package com.googlecode.gwt.test.internal.utils;

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Locale;
import java.util.Map;

/**
 * {@link LinkedHashMap} variant that stores String keys in a case-insensitive manner, for example
 * for key-based access in a results table.
 * <p>
 * <p>
 * Preserves the original order as well as the original casing of keys, while allowing for contains,
 * get and remove calls with any case of key.
 * <p>
 * <p>
 * Does <i>not</i> support <code>null</code> keys.
 */
public class LinkedCaseInsensitiveMap<V> extends LinkedHashMap<String, V> {

    private static final long serialVersionUID = 7744455217001115746L;

    private final Map<String, String> caseInsensitiveKeys;

    private final Locale locale;

    /**
     * Create a new LinkedCaseInsensitiveMap for the default Locale.
     *
     * @see java.lang.String#toLowerCase()
     */
    public LinkedCaseInsensitiveMap() {
        this(null);
    }

    /**
     * Create a new LinkedCaseInsensitiveMap that wraps a {@link LinkedHashMap} with the given
     * initial capacity and stores lower-case keys according to the default Locale.
     *
     * @param initialCapacity the initial capacity
     * @see java.lang.String#toLowerCase()
     */
    public LinkedCaseInsensitiveMap(int initialCapacity) {
        this(initialCapacity, null);
    }

    /**
     * Create a new LinkedCaseInsensitiveMap that wraps a {@link LinkedHashMap} with the given
     * initial capacity and stores lower-case keys according to the given Locale.
     *
     * @param initialCapacity the initial capacity
     * @param locale          the Locale to use for lower-case conversion
     * @see java.lang.String#toLowerCase(java.util.Locale)
     */
    public LinkedCaseInsensitiveMap(int initialCapacity, Locale locale) {
        super(initialCapacity);
        this.caseInsensitiveKeys = new HashMap<String, String>(initialCapacity);
        this.locale = (locale != null ? locale : Locale.getDefault());
    }

    /**
     * Create a new LinkedCaseInsensitiveMap that stores lower-case keys according to the given
     * Locale.
     *
     * @param locale the Locale to use for lower-case conversion
     * @see java.lang.String#toLowerCase(java.util.Locale)
     */
    public LinkedCaseInsensitiveMap(Locale locale) {
        super();
        this.caseInsensitiveKeys = new HashMap<String, String>();
        this.locale = (locale != null ? locale : Locale.getDefault());
    }

    @Override
    public void clear() {
        this.caseInsensitiveKeys.clear();
        super.clear();
    }

    @Override
    public boolean containsKey(Object key) {
        return (key instanceof String && this.caseInsensitiveKeys.containsKey(convertKey((String) key)));
    }

    @Override
    public V get(Object key) {
        if (key instanceof String) {
            return super.get(this.caseInsensitiveKeys.get(convertKey((String) key)));
        } else {
            return null;
        }
    }

    @Override
    public V put(String key, V value) {
        this.caseInsensitiveKeys.put(convertKey(key), key);
        return super.put(key, value);
    }

    @Override
    public V remove(Object key) {
        if (key instanceof String) {
            return super.remove(this.caseInsensitiveKeys.remove(convertKey((String) key)));
        } else {
            return null;
        }
    }

    /**
     * Convert the given key to a case-insensitive key.
     * <p>
     * The default implementation converts the key to lower-case according to this Map's Locale.
     *
     * @param key the user-specified key
     * @return the key to use for storing
     * @see java.lang.String#toLowerCase(java.util.Locale)
     */
    protected String convertKey(String key) {
        return key.toLowerCase(this.locale);
    }

}