/*
 * 989_seproot_export_run — sep-build of a ROOT unit whose `export fn`
 * references an unexported LOCAL type (#69, BUG-1).
 *
 * Root cause it guards: the `--sep` producer loop compiled EVERY package,
 * INCLUDING the root build-target, with the `.wwi`-producer `-I` flag.
 * `-I` triggers wwi_emit -> check_exported_type, which rejects an exported
 * declaration that references an unexported type. A terminal binary's root
 * legitimately has such a decl (`export fn use(a: *t)` over an unexported
 * local `type t`) — fine, because the root is never imported, so its `.wwi`
 * is never consumed. The combined build never passes `-I` -> builds+runs;
 * the sep build rejected the root -> blocked every real tool's sep-build.
 * Fix: for pi==root the producer invokes `w6c -c -o` WITHOUT `-I`.
 *
 * Graph (smallest reproducing shape): root -> { c (one real dep package) }.
 * The root exports `use(a: *t)` over the unexported local `type t`.
 *
 * Asserts (all COLD — per-stage WW_PKGCACHE wipes the package cache):
 *  1. Build + run, BOTH stages -> exit EXPECT_EXIT. Pre-fix the root w6c
 *     pass exited 1 ("exported declaration references unexported type"),
 *     so the build never produced a binary.
 *  2. cs==ww (rule 10): per-package `.s`/`.wwi`/`.unit.ww` for {c,__root}
 *     AND the final binary are byte-identical between the two drivers.
 *  3. NON-VACUITY (forced -I reject): re-run the EXACT pre-fix root
 *     invocation on the produced `__root.unit.ww` — `w6c -c -I <wwi> -o`
 *     MUST exit non-zero (the export-check fires on this pattern), while
 *     `w6c -c -o` (the post-fix root invocation) MUST exit 0. Demonstrated
 *     for BOTH compilers (w6c, w6c_ww). This is the bug, isolated.
 *  4. The root `.s` is produced and defines the exported fn symbol.
 *
 * Light wwstage-driver test (CLAUDE.md rule 14): all intermediates are
 * `-o`-redirected to /tmp, so it is phase-1 parallel-safe. Models
 * 989_sepdotpath_run.c conventions; 989 prefix per the sep-gate precedent.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/stat.h>

#define EXPECT_EXIT 37

static int
runwait(const char *cmd)
{
	int rc = system(cmd);
	if (rc == -1) return -1;
	if (WIFEXITED(rc)) return WEXITSTATUS(rc);
	return 1;
}

static const char *
absbin(void)
{
	const char *b = getenv("BIN");
	if (!b) b = "out/bin";
	if (b[0] == '/') return b;
	static char buf[2048];
	char cwd[1024];
	if (getcwd(cwd, sizeof cwd) == NULL) return NULL;
	snprintf(buf, sizeof buf, "%s/%s", cwd, b);
	return buf;
}

static int
slurp(const char *path, char **outbuf, size_t *outlen)
{
	FILE *f = fopen(path, "rb");
	if (!f) return -1;
	fseek(f, 0, SEEK_END);
	long n = ftell(f);
	fseek(f, 0, SEEK_SET);
	if (n < 0) { fclose(f); return -1; }
	char *b = malloc((size_t)n + 1);
	if (!b) { fclose(f); return -1; }
	if (fread(b, 1, (size_t)n, f) != (size_t)n) { free(b); fclose(f); return -1; }
	b[n] = '\0';
	fclose(f);
	*outbuf = b;
	*outlen = (size_t)n;
	return 0;
}

static int
files_eq(const char *a, const char *b)
{
	char *ba = NULL, *bb = NULL;
	size_t na = 0, nb = 0;
	if (slurp(a, &ba, &na) < 0 || slurp(b, &bb, &nb) < 0) {
		free(ba); free(bb);
		return -1;
	}
	int eq = (na == nb && memcmp(ba, bb, na) == 0);
	free(ba); free(bb);
	return eq ? 0 : 1;
}

