/*
 * Copyright (C) 2022 NHR@FAU, University Erlangen-Nuremberg.
 * All rights reserved. This file is part of nusif-solver.
 * Use of this source code is governed by a MIT style
 * license that can be found in the LICENSE file.
 */
#include <float.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "particletracing.h"
#include "solver.h"

#define U(i, j, k)                                                                       \
    u[(k) * (imaxLocal + 2) * (jmaxLocal + 2) + (j) * (imaxLocal + 2) + (i)]
#define V(i, j, k)                                                                       \
    v[(k) * (imaxLocal + 2) * (jmaxLocal + 2) + (j) * (imaxLocal + 2) + (i)]
#define W(i, j, k)                                                                       \
    w[(k) * (imaxLocal + 2) * (jmaxLocal + 2) + (j) * (imaxLocal + 2) + (i)]
#define S(i, j, k)                                                                       \
    seg[(k) * (imaxLocal + 2) * (jmaxLocal + 2) + (j) * (imaxLocal + 2) + (i)]

static int ts = 0;

#define XOFFSET    0
#define YOFFSET    1
#define ZOFFSET    2
#define XOFFSETEND 3
#define YOFFSETEND 4
#define ZOFFSETEND 5

static double sum(int* sizes, int size)
{
    double sum = 0;

    for (int i = 0; i < size; ++i) {
        sum += sizes[i];
    }

    return sum;
}

static double sumOffset(double* sizes, int init, int offset, int coord)
{
    double sum = 0;

    for (int i = init - offset; coord > 0; i -= offset, --coord) {
        sum += sizes[i];
    }

    return sum;
}

void printParticles(ParticleTracer* particletracer)
{
    for (int i = 0; i < particletracer->totalParticles; ++i) {
        printf("Rank : %d Particle position X : %.2f, Y : %.2f, flag : %d, total pt : "
               "%d, pointer : %d, xOffset : %.2f, yOffset : %.2f, xOffsetEnd : %.2f, "
               "yOffsetEnd : %.2f\n",
            particletracer->rank,
            particletracer->particlePool[i].x,
            particletracer->particlePool[i].y,
            particletracer->particlePool[i].flag,
            particletracer->totalParticles,
            particletracer->pointer,
            particletracer->xOffset,
            particletracer->yOffset,
            particletracer->xOffsetEnd,
            particletracer->yOffsetEnd);
    }
}
void injectParticles(ParticleTracer* particletracer, int* restrict seg)
{
    double x, y, z;
    int imaxLocal = particletracer->imaxLocal;
    int jmaxLocal = particletracer->jmaxLocal;
    int kmaxLocal = particletracer->kmaxLocal;
    for (int i = 0; i < particletracer->numberOfParticles; ++i) {
        x = particletracer->linSpaceLine[i].x;
        y = particletracer->linSpaceLine[i].y;
        z = particletracer->linSpaceLine[i].z;
        if (x >= particletracer->xOffset && y >= particletracer->yOffset &&
            z >= particletracer->zOffset && x <= particletracer->xOffsetEnd &&
            y <= particletracer->yOffsetEnd && y <= particletracer->zOffsetEnd) {
            // printf("\nRank : %d\n", particletracer->rank);
            // printf("\t%.2f >= %.2f && %.2f >= %.2f && %.2f <= %.2f && %.2f <= %.2f\n",x
            // , particletracer->xOffset ,y , particletracer->yOffset, x ,
            // particletracer->xOffsetEnd ,y , particletracer->yOffsetEnd);

            particletracer->particlePool[particletracer->pointer].x = x;
            particletracer->particlePool[particletracer->pointer].y = y;
            particletracer->particlePool[particletracer->pointer].z = z;

