/****************************************************************
 * 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   *
 *                                                              *
 *   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.apache.james.jmap.draft.model;

import java.util.Optional;

import javax.mail.Flags;

import org.apache.commons.lang3.StringUtils;

import com.google.common.base.MoreObjects;
import com.google.common.base.Objects;
import com.google.common.collect.ImmutableBiMap;
import com.google.common.collect.ImmutableList;
import com.ibm.icu.text.UnicodeSet;

public class Keyword {
    private static final int FLAG_NAME_MIN_LENGTH = 1;
    private static final int FLAG_NAME_MAX_LENGTH = 255;
    private static final UnicodeSet FLAG_NAME_PATTERN =
        new UnicodeSet("[[a-z][A-Z][0-9]]")
            .add('$')
            .add('_')
            .add('-')
            .freeze();

    public static final Keyword DRAFT = Keyword.of("$Draft");
    public static final Keyword SEEN = Keyword.of("$Seen");
    public static final Keyword FLAGGED = Keyword.of("$Flagged");
    public static final Keyword ANSWERED = Keyword.of("$Answered");
    public static final Keyword DELETED = Keyword.of("$Deleted");
    public static final Keyword RECENT = Keyword.of("$Recent");
    public static final Keyword FORWARDED = Keyword.of("$Forwarded");
    static final Boolean FLAG_VALUE = true;

    private static final ImmutableList<Keyword> NON_EXPOSED_IMAP_KEYWORDS = ImmutableList.of(Keyword.RECENT, Keyword.DELETED);
    private static final ImmutableBiMap<Flags.Flag, Keyword> IMAP_SYSTEM_FLAGS = ImmutableBiMap.<Flags.Flag, Keyword>builder()
        .put(Flags.Flag.DRAFT, DRAFT)
        .put(Flags.Flag.SEEN, SEEN)
        .put(Flags.Flag.FLAGGED, FLAGGED)
        .put(Flags.Flag.ANSWERED, ANSWERED)
        .put(Flags.Flag.RECENT, RECENT)
        .put(Flags.Flag.DELETED, DELETED)
        .build();
    public static final String VALIDATION_MESSAGE = "Flagname must not be null or empty, must have length form 1-255, " +
        "must not contain charater with hex from '\\u0000' to '\\u00019' or {'(' ')' '{' ']' '%' '*' '\"' '\\'} ";

    public static Optional<Keyword> parse(String flagName) {
        if (isValid(flagName)) {
            return Optional.of(new Keyword(flagName));
        }
        return Optional.empty();
    }


    public static Keyword of(String flagName) {
        return parse(flagName)
            .orElseThrow(() -> new IllegalArgumentException(VALIDATION_MESSAGE));
    }

    public static Keyword fromFlag(Flags.Flag flag) {
        return IMAP_SYSTEM_FLAGS.get(flag);
    }

    private static boolean isValid(String flagName) {
        if (StringUtils.isBlank(flagName)) {
            return false;
        }
        if (flagName.length() < FLAG_NAME_MIN_LENGTH || flagName.length() > FLAG_NAME_MAX_LENGTH) {
            return false;
        }
        if (!FLAG_NAME_PATTERN.containsAll(flagName)) {
            return false;
        }
        return true;
    }

    private final String flagName;

    public Keyword(String flagName) {
        this.flagName = flagName;
    }

    public String getFlagName() {
        return flagName;
    }

    public boolean isExposedImapKeyword() {
        return !NON_EXPOSED_IMAP_KEYWORDS.contains(this);
    }

    public boolean isDraft() {
        return DRAFT.equals(this);
    }

    public Optional<Flags.Flag> asSystemFlag() {
        return Optional.ofNullable(IMAP_SYSTEM_FLAGS.inverse()
            .get(this));
    }

    public Flags asFlags() {
        return asSystemFlag()
            .map(Flags::new)
            .orElse(new Flags(flagName));
    }

    @Override
    public final boolean equals(Object other) {
        if (other instanceof Keyword) {
            Keyword otherKeyword = (Keyword) other;
            return Objects.equal(flagName, otherKeyword.flagName);
        }
        return false;
    }

    @Override
    public final int hashCode() {
        return Objects.hashCode(flagName);
    }

    @Override
    public String toString() {
        return MoreObjects.toStringHelper(this)
            .add("flagName", flagName)
            .toString();
    }

}