/* 0 if `needle` occurs in the file at `path`, 1 if absent, -1 on read err. */
static int
file_contains(const char *path, const char *needle)
{
	char *b = NULL;
	size_t n = 0;
	if (slurp(path, &b, &n) < 0) return -1;
	int found = (strstr(b, needle) != NULL);
	free(b);
	return found ? 0 : 1;
}

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

int
main(void)
{
	const char *bin = absbin();
	if (!bin) return 1;
	char td[64], cmd[8192], p[1024];
	int fail = 0;

	snprintf(td, sizeof td, "/tmp/wwseproot_%d", getpid());
	snprintf(cmd, sizeof cmd, "rm -rf %s", td);
	runwait(cmd);
	mkdir(td, 0755);

	/* lib/c — one real dep package the root imports. */
	snprintf(p, sizeof p, "%s/lib", td);     mkdir(p, 0755);
	snprintf(p, sizeof p, "%s/lib/c", td);   mkdir(p, 0755);
	snprintf(p, sizeof p, "%s/lib/c/mod.ww", td);
	if (write_file(p, "package c;\nexport fn cval() i32 = { return 5; };\n"))
		{ fail++; goto out; }

	/* Root: `export fn use(a: *t)` over the UNEXPORTED local `type t` —
	 * exactly the pattern `-I`'s check_exported_type rejected. */
	char rootww[1024];
	snprintf(rootww, sizeof rootww, "%s/root.ww", td);
	if (write_file(rootww,
	    "package main;\n"
	    "import c;\n"
	    "type t = struct { v: i32 };\n"
	    "export fn use(a: *t) i32 = { return a.v; };\n"
	    "fn main() i32 = {\n"
	    "\tlet x: t = t { v = 42 };\n"
	    "\treturn use(&x) - c.cval();\n"
	    "};\n"))
		{ fail++; goto out; }

	struct { const char *drv, *tag; char prog[1024]; }
	stg[] = { { "ww", "cs", {0} }, { "ww_ww", "ww", {0} } };

	for (int s = 0; s < 2; s++) {
		snprintf(stg[s].prog, sizeof stg[s].prog, "%s/prog.%s", td, stg[s].tag);
		/* Per-stage fresh WW_PKGCACHE -> every package compiles COLD, so the
		 * `.s`/`.unit.ww` this gate inspects are always produced. */
		snprintf(cmd, sizeof cmd,
		    "WW_PKGCACHE='%s/cache.%s' timeout 240 %s/%s build --sep "
		    "-I %s/lib -o %s %s >/dev/null 2>&1",
		    td, stg[s].tag, bin, stg[s].drv, td, stg[s].prog, rootww);
		if (runwait(cmd) != 0) {
			fprintf(stderr, "seproot FAIL: %s build --sep (pre-fix: -I on root "
			    "rejects export-fn-over-unexported-type)\n", stg[s].drv);
			fail++;
			continue;
		}
		int rc = runwait(stg[s].prog);
		if (rc != EXPECT_EXIT) {
			fprintf(stderr, "seproot FAIL: %s prog exit=%d expected %d\n",
			    stg[s].drv, rc, EXPECT_EXIT);
			fail++;
		}
	}

