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

#define MAX_STUDENTS 100
#define MAX_NAME_LEN 50
#define MAX_ID_LEN 20
#define MAX_MAJOR_LEN 50
#define MAX_AWARDS_LEN 200
#define DATA_FILE "students.dat"

typedef struct {
	char id[MAX_ID_LEN];
	char name[MAX_NAME_LEN];
	char gender; // 'M' 或 'F'
	int age;
	char major[MAX_MAJOR_LEN];
	float gpa;
	char awards[MAX_AWARDS_LEN];
} Student;

Student students[MAX_STUDENTS];
int student_count = 0;

// 函数声明
void load_data();
void save_data();
void add_student();
void delete_student();
void update_student();
void search_student();
void display_student(Student s);
void list_all_students();
void sort_students();
void evaluate_students();
void statistics();
void show_menu();
void clear_input_buffer();

int main() {
	load_data();
	
	while (1) {
		show_menu();
		printf("请选择操作(1-9): ");
		char choice;
		scanf(" %c", &choice);
		clear_input_buffer();
		
		switch (choice) {
			case '1': add_student(); break;
			case '2': delete_student(); break;
			case '3': update_student(); break;
			case '4': search_student(); break;
			case '5': list_all_students(); break;
			case '6': sort_students(); break;
			case '7': evaluate_students(); break;
			case '8': statistics(); break;
			case '9': 
			save_data();
			printf("感谢使用，再见!\n");
			exit(0);
			default: 
			printf("无效的选择，请重新输入!\n");
		}
	}
	
	return 0;
}

void load_data() {
	FILE *file = fopen(DATA_FILE, "rb");
	if (file == NULL) {
		return; // 文件不存在，无需加载
	}
	
	student_count = fread(students, sizeof(Student), MAX_STUDENTS, file);
	fclose(file);
}

void save_data() {
	FILE *file = fopen(DATA_FILE, "wb");
	if (file == NULL) {
		printf("无法保存数据!\n");
		return;
	}
	
	fwrite(students, sizeof(Student), student_count, file);
	fclose(file);
}

void add_student() {
	if (student_count >= MAX_STUDENTS) {
		printf("学生数量已达上限，无法添加!\n");
		return;
	}
	
	printf("\n--- 添加学生信息 ---\n");
	Student s;
	
	printf("请输入学号: ");
	fgets(s.id, MAX_ID_LEN, stdin);
	s.id[strcspn(s.id, "\n")] = '\0'; // 移除换行符
	
	// 检查学号是否已存在
	for (int i = 0; i < student_count; i++) {
		if (strcmp(students[i].id, s.id) == 0) {
			printf("错误: 该学号已存在!\n");
			return;
		}
	}
	
	printf("请输入姓名: ");
	fgets(s.name, MAX_NAME_LEN, stdin);
	s.name[strcspn(s.name, "\n")] = '\0';
	
	printf("请输入性别(M/F): ");
	scanf(" %c", &s.gender);
	clear_input_buffer();
	s.gender = toupper(s.gender);
	
	printf("请输入年龄: ");
	scanf("%d", &s.age);
	clear_input_buffer();
	
	printf("请输入专业: ");
	fgets(s.major, MAX_MAJOR_LEN, stdin);
	s.major[strcspn(s.major, "\n")] = '\0';
	
	printf("请输入GPA(0-4): ");
	scanf("%f", &s.gpa);
	clear_input_buffer();
	
	printf("请输入获奖情况: ");
	fgets(s.awards, MAX_AWARDS_LEN, stdin);
	s.awards[strcspn(s.awards, "\n")] = '\0';
	
	students[student_count++] = s;
	save_data();
	printf("学生信息添加成功!\n");
}

void delete_student() {
	printf("\n--- 删除学生信息 ---\n");
	char id[MAX_ID_LEN];
	printf("请输入要删除的学生学号: ");
	fgets(id, MAX_ID_LEN, stdin);
	id[strcspn(id, "\n")] = '\0';
	
	for (int i = 0; i < student_count; i++) {
		if (strcmp(students[i].id, id) == 0) {
			// 将最后一个学生移到当前位置
			if (i < student_count - 1) {
				students[i] = students[student_count - 1];
			}
			student_count--;
			save_data();
			printf("学生信息删除成功!\n");
			return;
		}
	}
	
	printf("错误: 未找到该学号的学生!\n");
}

void update_student() {
	printf("\n--- 修改学生信息 ---\n");
	char id[MAX_ID_LEN];
	printf("请输入要修改的学生学号: ");
	fgets(id, MAX_ID_LEN, stdin);
	id[strcspn(id, "\n")] = '\0';
	
