/*
 * 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.maven.scm.provider.hg.command;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.maven.scm.ScmFileStatus;
import org.apache.maven.scm.util.AbstractConsumer;

/**
 * Base consumer to do common parsing for all hg commands.
 * <p>
 * More specific: log line each line if debug is enabled, get file status
 * and detect warnings from hg.
 *
 * @author <a href="mailto:thurner.rupert@ymono.net">thurner rupert</a>
 */
public class HgConsumer extends AbstractConsumer {

    /**
     * A list of known keywords from hg.
     */
    private static final Map<String, ScmFileStatus> IDENTIFIERS = new HashMap<>();

    /**
     * A list of known message prefixes from hg.
     */
    private static final Map<String, String> MESSAGES = new HashMap<>();

    /**
     * Number of lines to keep from Std.Err
     * This size is set to ensure that we capture enough info
     * but still keeps a low memory footprint.
     */
    private static final int MAX_STDERR_SIZE = 10;

    /**
     * A list of the MAX_STDERR_SIZE last errors or warnings.
     */
    private final List<String> stderr = new ArrayList<>();

    static {
        /* Statuses from hg add
         */
        IDENTIFIERS.put("adding", ScmFileStatus.ADDED);
        IDENTIFIERS.put("unknown", ScmFileStatus.UNKNOWN);
        IDENTIFIERS.put("modified", ScmFileStatus.MODIFIED);
        IDENTIFIERS.put("removed", ScmFileStatus.DELETED);
        IDENTIFIERS.put("renamed", ScmFileStatus.MODIFIED);

        /* Statuses from hg status;
         */
        IDENTIFIERS.put("A", ScmFileStatus.ADDED);
        IDENTIFIERS.put("?", ScmFileStatus.UNKNOWN);
        IDENTIFIERS.put("M", ScmFileStatus.MODIFIED);
        IDENTIFIERS.put("R", ScmFileStatus.DELETED);
        IDENTIFIERS.put("C", ScmFileStatus.CHECKED_IN);
        IDENTIFIERS.put("!", ScmFileStatus.MISSING);
        IDENTIFIERS.put("I", ScmFileStatus.UNKNOWN); // not precisely the same, but i think semantics work? - rwd

        MESSAGES.put("hg: WARNING:", "WARNING");
        MESSAGES.put("hg: ERROR:", "ERROR");
        MESSAGES.put("'hg' ", "ERROR"); // hg isn't found in windows path
    }

    public void doConsume(ScmFileStatus status, String trimmedLine) {
        // override this
    }

    /**
     * {@inheritDoc}
     */
    public void consumeLine(String line) {
        if (logger.isDebugEnabled()) {
            logger.debug(line);
        }
        String trimmedLine = line.trim();

        String statusStr = processInputForKnownIdentifiers(trimmedLine);

        // If its not a status report - then maybe its a message?
        if (statusStr == null) {
            boolean isMessage = processInputForKnownMessages(trimmedLine);
            // If it is then its already processed and we can ignore futher processing
            if (isMessage) {
                return;
            }
        } else {
            // Strip away identifier
            trimmedLine = trimmedLine.substring(statusStr.length());
            trimmedLine = trimmedLine.trim(); // one or more spaces
        }

        ScmFileStatus status = statusStr != null ? (IDENTIFIERS.get(statusStr.intern())) : null;
        doConsume(status, trimmedLine);
    }

    /**
     * Warnings and errors is usually printed out in Std.Err, thus for derived consumers
     * operating on Std.Out this would typically return an empty string.
     *
     * @return return the last lines interpreted as an warning or an error
     */
    public String getStdErr() {
        StringBuilder str = new StringBuilder();
        for (Iterator<String> it = stderr.iterator(); it.hasNext(); ) {
            str.append(it.next());
        }
        return str.toString();
    }

    private static String processInputForKnownIdentifiers(String line) {
        for (Iterator<String> it = IDENTIFIERS.keySet().iterator(); it.hasNext(); ) {
            String id = it.next();
            if (line.startsWith(id)) {
                return id;
            }
        }
        return null;
    }

    private boolean processInputForKnownMessages(String line) {
        for (Iterator<String> it = MESSAGES.keySet().iterator(); it.hasNext(); ) {
            String prefix = it.next();
            if (line.startsWith(prefix)) {
                stderr.add(line); // Add line
                if (stderr.size() > MAX_STDERR_SIZE) {
                    stderr.remove(0); // Rotate list
                }
                String message = line.substring(prefix.length());
                if (MESSAGES.get(prefix).equals("WARNING")) {
                    if (logger.isWarnEnabled()) {
                        logger.warn(message);
                    }
                } else {
                    if (logger.isErrorEnabled()) {
                        logger.error(message);
                    }
                }
                return true;
            }
        }
        return false;
    }
}
