#define __STDC_FORMAT_MACROS //to print 64bits unsigned integers
#include <inttypes.h>
#include <cgds/Vector.h>
#include <string.h>
#include <math.h>
#include <float.h>

char readInt(FILE* stream, int64_t* integer)
{
	*integer = 0;
	char curChar = fgetc(stream);
	int sign = (curChar == '-' ? -1 : 1);
	while (curChar < '0' || curChar > '9')
		curChar = fgetc(stream);
	ungetc(curChar, stream);
	while ((curChar = fgetc(stream)) >= '0' && curChar <= '9')
		*integer = 10 * (*integer) + (int64_t) (curChar - '0');
	(*integer) *= sign;
	return curChar;
}

char readReal(FILE* stream, float* real)
{
	int64_t integerPart;
	char nextChar = readInt(stream, &integerPart);
	int64_t fractionalPart = 0;
	int countZeros = 0;
	if (nextChar == '.')
	{
		//need to count zeros
		while ((nextChar = fgetc(stream)) == '0')
			countZeros++;
		if (nextChar >= '1' && nextChar <= '9')
		{
			ungetc(nextChar, stream);
			nextChar = readInt(stream, &fractionalPart);
		}
	}
	int64_t exponent = 0;
	if (nextChar == 'e' || nextChar == 'E')
		nextChar = readInt(stream, &exponent);
	*real = ( integerPart + (integerPart>0 ? 1. : -1.) * (float)fractionalPart
		/ pow(10,countZeros+floor(log10(fractionalPart>0 ? fractionalPart : 1)+1)) )
			* pow(10,exponent);
	return nextChar;
}

// Parse a line into integer+float (ID, raw power)
static void scan_line(FILE* ifile, int posID, uint32_t* ID, int posPower, float* rawPower)
{
	char nextChar;
	int position = 1;
	while (1)
	{
		if (position == posID)
		{
			int64_t ID_on64bits;
			nextChar = readInt(ifile, &ID_on64bits);
			*ID = (uint32_t)ID_on64bits;
		}
		else if (position == posPower)
		{
			float power = FLT_MAX; //"NA"
			nextChar = readReal(ifile, &power); //?? WARNING here... if empty field ?!
			*rawPower = (float) power;
		}
		else
			//erase the comma (and skip field then)
			nextChar = fgetc(ifile);

		//continue until next comma (or line end or file end)
		while (!feof(ifile) && nextChar != '\n' && nextChar != '\r' && nextChar != ',')
			nextChar = fgetc(ifile);
		position++;

		if (feof(ifile) || nextChar == '\n' || nextChar == '\r')
		{
			// skip all potential line feeds
			while (!feof(ifile) && nextChar == '\n' || nextChar == '\r')
				nextChar = fgetc(ifile);
			if (!feof(ifile))
				ungetc(nextChar, ifile);
			break;
		}
	}
}

// Main job: parse an "EDF-text file" into a conventional CSV file in rows, without header
void transform(const char* ifileName, const char* ofileName, uint32_t nbItems)
{
	// Use the header to know positions of ID and rawPower
	FILE* ifile = fopen(ifileName, "r");
	uint32_t headerShift = 0;
	char curChar;
	Vector* header = vector_new(char);
	do
	{
		curChar = fgetc(ifile);
		headerShift++;
		if (curChar == '\n' || curChar == '\r')
		{
			// Flush all potential other line feeds
			while (curChar == '\n' || curChar == '\r')
				curChar = fgetc(ifile);
			ungetc(curChar, ifile);
			break;
		}
		vector_push(header, curChar);
	}
	while (1);
	char* headerString = (char*)malloc((vector_size(header) + 1)*sizeof(char));
	VectorIterator* it = vector_get_iterator(header);
	int index = 0;
	while (vectorI_has_data(it))
	{
		vectorI_get(it, headerString[index]);
		vectorI_move_next(it);
		index++;
	}
	vectorI_destroy(it);
	headerString[index] = 0;
	vector_destroy(header);
	int position = 1, posID = 0, posPower = 0;
	char* columnDescriptor = strtok(headerString, ",");
	while (columnDescriptor != NULL)
	{
		if (!strcmp(columnDescriptor,"FK_CCU_ID") || !strcmp(columnDescriptor,"fk_ccu_id"))
			posID = position;
		else if (!strcmp(columnDescriptor,"CPP_PUISSANCE_BRUTE"))
			posPower = position;
		position++;
		columnDescriptor = strtok(NULL, ",");
	}
	free(headerString);

