/*
 * Copyright 2017 Cisco Systems, Inc.
 *
 * 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 com.cisco.gerrit.plugins.slack.message;

import com.cisco.gerrit.plugins.slack.config.ProjectConfig;
import com.google.gerrit.extensions.client.ChangeKind;
import com.google.gerrit.server.events.PatchSetCreatedEvent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static org.apache.commons.lang.StringUtils.substringBefore;

/**
 * A specific MessageGenerator implementation that can generate a message for a
 * patchset created event.
 *
 * @author Matthew Montgomery
 */
public class PatchSetCreatedMessageGenerator implements MessageGenerator
{
    private static final Logger LOGGER =
            LoggerFactory.getLogger(PatchSetCreatedMessageGenerator.class);

    private PatchSetCreatedEvent event;
    private ProjectConfig config;

    /**
     * Creates a new PatchSetCreatedMessageGenerator instance using the
     * provided PatchSetCreatedEvent instance.
     *
     * @param event The PatchSetCreatedEvent instance to generate a
     *              message for.
     */
    PatchSetCreatedMessageGenerator(PatchSetCreatedEvent event,
            ProjectConfig config)
    {
        if (event == null)
        {
            throw new NullPointerException("event cannot be null");
        }

        this.event = event;
        this.config = config;
    }

    private boolean unchangedChangeKind(ChangeKind kind)
    {
        switch (kind)
        {
            case TRIVIAL_REBASE:
                return true;
            case MERGE_FIRST_PARENT_UPDATE:
                return true;
            case NO_CODE_CHANGE:
                return true;
            case NO_CHANGE:
                return true;
            case REWORK:
                return false;
            default:
                LOGGER.warn("Unknown ChangeKind", kind);
        }
        // Default unknown ChangeKind's to changed
        return false;
    }

    @Override
    public boolean shouldPublish()
    {
        if (!config.isEnabled() || !config.shouldPublishOnPatchSetCreated())
        {
            return false;
        }

        // Ignore rebases or no code changes
        try
        {
            if (config.getIgnoreUnchangedPatchSet() &&
                unchangedChangeKind(event.patchSet.get().kind))
            {
                return false;
            }
        }
        catch (Exception e)
        {
            LOGGER.warn("Error checking patch set kind", e);
        }

        boolean result;
        result = true;

        try
        {
            Pattern pattern;
            pattern = Pattern.compile(config.getIgnore(), Pattern.DOTALL);

            Matcher matcher;
            matcher = pattern.matcher(event.change.get().commitMessage);

            // If the ignore pattern matches, publishing should not happen
            result = !matcher.matches();
        }
        catch (Exception e)
        {
            LOGGER.warn("The specified ignore pattern was invalid", e);
        }

        return result;
    }

    @Override
    public String generate()
    {
        String message;
        message = "";

        try
        {
            MessageTemplate template;
            template = new MessageTemplate();

            template.setChannel(config.getChannel());
            template.setName(event.uploader.get().name);
            template.setAction("proposed");
            template.setNumber(event.change.get().number);
            template.setProject(event.change.get().project);
            template.setBranch(event.change.get().branch);
            template.setUrl(event.change.get().url);
            template.setTitle(substringBefore(event.change.get().commitMessage, "\n"));

            message = template.render();
        }
        catch (Exception e)
        {
            LOGGER.error("Error generating message: " + e.getMessage(), e);
        }

        return message;
    }
}