/*
 * 782_fieldfn_leaf_collide_run — project #211 close, 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, cmd/wcc/check.c:1433/1490 `n->type = u->ret`), so it reads the
 * tagged 2-word return correctly. PRE-#211 wwstage cgen re-derived the
 * source shape by NAME (rhstaggedabicall → fnretlookupmod over the leaf,
 * with the receiver VARIABLE name as the "module"), mis-bound the scalar
 * global, and widened a 1-word AX into the tagged slot — a silent cs≠ww
 * miscompile (wrong runtime + divergent .s).
 *
 * THE FIX (#211, align wwstage UP to cstage, structural): rhstaggedabicall
 * (selfhost/cmd/wcc/cgenutil.ww) reads the checker-stamped result type off
 * the N_CALL node (`src.type_`, which check.ww's N_CALL stamps to the
 * callee fn-type's ret in both the SK_FN and the fn-VALUE/field paths)
 * instead of the leaf-name lookup. Mirrors harec selecting by interned
 * type id, not name (ref/harec/src/types.c:714). #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.
 *
 * Graduated to STAGE_CS | STAGE_WW + byte_id on #211 close: builds + runs
 * on both stages (exit 42) and asserts cs.s == ww.s (rule-10). A red means
 * #211 regressed — wwstage re-derived the call-result shape by leaf name
 * again, or the cstage call-result resolution broke.
 */
#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;		/* assert cs.s == ww.s */
};

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 | STAGE_WW, 1 },
};

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. */
static void
cleanup_tmp(const char *tmpdir, const char *base)
{
	char p[1024];
	snprintf(p, sizeof p, "%s/%s.ww", tmpdir, base); unlink(p);
	snprintf(p, sizeof p, "rm -rf %s/%s.sepwork %s/pkgc", tmpdir, base, tmpdir);
	if (system(p)) {} /* best-effort */
	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 *src)
{
	char cmd[2048];
	/* #93 sep layout: emit asm to <src-stem>.sepwork/__root.s; pin
	 * WW_PKGCACHE under tmpdir so out/.pkgcache is untouched. */
	snprintf(cmd, sizeof cmd,
	    "cd %s && b='%s'; WW_PKGCACHE=%s/pkgc timeout 180 %s build --sep "
	    "-o \"${b%%.ww}\" \"$b\" 2>/dev/null",
	    tmpdir, src, tmpdir, driver);
	return runwait(cmd);
}

/* run_row — build via driver, run the binary, return exit (or -1 on
 * build failure). */
static int
run_row(const char *driver, 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;
	if (build_via_driver(driver, tmpdir, src) == 0) {
		snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
		rc = runwait(outbin);
	} else {
		rc = -1;
	}
	cleanup_tmp(tmpdir, base);
	return rc;
}

/* asm_byte_identical — diff cstage vs wwstage .s. Parallel trees so
 * ww_ww writing intermediates next to the source doesn't clobber the
 * cstage .s (CLAUDE.md rule 14 phase split). Mirror of 783's helper. */
static int
asm_byte_identical(const char *cdrv, const char *wdrv, const struct row *r,
    int seq)
{
	char src[512], tdc[256], tdw[256], base[64], cs[512], ws[512];
	snprintf(tdc, sizeof tdc, "/tmp/ffl_%d_c_%d", getpid(), seq);
	snprintf(tdw, sizeof tdw, "/tmp/ffl_%d_w_%d", getpid(), seq);
	snprintf(base, sizeof base, "main782");
	mkdir(tdc, 0755);
	mkdir(tdw, 0755);
	snprintf(src, sizeof src, "%s/%s.ww", tdc, base);
	if (write_source(src, r->src) != 0) { cleanup_tmp(tdc, base); cleanup_tmp(tdw, base); return -1; }
	int rc = -1;
	if (build_via_driver(cdrv, tdc, src) != 0) goto out;
	snprintf(cs, sizeof cs, "%s/%s.sepwork/__root.s", tdc, base);

	snprintf(src, sizeof src, "%s/%s.ww", tdw, base);
	if (write_source(src, r->src) != 0) goto out;
	if (build_via_driver(wdrv, tdw, src) != 0) goto out;
	snprintf(ws, sizeof ws, "%s/%s.sepwork/__root.s", tdw, base);

	FILE *fc = fopen(cs, "rb");
	FILE *fw = fopen(ws, "rb");
	if (fc && fw) {
		rc = 0;
		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);
out:
	cleanup_tmp(tdc, base);
	cleanup_tmp(tdw, 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], wdrv[640];
	snprintf(cdrv, sizeof cdrv, "%s/ww",    bin);
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);

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

	for (int i = 0; i < n; i++) {
		const struct row *r = &rows[i];

		if (r->stage_mask & STAGE_CS) {
			total++;
			int got = run_row(cdrv, r, seq++);
			if (got != r->want_exit) {
				fprintf(stderr, "fieldfn_leaf_collide[cs][%s]: exit=%d want=%d\n",
				    r->label, got, r->want_exit);
				fail++;
			}
		}

		if (wwpresent && (r->stage_mask & STAGE_WW)) {
			total++;
			int got = run_row(wdrv, r, seq++);
			if (got != r->want_exit) {
				fprintf(stderr, "fieldfn_leaf_collide[ww][%s]: exit=%d want=%d\n",
				    r->label, got, r->want_exit);
				fail++;
			}
			if (r->byte_id) {
				total++;
				if (asm_byte_identical(cdrv, wdrv, r, seq++) != 0) {
					fprintf(stderr, "fieldfn_leaf_collide[byte-id][%s]: cstage vs wwstage asm differs\n",
					    r->label);
					fail++;
				}
			}
		}
	}

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