            int i = particletracer->particlePool[particletracer->pointer].x /
                    particletracer->dx;
            int j = particletracer->particlePool[particletracer->pointer].y /
                    particletracer->dy;
            int k = particletracer->particlePool[particletracer->pointer].z /
                    particletracer->dz;
            if (S(i, j, k) == NONE) {
                particletracer->particlePool[particletracer->pointer].flag = true;
                ++(particletracer->pointer);
                ++(particletracer->totalParticles);
            }
        }
    }
}

void advanceParticles(ParticleTracer* particletracer,
    double* restrict u,
    double* restrict v,
    double* restrict w,
    int* restrict seg,
    double time)
{
    int imax      = particletracer->imax;
    int jmax      = particletracer->jmax;
    int kmax      = particletracer->kmax;
    int imaxLocal = particletracer->imaxLocal;
    int jmaxLocal = particletracer->jmaxLocal;
    int kmaxLocal = particletracer->kmaxLocal;

    double dx = particletracer->dx;
    double dy = particletracer->dy;
    double dz = particletracer->dz;

    double xlength = particletracer->xlength;
    double ylength = particletracer->ylength;
    double zlength = particletracer->zlength;

    Particle buff[particletracer->size][100];

    for (int i = 0; i < particletracer->size; ++i) {
        for (int j = 0; j < 100; ++j) {
            buff[i][j].x    = 0.0;
            buff[i][j].y    = 0.0;
            buff[i][j].z    = 0.0;
            buff[i][j].flag = false;
        }
    }
    int particleBufIndex[particletracer->size];

    memset(particleBufIndex, 0, sizeof(particleBufIndex));

    for (int i = 0; i < particletracer->totalParticles; ++i) {
        if (particletracer->particlePool[i].flag == true) {
            double xTemp = particletracer->particlePool[i].x;
            double yTemp = particletracer->particlePool[i].y;
            double zTemp = particletracer->particlePool[i].z;

            double x = xTemp - particletracer->xOffset;
            double y = yTemp - particletracer->yOffset;
            double z = zTemp - particletracer->zOffset;

            int iCoord = (int)(x / dx) + 1;
            int jCoord = (int)((y + 0.5 * dy) / dy) + 1;
            int kCoord = (int)((z + 0.5 * dz) / dz) + 1;

            double x1 = (double)(iCoord - 1) * dx;
            double y1 = ((double)(jCoord - 1) - 0.5) * dy;
            double z1 = ((double)(kCoord - 1) - 0.5) * dz;

            double x2 = (double)iCoord * dx;
            double y2 = ((double)jCoord - 0.5) * dy;
            double z2 = ((double)kCoord - 0.5) * dz;

            double u_n =
                (1.0 / (dx * dy * dz)) *
                ((x2 - x) * (y2 - y) * (z2 - z) * U(iCoord - 1, jCoord - 1, kCoord - 1) +
                    (x - x1) * (y2 - y) * (z2 - z) * U(iCoord, jCoord - 1, kCoord - 1) +
                    (x2 - x) * (y - y1) * (z2 - z) * U(iCoord - 1, jCoord, kCoord - 1) +
                    (x - x1) * (y - y1) * (z2 - z) * U(iCoord, jCoord, kCoord - 1) +
                    (x2 - x) * (y2 - y) * (z - z1) * U(iCoord - 1, jCoord - 1, kCoord) +
                    (x - x1) * (y2 - y) * (z - z1) * U(iCoord, jCoord - 1, kCoord) +
                    (x2 - x) * (y - y1) * (z - z1) * U(iCoord - 1, jCoord, kCoord) +
                    (x - x1) * (y - y1) * (z - z1) * U(iCoord, jCoord, kCoord));

            double new_x = (x + particletracer->xOffset) + particletracer->dt * u_n;
            particletracer->particlePool[i].x = new_x;

            iCoord = (int)((x + 0.5 * dx) / dx) + 1;
            jCoord = (int)(y / dy) + 1;
            kCoord = (int)((z + 0.5 * dz) / dz) + 1;

