/*
 * gcc nv3h_read_gz.c -shared -Bsymbolic -I/zshare/rsi/idl_6.3/external/include -L/zshare/rsi/idl_6.3/bin/bin.linux.x86_64 -lidl -o nv3h_read_gz.so -fPIC -lz -ldl
 *
 * requires zlib 1.2.5 for gzbuffer -- will check for right version
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <zlib.h>
#include <dlfcn.h>
#include "idl_export.h"

char *chomp(char *s) {
	char *ss = s;
	while(*s && *s != '\n' && *s != '\r') s++;
 
	*s = '\0';
	return ss;
}

IDL_VPTR IDL_CDECL nv3h_read(int argc, IDL_VPTR argv[], char *argk) {

	IDL_MEMINT dims[IDL_MAX_ARRAY_DIM];

	int status;
	struct stat st_buf;

	void *dlhandle;
	int (*fn)(gzFile, int);
	char *zlibfile = "libz.so.1";
	char *zliberror;

	char messages[8192];
	char *filename = IDL_VarGetString(argv[0]);
	char *fname;

	double *buffer;
	IDL_VPTR vpTmp = NULL;
	IDL_VPTR vpPlainArgs[3];

	gzFile *myFp;
	char *line = malloc(sizeof(char) * 32768);
	ssize_t len = 0;
	double val;
	int nVals = 0;
	size_t size;
	char *endline = NULL;
	//char **comments = NULL;
	IDL_STRING *comments;
	static IDL_VPTR silent;
	static IDL_VPTR nx, ny;
	static IDL_VPTR	commentPtr;
	char *lineptr = NULL;
	long dataPosition = 0;
	long totalDataElements = 0;
	int longestComment = 0;
	int nComments = 0;
	int longestData = 0;
	int nData = 0;
	
	// make sure it's a file we can read
	status = stat(filename, &st_buf);
	if (status != 0) {
	// first see if adding .gz finds it
		strcpy(line, filename);
		strcat(line, ".gz");
		status = stat(line, &st_buf);
		fname = strdup(line);
		line[0] = '\0';
	} else {
		fname = strdup(filename);
	}
		

	if (status != 0) {
		free(line);
		sprintf(messages, "Error: Cannot read %s\n", fname);
		free(fname);
		IDL_Message(IDL_M_NAMED_GENERIC,IDL_MSG_RET, messages);
		return IDL_GettmpLong(0);
	}

	if (!(S_ISREG (st_buf.st_mode))) {
		free(line);
		sprintf(messages, "Error: Not a regular file: %s\n", fname);
		free(fname);
		IDL_Message(IDL_M_NAMED_GENERIC,IDL_MSG_RET, messages);
		return IDL_GettmpLong(0);
	}

	if ((myFp = gzopen(fname, "rb")) == NULL) {
		free(line);
		sprintf(messages, "Error: Cannot open %s.", fname);
		IDL_Message(IDL_M_NAMED_GENERIC,IDL_MSG_RET, messages);
		return IDL_GettmpLong(0);
	}
	dlhandle = dlopen("libz.so.1", RTLD_LAZY);
	fn = dlsym(dlhandle, "gzbuffer");
	if (((zliberror = dlerror()) == NULL) && dlhandle)
	{
		// I know I should use (*fn)(...) here but I know gzbuffer exists
		gzbuffer(myFp, 131070);
		dlclose(dlhandle);
	}
	IDL_StoreScalarZero(argv[1], IDL_TYP_LONG);
	IDL_ENSURE_SCALAR(argv[0]);
	IDL_EXCLUDE_EXPR(argv[1]);

	while ((gzgets(myFp, line, 32768)) != NULL) {
		len = strlen(line);
		if (*line != ';') {
			nData++;
			if (len > longestData) {
				dataPosition = gztell(myFp);
			}
			longestData = (len > longestData) ? len : longestData;
		} else {
			nComments++;
			longestComment = (len > longestComment) ? len : longestComment;
		}
	}
	gzseek(myFp, dataPosition-longestData, SEEK_SET);
	gzgets(myFp, line, 32768);
	lineptr = line;

	// find the number of data values per record
	while ((val = strtod(lineptr, &endline)) || (endline != lineptr)) {
		nVals++;
		lineptr = endline;
	}
	totalDataElements = nVals * nData;
//	dims[0] = totalDataElements;
	dims[0] = nVals;
	dims[1] = nData;

	static IDL_KW_PAR	kw_pars[] = { IDL_KW_FAST_SCAN,
				{"COMMENTS", IDL_TYP_STRING,1,IDL_KW_OUT,0,IDL_CHARA(commentPtr)},
				{"NX", IDL_TYP_LONG,1,IDL_KW_OUT|IDL_KW_ZERO,0,IDL_CHARA(nx)},
				{"NY", IDL_TYP_LONG,1,IDL_KW_OUT|IDL_KW_ZERO,0,IDL_CHARA(ny)},
				{"SILENT", IDL_TYP_LONG,1,IDL_KW_VIN,0,IDL_CHARA(silent)},
				{NULL} };
	IDL_KWCleanup(IDL_KW_MARK);
	IDL_KWGetParams(argc, argv, argk, kw_pars, vpPlainArgs, 1);
	if (commentPtr)
		IDL_StoreScalarZero(commentPtr, IDL_TYP_STRING);

	if (nx) {
		vpTmp = IDL_GettmpLong(nVals);
		IDL_VarCopy(vpTmp, nx);
	}
	if (ny) {
		vpTmp = IDL_GettmpLong(nData);
		IDL_VarCopy(vpTmp, ny);
	}

	buffer = (double *)IDL_MakeTempArray(IDL_TYP_DOUBLE,2, dims, IDL_ARR_INI_NOP, &vpTmp);
	IDL_VarCopy(vpTmp,argv[1]);

	dims[0] = nComments;
	dims[1] = 0;
	comments = (IDL_STRING *) IDL_MakeTempArray(IDL_TYP_STRING,1,dims, IDL_ARR_INI_NOP, &vpTmp);
	if (commentPtr)
		IDL_VarCopy(vpTmp, commentPtr);

	gzseek(myFp, 0, SEEK_SET);
	while ((gzgets(myFp, line, 32768)) != NULL) {
		len = strlen(line);
		lineptr = line;
		if (*line != ';') {
			while ((val = strtod(lineptr, &endline)) || (endline != lineptr)) {
				*buffer++ = val;
				lineptr = endline;
			}
		} else {
			IDL_StrStore(comments++,chomp(line));
		}
	}
	free(line);
	free(fname);
	line = NULL;

	gzclose(myFp);
	IDL_KWCleanup(IDL_KW_CLEAN);
	return IDL_GettmpLong(1);
}
int IDL_Load(void) {
	static IDL_SYSFUN_DEF2 function_addr[] = {
		{ nv3h_read, "NV3H_READ_GZ", 2, 2, IDL_SYSFUN_DEF_F_KEYWORDS },
	};

	IDL_SysRtnAdd(function_addr, TRUE, 1);
	return IDL_TRUE;
}