/*
 * 783_amp_fn_assign_run — project #206 close. Pins that a bare
 * `&fn_name` is assignable into a `*<fn-alias>` slot and a
 * `(*<fn-alias> | void)` tagged slot (the io vstream vtable shape)
 * WITHOUT the explicit `(&fn): *alias` cast that the lib/{io,memio,
 * fmt,bufio,log} vstream surfaces currently carry. #94 fold-eFinal
 * drops those casts wholesale once this is green.
 *
 * THE FIX (Option C, both stages, checker-only — cgen is a no-op
 * fn-pointer reinterpret): type_assignable / isassignable stay fully
 * NOMINAL (a materialized `*fn` value laundered into a `*alias` is
 * rejected, mirror of harec ref/harec/src/types.c:1039-1066). A
 * caller-site gate `assignable_addrfn` (cmd/wcc/check.c) /
 * `assignableaddrfn` (selfhost/cmd/wcc/check.ww) admits ONLY a DIRECT
 * `&`-of-fn-ident whose signature structurally matches the
 * destination's pointed-to fn alias, or — for a tagged dst — the
 * single matching ptr-to-fn variant (>=2 same-sig variants is
 * ambiguous → reject). This is harec's adopt-the-alias-at-the-`&`-site
 * rule (ref/harec/src/check.c:3594-3626) without threading a type
 * hint through the bottom-up expression checker.
 *
 * ROW POLARITY:
 *   POSITIVE execution assertions now live in the declarative compiler
 *   corpus. Their residual rows here compile BOTH stages and assert
 *   cs.s == ww.s (rule-10). `let_call` and `structlit_build` pin the
 *   let-binding and struct-literal-field-init gate sites.
 *   `fieldstore_dispatch` pins the eFinal SHIPPING shape: a bare &fn
 *   field-STORE into one slot of the three-slot io.vtable
 *   (reader/writer/closer), then a dispatcher match on a *vtable
 *   POINTER-param. It remains byte-id-clean: the
 *   single-slot local-composite zero-init divergence (project #213,
 *   reproduces with the cast form and a pure `(i32|void)` field — NOT a
 *   #206 regression) is a single-field artifact the real three-slot
 *   io.vtable does not hit.
 *
 *   The symmetric non-tagged rejection rows (`neg_launder`,
 *   `neg_samesig`) live in the declarative compiler corpus. Both checker
 *   paths report the common diagnostic fragment "not assignable".
 *
 *   NEGATIVE tagged-slot rows (`neg_ambiguous_tagged`,
 *   `neg_launder_tagged`) are pinned CSTAGE-ONLY. cstage REJECTS both.
 *   wwstage WRONGLY ACCEPTS them: its `(X | void)` tagged-assignability
 *   leniently matches any `*fn` against the `void` variant (project
 *   #214, the void-variant OVER-acceptance). #214 is an accept-INVALID
 *   hole and its close is REQUIRED BEFORE wwstage can become the
 *   authoritative selfhost checker; these rows graduate to STAGE_WW
 *   when #214 closes. Mirrors the 777/780/781/782 STAGE_CS carve-out.
 *
 * GATE POLARITY: must stay GREEN. Red means the #206 gate over- or
 * under-accepts or the stage output diverged.
 */
#include <stdio.h>
#include <stdlib.h>
#include <errno.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;		/* local source for asymmetric controls */
	const char *fixture;	/* declarative corpus source for byte rows */
	int stage_mask;
	int byte_id;		/* assert cs.s == ww.s */
	int expect_fail;	/* 1 = build MUST fail */
};

static const struct row rows[] = {
	/* POSITIVE byte-id: bare &fn into a *<fn-alias> let, then call. */
	{ "let_call",
	  NULL,
	  "test/wcc/data/r78_amp_fn_assign_let_call/case.ww",
	  STAGE_CS | STAGE_WW, 1, 0 },

	/* POSITIVE byte-id: struct-literal field-init of a (*alias|void)
	 * slot with bare &fn (the Hare `vtable{reader=&fn}` shape). Build
	 * only — no match (project #212 blocks struct-lit-tagged + match
	 * on wwstage cgen); the checker gate acceptance is what this pins. */
	{ "structlit_build",
	  NULL,
	  "test/wcc/data/r78_amp_fn_assign_structlit/case.ww",
	  STAGE_CS | STAGE_WW, 1, 0 },

