/*
 * 756_alias_chain_unwrap — sentinel for #22 alias-chain SRET/N_DOT
 * wedge. Pre-fix both stages single-peeled `if (t->kind == TY_NAMED)
 * t = t->under` in cg_sret_retsize / N_LET sizing / cgreturn / N_DOT
 * field-access (cstage) and structlookup-on-N_TNAME (wwstage); a
 * `type b = a;` over an alias-of-struct stacked two TY_NAMED layers
 * and the single peel bottomed out at the inner alias — still
 * TY_NAMED, not TY_STRUCT. Outcome: SRET-shaped returns silently
 * routed through the scalar-AX ABI (caller's receive slot
 * corrupted), let-init slots under-sized, and `s.field` reads
 * collapsed to base+0 instead of base+field_offset.
 *
 * Polarity (rule 10, mutual-symmetric): cstage's hot-path peels
 * graduated to a transitive `while (t->kind == TY_NAMED) t = t->under`
 * walk; wwstage's structlookup-misses fall through to aliaslookup +
 * recurse, mirroring slotsize's existing N_TNAME arm (cgenutil.ww
 * line 1955). The strings.tokenize wrapper shape (`type tokenizer =
 * bytes::tokenizer;`) is the original surfacing site (#22).
 *
 *   row                  | shape                                  | gate
 *   ---------------------+----------------------------------------+--------
 *   r1_i32_struct        | direct TY_STRUCT, no alias             | works pre-fix
 *   r2_slice_single      | `type a = struct{[]u8,[]u8,i64}`       | wedge pre-fix (RC=12)
 *                        | aliased once → `type b = a;`           |
 *   r3_slice_direct      | direct struct, slice fields            | works pre-fix
 *   r4_i32_double        | `type b = a; type a = struct{i32...}`  | wedge pre-fix (RC=14)
 *                        | aliased twice → `type c = b;`          |
 *
 * Each row asserts:
 *   - cstage RC == 0
 *   - wwstage RC == 0 (when w6c_ww present)
 *   - cstage and wwstage emit byte-identical asm
 *
 * Pre-fix: rows 2 and 4 fail the RC check on both stages and the
 * byte-id is also broken on rows 2/4 (one stage emits sret discipline,
 * the other emits the scalar-AX fall-through). Post-fix all 12
 * fixtures pass.
 */
#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;
}

struct row { const char *label; const char *src; };

static const struct row rows[] = {
	/* r1: direct i32-fields struct, no alias. Baseline — single
	 * TY_NAMED layer (the type itself) suffices for the existing
	 * single-peel pattern. */
	{ "r1_i32_struct",
	  "package main;\n"
	  "type r1 = struct {\n"
	  "\ta: i32, b: i32, c: i32, d: i32, e: i32, f: i32, g: i32,\n"
	  "\th: i32, i: i32, j: i32, k: i32, l: i32, m: i32, p: i32,\n"
	  "};\n"
	  "fn make_r1() r1 = {\n"
	  "\tlet b: r1;\n"
	  "\tb.p = 99i32;\n"
	  "\treturn b;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "\tlet s: r1 = make_r1();\n"
	  "\tif (s.p != 99i32) { return 11; };\n"
	  "\treturn 0;\n"
	  "};\n",
	},
	/* r2: slice-fields struct aliased once. Pre-fix wedge:
	 * `type r2_alias = r2_struct;` stacks two TY_NAMED layers, the
	 * single peel lands on the inner alias and the SRET gate falls
	 * through to scalar-AX. RC=12 pre-fix on both stages. */
	{ "r2_slice_single",
	  "package main;\n"
	  "type r2_struct = struct { in: []u8, delim: []u8, p: i64 };\n"
	  "type r2_alias = r2_struct;\n"
	  "fn make_r2() r2_alias = {\n"
	  "\tlet b: r2_struct;\n"
	  "\tb.p = 99i64;\n"
	  "\treturn b;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "\tlet s: r2_alias = make_r2();\n"
	  "\tif (s.p != 99i64) { return 12; };\n"
	  "\treturn 0;\n"
	  "};\n",
	},
	/* r3: slice-fields struct, no alias — baseline that proves the
	 * slice-payload sret discipline itself is unaffected. */
	{ "r3_slice_direct",
	  "package main;\n"
	  "type r3 = struct { in: []u8, delim: []u8, p: i64 };\n"
	  "fn make_r3() r3 = {\n"
	  "\tlet b: r3;\n"
	  "\tb.p = 99i64;\n"
	  "\treturn b;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "\tlet s: r3 = make_r3();\n"
	  "\tif (s.p != 99i64) { return 13; };\n"
	  "\treturn 0;\n"
	  "};\n",
	},
	/* r4: i32-fields struct double-aliased. Same wedge as r2 but
	 * chain length 3 — extra TY_NAMED layer between the alias and
	 * the struct. Confirms the discriminator is the chain length,
	 * not the field shape. RC=14 pre-fix on both stages. */
	{ "r4_i32_double",
	  "package main;\n"
	  "type r4_struct = struct {\n"
	  "\ta: i32, b: i32, c: i32, d: i32, e: i32, f: i32, g: i32,\n"
	  "\th: i32, i: i32, j: i32, k: i32, l: i32, m: i32, p: i32,\n"
	  "};\n"
	  "type r4_base = r4_struct;\n"
	  "type r4_alias = r4_base;\n"
	  "fn make_r4() r4_alias = {\n"
	  "\tlet b: r4_alias;\n"
	  "\tb.p = 99i32;\n"
	  "\treturn b;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "\tlet s: r4_alias = make_r4();\n"
	  "\tif (s.p != 99i32) { return 14; };\n"
	  "\treturn 0;\n"
	  "};\n",
	},
};

