#include "Generation.hpp"



size_t Generation::size = 500;
size_t Generation::living = Generation::size*0.25;
Fitness* Generation::fitness;
std::mt19937_64* Generation::re;


Generation::Generation()
{
	this->individuals.reserve(Generation::size);
}


void Generation::updateFitness()
{
	for (auto individual : this->individuals) {
		if (!individual.fitnessEvaluated) {
			individual.fitness = Generation::fitness->of(individual.chromosome);
			individual.fitnessEvaluated = true;
		}
	}
}


void Generation::cull(CullType algorithm)
{
	// sort by fitness
	std::sort(
		this->individuals.begin(),
		this->individuals.end(),
		[](Generation::Individual& a, Generation::Individual& b) -> bool {
			return a.fitness < b.fitness;
		}
	);
	
	// apply correct culling algorithm
	switch (algorithm) {
		case Generation::CUTOFF: this->cullCutoff(); break;
		case Generation::ROULETTE: this->cullRoulette(); break;
	}
}


void Generation::reproduce(float crossover)
{
	// sort by fitness/available
	std::sort(
		this->individuals.begin(),
		this->individuals.end(),
		[](Generation::Individual& a, Generation::Individual& b) -> bool {
			if (a.alive && b.alive) {
				return a.fitness < b.fitness;
			} else {
				return a.alive;
			}
		}
	);
	
	// reproduce according to parameters
	std::uniform_int_distribution<> alivedist(0, Generation::living-1);
	std::uniform_real_distribution<> crossoverdist(0, 1);
	auto it = this->individuals.begin() + Generation::living;
	for (; it!=this->individuals.end(); ++it) {
		auto father = this->individuals.begin() + alivedist(*Generation::re);
		
		if (crossoverdist(*Generation::re) <= crossover) {
			auto mother = this->individuals.begin() + alivedist(*Generation::re);
			it->chromosome = Chromosome(father->chromosome, mother->chromosome);
		} else {
			it->chromosome = father->chromosome;
		}
		
		it->alive = true;
		it->fitness = 0;
		it->fitnessEvaluated = false;
		
		it->chromosome.mutate();
	}
}


void Generation::cullCutoff()
{
	auto it = this->individuals.begin() + Generation::living;
	for (; it!=this->individuals.end(); ++it) {
		it->alive = false;
	}
}


void Generation::cullRoulette()
{
	// TODO: implement this
}