// Copyright 2023 wanderer <a_mirre at utb dot cz>
// SPDX-License-Identifier: GPL-3.0-or-later

package de

type (
	// DecisionVector is a []float64 abstraction representing the decision vector.
	DecisionVector []float64
	// FitnessVector is a []float64 abstraction representing the fitness vector.
	FitnessVector []float64
	// ConstraintVector is a []float64 abstraction representing the constraint vector.
	ConstraintVector []float64
)

// PopulationIndividual representats a single population individual.
type PopulationIndividual struct {
	CurX DecisionVector
	CurV DecisionVector
	CurC ConstraintVector
	CurF FitnessVector

	BestX DecisionVector
	BestC ConstraintVector
	BestF FitnessVector
}

// ChampionIndividual is a representation of the best individual currently
// available in the population.
type ChampionIndividual struct {
	X DecisionVector
	C ConstraintVector
	F FitnessVector
}

// Population groups population individuals (agents) with metadata about the population.
type Population struct {
	// Population is a slice of population individuals.
	Population []PopulationIndividual
	// Problem is the current benchmarking function this population is attempting to optimise.
	Problem string
	// Seed is the value used to (re)init population.
	Seed uint64
}

// GetIndividal returns a reference to individual at position n.
func (p *Population) GetIndividual(n uint) *PopulationIndividual { return &PopulationIndividual{} }
func (p *Population) GetBestIdx() int                            { return 0 }
func (p *Population) GetWorstIdx() int                           { return 0 }
func (p *Population) SetX(n int, nuX DecisionVector)             {}
func (p *Population) SetV(n int, nuV DecisionVector)             {}

// Init initialises all individuals.
func (p *Population) Init() {}

// Reinit reinitialises all individuals.
func (p *Population) Reinit() {}

// ReinitN reinitialises the individual at position n.
func (p *Population) ReinitN(n uint) {}
func (p *Population) Clear()         {}

// meanVelocity computes the mean current velocity of all individuals in the population.
func (p *Population) MeanVelocity() float64 { return 0.0 }

// newPopulation returns a pointer to a new, uninitialised population.
func newPopulation(benchProblem string, np int) *Population {
	p := &Population{}

	p.Problem = benchProblem

	// pre-alloc.
	p.Population = make([]PopulationIndividual, 0, np)

	return p
}