            x1 = ((double)(iCoord - 1) - 0.5) * dx;
            y1 = (double)(jCoord - 1) * dy;
            z1 = ((double)(kCoord - 1) - 0.5) * dz;

            x2 = ((double)iCoord - 0.5) * dx;
            y2 = (double)jCoord * dy;
            z2 = ((double)kCoord - 0.5) * dz;

            double v_n =
                (1.0 / (dx * dy * dz)) *
                ((x2 - x) * (y2 - y) * (z2 - z) * V(iCoord - 1, jCoord - 1, kCoord - 1) +
                    (x - x1) * (y2 - y) * (z2 - z) * V(iCoord, jCoord - 1, kCoord - 1) +
                    (x2 - x) * (y - y1) * (z2 - z) * V(iCoord - 1, jCoord, kCoord - 1) +
                    (x - x1) * (y - y1) * (z2 - z) * V(iCoord, jCoord, kCoord - 1) +
                    (x2 - x) * (y2 - y) * (z - z1) * V(iCoord - 1, jCoord - 1, kCoord) +
                    (x - x1) * (y2 - y) * (z - z1) * V(iCoord, jCoord - 1, kCoord) +
                    (x2 - x) * (y - y1) * (z - z1) * V(iCoord - 1, jCoord, kCoord) +
                    (x - x1) * (y - y1) * (z - z1) * V(iCoord, jCoord, kCoord));

            double new_y = (y + particletracer->yOffset) + particletracer->dt * v_n;
            particletracer->particlePool[i].y = new_y;

            iCoord = (int)((x + 0.5 * dx) / dx) + 1;
            jCoord = (int)((y + 0.5 * dy) / dy) + 1;
            kCoord = (int)(z / dz) + 1;

            x1 = ((double)(iCoord - 1) - 0.5) * dx;
            y1 = ((double)(jCoord - 1) - 0.5) * dy;
            z1 = (double)(kCoord - 1) * dz;

            x2 = ((double)iCoord - 0.5) * dx;
            y2 = ((double)jCoord - 0.5) * dy;
            z2 = (double)kCoord * dz;

            double w_n =
                (1.0 / (dx * dy * dz)) *
                ((x2 - x) * (y2 - y) * (z2 - z) * W(iCoord - 1, jCoord - 1, kCoord - 1) +
                    (x - x1) * (y2 - y) * (z2 - z) * W(iCoord, jCoord - 1, kCoord - 1) +
                    (x2 - x) * (y - y1) * (z2 - z) * W(iCoord - 1, jCoord, kCoord - 1) +
                    (x - x1) * (y - y1) * (z2 - z) * W(iCoord, jCoord, kCoord - 1) +
                    (x2 - x) * (y2 - y) * (z - z1) * W(iCoord - 1, jCoord - 1, kCoord) +
                    (x - x1) * (y2 - y) * (z - z1) * W(iCoord, jCoord - 1, kCoord) +
                    (x2 - x) * (y - y1) * (z - z1) * W(iCoord - 1, jCoord, kCoord) +
                    (x - x1) * (y - y1) * (z - z1) * W(iCoord, jCoord, kCoord));

            double new_z = (z + particletracer->zOffset) + particletracer->dt * w_n;
            particletracer->particlePool[i].z = new_z;

