/*
 * 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.addthis.hydra.util;

import java.util.List;

import com.addthis.basis.util.LessStrings;
import com.addthis.basis.util.Parameter;

import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * simple util to send emails
 */
public final class EmailUtil {
    private static final Logger log = LoggerFactory.getLogger(EmailUtil.class);
    private static final String FROM_ADDRESS = Parameter.value("email.fromAddress");
    private static final String MAILX_ACCOUNT = Parameter.value("email.mailxAccount");
    private static final String REPLY_TO = Parameter.value("email.replyTo");

    private EmailUtil() {}

    public static boolean email(String to, String subject, String body) {
        try {
            List<String> cmd = Lists.newArrayList("mailx", "-s " + subject);
            if (FROM_ADDRESS != null) {
                cmd.add("-S");
                cmd.add("from=" + FROM_ADDRESS);
            }
            if (REPLY_TO != null) {
                cmd.add("-S");
                cmd.add("replyto=" + REPLY_TO);
            }
            if (MAILX_ACCOUNT != null) {
                cmd.add("-A");
                cmd.add(MAILX_ACCOUNT);
            }
            cmd.add(to);
            String[] cmdArray = Iterables.toArray(cmd, String.class);
            ProcessExecutor executor = new ProcessExecutor.Builder(cmdArray).setStdin(body).build();
            boolean success = executor.execute();
            int exitValue = executor.exitValue();
            String standardError = executor.stderr();
            /*
             * If the process completed successfully but the standard error
             * log is non-empty then emit the standard error.
             */
            if (success && (exitValue == 0) && !LessStrings.isEmpty(standardError)) {
                log.warn("Stderr was non-empty in email with subject: {} to : {} due to subshell error : {} {}",
                         subject, to, exitValue, standardError);
            }
            return success && (exitValue == 0);
        } catch (Exception e) {
            log.warn("Unable to send email with subject: {} to : {}", subject, to, e);
            return false;
        }
    }
}