package org.argeo.slc.core.execution.tasks;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.io.IOUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.argeo.slc.SlcException;
import org.argeo.slc.execution.Executable;

public class SystemCall implements Executable {
	// TODO: specify environment variables

	private final Log log = LogFactory.getLog(getClass());

	private String execDir;

	private String cmd = null;
	private List<String> command = null;

	private Boolean synchronous = true;
	private Boolean captureStdIn = false;

	private String stdErrLogLevel = "ERROR";
	private String stdOutLogLevel = "INFO";

	private Map<String, List<String>> osCommands = new HashMap<String, List<String>>();
	private Map<String, String> osCmds = new HashMap<String, String>();

	public void execute() {
		try {
			if (log.isTraceEnabled()) {
				log.debug("os.name=" + System.getProperty("os.name"));
				log.debug("os.arch=" + System.getProperty("os.arch"));
				log.debug("os.version=" + System.getProperty("os.version"));
			}

			// Execution directory
			File dir = null;
			if (execDir != null) {
				// Replace '/' by local file separator, for portability
				execDir.replace('/', File.separatorChar);
				dir = new File(execDir).getCanonicalFile();
			}

			Process process = null;

			// Check if an OS specific command overrides
			String osName = System.getProperty("os.name");
			List<String> commandToUse = null;
			if (osCommands.containsKey(osName))
				commandToUse = osCommands.get(osName);
			else
				commandToUse = command;
			String cmdToUse = null;
			if (osCmds.containsKey(osName))
				cmdToUse = osCmds.get(osName);
			else
				cmdToUse = cmd;

			// Which command definition to use
			if (commandToUse == null && cmdToUse == null)
				throw new SlcException("Please specify a command.");
			else if (commandToUse != null && cmdToUse != null)
				throw new SlcException(
						"Specify the command either as a line or as a list.");
			else if (cmdToUse != null) {
				if (log.isTraceEnabled())
					log.trace("Execute '" + cmdToUse + "' in "
							+ getUsedDir(dir));
				process = Runtime.getRuntime().exec(cmdToUse, null, dir);
			} else if (commandToUse != null) {
				if (log.isTraceEnabled())
					log.trace("Execute '" + commandToUse + "' in "
							+ getUsedDir(dir));
				ProcessBuilder processBuilder = new ProcessBuilder(commandToUse);
				processBuilder.directory(dir);
				process = processBuilder.start();
			} else {
				// all cases covered previously
			}

			// Manage standard streams
			StreamReaderThread stdOutThread = new StreamReaderThread(process
					.getInputStream()) {
				protected void callback(String line) {
					stdOutCallback(line);
				}
			};
			stdOutThread.start();
			StreamReaderThread stdErrThread = new StreamReaderThread(process
					.getErrorStream()) {
				protected void callback(String line) {
					stdErrCallback(line);
				}
			};
			stdErrThread.start();
			if (captureStdIn)
				new StdInThread(process.getOutputStream()).start();

			// Wait for the end of the process
			if (synchronous) {
				Integer exitCode = process.waitFor();
				if (exitCode != 0) {
					Thread.sleep(5000);// leave the process a chance to log
					log.warn("Process return exit code " + exitCode);
				}
			} else {
				// asynchronous: return
			}
		} catch (Exception e) {
			throw new SlcException("Could not execute command " + cmd, e);
		}

	}

	/**
	 * Shortcut method returning the current exec dir if the specified one is
	 * null.
	 */
	private String getUsedDir(File dir) {
		if (dir == null)
			return System.getProperty("user.dir");
		else
			return dir.getPath();
	}

	protected void stdOutCallback(String line) {
		log(stdOutLogLevel, line);
	}

	protected void stdErrCallback(String line) {
		log(stdErrLogLevel, line);
	}

	protected void log(String logLevel, String line) {
		if ("ERROR".equals(logLevel))
			log.error(line);
		else if ("WARN".equals(logLevel))
			log.warn(line);
		else if ("INFO".equals(logLevel))
			log.info(line);
		else if ("DEBUG".equals(logLevel))
			log.debug(line);
		else if ("TRACE".equals(logLevel))
			log.trace(line);
		else
			throw new SlcException("Unknown log level " + logLevel);
	}

	public void setCmd(String command) {
		this.cmd = command;
	}

	public void setExecDir(String execdir) {
		this.execDir = execdir;
	}

	public void setStdErrLogLevel(String stdErrLogLevel) {
		this.stdErrLogLevel = stdErrLogLevel;
	}

	public void setStdOutLogLevel(String stdOutLogLevel) {
		this.stdOutLogLevel = stdOutLogLevel;
	}

	public void setSynchronous(Boolean synchronous) {
		this.synchronous = synchronous;
	}

	public void setCaptureStdIn(Boolean captureStdIn) {
		this.captureStdIn = captureStdIn;
	}

	public void setCommand(List<String> command) {
		this.command = command;
	}

	public void setOsCommands(Map<String, List<String>> osCommands) {
		this.osCommands = osCommands;
	}

	public void setOsCmds(Map<String, String> osCmds) {
		this.osCmds = osCmds;
	}

	protected abstract class StreamReaderThread extends Thread {
		private final InputStream stream;

		public StreamReaderThread(InputStream stream) {
			this.stream = stream;
		}

		@Override
		public void run() {
			BufferedReader in = null;
			try {
				in = new BufferedReader(new InputStreamReader(stream));
				String line = null;
				while ((line = in.readLine()) != null) {
					stdOutCallback(line);
				}
			} catch (IOException e) {
				if (log.isTraceEnabled()) {
					log.trace("Could not read stream", e);
					// catch silently
					// because the other methods
					// to check whether the stream
					// is closed would probably
					// be to costly
				}
			} finally {
				if (synchronous)
					IOUtils.closeQuietly(in);
			}
		}

		protected abstract void callback(String line);
	}

	protected class StdInThread extends Thread {
		private final OutputStream stream;

		public StdInThread(OutputStream stream) {
			this.stream = stream;
		}

		@Override
		public void run() {
			BufferedReader in = null;
			Writer out = null;
			try {
				out = new OutputStreamWriter(stream);
				in = new BufferedReader(new InputStreamReader(System.in));
				String line = null;
				while ((line = in.readLine()) != null) {
					out.write(line);
					out.write("\n");
					out.flush();
				}
			} catch (IOException e) {
				throw new SlcException("Could not write to stdin stream", e);
			} finally {
				if (synchronous) {
					IOUtils.closeQuietly(in);
					IOUtils.closeQuietly(out);
				}
			}
		}

	}
}