/*
 * 732_fnparams_bare_leaf_shadow — sentinel for the trio leaf-name
 * pattern's 7th leaf: wwstage's bare-leaf fnparamslookup
 * (selfhost/cmd/wcc/cgen.ww). Pins bare-leaf `foo(x)` calls (N_IDENT
 * callee) to a same-module-first walk so cgcall's widening detection
 * fires against the caller's own foo's param-type, not another
 * module's same-leaf-name foo sitting at the head of c.fnrets.
 *
 * Pre-fix wwstage's `fnparamslookup` walked c.fnrets head-first by
 * fname and returned the FIRST match's params. cgcall handed it
 * `callee.str` (the bare leaf from an N_IDENT callee) and the head-
 * pick silently picked a sibling module's same-leaf foo. When that
 * foo had a tagged-union param and the caller's own foo had a plain
 * scalar param, pushargsrev's `istaggedtype(c, pt)` then fired
 * against the wrong type and re-laid the i32 arg into a 2-word
 * tagged slot (MOVQ $7 push + MOVQ $0 tag push + 2 POPs into DI/SI)
 * instead of the caller-intended single push (MOVQ $7 push + POPQ DI).
 *
 * Cstage carries no sister bug: cmd/wcc/check.c N_CALL routes
 * `cexpr(c, n->lhs)` through scope_lookup_prefer for an N_IDENT
 * callee, then cmd/w6c/cgen.c reads params from the typed
 * `n->lhs->type`'s TY_FN sig — module-aware via the typed AST,
 * sidestepping any bare-leaf table. Same shape as #4a/#4b/#4c: cs vs
 * ws diverge on every same-leaf fn collision, but no in-tree corpus
 * declares two same-leaf fns with diverging tagged-vs-scalar param
 * shapes today, so 995_self_rebuild stays green.
 *
 * Seventh leaf of the trio graduation (after #27 aliaslookup, #28
 * fnparams *mod*-variant, #31 fnret *mod*-variant, #4a enum, #4b
 * struct, #4c def). fnparamslookupmod (the N_DOT consumer at
 * cgenexpr.ww:2876) already exists post-#28; this commit graduates
 * only the BARE-LEAF entry point. The two other bare-leaf callsites
 * (cgendecl.ww:420 scratch-reservation, cgenutil.ww:66
 * callee_variadic_param) consume the graduated lookup uniformly for
 * N_IDENT callees and stay structurally aligned with cgcall's
 * N_IDENT-branch — the cstage-natively-correct path. No
 * fnparamslookupmod re-routing of those two sites in this commit:
 * their N_DOT consumer surface (utf8.next called from strings, etc.)
 * has non-tagged param shape on both sides of every in-tree leaf
 * collision today, so the pre-existing head-pick stays accidentally
 * correct. A future stdlib port introducing a tagged-vs-scalar N_DOT
 * leaf collision will need the *mod re-routing — file at that
 * surfacing.
 *
 * Pin: row 1 sentinel-flips the bare-leaf graduation on wwstage —
 * revert the prefer pass and row 1 fails on wwstage (the extra
 * `POPQ SI` for the wrong-param-shape widening sneaks in). Cstage
 * sees one POPQ DI either way (typed AST is module-aware). Asserts
 * the single-pop shape inside the right TEXT sym + bad_imm
 * (`POPQ\tSI`) anti-check on each stage plus cs-vs-ws byte-id per
 * row.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.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;
}

struct row {
	const char *label;
	const char *src;
	const char *textsym;	/* TEXT sym containing the call */
	const char *want_imm;	/* substring that MUST appear */
	const char *bad_imm;	/* substring that MUST NOT appear */
};

