/*-----------------------------------------------------------------------------------------
 * Copyright (C) 2016  For the list of authors, see file AUTHORS.
 *
 * This file is part of IFOS.
 * 
 * IFOS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 2.0 of the License only.
 * 
 * IFOS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with IFOS. See file COPYING and/or <http://www.gnu.org/licenses/gpl-2.0.html>.
-----------------------------------------------------------------------------------------*/

/*-------------------------------------------------------------
 *  Check FD-Grid for stability and grid dispersion.
 *  If the stability criterion is not fullfilled the program will
 *  terminate.                   
 *
 *  ----------------------------------------------------------*/

#include <limits.h>
#include "fd.h"

void checkfd(FILE *fp, float ** prho, float ** ppi, float ** pu, float ** ptaus, float ** ptaup, float *peta, float *hc, float **srcpos, int nsrc, int **recpos, int ntr){

	extern float DH, DT, TS;
	extern float XREC1, XREC2, YREC1, YREC2;
        extern int NX, NY, MYID, PARAMETERIZATION, FW, L, NT, NDT, ACOUSTIC;
	extern int READREC, NPROCX,NPROCY, SRCREC, FREE_SURF;
        extern int SEISMO, SEIS_FORMAT[6];
	extern char SOURCE_FILE[STRING_SIZE], REC_FILE[STRING_SIZE];

	/* local variables */

	float  c = 0.0, cmax_p=0.0, cmin_p=1e9, cmax_s=0.0, cmin_s=1e9, fmax, gamma;
	float  cmax=0.0, cmin=1e9, dtstab, dhstab, cmax_r, cmin_r;
	float sumu, sumpi, ws, ts, ppi_ref = 0.0, pu_ref;
	int nfw=iround(FW/DH);
	int i, j, k, l, ny1=1, nx, ny, nx_min, ny_min;
	float srec_minx=DH*NX*NPROCX+1, srec_miny=DH*NY*NPROCY+1;
	float srec_maxx=-1.0, srec_maxy=-1.0;
	
	
	ws=2.0*PI/TS; /*center frequency of source*/
	
	nx=NX; ny=NY; 

	/* low Q frame not yet applied as a absorbing boundary */
	/* if (!FREE_SURF) ny1=1+nfw;*/
	nfw=0;
	
		

	/* find maximum model phase velocity of shear waves at infinite
	      frequency within the whole model */
	if(!ACOUSTIC){
		if (L){  /*viscoelastic*/
			for (i=1+nfw;i<=(nx-nfw);i++){
				for (j=ny1;j<=(ny-nfw);j++){
				
					sumu=0.0;
					for (l=1;l<=L;l++){
						ts=DT/peta[l];
						sumu=sumu+((ws*ws*ts*ts*ptaus[j][i])/(1.0+ws*ws*ts*ts));
					}
					
					if(PARAMETERIZATION==1){
						pu_ref=prho[j][i]*pu[j][i]*pu[j][i];
                    } else {
						pu_ref=pu[j][i];
                    }
						
					
					/* minimum phase velocity of shear waves */
					c=sqrt(pu_ref/(prho[j][i]*(1.0+sumu)));
									
					if (cmin_s>c) cmin_s=c;
					
					
					/* maximum phase velocity of shear waves */
					c=sqrt(pu_ref*(1.0+L*ptaus[j][i])/(prho[j][i]*(1.0+sumu)));
					
					if (cmax_s<c) cmax_s=c;
				}
			}
		} else { /*L=0, elastic*/
			for (i=1+nfw;i<=(nx-nfw);i++){
				for (j=ny1;j<=(ny-nfw);j++){

					if(PARAMETERIZATION==3){
						c=sqrt(pu[j][i]/prho[j][i]);
                    } else {
						c=pu[j][i];
					}

					if (cmax_s<c) cmax_s=c;
					if (cmin_s>c) cmin_s=c;
				}
			}
		}
	}
	
	/* find maximum model phase velocity of P-waves at infinite
		 frequency within the whole model */
	if (L){  /*viscoelastic*/
		for (i=1+nfw;i<=(nx-nfw);i++){
			for (j=ny1;j<=(ny-nfw);j++){
			        
				
				sumpi=0.0;
				for (l=1;l<=L;l++){
					ts=DT/peta[l];
					sumpi=sumpi+((ws*ws*ts*ts*ptaup[j][i])/(1.0+ws*ws*ts*ts));
				}
				
				if(PARAMETERIZATION==1){
					ppi_ref=prho[j][i]*ppi[j][i]*ppi[j][i];}
				if(PARAMETERIZATION==3){
					ppi_ref=ppi[j][i]+2*pu[j][i];}
					
