/*
 * cache.c
 *
 * Save the reflection datablock to save having to recalculate it
 *
 * (c) 2007 Gordon Ball <gfb21@cam.ac.uk>
 *	    Thomas White <taw27@cam.ac.uk>
 *
 *  dtr - Diffraction Tomography Reconstruction
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

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

#include "reflections.h"
#include "cache.h"

typedef struct struct_cacheheader {
	char top[16];
	int count;
	double scale;
} CacheHeader;

ReflectionContext *cache_load(const char *filename) {

	FILE *f;
	CacheHeader ch;
	ReflectionContext *rctx;
	size_t cachedreflection_size;
	int i;

	cachedreflection_size = sizeof(Reflection) - sizeof(Reflection *);

	rctx = reflection_init();
	f = fopen(filename, "rb");
	if ( !f ) {
		fprintf(stderr, "Couldn't read reflections from cache\n");
	}
	if ( fread(&ch, sizeof(CacheHeader), 1, f) == 0 ) {
		fprintf(stderr, "Couldn't read reflections from cache\n");
		fclose(f);
		return NULL;
	}
	
	for ( i=0; i<ch.count; i++ ) {
	
		Reflection *cr;
		
		cr = malloc(sizeof(Reflection));
		if ( fread(cr, cachedreflection_size, 1, f) == 0 ) {
			fprintf(stderr, "Couldn't read reflections from cache\n");
			fclose(f);
			free(cr);
			reflection_clear(rctx);
			return NULL;
		}
			
		cr->next = NULL;	/* Guarantee swift failure in the event of a screw-up */
		//printf("reading (%f,%f,%f) i=%f (%d,%d,%d) %d\n",cr->x,cr->y,cr->z,cr->intensity,cr->h,cr->k,cr->l,cr->type);
		reflection_add_from_reflection(rctx, cr);
		
	}
	
	fclose(f);
	
	return rctx;
}

int cache_save(const char *input_filename, ReflectionContext *rctx) {

	FILE *f;
	CacheHeader ch;
	Reflection *r;
	int count;
	const char top[16] = "DTRCACHE\0\0\0\0\0\0\0\0";
	size_t cachedreflection_size;
	char *cache_filename;
			
	cache_filename = malloc(strlen(input_filename)+7);
	strcpy(cache_filename, input_filename);
	strcat(cache_filename, ".cache");
	printf("Caching reflections to %s\n", cache_filename);
	
	cachedreflection_size = sizeof(Reflection) - sizeof(Reflection *);
	
	count = 0;
	r = rctx->reflections;
	while ( r != NULL ) {
		count++;
		r = r->next;
	};
	
	f = fopen(cache_filename, "wb");
	free(cache_filename);
	if ( f == NULL ) {
		printf("Couldn't save reflection cache\n");
		return -1;
	}
	memcpy(&ch.top, &top, sizeof(top));
	ch.count = count;
	ch.scale = 0.; //temp, currently doesn't do anything
	fwrite(&ch, sizeof(CacheHeader), 1, f);
	
	r = rctx->reflections;
	while ( r != NULL ) {
		
		fwrite(r, cachedreflection_size, 1, f);	/* Write the reflection block, stopping just short of the "next" pointer */
		r = r->next;
		
	};
	
	fclose(f);
	
	return 0;
	
}

unsigned int cache_is_cachefile(const char *filename) {

	FILE *fh;
	CacheHeader ch;
	size_t nread;

	fh = fopen(filename, "rb");
	nread = fread(&ch, sizeof(CacheHeader), 1, fh);
	fclose(fh);

	if ( nread != 1 ) {
		return 0;
	}
	
	if ( strncmp(ch.top, "DTRCACHE", 8) == 0 ) {
		return 1;
	}
	
	/* Backwards compatability */
	if ( strncmp(ch.top, "DTR-CACHE", 9) == 0 ) {
		return 1;
	}
	
	return 0;

}