#include <iostream>
#include <string>
#include <limits>
using namespace std;

bool readInt(const string& msg, int& x) {
    while (true) {
        cout << msg;
        if (cin >> x) return true;
        if (cin.eof()) return false;
        cin.clear();
        cin.ignore(numeric_limits<streamsize>::max(), '\n');
        cout << "Phai nhap so nguyen!\n";
    }
}
bool readDouble(const string& msg, double& x) {
    while (true) {
        cout << msg;
        if (cin >> x) return true;
        if (cin.eof()) return false;
        cin.clear();
        cin.ignore(numeric_limits<streamsize>::max(), '\n');
        cout << "Phai nhap so!\n";
    }
}
string readLine(const string& msg) {
    cout << msg;
    string s;
    getline(cin >> ws, s);
    return s;
}

struct Product { int id; string name; double price; int quantity; };
Product* findProduct(Product* products,int n,int id) {
    for(int i=0;i<n;++i) if(products[i].id==id) return &products[i];
    return nullptr;
}
void input(Product* ds,int n) {
    for(int i=0;i<n;++i) {
        cout<<"\nSan pham "<<i+1<<":\n";
        while(true) {
            if(!readInt("ID: ",ds[i].id)) return;
            if(findProduct(ds,i,ds[i].id)==nullptr) break;
            cout<<"ID trung!\n";
        }
        ds[i].name=readLine("Ten: ");
        do {if(!readDouble("Gia: ",ds[i].price)) return;
           if(ds[i].price<0)cout<<"Gia khong duoc am!\n";
        }while(ds[i].price<0);
        do {if(!readInt("So luong: ",ds[i].quantity)) return;
           if(ds[i].quantity<0)cout<<"So luong khong duoc am!\n";
        }while(ds[i].quantity<0);
    }
}
void show(Product* ds,int n) {
    for(int i=0;i<n;++i) cout<<ds[i].id<<" | "<<ds[i].name
        <<" | Gia: "<<ds[i].price<<" | Ton: "<<ds[i].quantity<<'\n';
}
void search(Product* ds,int n) {
    int id;if(!readInt("ID tim: ",id))return;
    Product* p=findProduct(ds,n,id);
    if(!p){cout<<"Khong tim thay!\n";return;}
    cout<<p->id<<" | "<<p->name<<" | "<<p->price<<" | "<<p->quantity<<'\n';
}
void buy(Product* ds,int n) {
    int id,k;if(!readInt("ID mua: ",id))return;
    Product* p=findProduct(ds,n,id);
    if(p==nullptr){cout<<"San pham khong ton tai!\n";return;}
    if(!readInt("So luong mua k: ",k))return;
    if(k<=0||k>p->quantity){cout<<"So luong mua khong hop le!\n";return;}
    p->quantity-=k;
    cout<<"Mua thanh cong! Con "<<p->quantity<<'\n';
}
void setPrice(Product* ds,int n,bool isManager) {
    if(!isManager){cout<<"User khong duoc doi gia!\n";return;}
    int id;if(!readInt("ID sua gia: ",id))return;
    Product* p=findProduct(ds,n,id);
    if(!p){cout<<"Khong tim thay!\n";return;}
    double price;if(!readDouble("Gia moi: ",price))return;
    if(price<0){cout<<"Gia khong hop le!\n";return;}
    p->price=price;cout<<"Da cap nhat gia!\n";
}
bool login(bool& isManager) {
    int role;if(!readInt("1.Manager 2.User: ",role))return false;
    if(role==2){isManager=false;return true;}
    if(role==1){string pass=readLine("Mat khau manager: ");
        if(pass=="M123"){isManager=true;return true;}}
    cout<<"Dang nhap that bai!\n";return false;
}
int main(){
    int n;if(!readInt("Nhap n (1..1000): ",n)||n<1||n>1000)return 0;
    Product* ds=new Product[n];input(ds,n);
    int mainChoice=-1;
    do {
        if(!readInt("\n1.Dang nhap 0.Thoat: ",mainChoice))break;
        if(mainChoice==1){bool isManager=false;
            if(!login(isManager))continue;
            int choice=-1;
            do{
                if(!readInt("\n1.Hien thi 2.Tim 3.Mua 4.Sua gia 0.Dang xuat: ",choice))break;
                switch(choice){
                    case 1:show(ds,n);break;
                    case 2:search(ds,n);break;
                    case 3:buy(ds,n);break;
                    case 4:setPrice(ds,n,isManager);break;
                    case 0:break;
                    default:cout<<"Lua chon sai!\n";
                }
            }while(choice!=0&&!cin.eof());
        }else if(mainChoice!=0)cout<<"Lua chon sai!\n";
    }while(mainChoice!=0&&!cin.eof());
    delete[] ds;ds=nullptr;return 0;
}