				/* minimum phase velocity of P waves */
				c=sqrt(ppi_ref/(prho[j][i]*(1.0+sumpi)));
				
				if (cmin_p>c) cmin_p=c;
				
				
				/* maximum phase velocity of shear waves */
				c=sqrt(ppi_ref*(1.0+L*ptaup[j][i])/(prho[j][i]*(1.0+sumpi)));
				
				if (cmax_p<c) cmax_p=c;
			}
		}
	}
	else{ /*L=0, elastic*/
		for (i=1+nfw;i<=(nx-nfw);i++){
			for (j=ny1;j<=(ny-nfw);j++){

				if(PARAMETERIZATION==3){
					c=sqrt((ppi[j][i]+2.0*pu[j][i])/prho[j][i]);}

				if(PARAMETERIZATION==1){
					c=ppi[j][i];}

				if (cmax_p<c) cmax_p=c;
				if (cmin_p>c) cmin_p=c;
			}
		}

	}


	if (MYID==0){
		fprintf(fp,"\n\n\n **Message from checkfd (printed by PE %d):\n",MYID);
		if(!ACOUSTIC){
		fprintf(fp," Minimum and maximum P-wave and S-wave velocities within subvolumes: \n ");
		fprintf(fp," MYID\t Vp_min(f=fc) \t Vp_max(f=inf) \t Vs_min(f=fc) \t Vsmax(f=inf) \n");}
		else{
		fprintf(fp," Minimum and maximum P-wave velocities within subvolumes: \n ");
		fprintf(fp," MYID\t Vp_min(f=fc) \t Vp_max(f=inf) \n");}
	}
	MPI_Barrier(MPI_COMM_WORLD);
	if(!ACOUSTIC)
	fprintf(fp," %d \t %e \t %e \t %e \t %e \n", MYID, cmin_p, cmax_p, cmin_s, cmax_s);
	else
	fprintf(fp," %d \t %e \t %e \n", MYID, cmin_p, cmax_p);

	if(ACOUSTIC==0){
		if (cmax_s>cmax_p) cmax=cmax_s; 
		else cmax=cmax_p;
		if (cmin_s<cmin_p) cmin=cmin_s; 
		else cmin=cmin_p;}
	else if(ACOUSTIC==1){
		cmax=cmax_p;
		cmin=cmin_p;
	}

	/* find global maximum for Vp and global minimum for Vs*/
	MPI_Allreduce(&cmax,&cmax_r,1,MPI_FLOAT,MPI_MAX,MPI_COMM_WORLD);
	MPI_Allreduce(&cmin,&cmin_r,1,MPI_FLOAT,MPI_MIN,MPI_COMM_WORLD);
	cmax=cmax_r;
	cmin=cmin_r;	

	fmax=2.0/TS;
	dhstab = (cmin/(hc[0]*fmax));
	gamma = fabs(hc[1]) + fabs(hc[2]) + fabs(hc[3]) + fabs(hc[4]) + fabs(hc[5]) + fabs(hc[6]);
	dtstab = DH/(sqrt(2)*gamma*cmax);
	/*dtstab=DH/(sqrt(2.0)*cmax);*/

	/* find global minimum for NX and NY */
	MPI_Allreduce(&NX,&nx_min,1,MPI_INT,MPI_MIN,MPI_COMM_WORLD);
	MPI_Allreduce(&NY,&ny_min,1,MPI_INT,MPI_MIN,MPI_COMM_WORLD);
	

