selfprivacy.org.app/lib/utils/password_generator.dart

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import 'dart:math';
var generator = PasswordGenerator();
String genPass() {
generator.generate(8);
return generator.getGeneratedValue();
}
///Generates a password.
///
///The password [_generatedValue] is of a specified length, including letters [_letterGen] of mixed cases,
///numbers [_numGen], and symbols[_symGen] depending on user choice.
class PasswordGenerator {
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late bool _letterGen;
late bool _numGen;
late bool _symGen;
late String _generatedValue;
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///Constructor.
///
///[_letterGen] is true to make password generation possible from the opening of the application, and
///[_generatedValue] is intialized to the value below so the text containing it can be first generated
///upon users request
PasswordGenerator() {
_letterGen = true;
_numGen = true;
_symGen = false;
_generatedValue = "Press Generate";
}
///Call to generate a value, of [n] length
void generate(int n) {
//Discards the old value
_generatedValue = "";
///Cannot generate a value without any character types selected
if (!_letterGen && !_numGen && !_symGen) {
_generatedValue = "No character type selected";
return;
}
///'Randomly' selectes caracter type to generate and append [toAppend] to [_generatedValue]
// ignore: unnecessary_statements
for (n; n > 0; n--) {
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String? toAppend;
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var random = new Random();
///loops until a valid character is generated, meaning the user has to check the character value
///to be generated. 'Randomly' picks a character type.
while (toAppend == null) {
int selector = random.nextInt(3);
if (selector == 0) {
toAppend = _generateLetter();
} else if (selector == 1) {
toAppend = _generateNumber();
} else {
toAppend = _generateSymbol();
}
}
_generatedValue += toAppend;
toAppend = null;
}
}
///Generates a letter when called.
String _generateLetter() {
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if (!_letterGen) return '';
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///Finds the integer value for the range between a-z and A-Z, with [base] UTF-16 value for lowercase letters and
///[baseUpper] UTF-16 value for uppercase letters
int base = "a".codeUnitAt(0);
int baseUpper = "A".codeUnitAt(0);
int maxRand = ("z".codeUnitAt(0) - base) + 1;
Random random = new Random();
///Randomly selects between upper and lower case generation, randomly generates value from [maxRand], then adding base,
///which creates a UTF-16 encoded character to be converted into a string of one character between a-z/A-Z.
///This string is then returned.
if (random.nextInt(2) == 0) {
return String.fromCharCodes([random.nextInt(maxRand) + base]);
} else {
return String.fromCharCodes([random.nextInt(maxRand) + baseUpper]);
}
}
///Generates a number when called
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String? _generateNumber() {
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if (!_numGen) return null;
///Finds the integer value for the range between 0-9
int base = "0".codeUnitAt(0);
int maxRand = ("9".codeUnitAt(0) - base) + 1;
Random random = new Random();
///Randomly generates value from [maxRand], then adding base, which creates a UTF-16 encoded character to be converted into a
///string of one character between 0-9. This string is then returned.
return String.fromCharCodes([random.nextInt(maxRand) + base]);
}
///Generates a symbol when called
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String? _generateSymbol() {
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if (!_symGen) return null;
///Finds the integer value for the range between symbols !-.
///(note) which includes symbols !"#$%&'()*+,=.
int base = "!".codeUnitAt(0);
int maxRand = (".".codeUnitAt(0) - base) + 1;
Random random = new Random();
///Randomly generates value from [maxRand], then adding base, which creates a UTF-16 encoded character to be
///converted into a string of one character between !-. . This string is then returned.
return String.fromCharCodes([random.nextInt(maxRand) + base]);
}
///Toggles letter generation
void checkLetterGen(bool value) {
_letterGen = value;
}
///Toggles number generation
void checkNumGen(bool value) {
_numGen = value;
}
///Toggles symbol generation
void checkSymGen(bool value) {
_symGen = value;
}
///Returns the generated value to be used by generator app
String getGeneratedValue() {
return _generatedValue;
}
}