// This program attempts to quickly determine the number of
// events in a CODA file by checking the start and the end.
// It does not use evio, rather, it just looks for a certain
// byte pattern indicating a bank header from which it can
// extract the event number. Taking the difference of the first
// and last event numbers gives the number of events in the file.
//
// NOTE: This does not work on all CODA formatted files. It
// was originally written for use by PrimEx on SunOS. It has
// been ported (but not really tested) for use by GlueX on
// Linux.

#include <iostream>
#include <iomanip>
using namespace std;

#include <stdio.h>
#include <stdlib.h>

#include <evio.h>

void Usage(void);

#define buff_size 327680

int main(int narg, char* argv[])
{

	if(narg<2)Usage();

	// Open EVIO file
	int handle;
	int err = evOpen((char*)argv[1],"r", &handle);
	if(err != S_SUCCESS){
		cout<<"0"<<endl;
		return 0;
	}
	
	// Read through all events in file
	unsigned long *buff = new unsigned long[buff_size];
	int Nevents=0;
	while(S_SUCCESS == evRead(handle, (unsigned long*)buff, buff_size))Nevents++;
	delete buff;
	
	// Close EVIO file
	if(handle)evClose(handle);
	
	// Print results
	cout<<Nevents<<endl;

	return 0;
}


void Usage(void)
{
	cout<<"Usage:"<<endl;
	cout<<"\t count_events file"<<endl;
	cout<<endl;
	cout<<"Count the number of events in a CODA formatted file."<<endl;
	cout<<"This will quickly search the beginning and end of the specified"<<endl;
	cout<<"file for CODA Event ID banks which contain the run number. The"<<endl;
	cout<<"difference between the last and first event numbers is reported."<<endl;
	cout<<endl;

	exit(0);
}

#if 0
// Byte-swap a single integer. Swapped value is returned
int swap_int(int source)
{
	int dest;
	char *s = (char*)&source;
	char *d = (char*)&dest + 4;

	*--d = *(s++);
	*--d = *(s++);
	*--d = *(s++);
	*--d = *(s++);
	return dest;
}

// The following routine tries to be very quick, but doesn't seem
// to work very well . I think it may be due to endian problems.
void OldMethod(void)
{
	// Check if we're a big endian machine or a little endian machine
	bool swap = false;
	unsigned int tmp = 0x01020304;
	if(*((char*)&tmp) == 0x04)swap=true;

	char *fname = argv[1];
	FILE *f = fopen(fname,"r");
	
	if(!f){
		cout<<"-1"<<endl;
		return 0; // exit without error so split_file.tcl won't crash
	}

	// Get first event from event ID bank
	char buff[buff_size];
	int Nbytes = fread(buff,1,buff_size,f);

	unsigned int FirstEvent = 0;
	unsigned int *iptr = (unsigned int*)buff;
	unsigned int head = (0<<0) + (1<<8) + (0xc000<<16);	
	if(swap)head=swap_int(head);
	for(int i=0;i<Nbytes/4;i++, iptr++){
	
		int s = iptr[0];
		if(swap)s = swap_int(s);
	
		if(s == 4 && iptr[1] == head){
			if(iptr[2]!=0)FirstEvent = iptr[2];
			break;
		}		
	}
	if(swap)FirstEvent = swap_int(FirstEvent);

	// Get File size
	fseek(f,0,SEEK_END);
	long fsize = ftell(f);

	// Get Last Event from event ID bank
	fseek(f,0,SEEK_END);
	unsigned int LastEvent = 0;
	int sop = 0;
	do{
		fseek(f,-buff_size,SEEK_CUR);
		sop+=buff_size;
		if(sop>fsize)fseek(f,0,SEEK_SET);
		Nbytes = fread(buff,1,buff_size,f);
		fseek(f,-Nbytes,SEEK_CUR);
		
		iptr = (unsigned int*)buff;
		for(int i=0;i<Nbytes/4;i++, iptr++){
			int s = iptr[0];
			if(swap)s = swap_int(s);
			if(s == 4 && iptr[1] == head){
				if(iptr[2]!=0)LastEvent = iptr[2];
			}       
		}
		
		if(swap)LastEvent = swap_int(LastEvent);
		
	}while(LastEvent<=0 && sop<fsize);

	//cout<<"First Event:"<<FirstEvent<<endl;
	//cout<<"Last Event:"<<LastEvent<<endl;
	//cout<<"Number Events in File:"<<LastEvent-FirstEvent+1<<endl;
	//cout<<LastEvent-FirstEvent+1<<endl;

	fclose(f);

	return 0;
}
#endif