static int
build_and_run(const char *driver, const struct row *r, int i)
{
	char src[64], tmpdir[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/acu_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/acu_%d_d_%d", getpid(), i);

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	fputs(r->src, f);
	fclose(f);

	mkdir(tmpdir, 0755);
	snprintf(cmd, sizeof cmd, "cd %s && %s build %s",
	    tmpdir, driver, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: build via %s failed\n",
		    r->label, driver);
		unlink(src); rmdir(tmpdir);
		return -1;
	}

	const char *base = strrchr(src, '/');
	base = base ? base + 1 : src;
	char outbin[128];
	snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
	char *dot = strrchr(outbin, '.');
	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
	int got = runwait(outbin);

	unlink(src); unlink(outbin); rmdir(tmpdir);
	return got;
}

static int
emit_s(const char *w6c, const struct row *r, int i, char *out_s, size_t cap)
{
	char src[96], cmd[1024];
	snprintf(src, sizeof src, "/tmp/acu_s_%d_%d.ww", getpid(), i);
	snprintf(out_s, cap, "/tmp/acu_s_%d_%d_%s.s",
	    getpid(), i, w6c[strlen(w6c) - 1] == 'w' ? "ww" : "c");

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	fputs(r->src, f);
	fclose(f);

	snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null", w6c, out_s, src);
	int rc = runwait(cmd);
	unlink(src);
	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);
	char cw6c[640], ww6c[640];
	snprintf(cw6c, sizeof cw6c, "%s/w6c", bin);
	snprintf(ww6c, sizeof ww6c, "%s/w6c_ww", bin);

	int have_ww = (access(wdrv, X_OK) == 0)
	    && (access(ww6c, X_OK) == 0);

	int n = (int)(sizeof rows / sizeof rows[0]);
	int total = 0, fail = 0;

	for (int i = 0; i < n; i++) {
		/* cstage RC */
		total++;
		int got_c = build_and_run(cdrv, &rows[i], i);
		if (got_c != 0) {
			fprintf(stderr,
			    "alias_chain[cstage][%s]: exit=%d want=0\n",
			    rows[i].label, got_c);
			fail++;
		}

		if (!have_ww) continue;

		/* wwstage RC */
		total++;
		int got_w = build_and_run(wdrv, &rows[i], i);
		if (got_w != 0) {
			fprintf(stderr,
			    "alias_chain[wwstage][%s]: exit=%d want=0\n",
			    rows[i].label, got_w);
			fail++;
		}

		/* byte-id cstage vs wwstage */
		total++;
		char cs_path[160], ws_path[160];
		if (emit_s(cw6c, &rows[i], i, cs_path, sizeof cs_path) != 0
		    || emit_s(ww6c, &rows[i], i, ws_path, sizeof ws_path) != 0) {
			fprintf(stderr,
			    "alias_chain[byte-id][%s]: emit failed\n",
			    rows[i].label);
			fail++;
			unlink(cs_path); unlink(ws_path);
			continue;
		}
		char cmpcmd[512];
		snprintf(cmpcmd, sizeof cmpcmd, "cmp -s %s %s",
		    cs_path, ws_path);
		if (runwait(cmpcmd) != 0) {
			fprintf(stderr,
			    "alias_chain[byte-id][%s]: cstage vs wwstage asm differs\n",
			    rows[i].label);
			fail++;
		}
		unlink(cs_path); unlink(ws_path);
	}

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