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

double getDSTN(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(int argc, char* argv[]) {
    // Simulation parameters
    const int numVerticesMin = 100;
    const int numVerticesMax = 1000;
    const int numVerticesStep = 100;

    float tauValues[] = {2.1f, 2.2f, 2.3f, 2.4f, 2.5f, 2.6f, 2.7f, 2.8f, 2.9f};

    const int totalDegreeSamples = 2000;

    auto getMixingTime = [](int n, float tau) {
        return int(30.0f * (50.0f - 30.0f * (tau - 2.0f)) * n);
    };
    constexpr int measurements = 50;
    constexpr int measureSkip = 200; // Take a sample every ... steps

    // Output file
    std::ofstream outfile;
    if (argc >= 2)
        outfile.open(argv[1]);
    else
        outfile.open("graphdata_dsp.m");
    if (!outfile.is_open()) {
        std::cout << "ERROR: Could not open output file.\n";
        return 1;
    }

    // Output Mathematica-style comment to indicate file contents
    outfile << "(*\n";
    outfile << "n from " << numVerticesMin << " to " << numVerticesMax
            << " step " << numVerticesStep << std::endl;
    outfile << "tauValues: " << tauValues << std::endl;
    outfile << "degreeSamples: " << totalDegreeSamples << std::endl;
    outfile << "mixingTime: 30 * (50 - 30 (tau - 2)) n\n";
    outfile << "data:\n";
    outfile << "1: {n,tau}\n";
    outfile << "2: avgTriangles\n";
    outfile << "3: dstn\n";
    outfile << "*)" << std::endl;

    outfile << '{';
    bool outputComma = false;

    std::mt19937 rng(std::random_device{}());
    Graph g;
    for (int numVertices = numVerticesMin; numVertices <= numVerticesMax;
         numVertices += numVerticesStep) {
        for (float tau : tauValues) {
            // For a single n,tau take samples over several instances of
            // the degree distribution.
            for (int degreeSample = 0; degreeSample < totalDegreeSamples;
                 ++degreeSample) {
                DegreeSequence ds;
                generatePowerlawGraph(numVertices, tau, g, ds, rng);

                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 movesDone = 0;
                int mixingTime = getMixingTime(numVertices,tau);

                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();
                }
                float avgTriangles =
                    float(trianglesTotal) / float(measurements);

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

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

                outfile << '{' << '{' << numVertices << ',' << tau << '}';
                outfile << ',' << avgTriangles;
                outfile << ',' << getDSTN(ds);
                outfile << '}' << std::flush;

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