/*
 * 784_xmod_alias_struct_collide_run — project #223 runtime + byte-id
 * net. A struct-field access through a pointer-ALIAS receiver
 * (`s.<field>` where `s` is a `type s = *vtable` alias) miscompiled in
 * wwstage when the alias leaf collided with a DIFFERENT module's
 * same-leaf STRUCT (the eFinal io.stream = *vtable alias vs the
 * memio.stream struct). cgen's #191 alias-peel loop
 * (selfhost/cmd/wcc/cgenexpr.ww cgdot) broke on the name-keyed
 * structlookup's any-module fallback — it found the FOREIGN struct,
 * halted the peel with the receiver still N_TNAME, skipped the
 * pointer-to-struct field-load arm, and the field load fell through to
 * the SB-global fallback: `MOVQ <field>(SB), AX` (an undefined symbol →
 * w6l link-fail / garbage). cstage is correct — type_chase_named
 * (cmd/w6c/cgen.c) follows the resolved NAMED.under POINTER chain
 * (module-correct), never a name re-lookup. Sibling of #208 (lossy
 * name-keyed resolution leaking to a global leaf, but in the CHECKER).
 *
 * Fix (wwstage-only align-down, cgenexpr.ww:1769 peel loop): the
 * struct-break is now MODULE-AWARE — break ONLY on a struct that THIS
 * module defines (structsamemod), a same-module ALIAS keeps peeling
 * (aliassamemod), and a foreign leaf falls back to the prior
 * any-module heuristic.
 *
 * GATE-BLIND in the bootstrap: the io.stream-alias vs memio.stream-
 * struct collision is the only same-leaf alias-vs-struct cross-module
 * pair, and it only entered the corpus at the #94 eFinal FLIP (master
 * never had it). A single-module synthetic does NOT trigger — the
 * collision needs a SECOND module contributing the same-leaf struct
 * into the corpus. Hence this 2-module probe.
 *
 *   row        | shape                                  | exit | byte-id
 *   -----------+----------------------------------------+------+--------
 *   collision  | sa: type s=*vtable + vtable{reader} +  |  42  | cs==ww
 *              |   dispatcher `read(x:s) match(x.reader)`|      |
 *              | sb: type s=struct{} (same leaf, NO     |      |
 *              |   reader field) — the #223 trigger     |      |
 *   symmetric  | sa: type s=struct{} + value-receiver   |  21  | cs==ww
 *              |   `geta(x:s)`; sb: type s=*vtable alias |      |
 *              |   — guards the same-module-struct break |      |
 *              |   still fires (a naive alias-first      |      |
 *              |   reorder would mis-peel A's struct)    |      |
 *   control    | sa: alias+vtable+dispatcher, NO foreign |  30  | cs==ww
 *              |   same-leaf struct — common io-like case|      |
 *
 * The dispatcher uses a BRANCHED callee (void arm → -1, fn-ptr arm →
 * v+100) so the field load actually feeds control flow (gate-blind
 * discipline). cstage `ww build` + run pins runtime; raw w6c vs w6c_ww
 * `.s` cmp on the driver-produced combined.ww pins rule-10 byte-id
 * (the discriminating net for #223 — pre-fix the dispatcher diverges
 * `MOVQ reader(SB)` vs the pointer-field load).
 *
 * Filed-not-fixed here: #224 (the broader cross-module same-leaf STRUCT
 * name-keying at structlookupchain) — distinct, not FLIP-triggered.
 */
#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;
}

static int
slurp_eq(const char *a, const char *b)
{
	FILE *fa = fopen(a, "rb");
	FILE *fb = fopen(b, "rb");
	if (!fa || !fb) { if (fa) fclose(fa); if (fb) fclose(fb); return -1; }
	int rc = 0;
	for (;;) {
		int ca = fgetc(fa);
		int cb = fgetc(fb);
		if (ca != cb) { rc = -1; break; }
		if (ca == EOF) break;
	}
	fclose(fa); fclose(fb);
	return rc;
}

struct file { const char *name; const char *src; };

struct scenario {
	const char *label;
	const struct file *files;	/* name==NULL terminates */
	int want_exit;
};