	/* POSITIVE byte-id: bare &fn FIELD-STORE into a (*reader|void) slot
	 * of the THREE-slot vtable (the exact io.vtable reader/writer/closer
	 * eFinal shape, test 775), then dispatcher match on a *vtable
	 * POINTER-param. The live-code-address call-through AND the void-arm
	 * discrimination are exercised, and cs.s == ww.s (rule-10). This is
	 * the eFinal SHIPPING path, so it MUST be byte-id-clean: the single-
	 * slot local-composite zero-init divergence (#213) is a single-field
	 * artifact that the real three-slot io.vtable does not hit. */
	{ "fieldstore_dispatch",
	  NULL,
	  "test/wcc/data/r78_amp_fn_assign_fieldstore_dispatch/case.ww",
	  STAGE_CS | STAGE_WW, 1, 0 },

	/* NEGATIVE cstage-only (#214 wwstage void-variant over-acceptance):
	 * two same-signature ptr-to-fn variants in the tagged dst — a direct
	 * &fn is ambiguous and must be rejected, never silently bound to one. */
	{ "neg_ambiguous_tagged",
	  "package main;\n"
	  "type reader = fn(x: i32) i32;\n"
	  "type writer = fn(x: i32) i32;\n"
	  "fn myfn(x: i32) i32 = { return x; };\n"
	  "fn main() i32 = {\n"
	  "    let x: (*reader | *writer | void) = &myfn;\n"
	  "    return 0;\n"
	  "};\n",
	  NULL,
	  STAGE_CS, 0, 1 },

	/* NEGATIVE cstage-only (#214): laundering a materialized *fn into a
	 * (*reader|void) tagged slot. cstage rejects nominally; wwstage's
	 * void-variant leniency wrongly accepts. */
	{ "neg_launder_tagged",
	  "package main;\n"
	  "type reader = fn(x: i32) i32;\n"
	  "fn rd(x: i32) i32 = { return x + 1; };\n"
	  "fn main() i32 = {\n"
	  "    let p = &rd;\n"
	  "    let s: (*reader | void) = p;\n"
	  "    return 0;\n"
	  "};\n",
	  NULL,
	  STAGE_CS, 0, 1 },
};

static int
cleanup_tmp(const char *tmpdir, const char *base)
{
	char p[1024];
	int rc = 0;
	snprintf(p, sizeof p, "%s/%s", tmpdir, base);
	if (unlink(p) != 0 && errno != ENOENT) rc = -1;
	snprintf(p, sizeof p, "%s/%s.ww", tmpdir, base);
	if (unlink(p) != 0 && errno != ENOENT) rc = -1;
	/* #93: the sep scratch dir + the tmpdir-owned outputs. */
	snprintf(p, sizeof p, "rm -rf %s/%s.sepwork", tmpdir, base);
	if (runwait(p) != 0) rc = -1;
	if (rmdir(tmpdir) != 0) rc = -1;
	return rc;
}

static int
write_source(const char *path, const struct row *r)
{
	FILE *in = NULL;
	if (r->fixture != NULL) {
		in = fopen(r->fixture, "rb");
		if (in == NULL) return -1;
	}
	FILE *f = fopen(path, "wb");
	if (!f) {
		if (in != NULL) fclose(in);
		return -1;
	}
	if (in != NULL) {
		int ioerr = 0;
		for (;;) {
			int ch = fgetc(in);
			if (ch == EOF) break;
			if (fputc(ch, f) == EOF) { ioerr = 1; break; }
		}
		if (ferror(in)) ioerr = 1;
		if (fclose(in) != 0) ioerr = 1;
		if (fclose(f) != 0) ioerr = 1;
		return ioerr ? -1 : 0;
	} else {
		if (fputs(r->src, f) == EOF) {
			fclose(f);
			return -1;
		}
	}
	return fclose(f) == 0 ? 0 : -1;
}

static int
build_via_driver(const char *driver, const char *tmpdir, const char *src)
{
	char cmd[2048];
	/* #93 sep layout: `-o <src-stem>` relocates artifacts to
	 * <stem>.sepwork/ under tmpdir. expect_fail rows still fail: a checker
	 * error makes w6c return nonzero regardless of artifact placement. */
	snprintf(cmd, sizeof cmd,
	    "cd %s && b='%s'; timeout 180 %s build "
	    "-o \"${b%%.ww}\" \"$b\" 2>/dev/null",
	    tmpdir, src, driver);
	return runwait(cmd);
}

