/**
 * @file
 * \brief This file implements different operations on the SparseData structure.
 *
 * Most functions on sparse vectors are first defined on SparseData, and
 * then packaged up as functions on sparse vectors using wrappers. 
 *
 * This is the general procedure for adding functionalities to sparse vectors:
 *  1. Write the function for SparseData.
 *  2. Wrap it up for SvecType in operators.c or sparse_vector.c.
 *  3. Make the function available in gp_svec.sql.
 */

#include <postgres.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <float.h>
#include "SparseData.h"
#include "utils/builtins.h"
#include "utils/syscache.h"
#include "parser/parse_func.h"
#include "access/htup.h"
#include "catalog/pg_proc.h"

void* array_pos_ref = NULL;

/** 
 * @return A SparseData structure with allocated empty dynamic 
 * StringInfo of unknown initial sizes.
 */
SparseData makeSparseData(void) {
	/* Allocate the struct */
	SparseData sdata = (SparseData)palloc(sizeof(SparseDataStruct));

	/* Allocate the included elements */
	sdata->vals  = makeStringInfo();
	sdata->index = makeStringInfo();
	sdata->vals->len = 0;
	sdata->index->len = 0;
	sdata->vals->cursor = 0;
	sdata->index->cursor = 0;
	sdata->unique_value_count=0;
	sdata->total_value_count=0;
	sdata->type_of_data = FLOAT8OID;
	return sdata;
}

/** 
 * @return A SparseData with zero storage in its StringInfos.
 */
SparseData makeEmptySparseData(void) {
	/* Allocate the struct */
	SparseData sdata = makeSparseData();

	/* Free the data area */
	pfree(sdata->vals->data);
	pfree(sdata->index->data);
	sdata->vals->data  = palloc(1);
	sdata->index->data = palloc(1);
	sdata->vals->maxlen=0;
	sdata->index->maxlen=0;
	return sdata;
}

/**
 * @param vals An array of data values
 * @param index An array of run-lengths
 * @param datasize The length of the vals array
 * @param indexsize The length of the index array
 * @param datatype The object ID of the elements represented in the vals array
 * @param unique_value_count The number of RLE blocks in the vals array
 * @param total_value_count The total number of individual elements represented in the vals and index arrays
 * @return A SparseData created in place using pointers to the vals and index data
 */
SparseData makeInplaceSparseData(char *vals, char *index,
		int datasize, int indexsize, Oid datatype,
		int unique_value_count, int total_value_count) {
	SparseData sdata = makeEmptySparseData();
	sdata->unique_value_count = unique_value_count;
	sdata->total_value_count  = total_value_count;
	
	/*
	 * Note: We are disobeying the constraints demanded in lib/stringinfo.h:
	 * We do not use terminating NULL characters for the data field of
	 * struct StringInfoData, i.e., sparse-vector code will not rely on
	 * data[len] == '\0'
	 */
	sdata->vals->data = vals;
	sdata->vals->len = datasize;
	sdata->vals->maxlen = sdata->vals->len;
	sdata->index->data = index;
	sdata->index->len = indexsize;
	sdata->index->maxlen = sdata->index->len;
	sdata->type_of_data = datatype;
	return sdata;
}

/**
 * @return A copy of an existing SparseData. 
 */
SparseData makeSparseDataCopy(SparseData source_sdata) {
	/* Allocate the struct */
	SparseData sdata = (SparseData)palloc(sizeof(SparseDataStruct));
	/* Allocate the included elements */
	sdata->vals = copyStringInfo(source_sdata->vals);
	sdata->index = copyStringInfo(source_sdata->index);
	sdata->type_of_data       = source_sdata->type_of_data;
	sdata->unique_value_count = source_sdata->unique_value_count;
	sdata->total_value_count  = source_sdata->total_value_count;
	return sdata;
}
/**
 * @param constant The value of an RLE block
 * @param dimension The size of an RLE block
 * @return A SparseData with a single RLE block of size dimension having value constant
 */
SparseData makeSparseDataFromDouble(double constant,int64 dimension) {
	char *bytestore=(char *)palloc(sizeof(char)*9);
	SparseData sdata = float8arr_to_sdata(&constant,1);
	int8_to_compword(dimension,bytestore); /* create compressed version of
					          int8 value */
	pfree(sdata->index->data);
	sdata->index->data = bytestore;
	sdata->index->len = int8compstoragesize(bytestore);
	sdata->total_value_count=dimension;
	if (sdata->index->maxlen < int8compstoragesize(bytestore)) {
		ereport(ERROR,(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
			       errmsg("Internal error")));
	}
	return sdata;
}

