/*
 * 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.math.BigInteger;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.text.Format;
import java.text.NumberFormat;
import java.util.Locale;

import org.apache.commons.validator.GenericValidator;

/**
 * Abstract class for Number Validation.
 * <p>
 * This is a <em>base</em> class for building Number Validators using format parsing.
 * </p>
 *
 * @since 1.3.0
 */
public abstract class AbstractNumberValidator extends AbstractFormatValidator {

    private static final long serialVersionUID = -3088817875906765463L;

    /**
     * Standard {@code NumberFormat} type.
     */
    public static final int STANDARD_FORMAT = 0;

    /**
     * Currency {@code NumberFormat} type.
     */
    public static final int CURRENCY_FORMAT = 1;

    /**
     * Percent {@code NumberFormat} type.
     */
    public static final int PERCENT_FORMAT = 2;

    /**
     * Compares two values as BigDecimals.
     *
     * @param value1 {@code BigDecimal} to compare.
     * @param value2 {@code BigDecimal} to which {@code value1} is to be compared.
     * @return -1, 0, or 1 as this {@code BigDecimal} is numerically less than, equal to, or greater than {@code val}.
     */
    static int compareTo(final Number value1, final Number value2) {
        return toBigDecimal(value1).compareTo(toBigDecimal(value2));
    }

    /**
     * Tests if the given value is finite.
     *
     * @param value The value to test.
     * @return {@code true} if the value is finite, {@code false} otherwise.
     */
    static boolean isFinite(final Number value) {
        if (value instanceof Double) {
            return Double.isFinite((Double) value);
        }
        if (value instanceof Float) {
            return Float.isFinite((Float) value);
        }
        return true;
    }

    static Format setParseBigDecimal(final Format format) {
        if (format instanceof DecimalFormat) {
            ((DecimalFormat) format).setParseBigDecimal(true);
        }
        return format;
    }

    static BigDecimal toBigDecimal(final Object value) {
        if (value instanceof Long || value instanceof Integer || value instanceof Short || value instanceof Byte) {
            return BigDecimal.valueOf(((Number) value).longValue());
        }
        if (value instanceof Double || value instanceof Float) {
            return BigDecimal.valueOf(((Number) value).doubleValue());
        }
        if (value instanceof BigDecimal) {
            return (BigDecimal) value;
        }
        if (value instanceof BigInteger) {
            return new BigDecimal((BigInteger) value);
        }
        // No more shortcuts, convert from a string.
        return new BigDecimal(value.toString());
    }

    static BigInteger toBigInteger(final Object value) {
        if (value instanceof Long || value instanceof Integer || value instanceof Short || value instanceof Byte) {
            return BigInteger.valueOf(((Number) value).longValue());
        }
        return toBigDecimal(value).toBigInteger();
    }

    /**
     * {@code true} if fractions are allowed or {@code false} if integers only.
     */
    private final boolean allowFractions;

    /**
     * The {@code NumberFormat} type to create for validation, default is STANDARD_FORMAT.
     */
    private final int formatType;

    /**
     * Constructs an instance with specified <em>strict</em> and <em>decimal</em> parameters.
     *
     * @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.
     */
    public AbstractNumberValidator(final boolean strict, final int formatType, final boolean allowFractions) {
        super(strict);
        this.allowFractions = allowFractions;
        this.formatType = formatType;
    }

    /**
     * Returns the <em>multiplier</em> of the {@code NumberFormat}.
     *
     * @param format The {@code NumberFormat} to determine the multiplier of.
     * @return The multiplying factor for the format.
     */
    protected int determineScale(final NumberFormat format) {
        if (!isStrict()) {
            return -1;
        }
        if (!isAllowFractions() || format.isParseIntegerOnly()) {
            return 0;
        }
        final int minimumFraction = format.getMinimumFractionDigits();
        final int maximumFraction = format.getMaximumFractionDigits();
        if (minimumFraction != maximumFraction) {
            return -1;
        }
        int scale = minimumFraction;
        if (format instanceof DecimalFormat) {
            final int multiplier = ((DecimalFormat) format).getMultiplier();
            if (multiplier == 100) { // CHECKSTYLE IGNORE MagicNumber
                scale += 2; // CHECKSTYLE IGNORE MagicNumber
            } else if (multiplier == 1000) { // CHECKSTYLE IGNORE MagicNumber
                scale += 3; // CHECKSTYLE IGNORE MagicNumber
            }
        } else if (formatType == PERCENT_FORMAT) {
            scale += 2; // CHECKSTYLE IGNORE MagicNumber
        }
        return scale;
    }

