/*
 * pgmio.c
 *
 *  Created on: Oct 31, 2019
 *      Author: lutton
 */

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

#include "pgmio.h"

file_node_t * get_pgm_files(char path[]){
	char end_point = path[strlen(path) - 1];
	char file_joiner[] = "/";
	if(end_point == '/'){
		file_joiner[0] = '\0';
	}

	DIR *d;
	struct dirent *dir;
	char file_name[256] = "";
	int file_count = 0;
	int name_length = 0;

	char file_extn[10] = "";
	char pgm_extn[10] = ".pgm";

	int file_idx = 0;
	d = opendir(path);

	file_node_t *head = NULL;
	file_node_t *current = NULL;

	if(d){
		// attempt to initialize first node
		while((dir = readdir(d)) != NULL){
			strncpy(file_name, dir->d_name,256);
			name_length = strlen(file_name);
			if(name_length > 4){
				for(int i = 0; i < 4; i++){
					file_extn[i] = file_name[name_length - 4 + i];
				}
				if(strcmp(pgm_extn, file_extn) == 0){
					head = (file_node_t *) malloc(sizeof(file_node_t));
					strcpy(head->file_name, file_name);
					strcat(strcat(strcpy(head->file_path, path), file_joiner), file_name);
					head->next = NULL;
					current = head;
					break;
				}
			}
		}

		while((dir = readdir(d)) != NULL){
			strncpy(file_name, dir->d_name,256);
			name_length = strlen(file_name);
			if(name_length > 4){
				for(int i = 0; i < 4; i++){
					file_extn[i] = file_name[name_length - 4 + i];
				}
				if(strcmp(pgm_extn, file_extn) == 0){
					current->next = (file_node_t *) malloc(sizeof(file_node_t));
					strcpy(current->next->file_name, file_name);
					strcat(strcat(strcpy(current->next->file_path, path), file_joiner), file_name);
					current->next->next = NULL;
					current = current->next;
				}
			}
		}
	} else {
		printf("Error: directory %s not found.\n", path);
	}
	closedir(d);

	return head;
}

int * get_pgm_dimensions(char path[]){
	int max_line_size = 256;
	char delim[2] = " ";

	// line 1 not used
	char line1[max_line_size];
	// dimensions stored in line 2
	char line2[max_line_size];

	FILE* img_file = fopen(path,"rb");
	if(!img_file){
		printf("File not found.\n");
		return NULL;
	}
	fgets(line1, max_line_size, img_file);
	fgets(line2, max_line_size, img_file);

	fclose(img_file);

	char *c_token = strtok(line2, delim);
	char *r_token = strtok(NULL, delim);
	char *z_token = strtok(NULL, delim);

	int *dims = (int *) malloc(sizeof(int) * 3);
	dims[DIM_ROWS] = atoi(r_token);
	dims[DIM_COLUMNS] = atoi(c_token);
	dims[DIM_SLICES] = atoi(z_token);

	return dims;
}

int get_pgm_size(char path[]){
	int *dims = get_pgm_dimensions(path);
	int sz = dims[0] * dims[1] * dims[2];
	return sz;
}

int get_pgm_dimension(char path[], dim_idx i){
	int *dims = get_pgm_dimensions(path);
	return dims[i];
}

unsigned char * pgm_read(char path[]){
	int sz = get_pgm_size(path);
	unsigned char *img = (unsigned char *) malloc(sizeof(char) * sz);
	// 3 header lines
	char line1[256];
	char line2[256];
	char line3[256];

	FILE* img_file = fopen(path,"rb");
	if(!img_file){
		printf("File not found.\n");
		free(img);
		return NULL;
	}
	fgets(line1, 256, img_file);
	fgets(line2, 256, img_file);
	fgets(line3, 256, img_file);

	fread(img, sizeof(char), sz, img_file);
	fclose(img_file);

	return img;
}

int pgm_write(unsigned char *img, char path[], int dims[]){
	char line1[] = "P5\n";
	char line2[256];
	sprintf(line2, "%d %d %d\n", dims[0], dims[1], dims[2]);
	char line3[] = "255\n";

	int sz = dims[0] * dims[1] * dims[2];

	FILE *img_file = fopen(path, "wb");
	fwrite(line1, sizeof(char), strlen(line1), img_file);
	fwrite(line2, sizeof(char), strlen(line2), img_file);
	fwrite(line3, sizeof(char), strlen(line3), img_file);
	fwrite(img, sizeof(char), sz, img_file);
	fclose(img_file);

	return 0;
}