/*
 * 826_alias_tuple_coerce — an alias of a tuple type, initialised with an
 * UNTYPED tuple literal, must coerce element-wise just like a direct tuple
 * (task #99). `type pair = (int, int); let x: pair = (3, 4)` was rejected by
 * cstage — `init (untyped_int, untyped_int) not assignable to declared pair`
 * — while the direct `let x: (int,int) = (3,4)` and the typed-alias
 * `let x: pair = (3:int, 4:int)` both compiled. wwstage already accepted+ran
 * the untyped-alias form correctly.
 *
 * ROOT (cstage only): cmd/wcc/type.c type_assignable's tuple-to-tuple arm
 * gated on the UN-chased `dst->kind == TY_TUPLE`. For `pair` (a TY_NAMED
 * alias) dst->kind is TY_NAMED, so the arm was skipped and the per-element
 * untyped->int coercion never ran. The fix chases TY_NAMED on both sides
 * before the tuple check (mirroring the #258 slice-borrow arm just below),
 * so an alias-of-tuple gets the same element-wise coercion as a direct tuple.
 * type_assignable is the shared assignability predicate, so INIT, FN-ARG and
 * RETURN positions all flip reject->accept in one spot. cstage-only —
 * wwstage check.ww/cgen are unchanged.
 *
 * The coercion still type-checks per element, so a genuinely mismatched
 * element type or wrong arity STILL louds — those are the negative controls.
 *
 *   row         | shape                                          | want
 *   ------------+------------------------------------------------+------
 *   init        | type pair=(int,int); let x:pair=(3,4); x.0+x.1 | 7
 *   fnarg       | fn g(p:pair); g((3,4)); p.0+p.1                | 7
 *   ret         | fn f() pair = { return (3,4); }; r.0+r.1       | 7
 *   mixed       | type box=(int,u16); let x:box=(3,4); coerce ea | 7
 *   ctrl_dir    | direct (int,int)=(3,4) (no-regress)            | 7
 *   ctrl_typed  | alias (3:int,4:int)   (no-regress)             | 7
 *
 * init / fnarg / ret / mixed are the mutation-sane rows: pre-fix cstage
 * build-FAILS them (the untyped->alias coercion was rejected); pre-fix
 * wwstage built but a two-field alias-tuple fn-arg read garbage (the param
 * spill half). Post-fix BOTH stages build+run the want.
 *
 * Negative controls (cstage must STILL loud — don't over-accept):
 *   neg_type    | let x:pair=(3,"s")    (element type mismatch)
 *   neg_arity   | let x:pair=(3,4,5)    (wrong arity)
 *
 * byte-id: the init, fnarg and ret rows are asserted byte-identical
 * (cstage==wwstage .s). #99 shipped in two halves — the cstage type.c chase
 * (init/fnarg/ret reject->accept) AND the wwstage cgendecl.ww tuple-PARAM
 * spill chase (the param twin: an alias param gated on the SYNTACTIC
 * N_TTUPLE node fell through to the scalar path, spilling one arg reg and
 * dropping the second tuple word, so a two-field read of an alias-tuple
 * fn-arg returned garbage in wwstage). With the wwstage half landed the
 * fnarg/ret prologues converge to cstage, so both read both fields and
 * match byte-for-byte. mixed (an init row) stays runtime-only.
 */
#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; int want; int byteid; };

static const struct row rows[] = {
	/* init — THE construct: untyped tuple literal -> alias, read both
	 * fields. byte-id clean across stages. */
	{ "init",
	  "package main;\n"
	  "type pair = (int, int);\n"
	  "export fn main() i32 = {\n"
	  "\tlet x: pair = (3, 4);\n"
	  "\treturn (x.0 + x.1): i32;\n"
	  "};\n",
	  7, 1 },

	/* fnarg — untyped tuple literal coerced into an alias-typed param at
	 * the call site, reading BOTH fields. The wwstage tuple-PARAM spill
	 * chase (cgendecl.ww, #99 second half) sizes the alias param slot 16B
	 * and spills both arg regs, so p.0+p.1 is correct and byte-identical
	 * to cstage. */
	{ "fnarg",
	  "package main;\n"
	  "type pair = (int, int);\n"
	  "fn g(p: pair) i32 = {\n"
	  "\treturn (p.0 + p.1): i32;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "\treturn g((3, 4));\n"
	  "};\n",
	  7, 1 },

	/* ret — untyped tuple literal coerced into the declared alias return
	 * type; the receiving alias-tuple let reads both fields, byte-id. */
	{ "ret",
	  "package main;\n"
	  "type pair = (int, int);\n"
	  "fn f() pair = {\n"
	  "\treturn (3, 4);\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "\tlet r: pair = f();\n"
	  "\treturn (r.0 + r.1): i32;\n"
	  "};\n",
	  7, 1 },

	/* mixed — heterogeneous element types under the alias; each untyped
	 * element coerces to its declared field type. runtime-only. */
	{ "mixed",
	  "package main;\n"
	  "type box = (int, u16);\n"
	  "export fn main() i32 = {\n"
	  "\tlet x: box = (3, 4);\n"
	  "\treturn (x.0 + (x.1: int)): i32;\n"
	  "};\n",
	  7, 0 },

	/* ctrl_dir — direct (un-aliased) tuple init; already worked, guards
	 * against a regression in the original tuple path. */
	{ "ctrl_dir",
	  "package main;\n"
	  "export fn main() i32 = {\n"
	  "\tlet x: (int, int) = (3, 4);\n"
	  "\treturn (x.0 + x.1): i32;\n"
	  "};\n",
	  7, 0 },

