// Vectors mirror ref/hare/strings/sub.ha where ww can express them.
// External strings_test package per the Go foo_test idiom (rule-5/9
// carve-out, task #16); the shared streq helper lives in
// helpers_test.ww — same-package test files compose in dir-mode
// (the package, not the file, is the unit of testing).
package strings_test;

import strings;
import encoding.utf8;
import test;

// ref/hare/strings/sub.ha:44 (@test fn sub), :79 (@test fn bytesub). Hare's
// 2-arg `sub(s, start)` rows are omitted: ww has no default-parameter
// syntax (filed as #37). bytesub now validates rune boundaries (#7).

@test fn sub_cases() void = {
	assert(!(!streq(strings.sub("a string", 0, 8), "a string")));
	assert(!(!streq(strings.sub("a string", 0, 1), "a")));
	assert(!(!streq(strings.sub("a string", 0, 3), "a s")));
	assert(!(!streq(strings.sub("a string", 2, 8), "string")));
	// start == end yields an empty borrowed view.
	assert(!(!streq(strings.sub("a string", 4, 4), "")));
	assert(!(strings.sub("a string", 4, 4).len != 0));
	// Hare vector — rune indices 1..3 over "こんにちは" select bytes
	// 3..9 ("んに"), not bytes 1..3.
	assert(!(!streq(strings.sub("こんにちは", 1, 3), "んに")));
	// 2-byte rune at rune index 1 in "héllo" — byte offsets 1..3.
	assert(!(!streq(strings.sub("héllo", 1, 2), "é")));
	// start == 0, end == rune-len of full string.
	assert(!(!streq(strings.sub("héllo", 0, 5), "héllo")));
};

@test fn sub_negative_aborts() void = {
	test.expectabort();
	strings.sub("abc", -1, 0);
};

// Match-shape mirrors Hare's `bytesub(...)!` at ref/hare/strings/sub.ha:
// 80-86. Inlined at each call site (rather than a helper that takes
// `(str | utf8.invalid)` by value) because the union-by-value path
// crashes — same lift-on-pass-by-value family as #48.
@test fn bytesub_cases() void = {
	match (strings.bytesub("a string", 0, 8)) {
	case let s: str          => { assert(!(!streq(s, "a string"))); };
	case let e: utf8.invalid => { abort(); };
	};
	match (strings.bytesub("a string", 0, 1)) {
	case let s: str          => { assert(!(!streq(s, "a"))); };
	case let e: utf8.invalid => { abort(); };
	};
	match (strings.bytesub("a string", 0, 3)) {
	case let s: str          => { assert(!(!streq(s, "a s"))); };
	case let e: utf8.invalid => { abort(); };
	};
	match (strings.bytesub("a string", 2, 8)) {
	case let s: str          => { assert(!(!streq(s, "string"))); };
	case let e: utf8.invalid => { abort(); };
	};
	match (strings.bytesub("a string", 4, 4)) {
	case let s: str          => { assert(!(!streq(s, ""))); };
	case let e: utf8.invalid => { abort(); };
	};
	// Hare vector — byte indices 3..9 over "こんにちは" select "んに".
	match (strings.bytesub("こんにちは", 3, 9)) {
	case let s: str          => { assert(!(!streq(s, "んに"))); };
	case let e: utf8.invalid => { abort(); };
	};
	// Rune/byte axis disagree on identical args (#3): sub(s,0,3) walks 3
	// runes and yields 9 bytes; bytesub(s,0,3) yields the first 3 bytes
	// — one 3-byte codepoint.
	assert(!(!streq(strings.sub("こんにちは", 0, 3), "こんに")));
	match (strings.bytesub("こんにちは", 0, 3)) {
	case let s: str          => { assert(!(!streq(s, "こ"))); };
	case let e: utf8.invalid => { abort(); };
	};
	// Borrowed view: ptr aliases input.
	let s: str = "hello";
	match (strings.bytesub(s, 1, 4)) {
	case let r: str => {
		assert(!(r.ptr != s.ptr + 1u64));
		assert(!(r.len != 3));
	};
	case let e: utf8.invalid => { abort(); };
	};
	// Hare's invalid row (ref/hare/strings/sub.ha:87) — start lands on
	// a continuation byte (2nd byte of "こ"), bytesub must reject (#7).
	match (strings.bytesub("こんにちは", 1, 3)) {
	case let r: str          => { abort(); };
	case let e: utf8.invalid => void;
	};
	// Symmetric: end lands on a continuation byte (2nd byte of "ん").
	match (strings.bytesub("こんにちは", 0, 4)) {
	case let r: str          => { abort(); };
	case let e: utf8.invalid => void;
	};
	// end == s.len bypasses the continuation check (s[end] is OOB).
	match (strings.bytesub("こんにちは", 0, 15)) {
	case let s: str          => { assert(!(!streq(s, "こんにちは"))); };
	case let e: utf8.invalid => { abort(); };
	};
};

@test fn bytesub_negative_aborts() void = {
	test.expectabort();
	strings.bytesub("abc", -1, 0);
};