/*
 * 773_isas_spread_variant — project #198: wwstage checker `is`/`as`
 * variant lookup walked the unflattened AST u.list (casevariantin via
 * typeeqast streq), so any variant introduced via a `...inner` spread
 * was invisible to the checker and rejected as "is/as: not a variant
 * of operand". Repro: `r: (size | io.eof | ...io.error); r is
 * io.underread;` — io.underread is in io.error's params chain, which
 * gets spliced into the parent union at tinfofornode L1827-1836, but
 * the AST u.list still holds the single `...io.error` entry that
 * streq("io.underread", "io.error") rejects.
 *
 * Fix: selfhost/cmd/wcc/check.ww checkisas (lines ~3441-3466). Route
 * through tinfo.params via flatvariantidxt (the same Phase-N helper
 * #179 cgmatch and #66 cgtagvariantidx use); fall back to casevariantin
 * AST walk when tinfo isn't available (defensive — non-#198 path stays
 * as-is). Mirrors cstage cmd/wcc/check.c:1662-1675 u->params + type_eq.
 * Closes the cgen-drain mini-cluster (#201 → #199 → #200 → #198).
 *
 * Coverage (5 rows):
 *   1. spread_is_inline_variant — `(size | io.eof | ...io.error)`,
 *                                  `r is io.underread`. THE BUG: pre-
 *                                  fix wwstage rejects with "is/as:
 *                                  not a variant of operand
 *                                  (io.underread)". Post-fix accepts;
 *                                  cgen tag-compare hits the flatten-
 *                                  spread index. No byte-id: layout-
 *                                  asymmetry on `...wrapper` (cstage
 *                                  flattens at resolve_type, wwstage
 *                                  computes maxsz off vt.size of the
 *                                  un-spliced alias — sibling task,
 *                                  not blocking checker correctness).
 *   2. direct_cross_mod_tagged   — `(size | io.eof | io.error)`,
 *                                  `r is io.error`. Direct cross-mod
 *                                  tagged variant (no spread). Regr-
 *                                  ession gate: AST-streq path always
 *                                  matched this; the new tinfo path
 *                                  must too. byte-id ON.
 *   3. cross_mod_named_void      — `(size | io.eof)`, `r is io.eof`.
 *                                  Cross-mod NAMED-void variant. Regr-
 *                                  ession gate for the io.eof shape
 *                                  used pervasively in the io fold.
 *                                  byte-id ON.
 *   4. same_module_variant       — `(i32 | str)`, `r is i32`. Bare
 *                                  same-module primitive variant.
 *                                  Lowest-bar regression gate: no
 *                                  cross-mod, no spread, no NAMED.
 *                                  byte-id ON.
 *   5. spread_as_inline_payload  — `(size | io.eof | ...io.error)`,
 *                                  `r as io.underread`. `as` twin of
 *                                  row 1: same checker path
 *                                  (checkisas dispatches on both
 *                                  N_TYPETEST and N_TYPEASSERT), with
 *                                  the payload-extract runtime gate.
 *                                  No byte-id (sibling, same as row 1).
 *
 * Per-row gates: cstage runtime exit, wwstage runtime exit, cs.s ==
 * ww.s byte-identical when byte_id != 0.
 *
 * GATE POLARITY: must stay GREEN. Rows 1/5 red means the tinfo.params
 * routing dropped a spread-flattened variant; row 2 red means the
 * direct cross-mod path broke; row 3 red means the NAMED-void path
 * broke; row 4 red means a same-module / same-package regression.
 */
#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 expected_exit;
	int stage_mask;
	int byte_id;
};