    /**
     * Gets the {@code NumberFormat} for the specified Locale.
     *
     * @param locale The locale a {@code NumberFormat} is required for, system default if null.
     * @return The {@code NumberFormat} to created.
     */
    protected Format getFormat(final Locale locale) {
        final NumberFormat formatter;
        switch (formatType) {
        case CURRENCY_FORMAT:
            if (locale == null) {
                formatter = NumberFormat.getCurrencyInstance();
            } else {
                formatter = NumberFormat.getCurrencyInstance(locale);
            }
            break;
        case PERCENT_FORMAT:
            if (locale == null) {
                formatter = NumberFormat.getPercentInstance();
            } else {
                formatter = NumberFormat.getPercentInstance(locale);
            }
            break;
        default:
            if (locale == null) {
                formatter = NumberFormat.getInstance();
            } else {
                formatter = NumberFormat.getInstance(locale);
            }
            if (!isAllowFractions()) {
                formatter.setParseIntegerOnly(true);
            }
            break;
        }
        return formatter;
    }

    /**
     * Gets a {@code NumberFormat} for the specified <em>pattern</em> and/or {@link Locale}.
     *
     * @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 currency format, system default if null.
     * @return The {@code NumberFormat} to created.
     */
    @Override
    protected Format getFormat(final String pattern, final Locale locale) {
        final NumberFormat formatter;
        if (GenericValidator.isBlankOrNull(pattern)) {
            formatter = (NumberFormat) getFormat(locale);
        } else if (locale == null) {
            formatter = new DecimalFormat(pattern);
        } else {
            formatter = new DecimalFormat(pattern, new DecimalFormatSymbols(locale));
        }
        if (!isAllowFractions()) {
            formatter.setParseIntegerOnly(true);
        }
        return formatter;
    }

    /**
     * Gets the type of {@code NumberFormat} created by this validator instance.
     *
     * @return The format type created.
     */
    public int getFormatType() {
        return formatType;
    }

    /**
     * Tests whether the number being validated is a decimal or integer.
     *
     * @return {@code true} if decimals are allowed or {@code false} if the number is an integer.
     */
    public boolean isAllowFractions() {
        return allowFractions;
    }

    /**
     * Tests if the value is within a specified range.
     *
     * @param value The value validation is being performed on.
     * @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 Number value, final Number min, final Number max) {
        return minValue(value, min) && maxValue(value, max);
    }

    /**
     * Tests validity using the specified {@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 {@code true} if the value is valid.
     */
    @Override
    public boolean isValid(final String value, final String pattern, final Locale locale) {
        return parse(value, pattern, locale) != null;
    }

    /**
     * Tests if the value is less than or equal to a maximum.
     *
     * <p>
     * For an integer validator the bound is compared exactly rather than narrowed to a {@code long}, so a {@code BigInteger} or {@code BigDecimal} bound outside
     * the long range keeps its magnitude and a fractional bound keeps its fractional part. A non-finite {@link Double} or {@link Float} operand keeps the
     * {@code doubleValue()} comparison, since {@code BigDecimal} cannot represent {@code NaN} or an infinity.
     * </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.
     */
    public boolean maxValue(final Number value, final Number max) {
        if (isAllowFractions()) {
            return value.doubleValue() <= max.doubleValue();
        }
        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.
     *
     * <p>
     * For an integer validator the bound is compared exactly rather than narrowed to a {@code long}, so a {@code BigInteger} or {@code BigDecimal} bound outside
     * the long range keeps its magnitude and a fractional bound keeps its fractional part. A non-finite {@link Double} or {@link Float} operand keeps the
     * {@code doubleValue()} comparison, since {@code BigDecimal} cannot represent {@code NaN} or an infinity.
     * </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.
     */
    public boolean minValue(final Number value, final Number min) {
        if (isAllowFractions()) {
            return value.doubleValue() >= min.doubleValue();
        }
        return isFinite(value) && isFinite(min) ? compareTo(value, min) >= 0 : value.doubleValue() >= min.doubleValue();
    }

    /**
     * Parses the value using the specified pattern.
     *
     * @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 value if valid or {@code null} if invalid.
     */
    protected Object parse(String value, final String pattern, final Locale locale) {
        value = value == null ? null : value.trim();
        final String value1 = value;
        if (GenericValidator.isBlankOrNull(value1)) {
            return null;
        }
        return parse(value, getFormat(pattern, locale));
    }

    /**
     * Processes the parsed value, performing any further validation and type conversion required.
     *
     * @param value     The parsed object created.
     * @param formatter The Format used to parse the value with.
     * @return The parsed value converted to the appropriate type if valid or {@code null} if invalid.
     */
    @Override
    protected abstract Object processParsedValue(Object value, Format formatter);
}
