/*
 * 722_match_slice_variant — Class A asm-presence + byte-id sentinel
 * for task #19. Pins that the variant tag chosen for a `[]T` arm in a
 * `(scalar | []T)` tagged union matches between cstage and wwstage at
 * BOTH dispatch (cgmatch's `CMPQ $K, AX`) and call-site (the
 * `MOVQ $K, AX` widening that materialises the tag for the slice
 * payload).
 *
 * Pre-fix wwstage's name-keyed flatvariantidx / str-shape fallback
 * landed on tag 0 for any `[]T` lookup (pat.str == "" because the
 * variant node is N_TSLICE, not N_TNAME). Both the case arm and the
 * call-site emitted `$0` — internally consistent inside wwstage, but
 * the cstage-vs-wwstage cmp -s diverges from cstage's correct `$1`.
 * Class A: silent until wwstage path engaged. 967_bytes_run was
 * compiled through cstage only and never tripped; lib/strings landing
 * pulls bytes through wwstage and surfaces the dispatch miscompile
 * via 995_self_rebuild.
 *
 * Asserts cmp -s byte-id on the canonical (u8 | []u8) probe plus
 * other (scalar | []scalar) shapes from rob's matrix.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include "wwtestpkg.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[] = {
	/* The canonical (u8 | []u8) repro from bytes.index. */
	{ "u8_slice_u8",
	  "fn pick(n: (u8 | []u8)) i32 = {\n"
	  "    match (n) {\n"
	  "    case let c: u8   => return 1;\n"
	  "    case let s: []u8 => return 2;\n"
	  "    };\n"
	  "    return 0;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "    let r1: i32 = pick(7u8);\n"
	  "    let buf: [2]u8;\n"
	  "    let r2: i32 = pick(buf[0:2]);\n"
	  "    if (r1 != 1) { return 11; };\n"
	  "    if (r2 != 2) { return 12; };\n"
	  "    return 0;\n"
	  "};\n" },
	/* Reverse-order shape (slice arm first): the same shape-fallback
	 * that lost (u8 | []u8) must also resolve ([]u8 | u8) without
	 * accidentally inverting via the str-shape collapse. */
	{ "slice_u8_then_u8",
	  "fn pick(n: ([]u8 | u8)) i32 = {\n"
	  "    match (n) {\n"
	  "    case let s: []u8 => return 1;\n"
	  "    case let c: u8   => return 2;\n"
	  "    };\n"
	  "    return 0;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "    let buf: [2]u8;\n"
	  "    let r1: i32 = pick(buf[0:2]);\n"
	  "    let r2: i32 = pick(7u8);\n"
	  "    if (r1 != 1) { return 11; };\n"
	  "    if (r2 != 2) { return 12; };\n"
	  "    return 0;\n"
	  "};\n" },
	/* Three-arm (u8 | []u8 | str): proves the slice axis composes with
	 * the existing str axis (str arm at idx 2 stays at idx 2). */
	{ "u8_slice_u8_str",
	  "fn pick(n: (u8 | []u8 | str)) i32 = {\n"
	  "    match (n) {\n"
	  "    case let c: u8   => return 1;\n"
	  "    case let s: []u8 => return 2;\n"
	  "    case let t: str  => return 3;\n"
	  "    };\n"
	  "    return 0;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "    let buf: [2]u8;\n"
	  "    if (pick(7u8) != 1)         { return 11; };\n"
	  "    if (pick(buf[0:2]) != 2)    { return 12; };\n"
	  "    if (pick(\"hi\") != 3)        { return 13; };\n"
	  "    return 0;\n"
	  "};\n" },
};

static int
emit_s(const char *w6c, const struct row *r, int i, char *out_s, size_t cap)
{
	char src[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/msv_asm_%d_%d.ww", getpid(), i);
	snprintf(out_s, cap, "/tmp/msv_asm_%d_%d_%s.s",
	    getpid(), i, w6c[strlen(w6c) - 1] == 'w' ? "ww" : "c");

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	wwtest_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 w6c[640], w6c_ww[640];
	snprintf(w6c, sizeof w6c, "%s/w6c", bin);
	snprintf(w6c_ww, sizeof w6c_ww, "%s/w6c_ww", bin);

	int have_ww = (access(w6c_ww, X_OK) == 0);

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

	for (int i = 0; i < n; i++) {
		char cs_path[128], ws_path[128];

		if (emit_s(w6c, &rows[i], i, cs_path, sizeof cs_path) != 0) {
			fprintf(stderr,
			    "match_slice_variant[cstage][%s]: w6c failed\n",
			    rows[i].label);
			fail++; total++; continue;
		}

		if (!have_ww) { unlink(cs_path); continue; }

		if (emit_s(w6c_ww, &rows[i], i, ws_path, sizeof ws_path) != 0) {
			fprintf(stderr,
			    "match_slice_variant[wwstage][%s]: w6c_ww failed\n",
			    rows[i].label);
			fail++; total++;
			unlink(cs_path);
			continue;
		}
		total++;
		char cmd[512];
		snprintf(cmd, sizeof cmd, "cmp -s %s %s", cs_path, ws_path);
		if (runwait(cmd) != 0) {
			fprintf(stderr,
			    "match_slice_variant[%s]: cstage vs wwstage asm differs\n",
			    rows[i].label);
			fail++;
		}

		unlink(cs_path); unlink(ws_path);
	}

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