/**
 * Frees up the memory occupied by sdata
 */
void freeSparseData(SparseData sdata) {
	pfree(sdata->vals);
	pfree(sdata->index);
	pfree(sdata);
}

/** 
 * Frees up the memory occupied by sdata, including the data elements of vals and index.
 */
void freeSparseDataAndData(SparseData sdata) {
	pfree(sdata->vals->data);
	pfree(sdata->index->data);
	freeSparseData(sdata);
}

/**
 * @param sinfo The StringInfo structure to be copied
 * @return A copy of sinfo
 */
StringInfo copyStringInfo(StringInfo sinfo) {
	StringInfo result;
	char *data;
	if (sinfo->data == NULL) {
		data = NULL;
	} else {
		data   = (char *)palloc(sizeof(char)*(sinfo->len+1));
		memcpy(data,sinfo->data,sinfo->len);
		data[sinfo->len] = '\0';
	}
	result = makeStringInfoFromData(data,sinfo->len);
	return result;
}

/**
 * @param data Pointer to an array of elements
 * @param len The size of the data array
 * @return A StringInfo from a data pointer and length
 */
StringInfo makeStringInfoFromData(char *data,int len) {
	StringInfo sinfo;
	sinfo = (StringInfo)palloc(sizeof(StringInfoData));
	sinfo->data   = data;
	sinfo->len    = len;
	sinfo->maxlen = len;
	sinfo->cursor = 0;
	return sinfo;
}

/**
 * @param array The array of doubles to be converted to a SparseData
 * @param count The size of array
 * @return A SparseData representation of an input array of doubles
 */
SparseData float8arr_to_sdata(double *array, int count) {
	return arr_to_sdata((char *)array, sizeof(float8), FLOAT8OID, count);
}

/**
 * @param array The array of values to be converted to values in SparseData
 * @param array_pos The array of positions to be converted to runs in SparseData
 * @param count The size of array
 * @return A SparseData representation of an input array of doubles
 */
SparseData position_to_sdata(double *array,int64 *array_pos, int count, int64 end, double base_val) {
	return posit_to_sdata((char *)array, array_pos, sizeof(float8), FLOAT8OID, count, end, (char *)&base_val);
}

/**
 * @param array The array of elements to be converted to a SparseData
 * @param width The size of the elements in array
 * @param type_of_data The object ID of the elements in array
 * @param count The size of array
 * @return A SparseData representation of an input array
 */
SparseData arr_to_sdata(char *array, size_t width, Oid type_of_data, int count){
	char *run_val=array;
	int64 run_len=1;
	SparseData sdata = makeSparseData();

	sdata->type_of_data=type_of_data;

	for (int i=1; i<count; i++) {
		char *curr_val=array+ (i*size_of_type(type_of_data));

		/*
		 * Note that special double values like denormalized numbers and exceptions
		 * like NaN are treated like any other value - if there are duplicates, the
		 * value of the special number is preserved and they are counted.
		 */
		if (memcmp(curr_val,run_val,width))
		{       /*run is interrupted, initiate new run */
			/* package up the finished run */
			add_run_to_sdata(run_val,run_len,width,sdata);
			/* mark beginning of new run */
			run_val=curr_val;
			run_len=1;
		} else 
		{ /* we're still in the same run */
			run_len++;
		}
	}
	add_run_to_sdata(run_val, run_len, width, sdata); /* package up the last run */

	/* Add the final tallies */
	sdata->unique_value_count = sdata->vals->len/width;
	sdata->total_value_count = count;

	return sdata;
}

int compar(const void *i, const void *j){
	return (int)((int64*)array_pos_ref)[*(int*)i] - ((int64*)array_pos_ref)[*(int*)j];
}

/**
 * @param array The values of the positions	
 * @param array_pos The position for the values
 * @param width The size of the element in the array
 * @param type_of_data tyep of the value element
 * @param count Number of element in the array
 * @param end Target size of the element
 * @return A SparseData representation of an input array
 */