/* ---- collision: the #223 bug ------------------------------------- */
static const struct file collision_files[] = {
	{ "sa.ww",
	  "package sa;\n"
	  "\n"
	  "export type reader = fn(x: s, v: i32) i32;\n"
	  "\n"
	  "export type vtable = struct {\n"
	  "	reader: (*reader | void),\n"
	  "};\n"
	  "\n"
	  "export type s = *vtable;\n"
	  "\n"
	  "export fn read(x: s, v: i32) i32 = {\n"
	  "	match (x.reader) {\n"
	  "	case void => return -1;\n"
	  "	case let f: *reader => return (*f)(x, v);\n"
	  "	};\n"
	  "};\n"
	  "\n"
	  "export fn mkvt(f: *reader) vtable = {\n"
	  "	return vtable { reader = f };\n"
	  "};\n"
	  "\n"
	  "export fn mkempty() vtable = {\n"
	  "	return vtable { reader = void };\n"
	  "};\n" },
	/* sb's `s` is a STRUCT sharing the leaf `s` with sa's alias — the
	 * name-keyed structlookup any-module fallback used to halt sa.read's
	 * alias-peel here. No `reader` field, so the mis-resolved field walk
	 * fell through to `MOVQ reader(SB)`. */
	{ "sb.ww",
	  "package sb;\n"
	  "\n"
	  "export type s = struct {\n"
	  "	a: i32,\n"
	  "	b: i32,\n"
	  "};\n" },
	{ "main.ww",
	  "package main;\n"
	  "\n"
	  "import sa;\n"
	  "import sb;\n"
	  "\n"
	  "fn cb(x: sa.s, v: i32) i32 = { return v + 100; };\n"
	  "\n"
	  "export fn main() i32 = {\n"
	  "	let vt = sa.mkvt((&cb): *sa.reader);\n"
	  "	let st: sa.s = &vt;\n"
	  "	let r = sa.read(st, 5);\n"
	  "	let vt2 = sa.mkempty();\n"
	  "	let st2: sa.s = &vt2;\n"
	  "	let r2 = sa.read(st2, 5);\n"
	  "	if (r != 105) { return 11; };\n"
	  "	if (r2 != -1) { return 12; };\n"
	  "	return 42;\n"
	  "};\n" },
	{ NULL, NULL }
};

/* ---- symmetric: A struct, B alias; receiver is A's struct value -- */
static const struct file symmetric_files[] = {
	{ "sa.ww",
	  "package sa;\n"
	  "\n"
	  "export type s = struct {\n"
	  "	a: i32,\n"
	  "	b: i32,\n"
	  "};\n"
	  "\n"
	  "export fn mk(av: i32, bv: i32) s = {\n"
	  "	return s { a = av, b = bv };\n"
	  "};\n"
	  "\n"
	  "export fn geta(x: s) i32 = {\n"
	  "	return x.a;\n"
	  "};\n" },
	{ "sb.ww",
	  "package sb;\n"
	  "\n"
	  "export type vtable = struct {\n"
	  "	q: i32,\n"
	  "};\n"
	  "\n"
	  "export type s = *vtable;\n" },
	{ "main.ww",
	  "package main;\n"
	  "\n"
	  "import sa;\n"
	  "import sb;\n"
	  "\n"
	  "export fn main() i32 = {\n"
	  "	let o = sa.mk(21, 8);\n"
	  "	let r = sa.geta(o);\n"
	  "	if (r != 21) { return 11; };\n"
	  "	return 21;\n"
	  "};\n" },
	{ NULL, NULL }
};

/* ---- control: same-module alias+vtable, no foreign same-leaf ----- */
static const struct file control_files[] = {
	{ "sa.ww",
	  "package sa;\n"
	  "\n"
	  "export type reader = fn(x: s, v: i32) i32;\n"
	  "\n"
	  "export type vtable = struct {\n"
	  "	reader: (*reader | void),\n"
	  "};\n"
	  "\n"
	  "export type s = *vtable;\n"
	  "\n"
	  "export fn read(x: s, v: i32) i32 = {\n"
	  "	match (x.reader) {\n"
	  "	case void => return -1;\n"
	  "	case let f: *reader => return (*f)(x, v);\n"
	  "	};\n"
	  "};\n"
	  "\n"
	  "export fn mkvt(f: *reader) vtable = {\n"
	  "	return vtable { reader = f };\n"
	  "};\n" },
	{ "main.ww",
	  "package main;\n"
	  "\n"
	  "import sa;\n"
	  "\n"
	  "fn cb(x: sa.s, v: i32) i32 = { return v + 100; };\n"
	  "\n"
	  "export fn main() i32 = {\n"
	  "	let vt = sa.mkvt((&cb): *sa.reader);\n"
	  "	let st: sa.s = &vt;\n"
	  "	let r = sa.read(st, 5);\n"
	  "	if (r != 105) { return 11; };\n"
	  "	return 30;\n"
	  "};\n" },
	{ NULL, NULL }
};

