/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.validator.routines;

import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.text.Format;
import java.text.NumberFormat;
import java.util.Locale;

/**
 * <strong>BigDecimal Validation</strong> and Conversion routines ({@code java.math.BigDecimal}).
 * <p>
 * This validator provides a number of methods for validating/converting a {@link String} value to a {@code BigDecimal} using {@link NumberFormat} to parse
 * either:
 * </p>
 * <ul>
 * <li>using the default format for the default {@link Locale}</li>
 * <li>using a specified pattern with the default {@link Locale}</li>
 * <li>using the default format for a specified {@link Locale}</li>
 * <li>using a specified pattern with a specified {@link Locale}</li>
 * </ul>
 * <p>
 * Use one of the {@code isValid()} methods to just validate or one of the {@code validate()} methods to validate and receive a <em>converted</em>
 * {@code BigDecimal} value.
 * </p>
 * <p>
 * Fraction/decimal values are automatically trimmed to the appropriate length.
 * </p>
 * <p>
 * Once a value has been successfully converted the following methods can be used to perform minimum, maximum and range checks:
 * </p>
 * <ul>
 * <li>{@code minValue()} checks whether the value is greater than or equal to a specified minimum.</li>
 * <li>{@code maxValue()} checks whether the value is less than or equal to a specified maximum.</li>
 * <li>{@code isInRange()} checks whether the value is within a specified range of values.</li>
 * </ul>
 * <p>
 * So that the same mechanism used for parsing an <em>input</em> value for validation can be used to format <em>output</em>, corresponding {@code format()}
 * methods are also provided. That is you can format either:
 * </p>
 * <ul>
 * <li>using the default format for the default {@link Locale}</li>
 * <li>using a specified pattern with the default {@link Locale}</li>
 * <li>using the default format for a specified {@link Locale}</li>
 * <li>using a specified pattern with a specified {@link Locale}</li>
 * </ul>
 *
 * @since 1.3.0
 */
public class BigDecimalValidator extends AbstractNumberValidator {

    private static final long serialVersionUID = -670320911490506772L;
    private static final BigDecimalValidator VALIDATOR = new BigDecimalValidator();

    /**
     * Compares the given {@code BigDecimal} with the given double value.
     *
     * @param bigDecimal The {@code BigDecimal} to compare.
     * @param value      The double value to compare with.
     * @return A negative integer, zero, or a positive integer as this {@code BigDecimal} is less than, equal to, or greater than the specified double value.
     */
    private static int compareTo(final BigDecimal bigDecimal, final double value) {
        return bigDecimal.compareTo(BigDecimal.valueOf(value));
    }

    /**
     * Gets the singleton instance of this validator.
     *
     * @return A singleton instance of the BigDecimalValidator.
     */
    public static BigDecimalValidator getInstance() {
        return VALIDATOR;
    }

    /**
     * Constructs a <em>strict</em> instance.
     */
    public BigDecimalValidator() {
        this(true);
    }

    /**
     * Construct an instance with the specified strict setting.
     *
     * @param strict {@code true} if strict {@code Format} parsing should be used.
     */
    public BigDecimalValidator(final boolean strict) {
        this(strict, STANDARD_FORMAT, true);
    }

    /**
     * Constructs an instance with the specified strict setting and format type.
     * <p>
     * The {@code formatType} specified what type of {@code NumberFormat} is created - valid types are:
     * </p>
     * <ul>
     * <li>AbstractNumberValidator.STANDARD_FORMAT -to create <em>standard</em> number formats (the default).</li>
     * <li>AbstractNumberValidator.CURRENCY_FORMAT -to create <em>currency</em> number formats.</li>
     * <li>AbstractNumberValidator.PERCENT_FORMAT -to create <em>percent</em> number formats (the default).</li>
     * </ul>
     *
     * @param strict         {@code true} if strict {@code Format} parsing should be used.
     * @param formatType     The {@code NumberFormat} type to create for validation, default is STANDARD_FORMAT.
     * @param allowFractions {@code true} if fractions are allowed or {@code false} if integers only.
     */
    protected BigDecimalValidator(final boolean strict, final int formatType, final boolean allowFractions) {
        super(strict, formatType, allowFractions);
    }

    /**
     * Returns a {@code Format} that parses to a {@code BigDecimal} so the exact value of the input is preserved.
     *
     * <p>
     * The superclass leaves {@link DecimalFormat} in its default mode, where {@code parse} yields a {@code Double} for a
     * fractional value and so rounds an input carrying more significant digits than a {@code double} can hold. Enabling
     * {@link DecimalFormat#setParseBigDecimal(boolean)} keeps the value as a {@code BigDecimal} through parsing.
     * </p>
     *
     * @param pattern The pattern used to validate the value against or {@code null} to use the default for the {@link Locale}.
     * @param locale  The locale to use for the format, system default if null.
     * @return The {@code Format} to use.
     */
    @Override
    protected Format getFormat(final String pattern, final Locale locale) {
        return setParseBigDecimal(super.getFormat(pattern, locale));
    }