SparseData posit_to_sdata(char *array, int64* array_pos, size_t width, Oid type_of_data, int count, int64 end, char *base_val){
	char *run_val=array;
	int64 run_len;
	SparseData sdata = makeSparseData();
	
	int *index = (int*)palloc(count*sizeof(int));
	for(int i = 0; i < count; ++i){
		index[i] = i;
	}
	
	/* this is a temp solutoin that will be in place only until qsort_r is a standard llibrary */
	array_pos_ref = array_pos;
	qsort(index, count, sizeof(int), compar);
	
	sdata->type_of_data=type_of_data;
	if(array_pos[index[0]] > 1){
		run_len = array_pos[index[0]]-1;
		add_run_to_sdata(base_val,run_len,width,sdata);
	}
	
	for (int i = 0; i<count; i++) {
		run_len=1;
		/*
		 * Note that special double values like denormalized numbers and exceptions
		 * like NaN are treated like any other value - if there are duplicates, the
		 * value of the special number is preserved and they are counted.
		 */
		while((i < count-1)&&((array_pos[index[i+1]] - array_pos[index[i]])==1)&&(memcmp((array+index[i]*size_of_type(type_of_data)),(array+index[i+1]*size_of_type(type_of_data)),width)==0)){
			run_len++;
			i++;
		}
		while((i < count-1)&&((array_pos[index[i+1]] - array_pos[index[i]])==0)){
			if((memcmp((array+index[i]*size_of_type(type_of_data)),(array+index[i+1]*size_of_type(type_of_data)),width)==0)){
				i++;
			}else{
				ereport(ERROR,
					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
					 errmsg("posit_to_sdata conflicting values for the same position")));
			}
		}
		run_val = array+index[i]*size_of_type(type_of_data);
		add_run_to_sdata(run_val,run_len,width,sdata);
		
		if(i < count-1){
			run_len = array_pos[index[i+1]]-array_pos[index[i]]-1;
			if(run_len > 0){
				add_run_to_sdata(base_val,run_len,width,sdata);
			}
		}else if(array_pos[index[i]] < end){
			run_len = end-array_pos[index[i]];
			if(run_len > 0){
				add_run_to_sdata(base_val,run_len,width,sdata);
			}
		}
	}
	
	/* Add the final tallies */
	sdata->unique_value_count = sdata->vals->len/width;
	sdata->total_value_count = count;
	pfree(index);
	return sdata;
}


/**
 * @param sdata The SparseData to be converted to an array of float8s
 * @return A float8[] representation of a SparseData
 */
double *sdata_to_float8arr(SparseData sdata) {
	double *array;
	int j, aptr;
	char *iptr;

	if (sdata->type_of_data != FLOAT8OID) {
		ereport(ERROR,(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
			errmsg("Data type of SparseData is not FLOAT64\n")));
	}

	if ((array=(double *)palloc(sizeof(double)*(sdata->total_value_count)))
	      == NULL)
	{
		ereport(ERROR,(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
			       errmsg("Error allocating memory for array\n")));
	}

	iptr = sdata->index->data;
	aptr = 0;
	for (int i=0; i<sdata->unique_value_count; i++) {
		for (j=0;j<compword_to_int8(iptr);j++,aptr++) {
			array[aptr] = ((double *)(sdata->vals->data))[i];
		}
		iptr+=int8compstoragesize(iptr);
	}

	if ((aptr) != sdata->total_value_count) 
	{
		ereport(ERROR,(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
		  errmsg("Array size is incorrect, is: %d and should be %d\n",
				aptr,sdata->total_value_count)));

		pfree(array);
		return NULL;
	}

	return array;
}

/**
 * @return An array of integers given the (compressed) count array of a SparseData
 */
int64 *sdata_index_to_int64arr(SparseData sdata) {
	char *iptr;
	int64 *array_ix = (int64 *)palloc(
			sizeof(int64)*(sdata->unique_value_count));

	iptr = sdata->index->data;
	for (int i=0; i<sdata->unique_value_count; i++,
			iptr+=int8compstoragesize(iptr)) {
		array_ix[i] = compword_to_int8(iptr);
	}
	return(array_ix);
}