	for (int i = 0; i < student_count; i++) {
		if (strcmp(students[i].id, id) == 0) {
			printf("当前学生信息:\n");
			display_student(students[i]);
			
			printf("\n请输入新的信息(留空则保持不变):\n");
			
			char input[MAX_NAME_LEN];
			
			printf("姓名[%s]: ", students[i].name);
			fgets(input, MAX_NAME_LEN, stdin);
			input[strcspn(input, "\n")] = '\0';
			if (strlen(input) > 0) {
				strcpy(students[i].name, input);
			}
			
			printf("性别[%c]: ", students[i].gender);
			char gender;
			scanf(" %c", &gender);
			clear_input_buffer();
			if (gender != '\n') {
				students[i].gender = toupper(gender);
			}
			
			printf("年龄[%d]: ", students[i].age);
			fgets(input, MAX_NAME_LEN, stdin);
			input[strcspn(input, "\n")] = '\0';
			if (strlen(input) > 0) {
				students[i].age = atoi(input);
			}
			
			printf("专业[%s]: ", students[i].major);
			fgets(input, MAX_MAJOR_LEN, stdin);
			input[strcspn(input, "\n")] = '\0';
			if (strlen(input) > 0) {
				strcpy(students[i].major, input);
			}
			
			printf("GPA[%.2f]: ", students[i].gpa);
			fgets(input, MAX_NAME_LEN, stdin);
			input[strcspn(input, "\n")] = '\0';
			if (strlen(input) > 0) {
				students[i].gpa = atof(input);
			}
			
			printf("获奖情况[%s]: ", students[i].awards);
			fgets(input, MAX_AWARDS_LEN, stdin);
			input[strcspn(input, "\n")] = '\0';
			if (strlen(input) > 0) {
				strcpy(students[i].awards, input);
			}
			
			save_data();
			printf("学生信息修改成功!\n");
			return;
		}
	}
	
	printf("错误: 未找到该学号的学生!\n");
}

void search_student() {
	printf("\n--- 查询学生信息 ---\n");
	printf("1. 按学号查询\n");
	printf("2. 按姓名查询\n");
	printf("3. 按专业查询\n");
	printf("请选择查询方式(1-3): ");
	
	char choice;
	scanf(" %c", &choice);
	clear_input_buffer();
	
	char query[MAX_NAME_LEN];
	int found = 0;
	
	switch (choice) {
	case '1':
		printf("请输入学号: ");
		fgets(query, MAX_ID_LEN, stdin);
		query[strcspn(query, "\n")] = '\0';
		
		printf("\n查询结果:\n");
		for (int i = 0; i < student_count; i++) {
			if (strcmp(students[i].id, query) == 0) {
				display_student(students[i]);
				found = 1;
			}
		}
		break;
		
	case '2':
		printf("请输入姓名: ");
		fgets(query, MAX_NAME_LEN, stdin);
		query[strcspn(query, "\n")] = '\0';
		
		printf("\n查询结果:\n");
		for (int i = 0; i < student_count; i++) {
			if (strstr(students[i].name, query) != NULL) {
				display_student(students[i]);
				found = 1;
			}
		}
		break;
		
	case '3':
		printf("请输入专业: ");
		fgets(query, MAX_MAJOR_LEN, stdin);
		query[strcspn(query, "\n")] = '\0';
		
		printf("\n查询结果:\n");
		for (int i = 0; i < student_count; i++) {
			if (strstr(students[i].major, query) != NULL) {
				display_student(students[i]);
				found = 1;
			}
		}
		break;
		
	default:
		printf("无效的选择!\n");
		return;
	}
	
	if (!found) {
		printf("未找到符合条件的学生!\n");
	}
}

void display_student(Student s) {
	printf("\n学号: %s\n", s.id);
	printf("姓名: %s\n", s.name);
	printf("性别: %c\n", s.gender);
	printf("年龄: %d\n", s.age);
	printf("专业: %s\n", s.major);
	printf("GPA: %.2f\n", s.gpa);
	printf("获奖情况: %s\n", s.awards);
	printf("------------------------------\n");
}

void list_all_students() {
	printf("\n--- 所有学生信息 ---\n");
	if (student_count == 0) {
		printf("没有学生信息!\n");
		return;
	}
	
	for (int i = 0; i < student_count; i++) {
		display_student(students[i]);
	}
}

void sort_students() {
	printf("\n--- 排序学生信息 ---\n");
	printf("1. 按学号排序\n");
	printf("2. 按姓名排序\n");
	printf("3. 按GPA排序\n");
	printf("4. 按年龄排序\n");
	printf("请选择排序方式(1-4): ");
	
	char choice;
	scanf(" %c", &choice);
	clear_input_buffer();
	
