StudyPlanner/src/db.c

/* Create a database and handel it
 * Created by Jan on 13.12.2024.
 * INPUT: query for previous state
 *        linked list of tasks to store
 *
 * OUTPUT:
 *        linked list of tasks from file
 *        OK
 *
 *
 */


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "planner.h"
#include "llist.h"

/*
write a complete linkedlist to a task csv file.
 */
void write_linkedlist_to_csv(llist *head, const char *filename) {
    //Open file with write permission
    FILE *file = fopen(filename, "w");
    //if there is no file or a wrong file path you become an error
    if (file == NULL) {
        perror("Could not open file\n");
    }

    //write the file header
    fprintf(file, "TaskName, Created, Deadline, Priority, Spare\n");

    // Iterate through the linked list and write the data to the CSV
    llist *current = head;
    while (current != NULL) {
        // Write the task data to the CSV file
        Task *task = (Task *) (current->data);
        fprintf(file, "%s, %llu, %llu, %d, %lu\n",
                task->name,
                task->created,
                task->deadline,
                task->priority,
                task->spare);


        current = current->next;
    }
    fclose(file); // Close the file
}


/*
read a task csv file and write the data in a linked list
 */

llist *write_csv_to_llist(const char *filename) {
    //initialize list
    llist *list = NULL;
    //Open file with read permission
    FILE *file = fopen(filename, "r");
    if (file == NULL) {
        perror("Could not open file\n");
    }
    char line[1024]; //Line Buffer
    int count = 0; //task counter
    fgets(line, sizeof(line), file); //read and ignore file head
    while (fgets(line, sizeof(line), file)) {
        count++;
        //remove newline sign
        line[strcspn(line, "\n")] = '\0';

        // column slice
        char *task_name = strtok(line, ",");
        char *task_creation_dateSTR = strtok(NULL, ",");
        char *task_deadline_dateSTR = strtok(NULL, ",");
        char *task_prioritySTR = strtok(NULL, ",");
        char *task_spareSTR = strtok(NULL, ",");


        // convert char in integer and date
        unsigned long long int task_creation_date = (unsigned long long int)strtoul(task_creation_dateSTR, NULL, 10);
        unsigned long long int task_deadline_date = (unsigned long long int)strtoul(task_deadline_dateSTR,NULL, 10);
        unsigned long int task_spare = (unsigned long int)strtoul(task_spareSTR,NULL, 10);
        int task_priority = (int)strtol(task_prioritySTR, NULL, 10);


        //create Task
        Task *task = newTask(task_name, task_creation_date, task_deadline_date, task_priority, task_spare);


        // Insert task into the linked list
        if (list == NULL) {
            // If the list is empty, initialize it with the first task
            list = llistNew(task, cmpTaskN);
        } else {
            // Append the task to the linked list
            llistAppend(list, task);
        }
    }
    fclose(file);
    return list;
}