static const struct scenario scenarios[] = {
	{ "collision", collision_files, 42 },
	{ "symmetric", symmetric_files, 21 },
	{ "control",   control_files,   30 },
};

static int
run_scenario(const char *bin, const char *cdrv, const char *wdrv,
    const struct scenario *sc)
{
	(void)bin;
	/* Private fixture dir — #215: srcd is this dir (not shared /tmp),
	 * so the driver's srcd-first import search can't pick up a
	 * polluting same-name file. mkdtemp gives a unique path. */
	char dir[] = "/tmp/ww784_XXXXXX";
	if (mkdtemp(dir) == NULL) {
		fprintf(stderr, "784[%s]: mkdtemp failed\n", sc->label);
		return -1;
	}

	char path[1024], cmd[4096];
	int rc = 0;

	for (int i = 0; sc->files[i].name; i++) {
		snprintf(path, sizeof path, "%s/%s", dir, sc->files[i].name);
		FILE *f = fopen(path, "wb");
		if (!f) { fprintf(stderr, "784[%s]: write %s\n", sc->label,
		    sc->files[i].name); rc = -1; goto done; }
		fputs(sc->files[i].src, f);
		fclose(f);
	}

	/* #94 sep layout: cstage --sep build + run pins runtime; pin
	 * WW_PKGCACHE under the scratch dir so out/.pkgcache is untouched. */
	snprintf(cmd, sizeof cmd,
	    "cd %s && WW_PKGCACHE=%s/pkgc_c %s build --sep -I %s -o %s/main %s/main.ww",
	    dir, dir, cdrv, dir, dir, dir);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "784[%s]: cstage build failed\n", sc->label);
		rc = -1; goto done;
	}
	snprintf(path, sizeof path, "%s/main", dir);
	int got = runwait(path);
	if (got != sc->want_exit) {
		fprintf(stderr, "784[%s]: cstage exit %d, want %d\n",
		    sc->label, got, sc->want_exit);
		rc = -1;
	}

	/* Byte-id net (the #223 discriminator): the wwstage driver's --sep
	 * build emits per-package w6c_ww asm; pre-fix the dispatcher diverges.
	 * The root + each imported pkg compile to separate <stem>.sepwork/<pkg>.s;
	 * concat (sorted glob, identical set both stages) for the compare. */
	char cs_s[1024], ws_s[1024];
	snprintf(cmd, sizeof cmd,
	    "cd %s && WW_PKGCACHE=%s/pkgc_w %s build --sep -I %s -o %s/mainww %s/main.ww",
	    dir, dir, wdrv, dir, dir, dir);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "784[%s]: ww_ww build failed\n", sc->label);
		rc = -1; goto done;
	}
	snprintf(cs_s, sizeof cs_s, "%s/all_cs.s", dir);
	snprintf(ws_s, sizeof ws_s, "%s/all_ww.s", dir);
	snprintf(cmd, sizeof cmd, "cat %s/main.sepwork/*.s > %s 2>/dev/null",
	    dir, cs_s); if (system(cmd)) {}
	snprintf(cmd, sizeof cmd, "cat %s/mainww.sepwork/*.s > %s 2>/dev/null",
	    dir, ws_s); if (system(cmd)) {}
	if (slurp_eq(cs_s, ws_s) != 0) {
		fprintf(stderr, "784[%s]: cs.s/ww.s DIFFER (rule-10 byte-id "
		    "violation — #223 regression)\n", sc->label);
		rc = -1;
	}

done:
	/* Best-effort cleanup of the private dir. */
	snprintf(cmd, sizeof cmd, "rm -rf %s", dir);
	(void)runwait(cmd);
	return rc;
}

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char absbin[2048];
	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[2100], wdrv[2100];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);
	if (access(wdrv, X_OK) != 0) {
		fprintf(stderr, "784: ww_ww missing — cannot run the cs==ww "
		    "byte-id gate (the whole point of this test)\n");
		return 1;
	}

	int n = (int)(sizeof scenarios / sizeof scenarios[0]);
	int fail = 0;
	for (int i = 0; i < n; i++) {
		if (run_scenario(bin, cdrv, wdrv, &scenarios[i]) != 0)
			fail++;
	}

	if (fail) {
		fprintf(stderr, "784 xmod_alias_struct_collide: %d/%d "
		    "scenarios failed\n", fail, n);
		return 1;
	}
	printf("xmod_alias_struct_collide: %d/%d ok (cstage run + cs==ww "
	    "byte-id)\n", n, n);
	return 0;
}