/*
 * 789_named_ptr_alias_variant_widen — project #15 close. Pins that
 * widening a BARE pointer into a tagged-union variant that is a NAMED
 * ALIAS of that pointer type computes the correct variant tag, on BOTH
 * stages byte-identically (rule-10).
 *
 * THE BUG (cgen, BOTH stages): cg_variant_match (cmd/w6c/cgen.c) /
 * cgvariantmatch (selfhost/cmd/wcc/cgenutil.ww), in the "exactly one
 * side NAMED" branch, only matched TAGGED-vs-TAGGED and otherwise
 * returned no-match. So widening a bare `*vtable` into the `stream`
 * (= *vtable) variant of `handle = (file | stream)` matched NO variant
 * → the tag-selection (cg_tag_for_variant / flatvariantidxt) defaulted
 * to tag 0 (= file). The eFinal `io.write(&cgoutstream.vt, buf)` in the
 * compiler's own emit path (cgen.ww:745, `&cgoutstream.vt` a bare
 * *io.vtable widening into io.handle) then dispatched the fd arm,
 * wrote asm to a garbage fd, and the w6c_ww it built miscompiled every
 * program (#15 — a "scale" red herring; it is per-call deterministic).
 *
 * THE FIX (#15 + drew proviso): the tag-selection does exact-match
 * first (unchanged); only when NO variant exact-matches does it
 * structurally match a BARE source against a NAMED-alias variant. A
 * NAMED source still binds its own NAMED variant (a bare `i64` into
 * `(i64 | oserror)` picks the exact `i64`, not the oserror alias). The
 * structural fallback is guarded the way #218 guards its nested-widen
 * site: a bare source matching >=2 NAMED variants is ambiguous without
 * nominal layout → LOUD hard-error, never a silent first-pick.
 *
 *   row                | shape                                   | exit | byte-id
 *   -------------------+-----------------------------------------+------+--------
 *   handle_widen       | bare *vtable widened into the `stream`  |  42  | cs==ww
 *                      |   (= *vtable) variant of (file|stream), |      |
 *                      |   summed 10x via the stream match arm   |      |
 *                      |   (pre-fix took the file arm → 86)      |      |
 *   degenerate_ambig   | (sa | sb), both = *vtable; a bare       | both | (reject
 *                      |   *vtable widen matches BOTH NAMED       |reject|  net)
 *                      |   variants → guard must LOUD hard-error  |      |
 *                      |   on BOTH stages (drew proviso lock)     |      |
 *
 * GATE POLARITY: must stay GREEN. Red on handle_widen means the
 * NAMED-ptr-alias-variant widen regressed (wrong tag); red on
 * degenerate_ambig means the >=2 ambiguity guard stopped firing.
 */
#include <stdio.h>
#include <stdlib.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;
}

#define STAGE_CS	1
#define STAGE_WW	2

struct row {
	const char *label;
	const char *src;
	int want_exit;
	int stage_mask;
	int byte_id;
	int expect_reject;	/* 1 = BOTH stages must hard-error */
};

static const struct row rows[] = {
	/* POSITIVE byte-id + runtime: bare *vtable widened into the NAMED
	 * `stream` variant — the #15 fix. */
	{ "handle_widen",
	  "package main;\n"
	  "type vtable = struct { x: i32 };\n"
	  "type stream = *vtable;\n"
	  "type file = i32;\n"
	  "type handle = (file | stream);\n"
	  "fn hwrite(h: handle, n: u64) u64 = {\n"
	  "	match (h) {\n"
	  "	case file => return 111u64;\n"
	  "	case let s: stream => return n;\n"
	  "	};\n"
	  "};\n"
	  "fn emit(v: *vtable, n: u64) u64 = { return hwrite(v, n); };\n"
	  "export fn main() i32 = {\n"
	  "	let vt: vtable; vt.x = 0;\n"
	  "	let sum: u64 = 0u64; let i: i32 = 0;\n"
	  "	for (i < 10) { sum = sum + emit(&vt, 4u64); i += 1; };\n"
	  "	if (sum == 40u64) { return 42; };\n"
	  "	return (sum: i32);\n"
	  "};\n",
	  42, STAGE_CS | STAGE_WW, 1, 0 },

	/* GUARD lock (drew proviso): a bare *vtable widened into a union of
	 * TWO NAMED *vtable aliases is ambiguous → BOTH stages hard-error. */
	{ "degenerate_ambig",
	  "package main;\n"
	  "type vtable = struct { x: i32 };\n"
	  "type sa = *vtable;\n"
	  "type sb = *vtable;\n"
	  "type h = (sa | sb);\n"
	  "fn w(x: h) i32 = { match (x) { case sa => return 1; case sb => return 2; }; };\n"
	  "fn emit(v: *vtable) i32 = { return w(v); };\n"
	  "export fn main() i32 = { let vt: vtable; vt.x = 0; return emit(&vt); };\n",
	  0, STAGE_CS | STAGE_WW, 0, 1 },
};

static void
cleanup_tmp(const char *tmpdir, const char *base)
{
	char p[1024];
	snprintf(p, sizeof p, "%s/%s",             tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "%s/%s.ww",          tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "rm -rf %s/%s.sepwork %s/pkgc", tmpdir, base, tmpdir);
	if (system(p)) {} /* best-effort */
	snprintf(p, sizeof p, "%s/%s.o",           tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "%s/%s.combined.ww", tmpdir, base); unlink(p);
	rmdir(tmpdir);
}

