add todo serialization

.gitignore

@@ -1,2 +1,3 @@
 todd
 *.o
+*.todd

Makefile

@@ -1,7 +1,7 @@
 .DEFAULT_GOAL := purge 
 
 todo.o:
-	cc -c todo.c -o todo.o
+	cc -c engine/todo.c -o todo.o
 
 main.o:
 	cc -c main.c -o main.o

engine/todo.c

@@ -0,0 +1,56 @@
+#include "todo.h"
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+// Memory management
+void todo_free_item(TodoItem *item) {
+  free(item->title);
+}
+
+// Item operations
+TodoItem todo_create_item(char *title) {
+  TodoItem item;
+  item.title_length = strlen(title);
+  item.title = malloc(item.title_length);
+  strcpy(item.title, title);
+  item.completed = false;
+
+  return item;
+}
+
+void todo_mark_item(TodoItem *item, bool_t completed) {
+  item->completed = completed;
+}
+
+void todo_print_item(TodoItem *item) {
+  printf("%s - ", item->title);
+  if (item->completed) {
+    printf("Completed\n");
+  } else {
+    printf("Not Completed\n");
+  }
+}
+
+// Serialization
+char *todo_item_serialize(TodoItem *item, int *buffer_size_out) {
+  // Layout of the serialized item:
+  // title_length - 1 byte
+  // title - title_length bytes
+  // completed - 1 byte
+  unsigned char title_length = item->title_length;  unsigned char completed_length = sizeof(item->completed);
+  int buffer_size = sizeof(unsigned char) + title_length + completed_length;
+
+  char *buffer = malloc(buffer_size);
+
+  // copy title length
+  memcpy(buffer, &title_length, sizeof(unsigned char));
+  // copy title
+  memcpy(buffer + sizeof(unsigned char), item->title, title_length);
+  // copy completed
+  memcpy(buffer + sizeof(unsigned char) + title_length, &item->completed, completed_length);
+
+  *buffer_size_out = buffer_size;
+
+  return buffer;
+}

engine/todo.h

@@ -0,0 +1,25 @@
+#ifndef TODO_H
+#define TODO_H
+#define TODO_MAX_TITLE_LENGTH 255
+
+#define true 1
+#define false 0
+typedef unsigned char bool_t;
+
+typedef struct {
+  unsigned char title_length;
+  char *title;
+  bool_t completed;
+} TodoItem;
+
+// Memory management
+void todo_free_item(TodoItem *item);
+
+// Item operations
+TodoItem todo_create_item(char *title);
+void todo_mark_item(TodoItem *item, bool_t completed);
+void todo_print_item(TodoItem *item);
+
+// Serialization
+char *todo_item_serialize(TodoItem *item, int *buffer_size_out);
+#endif

main.c

@@ -1,33 +1,39 @@
 #include <stdio.h>
 #include <string.h>
-#include "todo.h"
+#include <stdlib.h>
+#include "engine/todo.h"
+
+#define MAX_TODOS 10
+#define SAVE_FILE "todos.todd"
 
 enum Command {
   ADD = 'a',
   MARK = 'm',
   PRINT = 'p',
   REMOVE = 'r',
-  QUIT = 'q'
+  QUIT = 'q',
+
+  SERIALIZE = 's'
 };
 
 TodoItem todos[MAX_TODOS];
 int todos_count = 0;
 
-void add_todo() {
+void add_command_handler() {
-  char title[MAX_TODO_TITLE_LENGTH];
+  char title[TODO_MAX_TITLE_LENGTH];
   printf("Enter todo title: ");
-  fgets(title, MAX_TODO_TITLE_LENGTH - 1, stdin);
+  fgets(title, TODO_MAX_TITLE_LENGTH - 1, stdin);
   // remove the newline character from the buffer
   title[strlen(title) - 1] = '\0';
 
-  TodoItem item = create_todo(title);
+  TodoItem item = todo_create_item(title);
   todos[todos_count] = item;
   todos_count++;
 }
 
 void print_all_todos() {
   for (int i = 0; i < todos_count; i++) {
-    print_todo(&todos[i]);
+    todo_print_item(&todos[i]);
   }
 }
 
@@ -41,6 +47,9 @@ void remove_todo_at_index(int index) {
 int main(int argc, char **argv) {
   char cmd;
   int op_index = -1;
+  int bs;
+  FILE *file;
+
   do {
     printf("Enter command: ");
     cmd = getc(stdin);
@@ -52,7 +61,7 @@ int main(int argc, char **argv) {
           printf("No more space for new todos\n");
           break;
         }
-        add_todo();
+        add_command_handler();
         break;
       case MARK:
         do {
@@ -60,7 +69,7 @@ int main(int argc, char **argv) {
           op_index = getc(stdin) - '0';
           getc(stdin); // remove the newline character from the buffer
         } while (op_index < 0 || op_index >= todos_count);
-        mark_todo(&todos[op_index], !todos[op_index].completed);
+        todo_mark_item(&todos[op_index], !todos[op_index].completed);
         break;
       case PRINT:
         print_all_todos();
@@ -72,6 +81,20 @@ int main(int argc, char **argv) {
           getc(stdin); // remove the newline character from the buffer
         } while (op_index < 0 || op_index >= todos_count);
         remove_todo_at_index(op_index);
+      case SERIALIZE:
+        file = fopen(SAVE_FILE, "wb");
+        // write a magic value "TODD" to the file
+        fwrite("TODD", sizeof(char), 4, file);
+        // write the number of todos to the file
+        fwrite(&todos_count, sizeof(int), 1, file);
+        // write each todo to the file
+        for (int i = 0; i < todos_count; i++) {
+          char *buffer = todo_item_serialize(&todos[i], &bs);
+          fwrite(buffer, sizeof(char), bs, file);
+          free(buffer);
+        }
+        fclose(file);
+        break;
       case QUIT:
         break;
       default:
@@ -80,4 +103,8 @@ int main(int argc, char **argv) {
     }
 
   } while (cmd != QUIT);
+
+  for (int i = 0; i < todos_count; i++) {
+    todo_free_item(&todos[i]);
+  }
 }

todo.c

@@ -1,23 +0,0 @@
-#include "todo.h"
-#include <string.h>
-#include <stdio.h>
-
-TodoItem create_todo(const char *title) {
-  TodoItem item;
-  strncpy(item.title, title, MAX_TODO_TITLE_LENGTH);
-  item.completed = false;
-  return item;
-}
-
-void mark_todo(TodoItem *item, bool completed) {
-  (*item).completed = completed;
-}
-
-void print_todo(TodoItem *item) {
-  printf("%s - ", item->title);
-  if (item->completed) {
-    printf("Completed\n");
-  } else {
-    printf("Not Completed\n");
-  }
-}

todo.h

@@ -1,15 +0,0 @@
-#ifndef TODO_H
-#define TODO_H
-#include <stdbool.h>
-#define MAX_TODO_TITLE_LENGTH 32
-#define MAX_TODOS 10
-
-typedef struct {
-  char title[MAX_TODO_TITLE_LENGTH];
-  bool completed;
-} TodoItem;
-
-TodoItem create_todo(const char *title);
-void mark_todo(TodoItem *item, bool completed);
-void print_todo(TodoItem *item);
-#endif