/* file name: slist.c */
/* 單向鍵結鏈表，插入、刪除使用排序 */

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

void read_func(void);
void write_func(void);
void insert_func(void);
void sort_func(void);
void delete_func(void);
void display_func(void);
void modify_func(void);
void anykey_func(void);

struct student {
	char name[20];
	int score;
	struct student *next;
};

struct student *ptr, *head, *current, *prev;

void main(void)
{
	char option1;
	system("cls");
	read_func();
	while(1)
	{
		printf("****************************************\n");
		printf("              1.insert\n");
		printf("              2.delete\n");
		printf("              3.display\n");
		printf("              4.modify\n");
		printf("              5.quit\n");
		printf("****************************************\n");
		printf("   Please enter your choice (1-5)...");
		option1=getche();
		printf("\n");
		switch(option1)
		{
			case '1':
				insert_func();
				break;
			case '2':
				delete_func();
				break;
			case '3':
				display_func();
				break;
			case '4':
				modify_func();
				break;
			case '5':
				write_func();
				exit(0);
		}
	}
}

void read_func(void)
{
	FILE *fptr;

	head=(struct student *) malloc(sizeof(struct student));
	head->next = NULL;
	
	/* 開始時，若表中不存在數據，則要求輸入第一筆數據 */
	if((fptr=fopen("slist.dat","r")) == NULL)
	{
		printf(" Data file not exist\n");
		printf(" Press any key to edit first record...\n");
		getch();
		insert_func();
	}
	else
	{
		ptr=(struct student *) malloc(sizeof(struct student));
		while(fscanf(fptr, "%s %d", ptr->name, &ptr->score) != EOF)
		{
			sort_func();
			ptr=(struct student *) malloc(sizeof(struct student));
		}
		fclose(fptr);
	}
}

void write_func(void)
{
	FILE *fptr;
	fptr=fopen("slist.dat","w");
	current=head->next;
	while(current != NULL)
	{
		fprintf(fptr, "%s %d\n", current->name, current->score);
		current = current->next;
	}
	fclose(fptr);
}

void insert_func(void)
{
	char s_temp[4];
	ptr=(struct student *) malloc(sizeof(struct student));
	printf(" Student name : ");
	gets(ptr->name);
	printf(" Student score: ");
	gets(s_temp);
	ptr->score = atoi(s_temp);
    
	sort_func();
}

/*以分數高低由大到小排列*/
void sort_func(void)
{
	//插入數據
	prev = head;
	current = head->next;
	while ((current != NULL) && (current->score > ptr->score)) 
	{
		prev = current;
		current = current->next;
	}
	ptr->next = current;
	prev->next = ptr;
}

void delete_func(void)
{
	char del_name[20];
	printf(" Delete student name: ");
	gets(del_name);
	
	prev = head;
	current = head->next;
    while ((current != NULL) && (strcmp(current->name , del_name)!=0))
	{
		prev = current;
		current = current->next;
	}
	if (current != NULL)
	{
		prev->next = current->next;
		free(current);
		printf(" %s student record deleted\n",del_name);
	}
	else
		printf(" Student %s not found\n",del_name);

	anykey_func();
}

void modify_func(void)
{
	char n_temp[20],s_temp[4];
	printf(" Modify student name: ");
	gets(n_temp);
	current=head->next;

	while ((current != NULL) && (strcmp(current->name , n_temp)!=0))
	{
		prev = current;
		current = current->next;
	}
	if (current != NULL)
	{
		printf(" **************************\n");
		printf("  Student name : %s\n",current->name);
		printf("  Student score: %d\n",current->score);
		printf(" **************************\n");
		printf(" Please enter new score: ");
		gets(s_temp);
		current->score = atoi(s_temp);
		printf(" %s student record modified\n",n_temp);
	}
	else
		printf(" Student %s not found\n",n_temp);

	anykey_func();
}

void display_func(void)
{
	int count=0;
	system("cls");
	if(head->next == NULL) 
	{
		printf(" No student record\n");
	}
	else
	{
		printf("  NAME                SCORE\n");
		printf(" ---------------------------\n");
		current=head->next;
		while(current != NULL)
		{
			printf("  %-20s %3d\n", current->name, current->score);
			count++;
			current=current->next;
			if(count % 20 == 0) getch();
		}
		printf(" ---------------------------\n");
		printf(" Total %d record(s) found\n", count);
	}
	anykey_func();
}

void anykey_func(void)
{
	printf(" Press any key to continue...");
	getch();
	printf("\n");
}