	if (MYID == 0) {

	fprintf(fp," Global values for entire model: \n");
	if(!ACOUSTIC)
		fprintf(fp," Vp_max= %e m/s \t Vs_min=%e m/s \n\n", cmax,cmin);
	else
		fprintf(fp," Vp_max= %e m/s \t Vp_min=%e m/s \n\n", cmax,cmin);
	fprintf(fp,"\n\n ------------------ CHECK FOR GRID DISPERSION --------------------\n");
	fprintf(fp," To satisfactorily limit grid dispersion the number of gridpoints \n");
	if(!ACOUSTIC)
		fprintf(fp," per minimum wavelength (of S-waves) should be 6 (better more).\n");
	else
		fprintf(fp," per minimum wavelength (of P-waves) should be 6 (better more).\n");
	fprintf(fp," Here the minimum wavelength is assumed to be minimum model phase velocity \n");
	if(!ACOUSTIC)
		fprintf(fp," (of S-waves) at maximum frequency of the source\n");
	else
		fprintf(fp," (of P-waves) at maximum frequency of the source\n");
	fprintf(fp," devided by maximum frequency of the source.\n");
	fprintf(fp," Maximum frequency of the source is approximately %8.2f Hz\n",2.0/TS);
	if(!ACOUSTIC)
		fprintf(fp," The minimum wavelength (of S-waves) in the following simulation will\n");
	else
		fprintf(fp," The minimum wavelength (of P-waves) in the following simulation will\n");
	fprintf(fp," be %e meter.\n", cmin/fmax);
	fprintf(fp," Thus, the recommended value for DH is %e meter.\n", dhstab);
	fprintf(fp," You have specified DH= %e meter.\n\n", DH);
	if (DH>dhstab)
		warning(" Grid dispersion will influence wave propagation, choose smaller grid spacing (DH).");
	
	fprintf(fp," \n\n ----------------------- CHECK FOR STABILITY ---------------------\n");
	fprintf(fp," The following simulation is stable provided that\n\n");
	fprintf(fp," \t p=cmax*DT/DH < 1/(sqrt(2)*gamma),\n\n");
	fprintf(fp," where cmax is the maximum phase velocity at infinite frequency\n");
	fprintf(fp," and gamma = sum(|FD coeff.|)\n");

	fprintf(fp," In the current simulation cmax is %8.2f m/s .\n\n",cmax);

	fprintf(fp," DT is the timestep and DH is the grid size.\n\n");
	fprintf(fp," In this simulation the stability limit for timestep DT is %e seconds .\n",dtstab);
	fprintf(fp," You have specified DT= %e s.\n", DT);
	if (DT>dtstab)
		declare_error(" The simulation will get unstable, choose smaller DT. ");
	else fprintf(fp," The simulation will be stable.\n");


        fprintf(fp," \n\n --------------------- CHECK FOR INPUT ERRORS ---------------------\n");

	if ((SEISMO)&& (MYID==0)){
		fprintf(fp," Checking the number of seismogram samples. \n");
		fprintf(fp,"    Number of timesteps %d.\n", NT);
		fprintf(fp,"    Seismogram sampling rate in timesteps %d.\n", NDT);
		fprintf(fp,"    Number of seismogram output samples %d.\n", NT/NDT);

		/* SU and SEG-Y allow 32767 samples, furthermore the exist programs allow for 65535 samples
		and pseudo-SEG-Y formats allow foralmost arbitrarily long traces. 
		For binary and textual output the limit is arbitrary. USHRT_MAX is the limit of an unsigned short specified in limits.h */

		if ((SEIS_FORMAT[0]==1) && (NT/NDT)>( USHRT_MAX )) {
			fprintf(fp," Maximum allowed number of samples per trace in SU format: %d \n", USHRT_MAX );
			declare_error(" Sorry. Too many samples per receiver! \n");
		}
	}



	if ((SEISMO>0) && (MYID==0)) {
		srec_minx=DH*NX*NPROCX+1, srec_miny=DH*NY*NPROCY+1;
		srec_maxx=-1.0, srec_maxy=-1.0;
		fprintf(fp,"\n Checking for receiver position(s) specified in input file.\n");
		fprintf(fp,"    Global grid size in m: %5.2f (x) : %5.2f (y) \n",NX*DH*NPROCX,NY*DH*NPROCY);
		if (FREE_SURF==0) fprintf(fp,"    Global grid size in m(-width of abs.boundary) : \n        %5.2f-%5.2f (x in m) : %5.2f-%5.2f (y in m) \n",FW*DH,NX*DH*NPROCX-FW*DH,FW*DH,NY*DH*NPROCY-FW*DH);
		if (FREE_SURF==1) fprintf(fp,"    Global grid size in m(-width of abs.boundary) : \n        %5.2f-%5.2f (x in m) : %5.2f-%5.2f (y in m) \n",FW*DH,NX*DH*NPROCX-FW*DH,DH,NY*DH*NPROCY-FW*DH);

