#include "exports.hpp"
#include "graph.hpp"
#include "powerlaw.hpp"
#include "switchchain.hpp"
#include <algorithm>
#include <fstream>
#include <iostream>
#include <numeric>
#include <random>
#include <vector>

double getProperty(const DegreeSequence& ds) {
    std::vector<std::vector<double>> vals(ds.size());
    for (auto& v : vals) {
        v.resize(ds.size(), 0);
    }

    auto D = 0u;
    for (auto d : ds)
        D += d;

    double factor = 1.0 / double(D);

    for (auto i = 0u; i < ds.size(); ++i) {
        for (auto j = i + 1; j < ds.size(); ++j) {
            vals[i][j] = 1.0 - std::exp(-(ds[i] * ds[j] * factor));
        }
    }

    double result = 0.0;
    for (auto i = 0u; i < ds.size(); ++i) {
        for (auto j = i + 1; j < ds.size(); ++j) {
            for (auto k = j + 1; k < ds.size(); ++k) {
                result += vals[i][j] * vals[j][k] * vals[i][k];
            }
        }
    }
    return result;
}

int main() {
    // Generate a random degree sequence
    std::mt19937 rng(std::random_device{}());

    // Goal:
    // Degrees follow a power-law distribution with some parameter tau
    // Expect:  #tri = const * n^{ something }
    // The goal is to find the 'something' by finding the number of triangles
    // for different values of n and tau
    float tauValues[] = {2.1f, 2.5f, 2.9f};

    Graph g;

    std::ofstream outfile("graphdata_dsp.m");
    outfile << '{';
    bool outputComma = false;

    for (int numVertices = 1000; numVertices <= 1000; numVertices += 1000) {
        for (float tau : tauValues) {

            DegreeSequence ds(numVertices);
            powerlaw_distribution degDist(tau, 1, numVertices);
            //std::poisson_distribution<> degDist(12);

            // For a single n,tau take samples over several instances of
            // the degree distribution.
            // 500 samples seems to give reasonable results
            for (int degreeSample = 0; degreeSample < 2000; ++degreeSample) {
                // Generate a graph
                // might require multiple tries
                for (int i = 1; ; ++i) {
                    std::generate(ds.begin(), ds.end(),
                                  [&degDist, &rng] { return degDist(rng); });
                    // First make the sum even
                    unsigned int sum = std::accumulate(ds.begin(), ds.end(), 0);
                    if (sum % 2) {
                        continue;
                        // Can we do this: ??
                        ds.back()++;
                    }

                    if (g.createFromDegreeSequence(ds))
                        break;

                    // When 10 tries have not worked, output a warning
                    if (i % 10 == 0) {
                        std::cerr << "Warning: could not create graph from "
                                     "degree sequence. Trying again...\n";
                    }
                }

                SwitchChain chain;
                if (!chain.initialize(g)) {
                    std::cerr << "Could not initialize Markov chain.\n";
                    return 1;
                }

                std::cout << "Running n = " << numVertices << ", tau = " << tau
                          << ". \t" << std::flush;

                int mixingTime = 32*(32.0f - 10.0f*(tau - 2.0f)) * numVertices; //40000;
                constexpr int measurements = 50;
                constexpr int measureSkip =
                    200; // Take a sample every ... steps

                int movesDone = 0;

                long long trianglesTotal = 0;

                for (int i = 0; i < mixingTime; ++i) {
                    if (chain.doMove())
                        ++movesDone;
                }
                for (int i = 0; i < measurements; ++i) {
                    for (int j = 0; j < measureSkip; ++j)
                        if (chain.doMove())
                            ++movesDone;
                    trianglesTotal += chain.g.countTriangles();
                }

                std::cout << movesDone << '/' << mixingTime + measurements * measureSkip
                          << " moves succeeded ("
                          << 100.0f * float(movesDone) /
                                 float(mixingTime + measurements * measureSkip)
                          << "%).";
                std::cout << std::flush;
                //std::cout << std::endl;

                if (outputComma)
                    outfile << ',' << '\n';
                outputComma = true;

                float avgTriangles =
                    float(trianglesTotal) / float(measurements);
                outfile << '{' << '{' << numVertices << ',' << tau << '}';
                outfile << ',' << avgTriangles;
                outfile << ',' << getProperty(ds) << '}' << std::flush;

                std::cout << std::endl;
            }
        }
    }
    outfile << '}';
    return 0;
}