            // printf("Rank : %d\n", particletracer->rank);
            // printf("\tOld X : %.2f, translated X : %.2f, xOffset : %.2f, New X : %.2f,
            // iCoord : %d\n\tOld Y : %.2f, translated X : %.2f, yOffset : %.2f, New Y :
            // %.2f, jCoord : %d\n\n",xTemp, x, particletracer->xOffset, new_x, iCoord,
            // yTemp, y, particletracer->yOffset , new_y, jCoord); printf("\tU(iCoord - 1,
            // jCoord - 1) : %.2f, U(iCoord, jCoord - 1) : %.2f, U(iCoord - 1, jCoord) :
            // %.2f, U(iCoord, jCoord) : %.2f\n", U(iCoord - 1, jCoord - 1), U(iCoord,
            // jCoord - 1), U(iCoord - 1, jCoord), U(iCoord, jCoord)); printf("\tV(iCoord
            // - 1, jCoord - 1) : %.2f, V(iCoord, jCoord - 1) : %.2f, V(iCoord - 1,
            // jCoord) : %.2f, V(iCoord, jCoord) : %.2f\n\n", V(iCoord - 1, jCoord - 1),
            // V(iCoord, jCoord - 1), V(iCoord - 1, jCoord), V(iCoord, jCoord));
            // printf("\t U N : %.2f, V N : %.2f\n\n", u_n, v_n);

            if (((new_x < particletracer->xOffset) ||
                    (new_x >= particletracer->xOffsetEnd) ||
                    (new_y < particletracer->yOffset) ||
                    (new_y >= particletracer->yOffsetEnd) ||
                    (new_z < particletracer->zOffset) ||
                    (new_z >= particletracer->zOffsetEnd))) {
                // New logic to transfer particles to neighbouring ranks or discard the
                // particle.

                for (int i = 0; i < particletracer->size; ++i) {
                    if ((new_x >=
                            particletracer->offset[i + particletracer->size * XOFFSET]) &&
                        (new_x <= particletracer
                                      ->offset[i + particletracer->size * XOFFSETEND]) &&
                        (new_y >=
                            particletracer->offset[i + particletracer->size * YOFFSET]) &&
                        (new_y <= particletracer
                                      ->offset[i + particletracer->size * YOFFSETEND]) &&
                        (new_z >=
                            particletracer->offset[i + particletracer->size * ZOFFSET]) &&
                        (new_z <= particletracer
                                      ->offset[i + particletracer->size * ZOFFSETEND]) &&
                        i != particletracer->rank) {
                        buff[i][particleBufIndex[i]].x    = new_x;
                        buff[i][particleBufIndex[i]].y    = new_y;
                        buff[i][particleBufIndex[i]].z    = new_z;
                        buff[i][particleBufIndex[i]].flag = true;
                        ++particleBufIndex[i];
                    }
                }
                particletracer->particlePool[i].flag = false;

                int i_new = new_x / dx, j_new = new_y / dy, k_new = new_z / dz;

                int iOffset = particletracer->xOffset / dx,
                    jOffset = particletracer->yOffset / dy,
                    kOffset = particletracer->zOffset / dz;
                if (S(i_new - iOffset, j_new - jOffset, k_new - kOffset) != NONE) {
                    particletracer->particlePool[i].flag = false;
                }
            }
        }
    }

    for (int i = 0; i < particletracer->size; ++i) {
        if (i != particletracer->rank) {
            MPI_Send(buff[i],
                100,
                particletracer->mpi_particle,
                i,
                0,
                particletracer->comm);
        }
    }
    for (int i = 0; i < particletracer->size; ++i) {
        if (i != particletracer->rank) {
            MPI_Recv(buff[i],
                100,
                particletracer->mpi_particle,
                i,
                0,
                particletracer->comm,
                MPI_STATUS_IGNORE);
        }
    }
    for (int i = 0; i < particletracer->size; ++i) {
        if (i != particletracer->rank) {
            for (int j = 0; j < 100; ++j) {
                if (buff[i][j].flag == true) {
                    particletracer->particlePool[particletracer->pointer].x = buff[i][j]
                                                                                  .x;
                    particletracer->particlePool[particletracer->pointer].y = buff[i][j]
                                                                                  .y;
                    particletracer->particlePool[particletracer->pointer].z = buff[i][j]
                                                                                  .z;
                    particletracer->particlePool[particletracer->pointer].flag = true;
                    ++(particletracer->pointer);
                    ++(particletracer->totalParticles);
                }
            }
        }
    }
}

void freeParticles(ParticleTracer* particletracer)
{
    free(particletracer->particlePool);
    free(particletracer->linSpaceLine);
    free(particletracer->offset);
}

void writeParticles(ParticleTracer* particletracer)
{
    int collectedBuffIndex[particletracer->size];