/**
 * @param target The memory area to store the serialised SparseData
 * @para source The SparseData to be serialised
 * @return The serialisation of a SparseData structure
 */
void serializeSparseData(char *target, SparseData source)
{
	/* SparseDataStruct header */
	memcpy(target,source,SIZEOF_SPARSEDATAHDR);
	/* Two StringInfo structures describing the data and index */
	memcpy(SDATA_DATA_SINFO(target), source->vals,sizeof(StringInfoData));
	memcpy(SDATA_INDEX_SINFO(target),source->index,sizeof(StringInfoData));
	/* The unique data values */
	memcpy(SDATA_VALS_PTR(target),source->vals->data,source->vals->maxlen);
	/* The index values */
	memcpy(SDATA_INDEX_PTR(target),source->index->data,source->index->maxlen);

	/*
	 * Set pointers to the data areas of the serialized structure
	 * First the two StringInfo structures contained in the SparseData,
	 * then the data areas inside each of the two StringInfos.
	 */
	((SparseData)target)->vals = (StringInfo)SDATA_DATA_SINFO(target);
	((SparseData)target)->index = (StringInfo)SDATA_INDEX_SINFO(target);
	((StringInfo)(SDATA_DATA_SINFO(target)))->data = SDATA_VALS_PTR(target);
	if (source->index->data != NULL)
	{
		((StringInfo)(SDATA_INDEX_SINFO(target)))->data = SDATA_INDEX_PTR(target);
	} else {
		((StringInfo)(SDATA_INDEX_SINFO(target)))->data = NULL;
	}
}

/**
 * Prints a SparseData
 */
void printSparseData(SparseData sdata) {
	int value_count = sdata->unique_value_count;
	{
		char *indexdata = sdata->index->data;
		double *values  = (double *)(sdata->vals->data);
		for (int i=0; i<value_count; i++) {
			printf("run_length[%d] = %lld, ",i,(long long int)compword_to_int8(indexdata));
			printf("value[%d] = %f\n",i,values[i]);
			indexdata+=int8compstoragesize(indexdata);
		}
	}
}

/**
 * @param sdata The SparseData to be projected on
 * @param idx The index to be projected
 * @return The element of a SparseData at location idx. 
 */
double sd_proj(SparseData sdata, int idx) {
	char * ix = sdata->index->data;
	double * vals = (double *)sdata->vals->data;
	int read, i;

	/* error checking */
	if (0 >= idx || idx > sdata->total_value_count)
		ereport(ERROR, 
			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
			 errmsg("Index out of bounds.")));

	/* find desired block; as is normal in SQL, we start counting from one */
	read = compword_to_int8(ix);
	i = 0;
	while (read < idx) {
		ix += int8compstoragesize(ix);
		read += compword_to_int8(ix);
		i++;
	}
	return vals[i];
}

/**
 * @param sdata The SparseData from which to extract a subarray
 * @param start The start index of the desired subarray
 * @param end The end index of the desired subarray
 * @return The sub-array, indexed by start and end, of a SparseData. 
 */
SparseData subarr(SparseData sdata, int start, int end) {
	char * ix = sdata->index->data;
	double * vals = (double *)sdata->vals->data;
	SparseData ret = makeSparseData();
	size_t wf8 = sizeof(float8);
	
	if (start > end) 
		return reverse(subarr(sdata,end,start));

	/* error checking */
	if (0 >= start || start > end || end > sdata->total_value_count)
		ereport(ERROR, 
			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
			 errmsg("Array index out of bounds.")));

	/* find start block */
	int read = compword_to_int8(ix);
	int i = 0;
	while (read < start) {
		ix += int8compstoragesize(ix);
		read += compword_to_int8(ix);
		i++;
	}
	if (end <= read) {
		/* the whole subarray is in the first block, we are done */
		add_run_to_sdata((char *)(&vals[i]), end-start+1, wf8, ret);
		return ret;
	}
	/* else start building subarray */
	add_run_to_sdata((char *)(&vals[i]), read-start+1, wf8, ret);

	for (int j=i+1; j<sdata->unique_value_count; j++) {
		ix += int8compstoragesize(ix);
		int esize = compword_to_int8(ix);
		if (read + esize > end) {
			add_run_to_sdata((char *)(&vals[j]), end-read, wf8,ret);
			break;
		} 
		add_run_to_sdata((char *)(&vals[j]), esize, wf8, ret);
		read += esize;
		if (read == end) break;
	}
	return ret;
}