/* build_ok — 1 iff the build succeeds (used by expect_fail rows). */
static int
build_ok(const char *driver, const struct row *r, int seq)
{
	(void)seq;
	char tmpdir[] = "/tmp/afa_nf_XXXXXX";
	char src[512], base[64];
	if (mkdtemp(tmpdir) == NULL) return -1;
	snprintf(base,   sizeof base,   "main783");
	snprintf(src,    sizeof src,    "%s/%s.ww", tmpdir, base);
	if (write_source(src, r) != 0) {
		if (cleanup_tmp(tmpdir, base) != 0)
			fprintf(stderr, "amp_fn_assign[%s]: setup cleanup failed\n", r->label);
		return -1;
	}
	int br = build_via_driver(driver, tmpdir, src);
	if (cleanup_tmp(tmpdir, base) != 0) {
		fprintf(stderr, "amp_fn_assign[%s]: cleanup failed\n", r->label);
		return -1;
	}
	return br == 0;
}

/* asm_byte_identical — diff cstage vs wwstage .s. Parallel owned trees
 * keep each driver's retained <stem>.sepwork/__root.s distinct. */
static int
asm_byte_identical(const char *cdrv, const char *wdrv, const struct row *r,
    int seq)
{
	(void)seq;
	char src[512], base[64], cs[512], ws[512];
	char tdc[] = "/tmp/afa_c_XXXXXX";
	char tdw[] = "/tmp/afa_w_XXXXXX";
	snprintf(base, sizeof base, "main783");
	if (mkdtemp(tdc) == NULL) return -1;
	if (mkdtemp(tdw) == NULL) {
		if (cleanup_tmp(tdc, base) != 0)
			fprintf(stderr, "amp_fn_assign[%s]: setup cleanup failed\n", r->label);
		return -1;
	}
	snprintf(src, sizeof src, "%s/%s.ww", tdc, base);
	int rc = -1;
	if (write_source(src, r) != 0) goto out;
	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) != 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:
	if (cleanup_tmp(tdc, base) != 0) {
		fprintf(stderr, "amp_fn_assign[%s]: c cleanup failed\n", r->label);
		rc = -1;
	}
	if (cleanup_tmp(tdw, base) != 0) {
		fprintf(stderr, "amp_fn_assign[%s]: ww cleanup failed\n", r->label);
		rc = -1;
	}
	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) && r->expect_fail) {
			total++;
			int got = build_ok(cdrv, r, seq++);
			if (got != 0) {
				if (got > 0)
					fprintf(stderr, "amp_fn_assign[cs][%s]: built but expected reject\n",
					    r->label);
				else
					fprintf(stderr, "amp_fn_assign[cs][%s]: setup or cleanup failed\n",
					    r->label);
				fail++;
			}
		}

		if (wwpresent && (r->stage_mask & STAGE_WW)) {
			if (r->expect_fail) {
				total++;
				int got = build_ok(wdrv, r, seq++);
				if (got != 0) {
					if (got > 0)
						fprintf(stderr, "amp_fn_assign[ww][%s]: built but expected reject\n",
						    r->label);
					else
						fprintf(stderr, "amp_fn_assign[ww][%s]: setup or cleanup failed\n",
						    r->label);
					fail++;
				}
			} else if (r->byte_id) {
				total++;
				if (asm_byte_identical(cdrv, wdrv, r, seq++) != 0) {
					fprintf(stderr, "amp_fn_assign[byte-id][%s]: cstage vs wwstage asm differs\n",
					    r->label);
					fail++;
				}
			}
		}
	}

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