	// Estimate tsLength with a scan of the 3 first series
	uint32_t ID=0, lastID=0, refTsLength=0;
	float rawPower = 0.;
	scan_line(ifile, posID, &ID, posPower, &rawPower);
	//'sl' = sample lengths (short because a lot of comparisons then)
	uint32_t* sl = (uint32_t*) calloc(3, sizeof(uint32_t));
	for (int i=0; i<3; i++)
	{
		lastID = ID;
		while (ID == lastID)
		{
			sl[i]++;
			scan_line(ifile, posID, &ID, posPower, &rawPower);
		}
	}
	if (sl[0] <= sl[1] <= sl[2] || sl[1] <= sl[0] <= sl[2])
		refTsLength = sl[2];
	else if (sl[1] <= sl[2] <= sl[0] || sl[2] <= sl[1] <= sl[0])
		refTsLength = sl[0];
	else
		refTsLength = sl[1];
	free(sl);
	//go back at the beginning of the first series (ready to read '\n'...)
	fseek(ifile, headerShift-1, SEEK_SET);

	// output file to write time-series sequentially, CSV format.
	FILE* ofile = fopen(ofileName, "w");

	// process one client (ID in first column) at a time
	uint64_t processedLines = 0; //execution trace
	uint32_t seriesCount=0, skippedSeriesCount=0, tsLength=0;
	uint32_t mismatchLengthCount=0;
	float tsBuffer[refTsLength];
	lastID = 0;
	while (!feof(ifile))
	{
		// next element to read always start with a digit
		do
			curChar = fgetc(ifile);
		while (!feof(ifile) && (curChar < '0' || curChar > '9'));
		if (feof(ifile))
			break;
		ungetc(curChar, ifile);

		// read line
		scan_line(ifile, posID, &ID, posPower, &rawPower);
		if (ID != lastID)
		{
			//just starting a new time-series: must process the last one (if there is a last one !)
			if (lastID > 0)
			{
				if (tsLength == refTsLength)
				{
					for (int i=0; i<tsLength; i++)
					{
						char* format = i<tsLength-1 ? "%g," : "%g";
						fprintf(ofile, format, tsBuffer[i]);
					}
					fprintf(ofile, "\n");
					if (nbItems > 0 && ++seriesCount >= nbItems)
						break;
				}
				//if something wrong happened, skip series
				else
				{
					skippedSeriesCount++;
					if (tsLength != refTsLength)
						mismatchLengthCount++;
				}
			}

			// reinitialize flags
			tsLength = 0;
			lastID = ID;
		}

		//We cannot write more than refTsLength values
		if (tsLength < refTsLength)
			tsBuffer[tsLength++] = rawPower;

		if ((++processedLines) % 1000000 == 0)
			fprintf(stdout,"Processed %"PRIu64" lines\n", processedLines);
	}

	if (tsLength == refTsLength && (nbItems <= 0 || seriesCount < nbItems))
	{
		// flush last time-series if all conditions are met
		for (int i=0; i<tsLength; i++)
		{
			char* format = i<tsLength-1 ? "%g," : "%g";
			fprintf(ofile, format, tsBuffer[i]);
		}
		fprintf(ofile, "\n");
		seriesCount++;
	}
	else if (nbItems <= 0 || seriesCount < nbItems)
	{
		if (tsLength != refTsLength)
			mismatchLengthCount++;
	}

	// finally print some statistics
	if (seriesCount < nbItems)
		fprintf(stdout,"Warning: only %u series retrieved.\n",seriesCount);
	fprintf(stdout,"%u mismatch series lengths.\n",mismatchLengthCount);

	fclose(ifile);
	fclose(ofile);
}