/**
 * @param sdata The SparseData to be reversed
 * @return A copy of the input SparseData, with the order of the elements reversed. 
 */
SparseData reverse(SparseData sdata) {
	char * ix = sdata->index->data;
	double * vals = (double *)sdata->vals->data;
	SparseData ret = makeSparseData();
	size_t w = sizeof(float8);

	/* move to the last count array element */
	for (int j=0; j<sdata->unique_value_count-1; j++)
		ix += int8compstoragesize(ix);

	/* copy from right to left */
	for (int j=sdata->unique_value_count-1; j!=-1; j--) {
		add_run_to_sdata((char *)(&vals[j]),compword_to_int8(ix),w,ret);
		ix -= int8compstoragesize(ix);
	}
	return ret;
}

/** 
 * @param left The SparseData that comes first in the resulting concatenation
 * @param right The SparseData that comes second in the resulting concatenation
 * @return The concatenation of two input SparseData.
 */
SparseData concat(SparseData left, SparseData right) {
	if (left == NULL && right == NULL) {
		return NULL;
	} else if (left == NULL && right != NULL) {
		return makeSparseDataCopy(right);
	} else if (left != NULL && right == NULL) {
		return makeSparseDataCopy(left);
	}
	SparseData sdata = makeEmptySparseData();
	char *vals,*index;
	int l_val_len = left->vals->len;
	int r_val_len = right->vals->len;
	int l_ind_len = left->index->len;
	int r_ind_len = right->index->len;
	int val_len=l_val_len+r_val_len;
	int ind_len=l_ind_len+r_ind_len;
	
	vals = (char *)palloc(sizeof(char)*val_len);
	index = (char *)palloc(sizeof(char)*ind_len);
	
	memcpy(vals          ,left->vals->data,l_val_len);
	memcpy(vals+l_val_len,right->vals->data,r_val_len);
	memcpy(index,          left->index->data,l_ind_len);
	memcpy(index+l_ind_len,right->index->data,r_ind_len);
	
	sdata->vals  = makeStringInfoFromData(vals,val_len);
	sdata->index = makeStringInfoFromData(index,ind_len);
	sdata->type_of_data = left->type_of_data;
	sdata->unique_value_count = left->unique_value_count+
		right->unique_value_count;
	sdata->total_value_count  = left->total_value_count+
		right->total_value_count;
	return sdata;
}

static bool lapply_error_checking(Oid foid, List * funcname);

/**
 * This function applies an input function on all elements of a sparse data. 
 * The function is modelled after the corresponding function in R.
 *
 * @param func The name of the function to apply
 * @param sdata The input sparse data to be modified
 * @return A SparseData with the same dimension as sdata but with each element sdata[i] replaced by func(sdata[i]) 
 */
SparseData lapply(text * func, SparseData sdata) {
	Oid argtypes[1] = { FLOAT8OID };
	List * funcname = textToQualifiedNameList(func);
	SparseData result = makeSparseDataCopy(sdata);
	Oid foid = LookupFuncName(funcname, 1, argtypes, false);

	lapply_error_checking(foid, funcname);

	for (int i=0; i<sdata->unique_value_count; i++)
		valref(float8,result,i) = 
		    DatumGetFloat8(
		      OidFunctionCall1(foid,
				    Float8GetDatum(valref(float8,sdata,i))));
	return result;
}

/* This function checks for error conditions in lapply() function calls.
 */
static bool lapply_error_checking(Oid foid, List * func) {
	/* foid != InvalidOid; otherwise LookupFuncName would raise error.
	   Here we check that the return type of foid is float8. */
	HeapTuple ftup = SearchSysCache(PROCOID, 
					ObjectIdGetDatum(foid), 0, 0, 0);
	Form_pg_proc pform = (Form_pg_proc) GETSTRUCT(ftup);

	if (pform->prorettype != FLOAT8OID)
		ereport(ERROR, 
			(errcode(ERRCODE_DATATYPE_MISMATCH),
			 errmsg("return type of %s is not double", 
				NameListToString(func)))); 

	// check volatility

	ReleaseSysCache(ftup);
	return true;
}