// ostest — exercises lib/os surface that doesn't have a dedicated
// test elsewhere. Covers [[os.getenv]] (against env state pre-
// arranged by test/wcc/974_getenv_run.c) and a direct
// [[os.alloc]] / [[os.free]] roundtrip. memio's tests indirectly
// cover alloc/free; the direct row here pins the FFI shape under
// lib/os itself so future bindings refactors can't quietly drift.
//
// Convention follows the stdlib `_run` test fixtures: hand-rolled
// @test fns dispatched from `main()` in numeric order, with a
// `signalled` global the main fn bumps so a failing case exits with
// `WEXITSTATUS = signalled + 10` — the harness then knows which
// scenario tripped. Same shape as temptest / shlextest / fnmatchtest.
//
// Pre-arranged env state (set by 974_getenv_run.c via setenv/unsetenv
// before exec'ing `ww run lib/os/ostest.ww`):
//
//   WW_TEST_GETENV     = "hello-world"
//   WW_TEST_EMPTY      = ""           (set, but value is empty)
//   WW_TEST_NOT_SET    unset
//
// Don't `use io;` here — lib/os and lib/io both export read/write/
// close as C symbols that collide under the driver's flat-scope
// concat (task #17). os alone is sufficient: getenv + exit are the
// only primitives needed.

use os;

let signalled: i32 = 0;

fn fail() void = { os.exit(signalled + 10); };

fn streq(a: str, b: str) bool = {
	if (a.len != b.len) { return false; };
	let i: i32 = 0;
	for (i < a.len) {
		if (a[i] != b[i]) { return false; };
		i += 1;
	};
	return true;
};

// ---- getenv: set var → matching value -------------------------------

@test fn test_getenv_set() void = {
	let r = os.getenv("WW_TEST_GETENV");
	match (r) {
	case void => fail();
	case let s: str => {
		if (!streq(s, "hello-world")) { fail(); };
	};
	};
};

// ---- getenv: empty value (set but zero-length) ----------------------
//
// POSIX permits an env var with an empty value (`name=` in environ).
// getenv must return the empty str, NOT void — void is reserved for
// "name not present at all". This row exercises the boundary.

@test fn test_getenv_empty() void = {
	let r = os.getenv("WW_TEST_EMPTY");
	match (r) {
	case void => fail();
	case let s: str => {
		if (s.len != 0) { fail(); };
	};
	};
};

// ---- getenv: unset var → void ---------------------------------------

@test fn test_getenv_unset() void = {
	let r = os.getenv("WW_TEST_NOT_SET");
	match (r) {
	case void => {};
	case let s: str => fail();
	};
};

// ---- getenv: prefix-collision guard ---------------------------------
//
// Probes that "WW_TEST_GETEN" (a prefix of WW_TEST_GETENV) doesn't
// match. Without the explicit `entry[name.len] == '='` check in
// getenv, a naive prefix matcher would return the value of any
// longer-named var that starts with the queried name.

@test fn test_getenv_prefix_no_match() void = {
	let r = os.getenv("WW_TEST_GETEN");
	match (r) {
	case void => {};
	case let s: str => fail();
	};
};

// ---- alloc/free: mmap-backed runtime allocator ----------------------
//
// Direct round-trip. memio's dynamic-buffer tests already exercise
// os.alloc / os.free transitively; the row here pins the FFI shape
// at the lib/os layer (write+read-back proves the returned page is
// dereferenceable, not just non-nil).

@test fn test_alloc_free_roundtrip() void = {
	let p: *u8 = os.alloc(4096u64): *u8;
	if (p == nil: *u8) { fail(); };
	// Write a sentinel at the head and tail of the page, read it
	// back. A miscompiled binding (wrong arg order, wrong ABI, etc.)
	// would either fault or return zero here.
	p[0] = 90u8;		// 0x5a
	p[4095] = 165u8;	// 0xa5
	if (p[0] != 90u8) { fail(); };
	if (p[4095] != 165u8) { fail(); };
	os.free(p: *void, 4096u64);
};

export fn main() i32 = {
	signalled = 1; test_getenv_set();
	signalled = 2; test_getenv_empty();
	signalled = 3; test_getenv_unset();
	signalled = 4; test_getenv_prefix_no_match();
	signalled = 5; test_alloc_free_roundtrip();
	return 0;
};