	/* ctrl_typed — alias init with already-typed elements (no untyped
	 * coercion); already worked via the named-arm type_eq. */
	{ "ctrl_typed",
	  "package main;\n"
	  "type pair = (int, int);\n"
	  "export fn main() i32 = {\n"
	  "\tlet x: pair = (3: int, 4: int);\n"
	  "\treturn (x.0 + x.1): i32;\n"
	  "};\n",
	  7, 0 },
};

/* neg — cstage must STILL reject these (the coercion type-checks per
 * element; a type mismatch or wrong arity is not assignable). cstage-only:
 * wwstage pre-existingly over-accepts a mismatched tuple init (a separate
 * wwstage bug, out of #99 scope), so the negative is asserted against the
 * cstage driver only — the side #99 touches. */
static const char *neg[] = {
	/* neg_type — second element str vs declared int. */
	"package main;\n"
	"type pair = (int, int);\n"
	"export fn main() i32 = {\n"
	"\tlet x: pair = (3, \"s\");\n"
	"\treturn x.0: i32;\n"
	"};\n",

	/* neg_arity — three elements vs the two-element alias. */
	"package main;\n"
	"type pair = (int, int);\n"
	"export fn main() i32 = {\n"
	"\tlet x: pair = (3, 4, 5);\n"
	"\treturn x.0: i32;\n"
	"};\n",
};

static int
run_driver(const char *driver, const struct row *r, int i)
{
	char src[64], tmpdir[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/atc_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/atc_%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 2>/dev/null",
	    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;
}

/* build_should_fail — the negative control must error on `driver`; returns
 * 0 when the build correctly FAILS, non-zero when it wrongly succeeded. */
static int
build_should_fail(const char *driver, const char *src, int i)
{
	char s[64], tmpdir[64], cmd[1024];
	snprintf(s, sizeof s, "/tmp/atc_neg_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/atc_neg_%d_d_%d", getpid(), i);

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

	mkdir(tmpdir, 0755);
	snprintf(cmd, sizeof cmd, "cd %s && %s build %s 2>/dev/null",
	    tmpdir, driver, s);
	int rc = runwait(cmd);
	unlink(s);
	const char *base = strrchr(s, '/');
	base = base ? base + 1 : s;
	char outbin[128];
	snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
	char *dot = strrchr(outbin, '.');
	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
	unlink(outbin);
	rmdir(tmpdir);
	return rc == 0 ? -1 : 0;	/* build must NOT succeed */
}

/* asm_byte_identical — w6c vs w6c_ww .s for the same source must match. */
static int
asm_byte_identical(const char *bin, const struct row *r, int i)
{
	char src[64], cs[64], ws[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/atc_asm_%d_%d.ww", getpid(), i);
	snprintf(cs,  sizeof cs,  "/tmp/atc_asm_%d_%d_c.s", getpid(), i);
	snprintf(ws,  sizeof ws,  "/tmp/atc_asm_%d_%d_w.s", getpid(), i);

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

	snprintf(cmd, sizeof cmd, "%s/w6c -o %s %s 2>/dev/null", bin, cs, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: w6c errored\n", r->label);
		unlink(src);
		return -1;
	}
	snprintf(cmd, sizeof cmd, "%s/w6c_ww -o %s %s 2>/dev/null",
	    bin, ws, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: w6c_ww errored\n", r->label);
		unlink(src); unlink(cs);
		return -1;
	}

	FILE *fc = fopen(cs, "rb");
	FILE *fw = fopen(ws, "rb");
	int rc = 0;
	if (!fc || !fw) {
		rc = -1;
	} else {
		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);
	if (rc != 0)
		fprintf(stderr, "row[%s]: cstage vs wwstage asm differs\n",
		    r->label);
	unlink(src); unlink(cs); unlink(ws);
	return rc;
}

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char absbin[1024];
	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[1024];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	char wdrv[1024];
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);

	struct { const char *name; const char *path; int gated_on_existence; }
	drivers[] = {
		{ "cstage",  cdrv, 0 },
		{ "wwstage", wdrv, 1 },
		{ NULL, NULL, 0 },
	};

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

	for (int d = 0; drivers[d].name; d++) {
		if (drivers[d].gated_on_existence
		    && access(drivers[d].path, X_OK) != 0) {
			fprintf(stderr, "alias_tuple_coerce: skip %s (no %s)\n",
			    drivers[d].name, drivers[d].path);
			continue;
		}
		for (int i = 0; i < n; i++) {
			int got = run_driver(drivers[d].path, &rows[i], i);
			total++;
			if (got != rows[i].want) {
				fprintf(stderr,
				    "alias_tuple_coerce[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, rows[i].label,
				    got, rows[i].want);
				fail++;
			}
		}
	}

	/* Negative controls — cstage must STILL reject (don't over-accept).
	 * cstage-only: the #99 fix is cstage-side, and wwstage pre-existingly
	 * over-accepts a mismatched tuple init (out-of-scope wwstage bug). */
	for (int i = 0; i < nneg; i++) {
		total++;
		if (build_should_fail(cdrv, neg[i], i) != 0) {
			fprintf(stderr,
			    "alias_tuple_coerce[cstage][neg_%d]: built (should loud)\n",
			    i);
			fail++;
		}
	}

	/* byte-id — only rows flagged byteid (the INIT form). */
	if (access(wdrv, X_OK) == 0) {
		for (int i = 0; i < n; i++) {
			if (!rows[i].byteid) continue;
			total++;
			if (asm_byte_identical(bin, &rows[i], i) != 0)
				fail++;
		}
	}

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