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/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed 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
 *
 * http://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.tomitribe.util.hash;

// forked from com.google.common.base.Preconditions
final class Preconditions {
    private Preconditions() {
    }

    public static  T checkNotNull(T reference, String errorMessage) {
        if (reference == null) {
            throw new NullPointerException(errorMessage);
        }
        return reference;
    }

    public static void checkArgument(boolean expression, String errorMessage) {
        if (!expression) {
            throw new IllegalArgumentException(errorMessage);
        }
    }

    public static void checkArgument(boolean expression, String errorMessageTemplate, Object... errorMessageArgs) {
        if (!expression) {
            throw new IllegalArgumentException(format(errorMessageTemplate, errorMessageArgs));
        }
    }

    public static int checkPositionIndex(int index, int size) {
        return checkPositionIndex(index, size, "index");
    }

    public static int checkPositionIndex(int index, int size, String desc) {
        // Carefully optimized for execution by hotspot (explanatory comment above)
        if (index < 0 || index > size) {
            throw new IndexOutOfBoundsException(badPositionIndex(index, size, desc));
        }
        return index;
    }

    private static String badPositionIndex(int index, int size, String desc) {
        if (index < 0) {
            return format("%s (%s) must not be negative", desc, index);
        } else if (size < 0) {
            throw new IllegalArgumentException("negative size: " + size);
        } else { // index > size
            return format("%s (%s) must not be greater than size (%s)", desc, index, size);
        }
    }

    public static void checkPositionIndexes(int start, int end, int size) {
        // Carefully optimized for execution by hotspot (explanatory comment above)
        if (start < 0 || end < start || end > size) {
            throw new IndexOutOfBoundsException(badPositionIndexes(start, end, size));
        }
    }

    private static String badPositionIndexes(int start, int end, int size) {
        if (start < 0 || start > size) {
            return badPositionIndex(start, size, "start index");
        }
        if (end < 0 || end > size) {
            return badPositionIndex(end, size, "end index");
        }
        // end < start
        return format("end index (%s) must not be less than start index (%s)", end, start);
    }

    private static String format(String template, Object... args) {
        template = String.valueOf(template); // null -> "null"

        // start substituting the arguments into the '%s' placeholders
        StringBuilder builder = new StringBuilder(template.length() + 16 * args.length);
        int templateStart = 0;
        int i = 0;
        while (i < args.length) {
            int placeholderStart = template.indexOf("%s", templateStart);
            if (placeholderStart == -1) {
                break;
            }
            builder.append(template.substring(templateStart, placeholderStart));
            builder.append(args[i++]);
            templateStart = placeholderStart + 2;
        }
        builder.append(template.substring(templateStart));

        // if we run out of placeholders, append the extra args in square braces
        if (i < args.length) {
            builder.append(" [");
            builder.append(args[i++]);
            while (i < args.length) {
                builder.append(", ");
                builder.append(args[i++]);
            }
            builder.append(']');
        }

        return builder.toString();
    }
}