/* sList.c */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* 定義一指向 FILE 的指標 */
FILE *fptr;

/* 函式的原型宣告 */
void init_f(void);
void insertStudent(int id, char* name, double score);
void readFromFile(const char* filename);
void saveToFile(const char* filename);
void insert(void);
void del(void);
void modify(void);
void display(void);

// 定義學生節點結構
typedef struct Student {
	long int id;
    char name[10];
    double score;
    struct Student *rlink;
    struct Student *llink;
} Student;
Student *head, *pNode ,*tail, *current, *prev, *temp ;

//設一個 head，將左右鏈結皆指向本身
void init_f() {
    head = (Student *) malloc(sizeof(Student));
    tail = (Student *) malloc(sizeof(Student));
    
    // 初始化 head 和 tail
    head->llink = NULL;
    head->rlink = tail;
    
    tail->llink = head;
    tail->rlink = NULL;
}

// 在尾部插入新學生節點
void insertStudent(int id, char* name, double score) {

    Student* newNode = (Student*)malloc(sizeof(Student));
	
	
    newNode->id = id;
    strcpy(newNode->name, name);
    newNode->name[9] = '\0';
    newNode->score = score;

    // 插入到尾部之前
    newNode->rlink = tail;
    newNode->llink = tail->llink;
    tail->llink->rlink = newNode;
    tail->llink = newNode;
}

// 讀檔 
void readFromFile(const char* filename) {
	char line[100];
    FILE* fptr = fopen(filename, "r");
    if (fptr == NULL) {
        printf("無法打開檔案 %s\n", filename);
        return;
    }
    
    long int id;
    char name[10];
    double score;
    while(fgets(line ,sizeof(line) ,fptr)!=NULL){
    	if(sscanf(line,"%ld\t%9s\t%lf", &id, name, &score) == 3){
    		insertStudent(id, name, score);
		}
	}
    fclose(fptr);
    printf("顯示檔案資料\n");
}

// 存檔 
void saveToFile(const char* filename ) {
    FILE* fptr = fopen(filename, "w");
    if (fptr == NULL) {
        printf("無法打開檔案 %s 進行寫入\n", filename);
        return;
    }
    	Student* current = head->rlink;
    	while (current != tail ) {
	        fprintf(fptr, "%ld\t%s\t%.lf\n", current->id, current->name, current->score);
	        current = current->rlink;
	}
    
    fclose(fptr);
    printf("資料已成功\儲存到 %s\n", filename);
}

//顯示串列資料 
void printStudentList() {
	
	Student* current = head->rlink;
	printf("\n*******************************");
	
    if (current != NULL) {
        printf("\n%6s %10s %8s\n", "ID", "Name", "Score");
        printf("-------------------------------\n");
        while (current != tail) {
            printf("%6ld %10s %8.1f\n", current->id,current->name, current->score);
            /* 將指標移到下一個節點 */
            current = current->rlink;
        	}
    	}
    	/* 若是空的，則輸出鏈結串列無資料 */
    	else {
    	    printf("\n鏈結串列無資料\n");
    	}
    printf("*******************************\n\n");
}

int main(){
	init_f();
	readFromFile("list.txt");
	printStudentList();
    /* 利用一選單讓使用選擇功能項目 */
    int choice;
    do {
    	printf("************************\n");
        printf("鏈結串列的運作選單\n");
        printf("1. 加入一節點\n");
        printf("2. 刪除一節點\n");
        printf("3. 修改一節點\n");
        printf("4. 顯示所有節點\n");     
        printf("5. 結束\n");
        printf("請選擇: ");
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                insert();
                break;
            case 2:
                del();
                break;
            case 3:
                modify();
                break;
            case 4:
                printStudentList();
                break;
            case 5:
            	printf("\n程式結束\n");
                saveToFile("list.txt");
                exit(0);
            default:
                printf("輸入號碼不正確，請重新輸入\n");  
        }
        printf("\n");
    } while(choice != 5);
    getchar();
    return 0;
}

/* 按照分數由大至小加入一節點於鏈結串列 */
void insert()
{
    /* 利用 malloc() 函式配置記憶體*/
    Student* newNode = (Student*)malloc(sizeof(Student));

    printf("\n請輸入ID: ");
    scanf("%ld", &newNode->id);
    printf("請輸入姓名: ");
    scanf("%s", newNode->name);
    printf("請輸入分數: ");
    scanf("%lf", &newNode->score);
    
    /* 加入一節點於鏈結串列 */
    current = head->rlink;
    prev = head;
    
    // 插入到尾部之前
    newNode->rlink = tail;
    newNode->llink = tail->llink;
    tail->llink->rlink = newNode;
    tail->llink = newNode;
}

/* 刪除某一節點*/
void del()
{
    long int deleteID;
    /* 將 current 指標指向 head 的下一個節點 */
    current = head->rlink;
    prev = head;
    /* 先判斷鏈結串列是否為空 */
    if (current != NULL) {
        /* 若不是空的，則找尋欲刪除的節點 */
        printf("\n請輸入欲刪除的 ID: ");
        scanf("%ld", &deleteID);
        /* 找尋欲刪除的節點 */
        while ((current != tail) && (current->id != deleteID)) {
            prev = current;
            current = current->rlink;
        }
        /* 若找到，則將它刪除 */
        if (current != tail) {
			current->rlink->llink = prev;
			prev->rlink = current->rlink;
            printf("ID: %ld 已刪除\n", current->id);

            free(current);
        }
        /* 若沒有找到，則輸出找不到欲刪除節點的訊息*/
        else {
            printf("\n找不到欲刪除的節點\n");
        }
    }
    /* 若是空的，則輸出鏈結串列是空的訊息 */
    else {
        printf("鏈結串列是空的\n");
    }
}

/* 修改某一節點 */
void modify()
{
    Student *temp;
    long int modifyID;
    double modifyScore;
    int flag = 0;
    printf("\n請輸入欲修改節點的 ID: ");
    scanf("%ld", &modifyID);
    current = head->rlink;
    prev = head;
    
    /* 找尋欲修改的節點 */
    while (current != tail) {
        if (current->id == modifyID) {
            printf("目前欲修改節點的資料如下:\n");
            printf("%6ld %10s %8.1f\n\n", current->id,current->name, current->score);
            printf("請輸入欲修改的分數: ");
            scanf("%lf", &modifyScore);
            current->score = modifyScore;
            flag = 1;
            break;
        }
        else {
            prev = current;
            current = current->rlink;
        }
    }
    /* 判斷是否有找到欲修改的節點 */
    if (flag != 0) {
        /* 將 current 的節點指定給 temp */
//        temp = current;
//        prev->rlink = current->rlink;
        /* 將 temp 節點加入於鏈結串列 */
//        current = head->rlink;
//        prev = head;
//        while ((current != tail) && (temp->score < current->score)) {
//            prev = current;
//            current = current->rlink;
//        }
//        prev->rlink = temp;
//        temp->rlink = current;
    }
    else {
        printf("找不到欲修改的節點\n");
    }
}