/*
 * 650_dot_chain — chained dotted access through value-struct fields
 * must compile to a single load/store at (base + sum-of-offsets),
 * not silently lower to an undefined global symbol or shuffle stale
 * registers. Drew filed this from worker-bufio when the Hare-shaped
 * `scanner` embed in lib/bufio tripped the cgen.
 *
 * Each fixture exercises a different chain shape. The repro from
 * drew's bug report is row[0]; the rest pin: 3-deep chains, slice
 * pseudo-field tails (`s.buf.len`), global-rooted chains, and
 * mixed leaf widths (u8 / i32 / u32). `&o.i.a` address-of and i8
 * sign-extend leaves are deferred (tasks #9 / #10).
 *
 * Exercises both stages via `ww` (cstage) and `ww_ww` (wwstage)
 * when present, so a regression on either side is caught here.
 */
#include <stdio.h>
#include <stdlib.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; int want; };

static const struct row rows[] = {
	/* Drew's repro: 2-deep value-struct read AND write. Returns
	 * o.i.a (=10) + o.x (=5) = 15. */
	{ "drew_2deep_read_write",
	  "type inner = struct { a: i32, b: i32, c: i32 };\n"
	  "type outer = struct { i: inner, x: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let o: outer; o.i.a = 10; o.x = 5;\n"
	  "    return o.i.a + o.x;\n"
	  "};\n",
	  15 },
	/* 3-deep value-struct chain. Proves the spine walker is loop-
	 * shaped, not hardcoded to depth 2. */
	{ "value_struct_3deep",
	  "type a3 = struct { a: i32 };\n"
	  "type a2 = struct { a: a3 };\n"
	  "type a1 = struct { a: a2 };\n"
	  "fn main() i32 = {\n"
	  "    let v: a1;\n"
	  "    v.a.a.a = 7;\n"
	  "    return v.a.a.a;\n"
	  "};\n",
	  7 },
	/* Slice pseudo-field tail through a value-struct field: write
	 * .ptr/.len/.cap on s.buf where buf: []u8 is a struct field.
	 * Read back .len through the same chain. */
	{ "slice_field_pseudo",
	  "type bag = struct { buf: []u8, x: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let arr: [8]u8;\n"
	  "    let i: i32 = 0;\n"
	  "    for (i < 8) { arr[i] = i: u8; i = i + 1; };\n"
	  "    let b: bag;\n"
	  "    b.buf.ptr = &arr[0];\n"
	  "    b.buf.len = 5;\n"
	  "    b.buf.cap = 8;\n"
	  "    b.x = 0;\n"
	  "    return b.buf.len;\n"
	  "};\n",
	  5 },
	/* u8 leaf through a chained struct: round-trips a single byte
	 * unchanged (no narrow cast in play — direct MOVB write +
	 * MOVZBQ read). Pins the leaf-width dispatch in the walker. */
	{ "u8_leaf_through_chain",
	  "type holder = struct { val: u8, pad: u8 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let b: box;\n"
	  "    b.h.val = 99u8;\n"
	  "    b.h.pad = 0u8;\n"
	  "    b.tag = 0;\n"
	  "    return b.h.val: i32;\n"
	  "};\n",
	  99 },
	/* i32 leaf through a chained struct, value > 255 to confirm the
	 * MOVL store width (not silently narrowed to MOVB). Returns 42
	 * iff the full 4-byte value round-trips. */
	{ "i32_leaf_through_chain",
	  "type holder = struct { val: i32, pad: i32 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let b: box;\n"
	  "    b.h.val = 0x12345;\n"
	  "    b.h.pad = 0;\n"
	  "    b.tag = 0;\n"
	  "    if (b.h.val == 0x12345) { return 42; };\n"
	  "    return 0;\n"
	  "};\n",
	  42 },
	/* u32 leaf through a chained struct. Distinct write + read at
	 * the chained leaf, value chosen so the MOVL store + load
	 * round-trip preserves all four bytes. */
	{ "u32_leaf_through_chain",
	  "type holder = struct { val: u32, pad: u32 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let b: box;\n"
	  "    b.h.val = 4321u32;\n"
	  "    b.h.pad = 0u32;\n"
	  "    b.tag = 0;\n"
	  "    if (b.h.val == 4321u32) { return 42; };\n"
	  "    return 0;\n"
	  "};\n",
	  42 },
	/* Global-rooted chain: write+read through a top-level `let g`.
	 * Pins the LEAQ name(SB), CX → MOVQ disp(CX) path on both
	 * stages (the local-rooted rows above pin the BP-relative
	 * path). 11 + 3 = 14. */
	{ "global_root_chain",
	  "type inner = struct { a: i32, b: i32 };\n"
	  "type outer = struct { i: inner, x: i32 };\n"
