package base64;

import base64;

fn putstr(s: str, into: []u8, off: i32) i32 = {
	let i: i32 = 0;
	for (i < s.len) {
		into[off + i] = s[i];
		i += 1;
	};
	return off + s.len;
};

fn streq(buf: []u8, expect: str) bool = {
	if (buf.len != expect.len) { return false; };
	let i: i32 = 0;
	for (i < buf.len) {
		if (buf[i] != expect[i]) { return false; };
		i += 1;
	};
	return true;
};

fn encodevec(input: str, expect: str) void = {
	let inbuf: [128]u8;
	let outbuf: [128]u8;
	let n: i32 = putstr(input, inbuf[0:128], 0);
	let m: i32 = base64.encode(outbuf[0:128], inbuf[0:n]);
	if (m != expect.len) { let _: i32 = 1/0; };
	if (!streq(outbuf[0:m], expect)) { let _: i32 = 1/0; };
};

@test fn rfc4648_vectors() void = {
	encodevec("",       "");
	encodevec("f",      "Zg==");
	encodevec("fo",     "Zm8=");
	encodevec("foo",    "Zm9v");
	encodevec("foob",   "Zm9vYg==");
	encodevec("fooba",  "Zm9vYmE=");
	encodevec("foobar", "Zm9vYmFy");
};

fn decodevec(input: str, expect: str) void = {
	let inbuf: [128]u8;
	let outbuf: [128]u8;
	let n: i32 = putstr(input, inbuf[0:128], 0);
	let r: (i32 | base64.invalid) = base64.decode(outbuf[0:128], inbuf[0:n]);
	match (r) {
	case let m: i32 => {
		if (m != expect.len) { let _: i32 = 1/0; };
		if (!streq(outbuf[0:m], expect)) { let _: i32 = 1/0; };
	};
	case let e: base64.invalid => { let _: i32 = 1/0; };
	};
};

@test fn rfc4648_decode() void = {
	decodevec("",         "");
	decodevec("Zg==",     "f");
	decodevec("Zm8=",     "fo");
	decodevec("Zm9v",     "foo");
	decodevec("Zm9vYg==", "foob");
	decodevec("Zm9vYmE=", "fooba");
	decodevec("Zm9vYmFy", "foobar");
};

@test fn alphabet_full() void = {
	// Round-trip every 6-bit value (0..63) by encoding three bytes that
	// expose b0=0x00, b1=AA, b2=FF — the encoded chars depend on all
	// four positions including the >>2 path.
	let i: i32 = 0;
	for (i < 64) {
		let bits: u8 = i: u8;
		// Construct a triple [bits<<2, 0, 0] so the first encoded
		// char encodes `bits`. The other three chars are derivable
		// from the remaining bytes; we only check the first here.
		let inbuf: [3]u8;
		inbuf[0] = bits << 2u8;
		inbuf[1] = 0u8;
		inbuf[2] = 0u8;
		let outbuf: [4]u8;
		let m: i32 = base64.encode(outbuf[0:4], inbuf[0:3]);
		if (m != 4) { let _: i32 = 1/0; };
		// Decoding back must give us `bits` in the high 6 bits of [0].
		let r: (i32 | base64.invalid) = base64.decode(inbuf[0:3], outbuf[0:4]);
		match (r) {
		case let n: i32 => {
			if (n != 3) { let _: i32 = 1/0; };
			if ((inbuf[0] >> 2u8) != bits) { let _: i32 = 1/0; };
		};
		case let e: base64.invalid => { let _: i32 = 1/0; };
		};
		i += 1;
	};
};

@test fn invalid_inputs() void = {
	let inbuf: [16]u8;
	let outbuf: [16]u8;
	// Length not a multiple of 4.
	let n: i32 = putstr("abc", inbuf[0:16], 0);
	let r1: (i32 | base64.invalid) = base64.decode(outbuf[0:16], inbuf[0:n]);
	match (r1) {
	case let m: i32 => { let _: i32 = 1/0; };
	case let e: base64.invalid => void;
	};
	// Bad char ('@' is not in the std alphabet).
	let n2: i32 = putstr("Z@==", inbuf[0:16], 0);
	let r2: (i32 | base64.invalid) = base64.decode(outbuf[0:16], inbuf[0:n2]);
	match (r2) {
	case let m: i32 => { let _: i32 = 1/0; };
	case let e: base64.invalid => void;
	};
};

@test fn urlsafe_roundtrip() void = {
	// Byte sequence chosen so the std alphabet would use '+' and '/',
	// while url-safe replaces them with '-' and '_'. 0xFB = 11111011
	// hits index 62 in some quad, and 0xFF hits 63.
	let raw: [3]u8;
	raw[0] = 0xFBu8;
	raw[1] = 0xFFu8;
	raw[2] = 0xBFu8;
	let std: [8]u8;
	let url: [8]u8;
	let dec: [3]u8;
	let m1: i32 = base64.encode(std[0:8], raw[0:3]);
	let m2: i32 = base64.encodeurl(url[0:8], raw[0:3]);
	if (m1 != 4) { let _: i32 = 1/0; };
	if (m2 != 4) { let _: i32 = 1/0; };
	// Round-trip both ways.
	let r1: (i32 | base64.invalid) = base64.decode(dec[0:3], std[0:m1]);
	match (r1) {
	case let n: i32 => {
		if (n != 3) { let _: i32 = 1/0; };
		if (dec[0] != raw[0]) { let _: i32 = 1/0; };
		if (dec[1] != raw[1]) { let _: i32 = 1/0; };
		if (dec[2] != raw[2]) { let _: i32 = 1/0; };
	};
	case let e: base64.invalid => { let _: i32 = 1/0; };
	};
	let r2: (i32 | base64.invalid) = base64.decodeurl(dec[0:3], url[0:m2]);
	match (r2) {
	case let n: i32 => {
		if (n != 3) { let _: i32 = 1/0; };
		if (dec[0] != raw[0]) { let _: i32 = 1/0; };
		if (dec[1] != raw[1]) { let _: i32 = 1/0; };
		if (dec[2] != raw[2]) { let _: i32 = 1/0; };
	};
	case let e: base64.invalid => { let _: i32 = 1/0; };
	};
};

@test fn sizes() void = {
	if (base64.encodedsize(0)  != 0)  { let _: i32 = 1/0; };
	if (base64.encodedsize(1)  != 4)  { let _: i32 = 1/0; };
	if (base64.encodedsize(2)  != 4)  { let _: i32 = 1/0; };
	if (base64.encodedsize(3)  != 4)  { let _: i32 = 1/0; };
	if (base64.encodedsize(4)  != 8)  { let _: i32 = 1/0; };
	if (base64.encodedsize(6)  != 8)  { let _: i32 = 1/0; };
	if (base64.encodedsize(7)  != 12) { let _: i32 = 1/0; };
	if (base64.decodedsize(4)  != 3)  { let _: i32 = 1/0; };
	if (base64.decodedsize(8)  != 6)  { let _: i32 = 1/0; };
};

export fn main() i32 = {
	rfc4648_vectors();
	rfc4648_decode();
	alphabet_full();
	invalid_inputs();
	urlsafe_roundtrip();
	sizes();
	return 0;
};