    MPI_Gather(&particletracer->totalParticles,
        1,
        MPI_INT,
        collectedBuffIndex,
        1,
        MPI_INT,
        0,
        particletracer->comm);

    if (particletracer->rank != 0) {
        Particle buff[particletracer->totalParticles];
        for (int i = 0; i < particletracer->totalParticles; ++i) {
            buff[i].x    = particletracer->particlePool[i].x;
            buff[i].y    = particletracer->particlePool[i].y;
            buff[i].z    = particletracer->particlePool[i].z;
            buff[i].flag = particletracer->particlePool[i].flag;
            // printf("Rank : %d sending to rank 0 X : %.2f, Y : %.2f with totalpt :
            // %d\n", particletracer->rank, buff[i].x, buff[i].y,
            // particletracer->totalParticles);
        }
        MPI_Send(buff,
            particletracer->totalParticles,
            particletracer->mpi_particle,
            0,
            1,
            particletracer->comm);
    }
    if (particletracer->rank == 0) {
        char filename[50];
        FILE* fp;

        snprintf(filename, 50, "vtk_files/particles_%d.vtk", ts);
        fp = fopen(filename, "w");

        if (fp == NULL) {
            printf("Error!\n");
            exit(EXIT_FAILURE);
        }
        fprintf(fp, "# vtk DataFile Version 3.0\n");
        fprintf(fp, "PAMPI cfd solver particle tracing file\n");
        fprintf(fp, "ASCII\n");

        fprintf(fp, "DATASET UNSTRUCTURED_GRID\n");
        fprintf(fp, "FIELD FieldData 2\n");
        fprintf(fp, "TIME 1 1 double\n");
        fprintf(fp, "%d\n", ts);
        fprintf(fp, "CYCLE 1 1 int\n");
        fprintf(fp, "1\n");

        int overallTotalParticles = sum(collectedBuffIndex, particletracer->size);

        fprintf(fp, "POINTS %d float\n", overallTotalParticles);

        printf("Total particles : %d\n", overallTotalParticles);

        for (int i = 1; i < particletracer->size; ++i) {
            Particle recvBuff[collectedBuffIndex[i]];
            MPI_Recv(&recvBuff,
                collectedBuffIndex[i],
                particletracer->mpi_particle,
                i,
                1,
                particletracer->comm,
                MPI_STATUS_IGNORE);

            for (int j = 0; j < collectedBuffIndex[i]; ++j) {
                double x = recvBuff[j].x;
                double y = recvBuff[j].y;
                double z = recvBuff[j].z;
                fprintf(fp, "%f %f %f\n", x, y, z);
                // printf("Rank : 0 receiving from rank %d X : %.2f, Y : %.2f with totalpt
                // : %d\n", i, x, y, particletracer->totalParticles);
            }
        }
        for (int i = 0; i < particletracer->totalParticles; ++i) {
            double x = particletracer->particlePool[i].x;
            double y = particletracer->particlePool[i].y;
            double z = particletracer->particlePool[i].z;
            fprintf(fp, "%f %f %f\n", x, y, z);
        }

        fprintf(fp, "CELLS %d %d\n", overallTotalParticles, 2 * overallTotalParticles);

        for (int i = 0; i < overallTotalParticles; ++i) {
            fprintf(fp, "1 %d\n", i);
        }

        fprintf(fp, "CELL_TYPES %d\n", overallTotalParticles);

        for (int i = 0; i < overallTotalParticles; ++i) {
            fprintf(fp, "1\n");
        }

        fclose(fp);
    }

    ++ts;
}

void initParticleTracer(ParticleTracer* particletracer, Parameter* params, Solver* solver)
{
    /* initializing local properties from params */