	  "let g: outer;\n"
	  "fn main() i32 = {\n"
	  "    g.i.a = 11; g.x = 3;\n"
	  "    return g.i.a + g.x;\n"
	  "};\n",
	  14 },
	/* `*T` parameter, single-dot read: `fn f(o: *outer) i32 = o.f`.
	 * Already worked via the existing pointer-to-struct-field
	 * branch; pinned here so future refactors don't regress it. */
	{ "ptr_root_single_read",
	  "type outer = struct { f: i32, g: i32 };\n"
	  "fn get(o: *outer) i32 = { return o.f; };\n"
	  "fn main() i32 = {\n"
	  "    let x: outer; x.f = 42; x.g = 0;\n"
	  "    return get(&x);\n"
	  "};\n",
	  42 },
	/* `*T` parameter, single-dot write: `fn f(o: *outer) void = …`.
	 * Already worked via the via_ptr branch in N_ASSIGN; pinned
	 * for the same reason. */
	{ "ptr_root_single_write",
	  "type outer = struct { f: i32, g: i32 };\n"
	  "fn set(o: *outer) void = { o.f = 42; };\n"
	  "fn main() i32 = {\n"
	  "    let x: outer; x.f = 0; x.g = 0;\n"
	  "    set(&x);\n"
	  "    return x.f;\n"
	  "};\n",
	  42 },
	/* Drew's report shape — `*T` parameter, 2-deep read.
	 * Used to lower to `MOVQ a(SB), AX` (link-time undefined ref).
	 * Now the spine walker dereferences the root pointer. */
	{ "ptr_root_2deep_read",
	  "type inner = struct { a: i32, b: i32 };\n"
	  "type outer = struct { i: inner, x: i32 };\n"
	  "fn get(o: *outer) i32 = { return o.i.a; };\n"
	  "fn main() i32 = {\n"
	  "    let v: outer; v.i.a = 7; v.i.b = 0; v.x = 0;\n"
	  "    return get(&v);\n"
	  "};\n",
	  7 },
	/* `*T` parameter, 2-deep write — bufio.init shape.
	 * Previously silently dropped; now MOVQ off(BP), CX +
	 * store at total_off(CX). */
	{ "ptr_root_2deep_write",
	  "type inner = struct { a: i32, b: i32 };\n"
	  "type outer = struct { i: inner, x: i32 };\n"
	  "fn set(o: *outer) void = { o.i.a = 5; };\n"
	  "fn main() i32 = {\n"
	  "    let v: outer; v.i.a = 0; v.i.b = 0; v.x = 0;\n"
	  "    set(&v);\n"
	  "    return v.i.a;\n"
	  "};\n",
	  5 },
	/* 3-deep `*T`-rooted: proves the spine walker loops past the
	 * pointer-root hop and isn't hardcoded at depth 2. */
	{ "ptr_root_3deep",
	  "type a3 = struct { x: i32 };\n"
	  "type a2 = struct { a: a3 };\n"
	  "type a1 = struct { a: a2 };\n"
	  "fn put(p: *a1) void = { p.a.a.x = 9; };\n"
	  "fn get(p: *a1) i32  = { return p.a.a.x; };\n"
	  "fn main() i32 = {\n"
	  "    let v: a1; v.a.a.x = 0;\n"
	  "    put(&v);\n"
	  "    return get(&v);\n"
	  "};\n",
	  9 },
	/* `*T` *local* (not just param) — same emit path through
	 * localfind, but exercised separately for symmetry. */
	{ "ptr_root_local",
	  "type inner = struct { a: i32, b: i32 };\n"
	  "type outer = struct { i: inner, x: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let v: outer; v.i.a = 0; v.i.b = 0; v.x = 0;\n"
	  "    let p: *outer = &v;\n"
	  "    p.i.a = 13;\n"
	  "    return p.i.a;\n"
	  "};\n",
	  13 },
	/* str leaf field through a `*T`-rooted chain — exercises the
	 * (AX=ptr, BX=len) convention through the CX-base load. */
	{ "ptr_root_str_leaf",
	  "type holder = struct { s: str, pad: i32 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn put(b: *box) void = { b.h.s = \"abc\"; };\n"
	  "fn main() i32 = {\n"
	  "    let b: box;\n"
	  "    let empty: str; b.h.s = empty; b.h.pad = 0; b.tag = 0;\n"
	  "    put(&b);\n"
	  "    if (b.h.s.len == 3) { return 42; };\n"
	  "    return 0;\n"
	  "};\n",
	  42 },
	/* slice pseudo-field on a `*T`-rooted chain. .len of an empty
	 * slice round-trips through the CX-base load. */
	{ "ptr_root_slice_pseudo",
	  "type bag = struct { buf: []u8, x: i32 };\n"
	  "fn setlen(b: *bag, n: i32) void = { b.buf.len = n; };\n"
	  "fn main() i32 = {\n"
	  "    let b: bag;\n"
	  "    let nope: []u8; b.buf = nope; b.x = 0;\n"
	  "    setlen(&b, 5);\n"
	  "    return b.buf.len: i32;\n"
	  "};\n",
	  5 },
	/* f64 leaf field through a `*T`-rooted chain — exercises the
	 * X0 spill / MOVSD store path off the CX base. */
	{ "ptr_root_f64_leaf",
