/*-------------------------------------------------------------------------+
|                                                                          |
| Copyright 2005-2011 the ConQAT Project                                   |
|                                                                          |
| 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.conqat.lib.commons.region;

import java.io.Serializable;
import java.util.Comparator;
import java.util.Objects;

import org.conqat.lib.commons.js_export.ExportToJavaScript;

import com.fasterxml.jackson.annotation.JsonProperty;

/**
 * A simple region with only start and end. If you also need a description
 * string (origin), use {@link Region}. Both start and end positions are
 * inclusive.
 */
@ExportToJavaScript
public class SimpleRegion implements Comparable<SimpleRegion>, Serializable {

        /** Version for serialization. */
        private static final long serialVersionUID = 1;

        /** The name of the JSON property name for {@link #start}. */
        protected static final String START_PROPERTY = "start";

        /** The name of the JSON property name for {@link #end}. */
        protected static final String END_PROPERTY = "end";

        /**
         * Compares {@link SimpleRegion}s first by their start and then by their end.
         */
        public static final Comparator<SimpleRegion> START_AND_END_COMPARATOR = Comparator.comparing(SimpleRegion::getStart)
                        .thenComparing(SimpleRegion::getEnd);

        /** Region start position (inclusive). */
        @JsonProperty(START_PROPERTY)
        private final int start;

        /** Region end position (inclusive). */
        @JsonProperty(END_PROPERTY)
        private final int end;

        /** Constructor. */
        public SimpleRegion(int start, int end) {
                this.start = start;
                this.end = end;
        }

        /** Checks if the region contains a position */
        public boolean containsPosition(int position) {
                return (start <= position && end >= position);
        }

        /** Checks if two regions are overlapping */
        public boolean overlaps(SimpleRegion r) {
                // Region with smaller start value performs overlap check
                if (r.start < start) {
                        return r.overlaps(this);
                }

                return (start <= r.start && end >= r.start);
        }

        /** Checks if two regions are adjacent */
        public boolean adjacent(SimpleRegion r) {
                // Region with smaller start value performs adjacency check
                if (r.start < start) {
                        return r.adjacent(this);
                }

                return (end + 1 == r.start);
        }

        /**
         * Gets the end position of the region. This may be less than start for an empty
         * region (see also {@link #isEmpty()}).
         */
        public int getEnd() {
                return end;
        }

        /** Gets the start position of the region */
        public int getStart() {
                return start;
        }

        /**
         * Gets the length of the region. Empty regions have a length of 0.
         */
        public int getLength() {
                if (isEmpty()) {
                        return 0;
                }
                return end - start + 1;
        }

        /** Returns whether this region is empty. */
        public boolean isEmpty() {
                return end < start;
        }

        /** {@inheritDoc} */
        @Override
        public String toString() {
                return "[" + start + "-" + end + "]";
        }

        /** Compares regions by their start position */
        @Override
        public int compareTo(SimpleRegion other) {
                return Integer.compare(start, other.start);
        }

        /**
         * Returns whether start and end of the region is the same as for this region.
         */
        public boolean equalsStartEnd(SimpleRegion other) {
                return start == other.start && end == other.end;
        }

        /** {@inheritDoc} */
        @Override
        public int hashCode() {
                return Objects.hash(start, end);
        }

        /** {@inheritDoc} */
        @Override
        public boolean equals(Object other) {
                if (this == other) {
                        return true;
                }
                if (other == null) {
                        return false;
                }
                if (getClass() != other.getClass()) {
                        return false;
                }

                SimpleRegion otherRegion = (SimpleRegion) other;
                return equalsStartEnd(otherRegion);
        }
}