using System;
using System.Collections.Generic;
using Random = UnityEngine.Random;

public class NeuralNetwork : IComparable<NeuralNetwork> {

    private int[] _layers; //layers of the neural network
    private float[][] _neurons; //neurons of the neural network
    public float[][][] _weights; //weights of the neural network
    private float _score; //score of the neural network
    
    /// <summary>
    /// Creates a new neural network with the given layers
    /// </summary>
    /// <param name="layers">The layers with the count of the individual neurons</param>
    public NeuralNetwork(in int[] layers) {
        _layers = new int[layers.Length];
        for (int i = 0; i < layers.Length; i++) {
            _layers[i] = layers[i];
        }
        
        InitializeNeurons();
        InitializeWeights();
    }

    /// <summary>
    /// Copy a NeuralNetwork
    /// </summary>
    /// <param name="network">The NeuralNetwork you wanna copy</param>
    public NeuralNetwork(in NeuralNetwork network) {
        _layers = new int[network._layers.Length];
        for (var i = 0; i < network._layers.Length; i++) {
            _layers[i] = network._layers[i];
        }
        
        InitializeNeurons();
        
        CopyWeights(network._weights);
    }
    
    /// <summary>
    /// Calculate output based on ihe given input
    /// </summary>
    /// <param name="inputs">The values at the first layer</param>
    /// <returns></returns>
    public float[] FeedForward(in float[] inputs) {
        for (int i = 0; i < inputs.Length; i++) {
            _neurons[0][i] = inputs[i];
        }

        for (int i = 1; i < _layers.Length; i++) {
            for (int j = 0; j < _neurons[i].Length; j++) {
                float value = 0.25f;
                
                for (int k = 0; k < _neurons[i - 1].Length; k++) {
                    value += _weights[i - 1][j][k] * _neurons[i - 1][k];
                }

                _neurons[i][j] = (float)Math.Tan(value);
            }
        }
        
        return _neurons[_neurons.Length - 1];
    }

    /// <summary>
    /// Randomize the weights of the neural network
    /// </summary>
    public void Mutate() {
        for (int i = 0; i < _weights.Length; i++) {
            for (int j = 0; j < _weights[i].Length; j++) {
                for (int k = 0; k < _weights[i][j].Length; k++) {
                    float weight = _weights[i][j][k];
                    
                    float random = Random.value * 100.0f;

                    switch (random) {
                        case 2.0f:
                            weight *= -1;
                            break;
                        
                        case 4.0f:
                            weight = Random.Range(-0.5f, 0.5f);
                            break;
                        
                        case 6.0f:
                            weight *= Random.Range(0.0f, 1.0f) + 1;
                            break;
                        
                        case 8.0f:
                            weight *= Random.Range(0.0f, 1.0f);
                            break;
                    }
                    
                    _weights[i][j][k] = weight;
                }
            }
        }
    }
    
    public void AddScore(in float score) => _score += score;
    public void SetScore(in float score) => _score = score;
    public float GetScore() => _score;

    private void InitializeNeurons() {
        List<float[]> neurons = new List<float[]>();

        for (int i = 0; i < _layers.Length; i++) {
            neurons.Add(new float[_layers[i]]);
        }
        
        _neurons = neurons.ToArray();
    }
    
    private void InitializeWeights() {
        List<float[][]> weights = new List<float[][]>();
        
        for (int i = 1; i < _layers.Length; i++) {
            List<float[]> layerWeights = new List<float[]>();
            
            int neuronsInPreviousLayer = _layers[i - 1];
            
            for (int j = 0; j < _neurons[i].Length; j++) {
                float[] neuronWeights = new float[neuronsInPreviousLayer];
                
                for (int k = 0; k < neuronsInPreviousLayer; k++) {
                    neuronWeights[k] = Random.value - 0.5f;
                }
                
                layerWeights.Add(neuronWeights);
            }
            
            weights.Add(layerWeights.ToArray());
        }
        
        _weights = weights.ToArray();
    }
    
    private void CopyWeights(in float[][][] weights) {
        _weights = new float[weights.Length][][];
        
        for (int i = 0; i < weights.Length; i++) {
            _weights[i] = new float[weights[i].Length][];
            
            for (int j = 0; j < weights[i].Length; j++) {
                _weights[i][j] = new float[weights[i][j].Length];
                
                for (int k = 0; k < weights[i][j].Length; k++) {
                    _weights[i][j][k] = weights[i][j][k];
                }
            }
        }
    }

    public int CompareTo(NeuralNetwork other) {
        if (other == null) {
            return 1;
        }

        if (other._score > _score) {
            return -1;
        }
        
        if (other._score < _score) {
            return 1;
        }
        
        return 0;
    }
}