// Purpose. Strategy design pattern lab.
//
// Problem. Data entry validation is lumped in one function with a large
// monolithic case statement. In a more sophisticated application there
// might be multiple parallel case statements and the validation code
// could easily become several pages in length. If new validation
// requirements surface, the situation is exacerbated.
//
// Strategy. "Abtract out" the validation mechanism into its own class
// hierarchy - interface in a base class, implementation in derived classes.
//
// Assignment.
// o Create a Validation base class that can serve as an umbrella for the
// three different validation requirements
// o Move the interface of the validate() method to the Validation hierarchy
// o Move each part of the "case" statement in validate() to its own derived
// class
// o In DataEntry, replace the "type" attribute and the validate() method
// with a Validation* attribute
// o Initialize the Validation* member, inside setValidationType()
// o In interact(), delegate the validation to the Validation* member
// o main() will stay the same

#include <iostream.h>
#include <string.h>

int isdigit( char ch ) { return (ch >= '0' && ch <= '9') ? 1 : 0; }
int isupper( char ch ) { return (ch >= 'A' && ch <= 'Z') ? 1 : 0; }
int islower( char ch ) { return (ch >= 'a' && ch <= 'z') ? 1 : 0; }

class DataEntry {
public:
void setValidationType( char ch ) { type = ch; }
void interact();
private:
char type;
int validate( char* );
};

void DataEntry::interact() {
char answer[20];
cout << "Prompt: ";
cin >> answer;
while (strcmp( answer, "quit" )) {
if (validate( answer )) cout << "*** good ***" << endl;
else cout << "*** bad ***" << endl;
cout << "Prompt: ";
cin >> answer;
} }

int DataEntry::validate( char* input ) {
int valid;
unsigned i;
valid = 1;
if (type == 'n') {
for (i=0; i < strlen(input); i++)
if ( ! isdigit( input[i] ) ) {
valid = 0;
break;
}
} else if (type == 'u') {
for (i=0; i < strlen(input); i++)
if ( ! isupper( input[i] ) ) {
valid = 0;
break;
}
} else if (type == 'l') {
for (i=0; i < strlen(input); i++)
if ( ! islower( input[i] ) ) {
valid = 0;
break;
}
}
return valid;
}

void main( void ) {
DataEntry dialog;
char answer;

cout << "Input type [ (n)umber, (u)pper, (l)ower, e(x)it ]: ";
cin >> answer;
while (answer != 'x') {
dialog.setValidationType(answer);
dialog.interact();
cout << "Input type [ (n)umber, (u)pper, (l)ower, e(x)it ]: ";
cin >> answer;
} }

// Input type [ (n)umber, (u)pper, (l)ower, e(x)it ]: n
// Prompt: sdf
// *** bad ***
// Prompt: 234
// *** good ***
// Prompt: quit
// Input type [ (n)umber, (u)pper, (l)ower, e(x)it ]: u
// Prompt: sdf
// *** bad ***
// Prompt: 234
// *** bad ***
// Prompt: GHJ
// *** good ***
// Prompt: quit
// Input type [ (n)umber, (u)pper, (l)ower, e(x)it ]: x