    particletracer->numberOfParticles = params->numberOfParticles;
    particletracer->startTime         = params->startTime;
    particletracer->injectTimePeriod  = params->injectTimePeriod;
    particletracer->writeTimePeriod   = params->writeTimePeriod;

    particletracer->dt = params->dt;
    particletracer->dx = params->xlength / params->imax;
    particletracer->dy = params->ylength / params->jmax;
    particletracer->dz = params->zlength / params->kmax;

    particletracer->xlength = params->xlength;
    particletracer->ylength = params->ylength;
    particletracer->zlength = params->zlength;

    particletracer->x1 = params->x1;
    particletracer->y1 = params->y1;
    particletracer->z1 = params->z1;
    particletracer->x2 = params->x2;
    particletracer->y2 = params->y2;
    particletracer->z2 = params->z2;

    particletracer->lastInjectTime = params->startTime;
    particletracer->lastUpdateTime = params->startTime;
    particletracer->lastWriteTime  = params->startTime;

    particletracer->pointer        = 0;
    particletracer->totalParticles = 0;

    particletracer->imax = params->imax;
    particletracer->jmax = params->jmax;
    particletracer->kmax = params->kmax;

    particletracer->imaxLocal = solver->comm.imaxLocal;
    particletracer->jmaxLocal = solver->comm.jmaxLocal;
    particletracer->kmaxLocal = solver->comm.kmaxLocal;

    particletracer->estimatedNumParticles = (particletracer->imaxLocal *
                                             particletracer->jmaxLocal *
                                             particletracer->kmaxLocal);

    particletracer->particlePool = malloc(
        sizeof(Particle) * particletracer->estimatedNumParticles);

    for (int i = 0; i < particletracer->estimatedNumParticles; ++i) {
        particletracer->particlePool[i].x    = 0.0;
        particletracer->particlePool[i].y    = 0.0;
        particletracer->particlePool[i].z    = 0.0;
        particletracer->particlePool[i].flag = false;
    }

    particletracer->linSpaceLine = malloc(
        sizeof(Particle) * particletracer->numberOfParticles);

    /* duplicating communication from solver */
    MPI_Comm_dup(solver->comm.comm, &particletracer->comm);

    particletracer->rank = solver->comm.rank;
    particletracer->size = solver->comm.size;

    particletracer->offset = (double*)malloc(sizeof(double) * 4 * particletracer->size);

    memcpy(particletracer->dims, solver->comm.dims, sizeof(solver->comm.dims));

    memcpy(particletracer->coords, solver->comm.coords, sizeof(solver->comm.coords));

    double offset[6][particletracer->size];

    particletracer->xOffset    = solver->xOffset;
    particletracer->yOffset    = solver->yOffset;
    particletracer->zOffset    = solver->zOffset;
    particletracer->xOffsetEnd = solver->xOffsetEnd;
    particletracer->yOffsetEnd = solver->yOffsetEnd;
    particletracer->zOffsetEnd = solver->zOffsetEnd;

    // printf("Rank : %d, xOffset : %.2f, yOffset : %.2f, zOffset : %.2f, xOffsetEnd :
    // %.2f, yOffsetEnd : %.2f, zOffsetEnd : %.2f\n", particletracer->rank,
    // particletracer->xOffset, particletracer->yOffset, particletracer->zOffset,
    // particletracer->xOffsetEnd, particletracer->yOffsetEnd,
    // particletracer->zOffsetEnd);