    /**
     * Tests if the value is within a specified range.
     *
     * @param value The {@code Number} value to check.
     * @param min   The minimum value of the range.
     * @param max   The maximum value of the range.
     * @return {@code true} if the value is within the specified range.
     */
    public boolean isInRange(final BigDecimal value, final double min, final double max) {
        return minValue(value, min) && maxValue(value, max);
    }

    /**
     * Tests if the value is less than or equal to a maximum.
     *
     * @param value The value validation is being performed on.
     * @param max   The maximum value.
     * @return {@code true} if the value is less than or equal to the maximum.
     */
    public boolean maxValue(final BigDecimal value, final double max) {
        return Double.isFinite(max) ? compareTo(value, max) <= 0 : value.doubleValue() <= max;
    }

    /**
     * Tests if the value is less than or equal to a maximum, comparing the exact values.
     *
     * <p>
     * This overrides the {@link Number} overload inherited from the superclass, which narrows the value to a {@code double} before comparing and so loses
     * precision for a {@code BigDecimal} that differs from the bound only beyond double precision. A non-finite {@link Double} or {@link Float} operand keeps
     * the {@code doubleValue()} comparison so the documented infinity behavior is unchanged.
     * </p>
     *
     * @param value The value validation is being performed on.
     * @param max   The maximum value.
     * @return {@code true} if the value is less than or equal to the maximum.
     */
    @Override
    public boolean maxValue(final Number value, final Number max) {
        return isFinite(value) && isFinite(max) ? compareTo(value, max) <= 0 : value.doubleValue() <= max.doubleValue();
    }

    /**
     * Tests if the value is greater than or equal to a minimum.
     *
     * @param value The value validation is being performed on.
     * @param min   The minimum value.
     * @return {@code true} if the value is greater than or equal to the minimum.
     */
    public boolean minValue(final BigDecimal value, final double min) {
        return Double.isFinite(min) ? compareTo(value, min) >= 0 : value.doubleValue() >= min;
    }

    /**
     * Tests if the value is greater than or equal to a minimum, comparing the exact values.
     *
     * <p>
     * This overrides the {@link Number} overload inherited from the superclass, which narrows the value to a {@code double} before comparing and so loses
     * precision for a {@code BigDecimal} that differs from the bound only beyond double precision. A non-finite {@link Double} or {@link Float} operand keeps
     * the {@code doubleValue()} comparison so the documented infinity behavior is unchanged.
     * </p>
     *
     * @param value The value validation is being performed on.
     * @param min   The minimum value.
     * @return {@code true} if the value is greater than or equal to the minimum.
     */
    @Override
    public boolean minValue(final Number value, final Number min) {
        return isFinite(value) && isFinite(min) ? compareTo(value, min) >= 0 : value.doubleValue() >= min.doubleValue();
    }

    /**
     * Converts the parsed value to a {@code BigDecimal}.
     *
     * @param value     The parsed {@code Number} object created.
     * @param formatter The Format used to parse the value with.
     * @return The parsed {@code Number} converted to a {@code BigDecimal}.
     */
    @Override
    protected Object processParsedValue(final Object value, final Format formatter) {
        BigDecimal decimal = toBigDecimal(value);
        final int scale = determineScale((NumberFormat) formatter);
        if (scale >= 0) {
            decimal = decimal.setScale(scale, BigDecimal.ROUND_DOWN);
        }
        return decimal;
    }

    /**
     * Validates and converts a {@code BigDecimal} using the default {@link Locale}.
     *
     * @param value The value validation is being performed on.
     * @return The parsed {@code BigDecimal} if valid or {@code null} if invalid.
     */
    public BigDecimal validate(final String value) {
        return (BigDecimal) parse(value, (String) null, (Locale) null);
    }

    /**
     * Validates and converts a {@code BigDecimal} using the specified {@link Locale}.
     *
     * @param value  The value validation is being performed on.
     * @param locale The locale to use for the number format, system default if null.
     * @return The parsed {@code BigDecimal} if valid or {@code null} if invalid.
     */
    public BigDecimal validate(final String value, final Locale locale) {
        return (BigDecimal) parse(value, (String) null, locale);
    }

    /**
     * Validates and converts a {@code BigDecimal} using the specified <em>pattern</em>.
     *
     * @param value   The value validation is being performed on.
     * @param pattern The pattern used to validate the value against, or the default for the {@link Locale} if {@code null}.
     * @return The parsed {@code BigDecimal} if valid or {@code null} if invalid.
     */
    public BigDecimal validate(final String value, final String pattern) {
        return (BigDecimal) parse(value, pattern, (Locale) null);
    }

    /**
     * Validates and converts a {@code BigDecimal} using the specified pattern and/ or {@link Locale}.
     *
     * @param value   The value validation is being performed on.
     * @param pattern The pattern used to validate the value against, or the default for the {@link Locale} if {@code null}.
     * @param locale  The locale to use for the date format, system default if null.
     * @return The parsed {@code BigDecimal} if valid or {@code null} if invalid.
     */
    public BigDecimal validate(final String value, final String pattern, final Locale locale) {
        return (BigDecimal) parse(value, pattern, locale);
    }
}