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

static int
build_via_driver(const char *driver, const char *tmpdir, const char *src)
{
	char cmd[2048];
	/* #93 sep layout: emit asm to <src-stem>.sepwork/__root.s; pin
	 * WW_PKGCACHE under tmpdir so out/.pkgcache is untouched. */
	snprintf(cmd, sizeof cmd,
	    "cd %s && b='%s'; WW_PKGCACHE=%s/pkgc timeout 180 %s build --sep "
	    "-o \"${b%%.ww}\" \"$b\" 2>/dev/null",
	    tmpdir, src, tmpdir, driver);
	return runwait(cmd);
}

static int
run_row(const char *driver, const struct row *r, int seq)
{
	char tmpdir[256], src[512], base[64], outbin[768];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/npav_%d_d_%d", getpid(), seq);
	snprintf(base,   sizeof base,   "main789");
	snprintf(src,    sizeof src,    "%s/%s.ww", tmpdir, base);
	mkdir(tmpdir, 0755);
	if (write_source(src, r->src) != 0) { cleanup_tmp(tmpdir, base); return -1; }
	int rc;
	if (build_via_driver(driver, tmpdir, src) == 0) {
		snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
		rc = runwait(outbin);
	} else {
		rc = -1;
	}
	cleanup_tmp(tmpdir, base);
	return rc;
}

/* build_fails — 1 iff the driver build FAILS (used by expect_reject). */
static int
build_fails(const char *driver, const struct row *r, int seq)
{
	char tmpdir[256], src[512], base[64];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/npav_%d_x_%d", getpid(), seq);
	snprintf(base,   sizeof base,   "main789");
	snprintf(src,    sizeof src,    "%s/%s.ww", tmpdir, base);
	mkdir(tmpdir, 0755);
	if (write_source(src, r->src) != 0) { cleanup_tmp(tmpdir, base); return 0; }
	int br = build_via_driver(driver, tmpdir, src);
	cleanup_tmp(tmpdir, base);
	return br != 0;
}

static int
asm_byte_identical(const char *cdrv, const char *wdrv, const struct row *r,
    int seq)
{
	char src[512], tdc[256], tdw[256], base[64], cs[512], ws[512];
	snprintf(tdc, sizeof tdc, "/tmp/npav_%d_c_%d", getpid(), seq);
	snprintf(tdw, sizeof tdw, "/tmp/npav_%d_w_%d", getpid(), seq);
	snprintf(base, sizeof base, "main789");
	mkdir(tdc, 0755);
	mkdir(tdw, 0755);
	snprintf(src, sizeof src, "%s/%s.ww", tdc, base);
	if (write_source(src, r->src) != 0) { cleanup_tmp(tdc, base); cleanup_tmp(tdw, base); return -1; }
	int rc = -1;
	if (build_via_driver(cdrv, tdc, src) != 0) goto out;
	snprintf(cs, sizeof cs, "%s/%s.sepwork/__root.s", tdc, base);
	snprintf(src, sizeof src, "%s/%s.ww", tdw, base);
	if (write_source(src, r->src) != 0) goto out;
	if (build_via_driver(wdrv, tdw, src) != 0) goto out;
	snprintf(ws, sizeof ws, "%s/%s.sepwork/__root.s", tdw, base);
	FILE *fc = fopen(cs, "rb");
	FILE *fw = fopen(ws, "rb");
	if (fc && fw) {
		rc = 0;
		for (;;) {
			int a = fgetc(fc);
			int b = fgetc(fw);
			if (a != b) { rc = -1; break; }
			if (a == EOF) break;
		}
	}
	if (fc) fclose(fc);
	if (fw) fclose(fw);
out:
	cleanup_tmp(tdc, base);
	cleanup_tmp(tdw, base);
	return rc;
}

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char cwd[256];
	if (getcwd(cwd, sizeof cwd) == NULL) return 1;
	char absbin[512];
	if (bin[0] != '/') {
		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
		bin = absbin;
	}

	char cdrv[640], wdrv[640];
	snprintf(cdrv, sizeof cdrv, "%s/ww",    bin);
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);

	int n = (int)(sizeof rows / sizeof rows[0]);
	int total = 0, fail = 0, seq = 0;
	int wwpresent = (access(wdrv, X_OK) == 0);

	for (int i = 0; i < n; i++) {
		const struct row *r = &rows[i];

		if (r->stage_mask & STAGE_CS) {
			total++;
			if (r->expect_reject) {
				if (!build_fails(cdrv, r, seq++)) {
					fprintf(stderr, "npav[cs][%s]: built but expected reject\n",
					    r->label);
					fail++;
				}
			} else {
				int got = run_row(cdrv, r, seq++);
				if (got != r->want_exit) {
					fprintf(stderr, "npav[cs][%s]: exit=%d want=%d\n",
					    r->label, got, r->want_exit);
					fail++;
				}
			}
		}

		if (wwpresent && (r->stage_mask & STAGE_WW)) {
			total++;
			if (r->expect_reject) {
				if (!build_fails(wdrv, r, seq++)) {
					fprintf(stderr, "npav[ww][%s]: built but expected reject\n",
					    r->label);
					fail++;
				}
			} else {
				int got = run_row(wdrv, r, seq++);
				if (got != r->want_exit) {
					fprintf(stderr, "npav[ww][%s]: exit=%d want=%d\n",
					    r->label, got, r->want_exit);
					fail++;
				}
				if (r->byte_id) {
					total++;
					if (asm_byte_identical(cdrv, wdrv, r, seq++) != 0) {
						fprintf(stderr, "npav[byte-id][%s]: cstage vs wwstage asm differs\n",
						    r->label);
						fail++;
					}
				}
			}
		}
	}

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