/*
 * 782_fieldfn_leaf_collide_run — cstage-only pin for project #211, the
 * cgen sibling of #208 (the checker fix).
 *
 * SHAPE: a value-receiver fn-pointer FIELD call `s.pull(...)` whose leaf
 * name `pull` COLLIDES with a same-module GLOBAL fn `pull` of a DIFFERENT
 * register shape — the field returns a tagged `(i64 | sentinel)` (2-word
 * AX=tag/DX=word0 ABI), the global returns a scalar `i64` (1-word AX).
 * cstage resolves the call result from the CALLEE's own type (the field's
 * fn type), so it reads the tagged 2-word return correctly. wwstage cgen
 * re-derives the return type by NAME (fnretlookup over the leaf, with the
 * receiver VARIABLE name as the "module"), mis-binds the scalar global,
 * and widens a 1-word AX into the tagged slot — a silent cs≠ww miscompile
 * (wrong runtime + divergent .s). See selfhost/cmd/wcc/cgen.ww fnretlookup.
 *
 * WHY cstage-only (carve-out idiom, mirror of 777/780/781): exercising
 * this row under wwstage would trip #211 (asm differs, runtime wrong), so
 * STAGE_WW + byte_id are withheld until #211 closes. The row pins the
 * cstage-correct behaviour (the spec) so #211's fix is a graduation, not
 * a regression. #211 was MASKED until #208 landed: pre-#208 the wwstage
 * checker rejected this shape ("is/as: operand is not a tagged union")
 * before cgen ran, so the cgen path was unreachable.
 *
 *   row                  | what it pins
 *   ---------------------+----------------------------------------------
 *   field_vs_global_leaf | s.pull(&s,5) routes to the FIELD impl
 *                        | (srcpull → 105), NOT the same-named global
 *                        | `pull` (→ 14). `r is i64` / `r as i64` prove
 *                        | the result is the tagged field type. The
 *                        | global stays live (g = pull(3) = 14) so the
 *                        | collision is real, not dead-code-elided.
 *
 * GATE POLARITY: must stay GREEN. A red means the cstage call-result
 * resolution regressed on a value-receiver fn-ptr field call.
 *
 * GRADUATES to STAGE_CS | STAGE_WW + byte_id on #211 close.
 */
#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;
}

#define STAGE_CS	1
#define STAGE_WW	2

struct row {
	const char *label;
	const char *src;
	int want_exit;
	int stage_mask;
	int byte_id;
};

static const struct row rows[] = {
	{ "field_vs_global_leaf",
	  "package main;\n"
	  "type sentinel = void;\n"
	  "fn pull(x: i64) i64 = {\n"
	  "    return x + 11i64;\n"
	  "};\n"
	  "type src = struct {\n"
	  "    pull: fn(s: *src, k: i64) (i64 | sentinel),\n"
	  "};\n"
	  "fn srcpull(s: *src, k: i64) (i64 | sentinel) = {\n"
	  "    return k + 100i64;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "    let s: src;\n"
	  "    s.pull = srcpull;\n"
	  "    let g: i64 = pull(3i64);\n"
	  "    let r = s.pull(&s, 5i64);\n"
	  "    let out: i64 = -1i64;\n"
	  "    if (r is i64) { out = r as i64; };\n"
	  "    if (out == 105i64 && g == 14i64) { return 42; };\n"
	  "    return 1i32;\n"
	  "};\n",
	  42,
	  STAGE_CS, 0 },
};

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

/* Per-row tmpdir cleanup. ww_ww writes intermediates next to the source
 * (filed task #15); cstage ww does too. Sweep then rmdir. Mirror of
 * 777's cleanup_tmp. */
static void
cleanup_tmp(const char *tmpdir, const char *base)
{
	char p[640];
	snprintf(p, sizeof p, "%s/%s.ww", tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "%s/%s.s",  tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "%s/%s.o",  tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "%s/%s.combined.ww", tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "%s/%s",    tmpdir, base); unlink(p);
	rmdir(tmpdir);
}

static int
build_via_driver(const char *driver, const char *tmpdir, const char *cwd,
    const char *src)
{
	char cmd[2048];
	snprintf(cmd, sizeof cmd,
	    "cd %s && timeout 180 %s build -I %s/lib %s 2>/dev/null",
	    tmpdir, driver, cwd, src);
	return runwait(cmd);
}

static int
run_row(const char *driver, const char *cwd, const struct row *r, int seq)
{
	char tmpdir[256], src[512], base[64], outbin[768];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/ffl_%d_d_%d", getpid(), seq);
	snprintf(base,   sizeof base,   "main782");
	snprintf(src,    sizeof src,    "%s/%s.ww", tmpdir, base);
	mkdir(tmpdir, 0755);
	if (write_source(src, r->src) != 0) { cleanup_tmp(tmpdir, base); return -1; }
	int rc;
	int br = build_via_driver(driver, tmpdir, cwd, src);
	if (br == 0) {
		snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
		rc = runwait(outbin);
	} else {
		rc = -1;
	}
	cleanup_tmp(tmpdir, base);
	return rc;
}

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char cwd[256];
	if (getcwd(cwd, sizeof cwd) == NULL) return 1;
	char absbin[512];
	if (bin[0] != '/') {
		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
		bin = absbin;
	}

	char cdrv[640];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);

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

	for (int i = 0; i < n; i++) {
		/* #211: cstage-only carve-out. No STAGE_WW row until #211
		 * (cgen name-keyed call-return mis-resolution) closes. */
		if (rows[i].stage_mask & STAGE_CS) {
			total++;
			int got = run_row(cdrv, cwd, &rows[i], seq++);
			if (got != rows[i].want_exit) {
				fprintf(stderr,
				    "fieldfn_leaf_collide[cs][%s]: exit=%d want=%d\n",
				    rows[i].label, got, rows[i].want_exit);
				fail++;
			}
		}
	}

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