    MPI_Allgather(&particletracer->xOffset,
        1,
        MPI_DOUBLE,
        offset[0],
        1,
        MPI_DOUBLE,
        particletracer->comm);
    MPI_Allgather(&particletracer->yOffset,
        1,
        MPI_DOUBLE,
        offset[1],
        1,
        MPI_DOUBLE,
        particletracer->comm);
    MPI_Allgather(&particletracer->zOffset,
        1,
        MPI_DOUBLE,
        offset[2],
        1,
        MPI_DOUBLE,
        particletracer->comm);
    MPI_Allgather(&particletracer->xOffsetEnd,
        1,
        MPI_DOUBLE,
        offset[3],
        1,
        MPI_DOUBLE,
        particletracer->comm);
    MPI_Allgather(&particletracer->yOffsetEnd,
        1,
        MPI_DOUBLE,
        offset[4],
        1,
        MPI_DOUBLE,
        particletracer->comm);
    MPI_Allgather(&particletracer->zOffsetEnd,
        1,
        MPI_DOUBLE,
        offset[5],
        1,
        MPI_DOUBLE,
        particletracer->comm);

    memcpy(particletracer->offset, offset, sizeof(offset));

    // if(particletracer->rank == 0)
    // {
    //     for(int i = 0;i < particletracer->size; ++i)
    //     {
    //         printf("Rank : %d, xLocal : %.2f, yLocal : %.2f, zLocal : %.2f\n", i,
    //         xLocal[i], yLocal[i], zLocal[i]);
    //     }
    //     for(int i = 0;i < particletracer->size; ++i)
    //     {
    //         printf("Rank : %d and its xOffset : %.2f, yOffset : %.2f, zOffset :
    //         %.2f,xOffsetEnd : %.2f, yOffsetEnd : %.2f, zOffsetEnd : %.2f\n", i,
    //         particletracer->offset[i + particletracer->size * XOFFSET],
    //         particletracer->offset[i + particletracer->size * YOFFSET],
    //         particletracer->offset[i + particletracer->size * ZOFFSET] ,
    //         particletracer->offset[i + particletracer->size * XOFFSETEND],
    //         particletracer->offset[i + particletracer->size * YOFFSETEND],
    //         particletracer->offset[i + particletracer->size * ZOFFSETEND]);
    //     }
    // }

    for (int i = 0; i < particletracer->numberOfParticles; ++i) {
        // double spacing                      = (double)i /
        // (double)(particletracer->numberOfParticles - 1);
        // particletracer->linSpaceLine[i].x   = spacing * particletracer->x1 + (1.0 -
        // spacing) * particletracer->x2; particletracer->linSpaceLine[i].y   = spacing *
        // particletracer->y1 + (1.0 - spacing) * particletracer->y2;
        // particletracer->linSpaceLine[i].z   = spacing * particletracer->z1 + (1.0 -
        // spacing) * particletracer->z2;

        particletracer->linSpaceLine[i].x = particletracer->x1;
        particletracer->linSpaceLine[i].y = (double)rand() / RAND_MAX *
                                            particletracer->ylength;
        particletracer->linSpaceLine[i].z = (double)rand() / RAND_MAX *
                                            particletracer->zlength;

        particletracer->linSpaceLine[i].flag = true;
    }

    // Create the mpi_particle datatype
    MPI_Datatype mpi_particle;
    int lengths[4] = { 1, 1, 1, 1 };

    MPI_Aint displacements[4];
    Particle dummy_particle;
    MPI_Aint base_address;
    MPI_Get_address(&dummy_particle, &base_address);
    MPI_Get_address(&dummy_particle.x, &displacements[0]);
    MPI_Get_address(&dummy_particle.y, &displacements[1]);
    MPI_Get_address(&dummy_particle.z, &displacements[2]);
    MPI_Get_address(&dummy_particle.flag, &displacements[3]);
    displacements[0]      = MPI_Aint_diff(displacements[0], base_address);
    displacements[1]      = MPI_Aint_diff(displacements[1], base_address);
    displacements[2]      = MPI_Aint_diff(displacements[2], base_address);
    displacements[3]      = MPI_Aint_diff(displacements[3], base_address);
    MPI_Datatype types[4] = { MPI_DOUBLE, MPI_DOUBLE, MPI_DOUBLE, MPI_C_BOOL };
    MPI_Type_create_struct(4,
        lengths,
        displacements,
        types,
        &particletracer->mpi_particle);
    MPI_Type_commit(&particletracer->mpi_particle);
}