/* Source ordering picks which module's `fn foo` sits at the head of
 * c.fnrets after collectfnrets' head-prepend walk. The LAST `fn foo`
 * in source order ends at the head — that's the leaf-collision the
 * same-module-first walk must beat. Caller is inside alpha; alpha's
 * foo has plain i32 param (no widening), beta's foo has tagged
 * `(i32 | void)` param (widening would re-lay 7 into a 2-word slot
 * + emit a tag push + 2 POPs). */
static const struct row rows[] = {
	{ "bare_leaf_same_module",
	  "package gamma;\n"
	  "import alpha;\n"
	  "import beta;\n"
	  "export fn main() i32 = { return 0; };\n"
	  "package alpha;\n"
	  "export fn foo(x: i32) i32 = { return x; };\n"
	  "export fn alphacaller() i32 = { return foo(7); };\n"
	  "package beta;\n"
	  "export fn foo(x: (i32 | void)) i32 = {\n"
	  "    match (x) {\n"
	  "    case let v: i32 => return v;\n"
	  "    case void       => return 0;\n"
	  "    };\n"
	  "};\n",
	  "TEXT alpha.alphacaller", "POPQ\tDI", "POPQ\tSI" },
};

static int
slurp(const char *path, char *buf, size_t cap)
{
	FILE *f = fopen(path, "rb");
	if (!f) return -1;
	size_t n = fread(buf, 1, cap - 1, f);
	fclose(f);
	buf[n] = '\0';
	return (int)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/fpb_%d_%d.ww", getpid(), i);
	snprintf(out_s, cap, "/tmp/fpb_%d_%d_%s.s",
	    getpid(), i, w6c[strlen(w6c) - 1] == 'w' ? "ww" : "c");

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	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;
}

/* Inside the named TEXT sym, before its first RET, the want_imm MUST
 * appear and the bad_imm MUST NOT. bad_imm flags pre-fix bare-leaf
 * head-walk picking beta's (i32|void)-param foo and emitting the
 * extra POPQ SI for the wrongly-widened 2-word tagged slot. */
static int
check_imm(const char *spath, const struct row *r, const char *stage)
{
	char buf[1 << 14];
	if (slurp(spath, buf, sizeof buf) < 0) {
		fprintf(stderr, "row[%s][%s]: cannot read %s\n",
		    r->label, stage, spath);
		return -1;
	}
	const char *fn = strstr(buf, r->textsym);
	if (!fn) {
		fprintf(stderr, "row[%s][%s]: no %s in %s\n",
		    r->label, stage, r->textsym, spath);
		return -1;
	}
	const char *ret = strstr(fn, "\tRET");
	if (!ret) {
		fprintf(stderr, "row[%s][%s]: no RET inside %s\n",
		    r->label, stage, r->textsym);
		return -1;
	}
	const char *good = strstr(fn, r->want_imm);
	if (!good || good >= ret) {
		fprintf(stderr,
		    "row[%s][%s]: want_imm %s missing inside %s\n",
		    r->label, stage, r->want_imm, r->textsym);
		return -1;
	}
	const char *bad = strstr(fn, r->bad_imm);
	if (bad && bad < ret) {
		fprintf(stderr,
		    "row[%s][%s]: bad_imm %s present inside %s — wrong-module foo widened\n",
		    r->label, stage, r->bad_imm, r->textsym);
		return -1;
	}
	return 0;
}

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,
			    "fnparams_bare_leaf_shadow[cstage][%s]: w6c failed\n",
			    rows[i].label);
			fail++; total++; continue;
		}
		total++;
		if (check_imm(cs_path, &rows[i], "cstage") != 0) fail++;

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

		if (emit_s(w6c_ww, &rows[i], i, ws_path, sizeof ws_path) != 0) {
			fprintf(stderr,
			    "fnparams_bare_leaf_shadow[wwstage][%s]: w6c_ww failed\n",
			    rows[i].label);
			fail++; total++;
			unlink(cs_path); continue;
		}
		total++;
		if (check_imm(ws_path, &rows[i], "wwstage") != 0) fail++;

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

		unlink(cs_path); unlink(ws_path);
	}

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