	// 简单的冒泡排序
	for (int i = 0; i < student_count - 1; i++) {
		for (int j = 0; j < student_count - i - 1; j++) {
			int swap = 0;
			
			switch (choice) {
			case '1':
				if (strcmp(students[j].id, students[j+1].id) > 0) {
					swap = 1;
				}
				break;
				
			case '2':
				if (strcmp(students[j].name, students[j+1].name) > 0) {
					swap = 1;
				}
				break;
				
			case '3':
				if (students[j].gpa < students[j+1].gpa) {
					swap = 1;
				}
				break;
				
			case '4':
				if (students[j].age > students[j+1].age) {
					swap = 1;
				}
				break;
				
			default:
				printf("无效的选择!\n");
				return;
			}
			
			if (swap) {
				Student temp = students[j];
				students[j] = students[j+1];
				students[j+1] = temp;
			}
		}
	}
	
	save_data();
	printf("排序完成!\n");
	list_all_students();
}

void evaluate_students() {
	printf("\n--- 学生评优评奖 ---\n");
	printf("1. 显示GPA前3名的学生\n");
	printf("2. 显示有获奖记录的学生\n");
	printf("请选择评优方式(1-2): ");
	
	char choice;
	scanf(" %c", &choice);
	clear_input_buffer();
	
	switch (choice) {
		case '1': {
			// 先按GPA排序
			for (int i = 0; i < student_count - 1; i++) {
				for (int j = 0; j < student_count - i - 1; j++) {
					if (students[j].gpa < students[j+1].gpa) {
						Student temp = students[j];
						students[j] = students[j+1];
						students[j+1] = temp;
					}
				}
			}
			
			int limit = student_count < 3 ? student_count : 3;
			printf("\nGPA前%d名的学生:\n", limit);
			for (int i = 0; i < limit; i++) {
				display_student(students[i]);
			}
			break;
		}
		
		case '2': {
			int found = 0;
			printf("\n有获奖记录的学生:\n");
			for (int i = 0; i < student_count; i++) {
				if (strlen(students[i].awards) > 0) {
					display_student(students[i]);
					found = 1;
				}
			}
			
			if (!found) {
				printf("没有学生有获奖记录!\n");
			}
			break;
		}
		
	default:
		printf("无效的选择!\n");
	}
}

void statistics() {
	printf("\n--- 统计信息 ---\n");
	printf("总学生数: %d\n", student_count);
	
	if (student_count == 0) {
		return;
	}
	
	// 按性别统计
	int male_count = 0, female_count = 0;
	for (int i = 0; i < student_count; i++) {
		if (toupper(students[i].gender) == 'M') {
			male_count++;
		} else {
			female_count++;
		}
	}
	printf("男生人数: %d, 女生人数: %d\n", male_count, female_count);
	
	// 平均GPA
	float total_gpa = 0;
	for (int i = 0; i < student_count; i++) {
		total_gpa += students[i].gpa;
	}
	printf("平均GPA: %.2f\n", total_gpa / student_count);
	
	// 按专业统计
	printf("\n各专业人数:\n");
	char majors[MAX_STUDENTS][MAX_MAJOR_LEN];
	int counts[MAX_STUDENTS] = {0};
	int major_count = 0;
	
	for (int i = 0; i < student_count; i++) {
		int found = 0;
		for (int j = 0; j < major_count; j++) {
			if (strcmp(majors[j], students[i].major) == 0) {
				counts[j]++;
				found = 1;
				break;
			}
		}
		
		if (!found) {
			strcpy(majors[major_count], students[i].major);
			counts[major_count] = 1;
			major_count++;
		}
	}
	
	for (int i = 0; i < major_count; i++) {
		printf("%s: %d人\n", majors[i], counts[i]);
	}
}

void show_menu() {
	printf("\n=== 学生信息管理系统 ===\n");
	printf("1. 添加学生信息\n");
	printf("2. 删除学生信息\n");
	printf("3. 修改学生信息\n");
	printf("4. 查询学生信息\n");
	printf("5. 显示所有学生\n");
	printf("6. 排序学生信息\n");
	printf("7. 学生评优评奖\n");
	printf("8. 统计信息\n");
	printf("9. 退出系统\n");
}

void clear_input_buffer() {
	while (getchar() != '\n');
}