void printParticleTracerParameters(ParticleTracer* particletracer)
{
    printf("Particle Tracing data:\n");
    printf("Rank : %d\n", particletracer->rank);
    printf("\tNumber of particles : %d being injected for every period of %.2f\n",
        particletracer->numberOfParticles,
        particletracer->injectTimePeriod);
    printf("\tstartTime : %.2f\n", particletracer->startTime);
    printf("\t(Line along which the particles are to be injected) \n\tx1 : %.2f, y1 : "
           "%.2f, z1 : %.2f, x2 : %.2f, y2 : %.2f,  z2 : %.2f\n",
        particletracer->x1,
        particletracer->y1,
        particletracer->z1,
        particletracer->x2,
        particletracer->y2,
        particletracer->z2);
    printf("\tPointer : %d, TotalParticles : %d\n",
        particletracer->pointer,
        particletracer->totalParticles);
    printf("\tdt : %.2f, dx : %.2f, dy : %.2f, dz : %.2f\n",
        particletracer->dt,
        particletracer->dx,
        particletracer->dy,
        particletracer->dz);
    printf("\tcoord[0] : %d, coord[1] : %d, coord[2] : %d\n",
        particletracer->coords[IDIM],
        particletracer->coords[JDIM],
        particletracer->coords[KDIM]);
    printf("\txOffset : %.2f, yOffset : %.2f, zOffset : %.2f\n",
        particletracer->xOffset,
        particletracer->yOffset,
        particletracer->zOffset);
    printf("\txOffsetEnd : %.2f, yOffsetEnd : %.2f, zOffsetEnd : %.2f\n",
        particletracer->xOffsetEnd,
        particletracer->yOffsetEnd,
        particletracer->zOffsetEnd);
    printf("\txLocal : %.2f, yLocal : %.2f, zLocal : %.2f\n",
        particletracer->xLocal,
        particletracer->yLocal,
        particletracer->zLocal);
}

void trace(ParticleTracer* particletracer,
    double* restrict u,
    double* restrict v,
    double* restrict w,
    int* restrict seg,
    double time)
{
    if (time >= particletracer->startTime) {
        if ((time - particletracer->lastInjectTime) >= particletracer->injectTimePeriod) {
            injectParticles(particletracer, seg);
            particletracer->lastInjectTime = time;
        }
        if ((time - particletracer->lastWriteTime) >= particletracer->writeTimePeriod) {
            writeParticles(particletracer);
            particletracer->lastWriteTime = time;
        }
        advanceParticles(particletracer, u, v, w, seg, time);
        compress(particletracer);
        particletracer->lastUpdateTime = time;
    }
}

void compress(ParticleTracer* particletracer)
{
    Particle* memPool = particletracer->particlePool;
    Particle tempPool[particletracer->totalParticles];

    for (int i = 0; i < particletracer->totalParticles; ++i) {
        tempPool[i].x    = 0.0;
        tempPool[i].y    = 0.0;
        tempPool[i].z    = 0.0;
        tempPool[i].flag = false;
    }
    int totalParticles = 0;

    for (int i = 0; i < particletracer->totalParticles; ++i) {
        if (memPool[i].flag == true) {
            tempPool[totalParticles].x    = memPool[i].x;
            tempPool[totalParticles].y    = memPool[i].y;
            tempPool[totalParticles].z    = memPool[i].z;
            tempPool[totalParticles].flag = memPool[i].flag;
            ++totalParticles;
        }
    }

    particletracer->totalParticles = totalParticles;
    particletracer->pointer        = totalParticles;

    memcpy(particletracer->particlePool, tempPool, totalParticles * sizeof(Particle));
}