	/* cs==ww (rule 10): per-package .s/.unit.ww + final binary. The root's
	 * `.wwi` is intentionally NOT produced (the fix), so it is excluded
	 * here and asserted ABSENT below; the dep `c` still emits a `.wwi`. */
	const char *pkgs[] = { "c", "__root" };
	for (int i = 0; i < 2; i++) {
		const char *suf[] = { ".s", ".wwi", ".unit.ww" };
		for (int k = 0; k < 3; k++) {
			if (strcmp(pkgs[i], "__root") == 0 && strcmp(suf[k], ".wwi") == 0)
				continue;
			char a[1024], b[1024];
			snprintf(a, sizeof a, "%s/prog.%s.sepwork/%s%s",
			    td, stg[0].tag, pkgs[i], suf[k]);
			snprintf(b, sizeof b, "%s/prog.%s.sepwork/%s%s",
			    td, stg[1].tag, pkgs[i], suf[k]);
			if (files_eq(a, b) != 0) {
				fprintf(stderr, "seproot FAIL: cs!=ww for %s%s (rule 10)\n",
				    pkgs[i], suf[k]);
				fail++;
			}
		}
	}
	if (files_eq(stg[0].prog, stg[1].prog) != 0) {
		fprintf(stderr, "seproot FAIL: cs exe != ww exe (rule 10)\n");
		fail++;
	}

	/* NON-VACUITY: the fix omits `-I` for the root, so the root's `.wwi`
	 * (the producer flag's only effect) must NOT exist — BOTH stages. */
	for (int s = 0; s < 2; s++) {
		char rw[1024];
		snprintf(rw, sizeof rw, "%s/prog.%s.sepwork/__root.wwi", td, stg[s].tag);
		if (access(rw, 0) == 0) {
			fprintf(stderr, "seproot FAIL: %s produced __root.wwi (-I still "
			    "passed for the root)\n", stg[s].drv);
			fail++;
		}
	}

	/* NON-VACUITY: replay the EXACT pre-fix root invocation on the produced
	 * `__root.unit.ww`. With `-I` (the .wwi producer) the export-check fires
	 * and w6c exits non-zero; without `-I` (the post-fix invocation) it
	 * exits 0. Proven for BOTH compilers. */
	{
		char unit[1024], wwi[1024], asmf[1024];
		snprintf(unit, sizeof unit, "%s/prog.cs.sepwork/__root.unit.ww", td);
		struct { const char *comp; } cc[] = { { "w6c" }, { "w6c_ww" } };
		for (int j = 0; j < 2; j++) {
			snprintf(wwi, sizeof wwi, "%s/nv.%s.wwi", td, cc[j].comp);
			snprintf(asmf, sizeof asmf, "%s/nv.%s.s", td, cc[j].comp);
			snprintf(cmd, sizeof cmd,
			    "%s/%s -c -I %s -o %s %s >/dev/null 2>&1",
			    bin, cc[j].comp, wwi, asmf, unit);
			if (runwait(cmd) == 0) {
				fprintf(stderr, "seproot FAIL: %s -c -I accepted the root "
				    "export-over-unexported-type (bug not reproduced -> "
				    "vacuous gate)\n", cc[j].comp);
				fail++;
			}
			snprintf(cmd, sizeof cmd,
			    "%s/%s -c -o %s %s >/dev/null 2>&1",
			    bin, cc[j].comp, asmf, unit);
			if (runwait(cmd) != 0) {
				fprintf(stderr, "seproot FAIL: %s -c -o (no -I) rejected the "
				    "root unit (post-fix invocation must succeed)\n",
				    cc[j].comp);
				fail++;
			}
		}
	}

	/* The root `.s` is produced and defines the exported fn. */
	{
		char rs[1024];
		snprintf(rs, sizeof rs, "%s/prog.cs.sepwork/__root.s", td);
		if (file_contains(rs, "use") != 0) {
			fprintf(stderr, "seproot FAIL: __root.s lacks the exported `use` "
			    "symbol (root compile produced no code)\n");
			fail++;
		}
	}

out:
	snprintf(cmd, sizeof cmd, "rm -rf %s", td);
	runwait(cmd);
	if (fail) {
		fprintf(stderr, "seproot: %d check(s) failed\n", fail);
		return 1;
	}
	printf("seproot: root `export fn use(a:*t)` over unexported `type t` "
	    "via build_one_sep — build+run (exit %d) + cs==ww per-pkg + final "
	    "binary + forced -I rejects (bug) while -o accepts (both compilers)\n",
	    EXPECT_EXIT);
	return 0;
}