#include<stdio.h>
#include<malloc.h>
#include<string.h>

int total = 0;

struct data{
	char num[10];
	int amount;
	struct data *next;
	struct data *prev;
};

struct data *head = NULL;
struct data *tail = NULL;

struct data* search(char num[]){
	struct data *node;

	while(node != NULL){
		if(strcmp(num,node->num) == 0){
			return node;
		}
		node = node->next;
	}
	return NULL;
}

void insert(){
	char num[10];
	int amount;
	struct data *placed;

	printf("input invoice number [5 characters]: ");
	scanf("%s",&num);
	int length = strlen(num);
	printf("%d",length);
	while(length != 5){
		printf("a\n");
		printf("input invoice number [5 characters]: ");
		scanf("%s",&num);
	}
	placed = search(num);
	while(placed != NULL){
		printf("invoice number already exists\n");
		printf("input invoice number [5 characters]: ");
		scanf("%s",&num);
		while(strlen(num) > 5 or strlen(num) < 5){
			printf("input invoice number [5 characters]: ");
			scanf("%s",&num);
		}
		placed = search(num);
	}

	printf("input amount [1000..500000]: ");
	scanf("%d",&amount);
	while(amount < 1000 or amount > 500000){
		printf("input amount [1000..500000]: ");
		scanf("%d",&amount);
	}
	total = total + amount;

	struct data *node = (struct data*) malloc(sizeof(struct data));
	node->next = NULL;
	strcpy(node->num,num);
	node->amount = amount;
	tail->next = node;
	node->prev = tail;
	tail = node;
}

void display(){
	printf("No | InvoiceNo | Amount\n");
	printf("=======================\n");

	struct data *node;
	node = head;
	int count = 1;
	while(node != NULL){
		printf("%d | %7s | %7d\n",count,node->num,node->amount);
		count++;
		node = node->next;
	}
	printf("=======================\n");
	printf("Total Amount : %7d\n",total);
}

void update(){
	struct data *temp;
	struct data *pos;
	char num[10];
	char amount;

	printf("input invoice number [5 characters]: ");
	getchar();
	scanf("%s",&num);
	while(strlen(num) > 5 or strlen(num) < 5){
		printf("input invoice number [5 characters]: ");
		scanf("%s",&num);
	}
	pos = search(num);
	while(pos == NULL){
		printf("invoice number dosen't exist\n");
		printf("input invoice number [5 characters]: ");
		scanf("%s",&num);
		while(strlen(num) > 5 or strlen(num) < 5){
			printf("input invoice number [5 characters]: ");
			scanf("%s",&num);
		}
		pos = search(num);
	}
	printf("input new amount [1000..500000]: ");
	scanf("%d",&amount);
	while(amount < 1000 or amount > 500000){
		printf("input new amount [1000..500000]: ");
		scanf("%d",&amount);
	}
	total = total - pos->amount;
	pos->amount = amount;
	total = total + amount;

}

void del(struct data *node){
	struct data *temp;
	struct data *temp2;
	temp = node->prev;
	temp2 = node->next;
	temp->next = temp2;
	temp2->prev = temp;
	free(node);
}

void pay(){
	int payment;

	printf("Input Payment [0..%d] : ",total);
	scanf("%d", &payment);
	while(payment < 0 or payment > total){
		printf("Input Payment [0..%d] : ",total);
		scanf("%d", &payment);
	}

	struct data *node;
	node = head;
	while(payment != 0 or node != NULL){
		if(payment > node->amount){
			payment = payment - node->amount;
			total = total - node->amount;
			del(node);
		}
		else{
			node->amount = node->amount - payment;
			total = total - payment;
			payment = 0;
		}
		node = node->next;
	}
}

void clear(){
	struct data *curr;
	struct data *temp;
	curr = head;

	while(curr != NULL){
		temp = curr;
		curr = curr->next;
		free(temp);
	}
}

int menu(){
	int menum;
	display();
	printf("1. Insert Debt\n");
	printf("2. Pay Debt\n");
	printf("3. Update\n");
	printf("4. Exit\n");
	printf("Masukan pilihan : ");
	scanf("%d",&menum);
	return menum;
}

int main(){
	int menum = 0;

	do{
		menum = menu();
		if(menum == 1){
			insert();
		}
		else if(menum == 2){
			pay();
		}
		else if(menum == 3){
			update();
		}
		else if(menum == 4){
			clear();
		}
	}while(menum!=4);

}