                        /* find maximum and minimum source positions coordinate ---- from input file*/
                        /*for usability reasons, "z" - as commonly used - denotes the depth (vertical direction),
                  however, internally "y" is used for the vertical coordinate,
                  we simply switch the "y" and "z" coordinate as read in the input file,
                  therefore we determine the minimum/maximum position in y-direction by the ZREC1 variable and vice versa.
                  this has to be considered for the receiver line coordinates specified in both the input file and separate source/receiver files*/

		if (READREC==0) {
			if (XREC1>XREC2) {
				srec_maxx=XREC1;
				srec_minx=XREC2;
			}
			else {
				srec_maxx=XREC2;
				srec_minx=XREC1;
			}
			if (YREC1>YREC2) {
				srec_maxy=YREC1;
				srec_miny=YREC2;
			}
			else {
				srec_maxy=YREC2;
				srec_miny=YREC1;
			}
			fprintf(fp,"    Number of receiver positions in input file : %i \n", ntr);
		}
		if (READREC==1) {
			/* find maximum and minimum source positions coordinate ---- from receiver file*/
			for (k=1;k<=ntr;k++){
				/* find maximum source positions coordinate*/
				if ((recpos[1][k]*DH)>srec_maxx) srec_maxx=recpos[1][k]*DH;
				if ((recpos[2][k]*DH)>srec_maxy) srec_maxy=recpos[2][k]*DH;
				/* find minimum source positions coordinate*/
				if ((recpos[1][k]*DH)<srec_minx) srec_minx=recpos[1][k]*DH;
				if ((recpos[2][k]*DH)<srec_miny) srec_miny=recpos[2][k]*DH;
			}
			fprintf(fp,"    Number of receiver positions in receiver file %s : %i \n", REC_FILE, ntr);
		}



		fprintf(fp,"    Minimum receiver position coordinates : %5.2f (x) : %5.2f (y) \n",srec_minx,srec_miny);
		fprintf(fp,"    Maximum receiver position coordinates : %5.2f (x) : %5.2f (y) \n",srec_maxx,srec_maxy);
		/* checking if receiver coordinate of first receiver in line specified in input-file is inside the global grid */
		if (((srec_maxx<0.0) || (srec_maxy<0.0)) || ((srec_minx<0.0) || (srec_miny<0.0))) {
			declare_error("\n\n Coordinate of at least one receiver location is outside the global grid. \n\n");
		}
		if ((srec_maxx>NX*DH*NPROCX) || (srec_maxy>NY*DH*NPROCY)) {
			declare_error("\n\n Coordinate of at least one receiver location is outside the global grid. \n\n");
		}
		/* checking if receiver coordinate of first receiver in line specified in input-file is outside the Absorbing Boundary  */
		if ((srec_maxx<(FW*DH)) || (srec_minx<(FW*DH))) {
			/* this warning appears, when at least a single receiver is located in AB between 0 - FW+DX/DX/DZ ("inner boundary")*/
			warning("\n\n Coordinate of at least one receiver location is inside the Absorbing Boundary (warning 1, left boundary). \n\n");
		}
		if (srec_maxx>(NX*DH*NPROCX-FW*DH)) {
			/* this warning appears, when at least a single receiver is located in AB between NX/NY/NZ-FW+DX/DX/DZ and NX/NY/NZ ("outer boundary")*/
			warning("\n\n Coordinate of at least one receiver location is inside the Absorbing Boundary (warning 2, right boundary). \n\n");
		}
		if (srec_maxy>(NY*DH*NPROCY-FW*DH)) {
			/* this warning appears, when at least a single receiver is located in AB between NX/NY/NZ-FW+DX/DX/DZ and NX/NY/NZ ("outer boundary")*/
			warning("\n\n Coordinate of at least one receiver location is inside the Absorbing Boundary (warning 3, lower boundary). \n\n");
		}
		if ((srec_miny<(FW*DH)) && !(FREE_SURF)) {
			/* this warning appears, when at least a single receiver is located in AB between NX/NY/NZ-FW+DX/DX/DZ and NX/NY/NZ ("outer boundary")*/
			warning("\n\n Coordinate of at least one receiver location is inside the Absorbing Boundary (warning 4, top boundary). \n\n");
		}

		fprintf(fp," ... complete, receiver position specified in input file are located within the global grid.\n");