static const struct row rows[] = {
	{ "spread_is_inline_variant",
	  "package main;\n"
	  "import io;\n"
	  "type rsh = (size | io.eof | ...io.error);\n"
	  "export fn main() i32 = {\n"
	  "    let r: rsh = 42: size;\n"
	  "    if (r is io.underread) { return 1; };\n"
	  "    if (r is io.eof) { return 2; };\n"
	  "    if (r is size) { return 3; };\n"
	  "    return 0;\n"
	  "};\n",
	  3,
	  STAGE_CS | STAGE_WW, 0 },
	{ "direct_cross_mod_tagged",
	  "package main;\n"
	  "import io;\n"
	  "export fn main() i32 = {\n"
	  "    let r: (size | io.eof | io.error) = 42: size;\n"
	  "    if (r is io.error) { return 1; };\n"
	  "    if (r is io.eof) { return 2; };\n"
	  "    if (r is size) { return 3; };\n"
	  "    return 0;\n"
	  "};\n",
	  3,
	  STAGE_CS | STAGE_WW, 1 },
	{ "cross_mod_named_void",
	  "package main;\n"
	  "import io;\n"
	  "export fn main() i32 = {\n"
	  "    let r: (size | io.eof) = 42: size;\n"
	  "    if (r is io.eof) { return 1; };\n"
	  "    if (r is size) { return 3; };\n"
	  "    return 0;\n"
	  "};\n",
	  3,
	  STAGE_CS | STAGE_WW, 1 },
	{ "same_module_variant",
	  "package main;\n"
	  "export fn main() i32 = {\n"
	  "    let r: (i32 | str) = 3: i32;\n"
	  "    if (r is i32) { return 3; };\n"
	  "    if (r is str) { return 1; };\n"
	  "    return 0;\n"
	  "};\n",
	  3,
	  STAGE_CS | STAGE_WW, 1 },
	{ "spread_as_inline_payload",
	  "package main;\n"
	  "import io;\n"
	  "type rsh = (size | io.eof | ...io.error);\n"
	  "fn pick(b: i32) rsh = {\n"
	  "    if (b == 1) { let u: io.underread = 7: i32: io.underread; return u; };\n"
	  "    return 42: size;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "    let r = pick(1);\n"
	  "    let u = r as io.underread;\n"
	  "    return u: i32;\n"
	  "};\n",
	  7,
	  STAGE_CS | STAGE_WW, 0 },
};

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 void
cleanup_tmp(const char *tmpdir, const char *base)
{
	char p[512];
	snprintf(p, sizeof p, "%s/%s.ww", tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "%s/%s.o",  tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "%s/%s.combined.ww", tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "%s/%s",    tmpdir, base); unlink(p);
	/* #93: the sep scratch dir + the tmpdir-pinned pkgcache. */
	snprintf(p, sizeof p, "rm -rf %s/%s.sepwork %s/pkgc", tmpdir, base, tmpdir);
	if (system(p)) {} /* best-effort */
	rmdir(tmpdir);
}

static int
build_via_driver(const char *driver, const char *tmpdir, const char *src)
{
	char cmd[1024];
	/* #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/isas_%d_d_%d", getpid(), seq);
	snprintf(src,    sizeof src,    "%s/main773.ww", tmpdir);
	snprintf(base,   sizeof base,   "main773");
	mkdir(tmpdir, 0755);
	if (write_source(src, r->src) != 0) {
		cleanup_tmp(tmpdir, base);
		return -1;
	}
	int rc = -1;
	if (build_via_driver(driver, tmpdir, src) == 0) {
		snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
		rc = runwait(outbin);
	}
	cleanup_tmp(tmpdir, base);
	return rc;
}

/* Parallel tmpdirs per CLAUDE.md rule 14 — ww_ww writes intermediates
 * next to the source so concurrent cstage/wwstage builds against the
 * same path would race. */
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/isas_%d_c_%d", getpid(), seq);
	snprintf(tdw, sizeof tdw, "/tmp/isas_%d_w_%d", getpid(), seq);
	snprintf(base, sizeof base, "main773");
	mkdir(tdc, 0755);
	mkdir(tdw, 0755);
	snprintf(src, sizeof src, "%s/main773.ww", tdc);
	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/main773.ww", tdw);
	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 absbin[512];
	if (bin[0] != '/') {
		char cwd[256];
		if (getcwd(cwd, sizeof cwd) == NULL) return 1;
		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;
	int wwpresent = (access(wdrv, X_OK) == 0);
	int seq = 0;

	for (int i = 0; i < n; i++) {
		if (rows[i].stage_mask & STAGE_CS) {
			total++;
			int got = run_row(cdrv, &rows[i], seq++);
			if (got != rows[i].expected_exit) {
				fprintf(stderr,
				    "isas_spread_variant[cstage run][%s]: exit=%d want=%d\n",
				    rows[i].label, got, rows[i].expected_exit);
				fail++;
			}
		}
		if (wwpresent && (rows[i].stage_mask & STAGE_WW)) {
			total++;
			int got = run_row(wdrv, &rows[i], seq++);
			if (got != rows[i].expected_exit) {
				fprintf(stderr,
				    "isas_spread_variant[wwstage run][%s]: exit=%d want=%d\n",
				    rows[i].label, got, rows[i].expected_exit);
				fail++;
			}
			if (rows[i].byte_id) {
				total++;
				if (asm_byte_identical(cdrv, wdrv, &rows[i], seq++) != 0) {
					fprintf(stderr,
					    "isas_spread_variant[byte-id][%s]: cstage vs wwstage asm differs\n",
					    rows[i].label);
					fail++;
				}
			}
		}
	}

	if (!wwpresent)
		fprintf(stderr, "isas_spread_variant: skip wwstage (no %s)\n", wdrv);

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