && %s build %s >/dev/null 2>&1", fixdir, driver, src);
	int rc = runwait(cmd);
	if (rc == 0) {
		fprintf(stderr,
		    "param_shadow_mod[neg_%s]: build unexpectedly succeeded "
		    "— shadow rule did not fire\n", tag);
		return 1;
	}
	return 0;
}

static int
run_pos(const char *driver, const char *fixdir)
{
	char cmd[2048];
	snprintf(cmd, sizeof cmd,
	    "cd %s && %s build pos_rename.ww >/dev/null 2>&1",
	    fixdir, driver);
	if (runwait(cmd) != 0) {
		fprintf(stderr,
		    "param_shadow_mod[pos_rename]: build failed — rule "
		    "over-triggered on the rename\n");
		return 1;
	}
	char bin[2048];
	snprintf(bin, sizeof bin, "%s/pos_rename", fixdir);
	int got = runwait(bin);
	unlink(bin);
	if (got != 42) {
		fprintf(stderr,
		    "param_shadow_mod[pos_rename]: exit=%d want=42\n", got);
		return 1;
	}
	return 0;
}

/*
 * neg_selfimp — the bare self-import `package selfimp; import selfimp;`
 * (selfimp/selfimptest.ww). #16 check-(c) hard-rejects it; both w6c and
 * w6c_ww must fail with the "self-import" diagnostic. Compile-only
 * (-o /dev/null): w6c/w6c_ww do not expand imports, but check-(c) fires
 * at the N_USE install seam before resolution, so a lone file rejects
 * directly — NOT a wwstage driver invocation, so rule-14-safe in 7xx.
 */
static int
run_neg_selfimp(const char *comp, const char *fixdir, const char *tag)
{
	char errp[96], cmd[2048];
	snprintf(errp, sizeof errp, "/tmp/psm_selfimp_%s_%d.err", tag, getpid());
	snprintf(cmd, sizeof cmd,
	    "cd %s && %s selfimp/selfimptest.ww -o /dev/null 2>%s",
	    fixdir, comp, errp);
	int rc = runwait(cmd);
	if (rc == 0) {
		fprintf(stderr, "param_shadow_mod[neg_selfimp-%s]: accepted "
		    "self-import (expected reject)\n", tag);
		unlink(errp);
		return 1;
	}
	FILE *f = fopen(errp, "rb");
	int found = 0;
	if (f) {
		char buf[4096];
		size_t n = fread(buf, 1, sizeof buf - 1, f);
		fclose(f);
		buf[n] = '\0';
		found = strstr(buf, "self-import") != NULL;
	}
	unlink(errp);
	if (!found) {
		fprintf(stderr, "param_shadow_mod[neg_selfimp-%s]: rejected "
		    "but no 'self-import' on stderr\n", tag);
		return 1;
	}
	return 0;
}

/*
 * pos_crossmod — surviving shadow-TOLERANCE in legit form. The bundle
 * imports `shadowmod` from module paramshadowmod and pulls module
 * `crossmod`, whose probe() has a param named `shadowmod`. src_imports
 * filters by the binding's own module, so crossmod's param does NOT trip
 * (crossmod carries no `import shadowmod`) even though a sibling module
 * imports that leaf. Build + run; exit = 2 (len "hi").
 */
static int
run_pos_crossmod(const char *driver, const char *fixdir)
{
	char cmd[2048];
	snprintf(cmd, sizeof cmd,
	    "cd %s && %s build pos_crossmod.ww >/dev/null 2>&1",
	    fixdir, driver);
	if (runwait(cmd) != 0) {
		fprintf(stderr,
		    "param_shadow_mod[pos_crossmod]: build failed — shadow "
		    "rule over-triggered on a cross-module param\n");
		return 1;
	}
	char bin[2048];
	snprintf(bin, sizeof bin, "%s/pos_crossmod", fixdir);
	int got = runwait(bin);
	unlink(bin);
	if (got != 2) {
		fprintf(stderr,
		    "param_shadow_mod[pos_crossmod]: exit=%d want=2\n", got);
		return 1;
	}
	return 0;
}

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], w6c[1024], w6c_ww[1024];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	snprintf(w6c, sizeof w6c, "%s/w6c", bin);
	snprintf(w6c_ww, sizeof w6c_ww, "%s/w6c_ww", bin);

	char fixdir[1024];
	if (getcwd(fixdir, sizeof fixdir) == NULL) return 1;
	size_t cwd_n = strlen(fixdir);
	const char *rel = "/test/wcc/data/paramshadowmod";
	if (cwd_n + strlen(rel) + 1 >= sizeof fixdir) return 1;
	memcpy(fixdir + cwd_n, rel, strlen(rel) + 1);

	int fail = 0, total = 0;
	total++; fail += run_neg(cdrv, fixdir, "param");
	total++; fail += run_neg(cdrv, fixdir, "let");
	total++; fail += run_neg(cdrv, fixdir, "mlet");
	total++; fail += run_neg(cdrv, fixdir, "forrange_single");
	total++; fail += run_neg(cdrv, fixdir, "forrange_tuple");
	total++; fail += run_neg(cdrv, fixdir, "mcase");
	total++; fail += run_pos(cdrv, fixdir);
	/* neg_selfimp: both compilers reject the self-import (compile-only,
	 * rule-14-safe). w6c always; w6c_ww when built. */
	total++; fail += run_neg_selfimp(w6c, fixdir, "cstage");
	if (access(w6c_ww, X_OK) == 0) {
		total++; fail += run_neg_selfimp(w6c_ww, fixdir, "wwstage");
	}
	total++; fail += run_pos_crossmod(cdrv, fixdir);

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