/*
 * 950_selfcheck — selfhost typechecker emits the same errors the
 * C-side checker does for tagged-union misuse.
 *
 * Each row is a .ww fixture + an expected stderr substring. We run
 * `wwdump_ww -r` (which invokes the selfhost checker's resolve +
 * typed passes) and grep for the substring.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>

static int
runcap(const char *cmd, char **outerr, size_t *outlen)
{
	char tmp[256];
	snprintf(tmp, sizeof tmp, "/tmp/wwd_sc_%d", getpid());
	char full[2048];
	snprintf(full, sizeof full, "%s 2>%s 1>/dev/null", cmd, tmp);
	int rc = system(full);
	FILE *f = fopen(tmp, "rb");
	if (!f) { unlink(tmp); return -1; }
	fseek(f, 0, SEEK_END);
	long n = ftell(f);
	fseek(f, 0, SEEK_SET);
	char *b = malloc((size_t)n + 1);
	if (!b) { fclose(f); unlink(tmp); return -1; }
	if (fread(b, 1, (size_t)n, f) != (size_t)n) {
		free(b); fclose(f); unlink(tmp); return -1;
	}
	b[n] = '\0';
	fclose(f); unlink(tmp);
	*outerr = b; *outlen = (size_t)n;
	(void)rc;
	return 0;
}

static int
writefile(const char *path, const char *src)
{
	FILE *f = fopen(path, "wb");
	if (!f) return -1;
	fputs(src, f);
	fclose(f);
	return 0;
}

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

static const struct row rows[] = {
	/* match: missing variant */
	{ "fn pick() (i32 | str | bool) = { return 1; };\n"
	  "fn caller() void = {\n"
	  "  let v: (i32 | str | bool) = pick();\n"
	  "  match (v) {\n"
	  "    case let x: i32 => { };\n"
	  "    case let x: str => { };\n"
	  "  };\n"
	  "};\n",
	  "match: variant not handled" },
	/* ?: enclosing not tagged */
	{ "fn inner() (i32 | str) = { return 1; };\n"
	  "fn caller() i32 = {\n"
	  "  let v: i32 = inner()?;\n"
	  "  return v;\n"
	  "};\n",
	  "?: enclosing fn return is not tagged" },
	/* ?: error variant not in enclosing return */
	{ "fn inner() (i32 | str | bool) = { return 1; };\n"
	  "fn caller() (i32 | str) = {\n"
	  "  let v: i32 = inner()?;\n"
	  "  return v;\n"
	  "};\n",
	  "?: error variant not in enclosing return" },
	/* !-flag aware: legal case (one success, two errors propagated) */
	{ "type invalid = !i32;\n"
	  "type overflow = !void;\n"
	  "fn parse() (i64 | invalid | overflow) = { return 0i64; };\n"
	  "fn caller() (i64 | invalid | overflow) = {\n"
	  "  let v: i64 = parse()?;\n"
	  "  return v + 1;\n"
	  "};\n",
	  NULL },	/* expect no error */
	/* !-flag aware: missing one error variant in enclosing return */
	{ "type invalid = !i32;\n"
	  "type overflow = !void;\n"
	  "fn parse() (i64 | invalid | overflow) = { return 0i64; };\n"
	  "fn caller() (i64 | invalid) = {\n"
	  "  let v: i64 = parse()?;\n"
	  "  return v + 1;\n"
	  "};\n",
	  "?: error variant not in enclosing return" },
	/* case T => names a non-variant */
	{ "fn pick() (i32 | str) = { return 1; };\n"
	  "fn caller() void = {\n"
	  "  let v: (i32 | str) = pick();\n"
	  "  match (v) {\n"
	  "    case let n: i32 => { };\n"
	  "    case let s: str => { };\n"
	  "    case let f: f64 => { };\n"
	  "  };\n"
	  "};\n",
	  "case: not a variant" },
	/* is T where T isn't a variant of the operand */
	{ "fn pick() (i32 | str) = { return 1; };\n"
	  "fn caller() void = {\n"
	  "  let v: (i32 | str) = pick();\n"
	  "  if (v is f64) { };\n"
	  "};\n",
	  "is/as: not a variant" },
	/* let init-type mismatch on primitives */
	{ "fn caller() void = {\n"
	  "  let x: bool = 42;\n"
	  "};\n",
	  "let: not assignable" },
	/* return type mismatch */
	{ "fn caller() i32 = {\n"
	  "  return \"hi\";\n"
	  "};\n",
	  "return: not assignable" },
};

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char wwdump[2048];
	snprintf(wwdump, sizeof wwdump, "%s/wwdump_ww", bin);

	int n = sizeof rows / sizeof rows[0];
	int fail = 0;
	for (int i = 0; i < n; i++) {
		char path[64];
		snprintf(path, sizeof path, "/tmp/wwd_sc_%d_%d.ww", getpid(), i);
		if (writefile(path, rows[i].src) != 0) { fail++; continue; }
		char cmd[2048];
		snprintf(cmd, sizeof cmd, "%s -r %s", wwdump, path);
		char *err = NULL; size_t elen = 0;
		runcap(cmd, &err, &elen);
		const char *want = rows[i].expect;
		int got_match = (err && want && strstr(err, want) != NULL);
		int expected_no_err = (want == NULL);
		int err_present = err && strstr(err,
		    "match: variant not handled") != NULL;
		err_present = err_present || (err && strstr(err,
		    "?: error variant not in enclosing return") != NULL);
		err_present = err_present || (err && strstr(err,
		    "?: enclosing fn return is not tagged") != NULL);
		err_present = err_present || (err && strstr(err,
		    "?: enclosing fn has no tagged-union return") != NULL);
		err_present = err_present || (err && strstr(err,
		    "case: not a variant") != NULL);
		err_present = err_present || (err && strstr(err,
		    "is/as: not a variant") != NULL);
		err_present = err_present || (err && strstr(err,
		    "is/as: operand is not a tagged union") != NULL);
		err_present = err_present || (err && strstr(err,
		    "let: not assignable") != NULL);
		err_present = err_present || (err && strstr(err,
		    "return: not assignable") != NULL);
		int ok;
		if (expected_no_err) ok = !err_present;
		else                 ok = got_match;
		if (!ok) {
			fprintf(stderr,
			    "row %d failed: expected %s, got stderr:\n%s\n",
			    i, want ? want : "(no error)", err ? err : "(empty)");
			fail++;
		}
		free(err);
		unlink(path);
	}
	if (fail) {
		fprintf(stderr, "%d/%d selfcheck rows failed\n", fail, n);
		return 1;
	}
	printf("selfcheck: %d/%d ok\n", n, n);
	return 0;
}