	  "type holder = struct { v: f64, pad: i32 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn put(b: *box) void = { b.h.v = 0.5f64; };\n"
	  "fn main() i32 = {\n"
	  "    let b: box; b.h.v = 0.0f64; b.h.pad = 0; b.tag = 0;\n"
	  "    put(&b);\n"
	  "    if (b.h.v == 0.5f64) { return 42; };\n"
	  "    return 0;\n"
	  "};\n",
	  42 },
	/* Sub-word leaf widths through a `*T`-rooted chain — pins
	 * fldloadop / fldstoreop on the CX-base path. u8/i8/u16/i16/i32
	 * all stored then read back through the inner pointer. */
	{ "ptr_root_subword_u8",
	  "type holder = struct { v: u8, pad: u8 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn put(b: *box) void = { b.h.v = 99u8; };\n"
	  "fn main() i32 = {\n"
	  "    let b: box; b.h.v = 0u8; b.h.pad = 0u8; b.tag = 0;\n"
	  "    put(&b);\n"
	  "    return b.h.v: i32;\n"
	  "};\n",
	  99 },
	{ "ptr_root_subword_i32",
	  "type holder = struct { v: i32, pad: i32 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn put(b: *box) void = { b.h.v = 0x12345; };\n"
	  "fn main() i32 = {\n"
	  "    let b: box; b.h.v = 0; b.h.pad = 0; b.tag = 0;\n"
	  "    put(&b);\n"
	  "    if (b.h.v == 0x12345) { return 42; };\n"
	  "    return 0;\n"
	  "};\n",
	  42 },
	{ "ptr_root_subword_i16",
	  "type holder = struct { v: i16, pad: i16 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn put(b: *box) void = { b.h.v = 4321i16; };\n"
	  "fn main() i32 = {\n"
	  "    let b: box; b.h.v = 0i16; b.h.pad = 0i16; b.tag = 0;\n"
	  "    put(&b);\n"
	  "    if (b.h.v == 4321i16) { return 42; };\n"
	  "    return 0;\n"
	  "};\n",
	  42 },
	/* Negative signed leaf widths through a `*T`-rooted chain.
	 * Stored value's sign bit must round-trip — pins localloadop /
	 * fldloadop sign-extension on the CX-base path so `*T`-rooted
	 * chains don't silently widen to a positive bit pattern. i8, i16
	 * and i32 each store −7 and check `< 0` after the chained read. */
	{ "ptr_root_subword_i8_neg",
	  "type holder = struct { v: i8, pad: i8 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn put(b: *box) void = { b.h.v = -7i8; };\n"
	  "fn main() i32 = {\n"
	  "    let b: box; b.h.v = 0i8; b.h.pad = 0i8; b.tag = 0;\n"
	  "    put(&b);\n"
	  "    let r: i32 = b.h.v: i32;\n"
	  "    if (r == -7) { return 42; };\n"
	  "    return 0;\n"
	  "};\n",
	  42 },
	{ "ptr_root_subword_i16_neg",
	  "type holder = struct { v: i16, pad: i16 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn put(b: *box) void = { b.h.v = -7i16; };\n"
	  "fn main() i32 = {\n"
	  "    let b: box; b.h.v = 0i16; b.h.pad = 0i16; b.tag = 0;\n"
	  "    put(&b);\n"
	  "    let r: i32 = b.h.v: i32;\n"
	  "    if (r == -7) { return 42; };\n"
	  "    return 0;\n"
	  "};\n",
	  42 },
	{ "ptr_root_subword_i32_neg",
	  "type holder = struct { v: i32, pad: i32 };\n"
	  "type box    = struct { h: holder, tag: i32 };\n"
	  "fn put(b: *box) void = { b.h.v = -7; };\n"
	  "fn main() i32 = {\n"
	  "    let b: box; b.h.v = 0; b.h.pad = 0; b.tag = 0;\n"
	  "    put(&b);\n"
	  "    if (b.h.v < 0) { return 42; };\n"
	  "    return 0;\n"
	  "};\n",
	  42 },
	/* Round-trip across the aliasing seam: caller writes via the
	 * local value, callee reads via the `*T`-rooted chain — and
	 * vice versa. Pins that both branches index the SAME slot
	 * (same field offsets resolved off the right base). */
	{ "ptr_root_roundtrip_local_write_ptr_read",
	  "type inner = struct { a: i32, b: i32 };\n"
	  "type outer = struct { i: inner, x: i32 };\n"
	  "fn get(o: *outer) i32 = { return o.i.a; };\n"
	  "fn main() i32 = {\n"
	  "    let o: outer; o.i.a = 0; o.i.b = 0; o.x = 0;\n"
	  "    let p: *outer = &o;\n"
	  "    o.i.a = 42;\n"
	  "    return get(p);\n"
	  "};\n",
	  42 },
	{ "ptr_root_roundtrip_ptr_write_local_read",
	  "type inner = struct { a: i32, b: i32 };\n"
	  "type outer = struct { i: inner, x: i32 };\n"
	  "fn main() i32 = {\n"
	  "    let o: outer; o.i.a = 0; o.i.b = 0; o.x = 0;\n"
	  "    let p: *outer = &o;\n"
	  "    p.i.a = 42;\n"
	  "    return o.i.a;\n"
	  "};\n",
	  42 },
};