	}





	if ((SRCREC==1)&& (MYID==0)){
		srec_minx=DH*NX*NPROCX+1, srec_miny=DH*NY*NPROCY+1;
		srec_maxx=-1.0, srec_maxy=-1.0;
		fprintf(fp,"\n Checking for source position(s) specified in source file. \n");
		fprintf(fp,"    Global grid size in m: %5.2f (x) : %5.2f (y) \n",NX*DH*NPROCX,NY*DH*NPROCY);
		if (FREE_SURF==0) fprintf(fp,"    Global grid size in m (-width of abs.boundary) : \n        %5.2f-%5.2f (x in m) : %5.2f-%5.2f (y in m) \n",FW*DH,NX*DH*NPROCX-FW*DH,FW*DH,NY*DH*NPROCY-FW*DH);
		if (FREE_SURF==1) fprintf(fp,"    Global grid size in m(-width of abs.boundary) : \n        %5.2f-%5.2f (x in m) : %5.2f-%5.2f (y in m) \n",FW*DH,NX*DH*NPROCX-FW*DH,DH,NY*DH*NPROCY-FW*DH);


		for (k=1;k<=nsrc;k++){
			/* find maximum source positions coordinate*/
			if (srcpos[1][k]>srec_maxx) srec_maxx=srcpos[1][k];
			if (srcpos[2][k]>srec_maxy) srec_maxy=srcpos[2][k];
			/* find minimum source positions coordinate*/
			if (srcpos[1][k]<srec_minx) srec_minx=srcpos[1][k];
			if (srcpos[2][k]<srec_miny) srec_miny=srcpos[2][k];
		}

		fprintf(fp,"    Number of source positions in source file %s. : %i.\n", SOURCE_FILE, nsrc);
		fprintf(fp,"    Minimum source position coordinates : %5.2f (x) : %5.2f (y) \n",srec_minx,srec_miny);
		fprintf(fp,"    Maximum source position coordinates : %5.2f (x) : %5.2f (y) \n",srec_maxx,srec_maxy);
		/* checking if receiver coordinate of first receiver in line specified in input-file is inside the global grid */
		if (((srec_maxx<0.0) || (srec_maxy<0.0)) || ((srec_minx<0.0) || (srec_miny<0.0))) {
			declare_error("\n\n Coordinate of at least one source location is outside the global grid. \n\n");
		}
		if ((srec_maxx>NX*DH*NPROCX) || (srec_maxy>NY*DH*NPROCY)) {
			declare_error("\n\n Coordinate of at least one source location is outside the global grid. \n\n");
		}
		/* checking if receiver coordinate of first receiver in line specified in input-file is outside the Absorbing Boundary  */
		if ((srec_maxx<(FW*DH)) || (srec_minx<(FW*DH))) {
			/* this warning appears, when at least a single receiver is located in AB between 0 - FW+DX/DX/DZ ("inner boundary")*/
			warning("\n\n Coordinate of at least one source location is inside the Absorbing Boundary (warning 1, left boundary). \n\n");
		}
		if (srec_maxx>(NX*DH*NPROCX-FW*DH)) {
			/* this warning appears, when at least a single receiver is located in AB between NX/NY/NZ-FW+DX/DX/DZ and NX/NY/NZ ("outer boundary")*/
			warning("\n\n Coordinate of at least one source location is inside the Absorbing Boundary (warning 2, right boundary). \n\n");
		}
		if (srec_maxy>(NY*DH*NPROCY-FW*DH)) {
			/* this warning appears, when at least a single receiver is located in AB between NX/NY/NZ-FW+DX/DX/DZ and NX/NY/NZ ("outer boundary")*/
			warning("\n\n Coordinate of at least one source location is inside the Absorbing Boundary (warning 3, lower boundary). \n\n");
		}
		if ((srec_miny<(FW*DH)) && !(FREE_SURF)) {
			/* this warning appears, when at least a single receiver is located in AB between NX/NY/NZ-FW+DX/DX/DZ and NX/NY/NZ ("outer boundary")*/
			warning("\n\n Coordinate of at least one source location is inside the Absorbing Boundary (warning 4, top boundary). \n\n");
		}
		fprintf(fp," ...complete, all source position(s) specified in source file are located within the global grid.\n");

	}





	fprintf(fp,"\n\n ----------------------- ABSORBING BOUNDARY ------------------------\n");
        if((FW>nx_min)||(FW>ny_min)){
	  declare_error(" The width of the absorbing boundary is larger than one computational domain. Choose smaller FW or use less CPUs.");
	}

	fprintf(fp," Width (FW) of absorbing frame should be at least 10 gridpoints.\n");
	fprintf(fp," You have specified a width of %d gridpoints.\n",FW);
	if (FW<10) 
		warning(" Be aware of artificial reflections from grid boundaries ! \n");

	}
	
	MPI_Barrier(MPI_COMM_WORLD);
	
}