module main;

import std.stdio;
import std.process;
import std.conv;

private immutable (char[][]) elementNames = [['x', 'y', 'z', 'w'], ['r', 'g', 'b', 'a'], ['s', 't', 'p', 'q']];

int main(string[] argv) {
	alias Vec!4 Vec4;

	Vec4 v = Vec4(1, 2, 3, 4);

	writeln(v.bgra); // Prints Vec!(4)([3, 2, 1, 4])
	writeln(v.rg); // Prints Vec!(2)([1, 2])

	return 0;
}

struct Vec(size_t size) {
	alias size Size;

	mixin(generateConstructor(Size));

	mixin(generateProperties(Size));

	auto opDispatch(string s)() {
		mixin(generateSwizzle(s));
	}

	float v[Size];
}

private string generateConstructor(size_t size) {
	string constructorParams;
	string constructorBody;

	foreach(i; 0..size) {
		string paramName = "v" ~ to!string(i);
		constructorParams ~= "float " ~ paramName ~ "=0,";
		constructorBody ~= "v[" ~ to!string(i) ~ "] = " ~ paramName ~ ";";
	}

	return "this(" ~ constructorParams[0..$-1] ~ "){" ~ constructorBody ~ "}";
}

private string generateProperties(size_t size) {
	string props;

	foreach(names; elementNames) {
		foreach(i, name; names[0..size]) {
			props ~= "@property float " ~ name ~ "() const { return v[" ~ to!string(i) ~ "]; }";
			props ~= "@property void " ~ name ~ "(float f) { v[" ~ to!string(i) ~ "] = f; }";
		}
	}

	return props;
}

private string generateSwizzle(string elements) {
	string swizzleImpl = "return Vec!" ~ to!string(elements.length) ~ "(";

	foreach(e; elements) {
		swizzleImpl ~= e ~ ",";
	}

	return swizzleImpl[0..$-1] ~ ");";
}