fi.jubic.easyconfig.internal.parameter.MappableParameter Maven / Gradle / Ivy
package fi.jubic.easyconfig.internal.parameter;
import fi.jubic.easyconfig.internal.Result;
import fi.jubic.easyconfig.providers.EnvProvider;
import javax.annotation.Nullable;
import java.util.Optional;
import java.util.function.BiFunction;
/**
* A single parameter instance that can be injected into an initializer.
*
* @param the type of the parameter
*/
public final class MappableParameter implements Mappable {
private final String variableName;
private final Class parameterClass;
private final boolean nullable;
private final boolean noPrefix;
private final BiFunction> parser;
@Nullable
private final T defaultValue;
MappableParameter(
String variableName,
Class parameterClass,
boolean nullable,
boolean noPrefix,
BiFunction> parser,
@Nullable T defaultValue
) {
if (nullable && (defaultValue != null)) {
throw new IllegalStateException();
}
this.variableName = variableName;
this.parameterClass = parameterClass;
this.nullable = nullable;
this.noPrefix = noPrefix;
this.parser = parser;
this.defaultValue = defaultValue;
}
@Override
public Result initialize(String prefix, EnvProvider envProvider) {
String effectiveVariableName = noPrefix
? variableName
: prefix + variableName;
return envProvider.getVariable(effectiveVariableName)
.map(strVal -> parser.apply(prefix, strVal))
.orElseGet(() -> {
if (nullable) {
return Result.of(null);
}
return Optional.ofNullable(defaultValue)
.map(Result::of)
.orElseGet(() -> Result.message(
String.format(
"Missing variable \"%s\" [%s]",
effectiveVariableName,
parameterClass.getSimpleName()
)
));
});
}
}