static int
run_driver(const char *driver, const struct row *r, int i)
{
	char tmpdir[64], src[128], outbin[128], rmcmd[160], cmd[1024];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/wdc_%d_d_%d", getpid(), i);
	mkdir(tmpdir, 0755);
	snprintf(src, sizeof src, "%s/wdc_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(outbin, sizeof outbin, "%s/wdc_%d_%d", tmpdir, getpid(), i);
	snprintf(rmcmd, sizeof rmcmd, "rm -rf %s", tmpdir);

	FILE *f = fopen(src, "wb");
	if (!f) { runwait(rmcmd); return -1; }
	wwtest_fputs(r->src, f);
	fclose(f);

	snprintf(cmd, sizeof cmd, "%s build -o %s %s",
	    driver, outbin, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: build via %s failed\n",
		    r->label, driver);
		runwait(rmcmd);
		return -1;
	}

	int got = runwait(outbin);

	runwait(rmcmd);
	return got;
}

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char absbin[1024];
	if (bin[0] != '/') {
		char cwd[1024];
		if (getcwd(cwd, sizeof cwd) == NULL) return 1;
		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
		bin = absbin;
	}

	char cdrv[1024];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	char wdrv[1024];
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);

	struct { const char *name; const char *path; int gated_on_existence; }
	drivers[] = {
		{ "cstage", cdrv, 0 },
		{ "wwstage", wdrv, 1 },
		{ NULL, NULL, 0 },
	};

	int n = (int)(sizeof rows / sizeof rows[0]);
	int total = 0, fail = 0;
	for (int d = 0; drivers[d].name; d++) {
		if (drivers[d].gated_on_existence
		    && access(drivers[d].path, X_OK) != 0) {
			fprintf(stderr, "dot_chain: skip %s (no %s)\n",
			    drivers[d].name, drivers[d].path);
			continue;
		}
		for (int i = 0; i < n; i++) {
			int got = run_driver(drivers[d].path, &rows[i], i);
			total++;
			if (got != rows[i].want) {
				fprintf(stderr,
				    "dot_chain[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, rows[i].label,
				    got, rows[i].want);
				fail++;
			}
		}
	}
	if (fail) {
		fprintf(stderr,
		    "dot_chain: %d/%d fixtures failed\n", fail, total);
		return 1;
	}
	printf("dot_chain: %d/%d ok\n", total, total);
	return 0;
}