// Copyright 2015 The Bazel Authors. All rights reserved.
//
// 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.google.devtools.build.lib.runtime;

import com.google.common.eventbus.Subscribe;
import com.google.devtools.build.lib.actions.ActionCompletionEvent;
import com.google.devtools.build.lib.actions.ActionStartedEvent;
import com.google.devtools.build.lib.analysis.AnalysisPhaseCompleteEvent;
import com.google.devtools.build.lib.analysis.NoBuildEvent;
import com.google.devtools.build.lib.buildtool.buildevent.BuildCompleteEvent;
import com.google.devtools.build.lib.buildtool.buildevent.BuildStartingEvent;
import com.google.devtools.build.lib.buildtool.buildevent.ExecutionProgressReceiverAvailableEvent;
import com.google.devtools.build.lib.buildtool.buildevent.TestFilteringCompleteEvent;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.events.EventKind;
import com.google.devtools.build.lib.pkgcache.LoadingPhaseCompleteEvent;
import com.google.devtools.build.lib.skyframe.LoadingPhaseStartedEvent;
import com.google.devtools.build.lib.util.Clock;
import com.google.devtools.build.lib.util.io.AnsiTerminal;
import com.google.devtools.build.lib.util.io.AnsiTerminalWriter;
import com.google.devtools.build.lib.util.io.LineCountingAnsiTerminalWriter;
import com.google.devtools.build.lib.util.io.LineWrappingAnsiTerminalWriter;
import com.google.devtools.build.lib.util.io.OutErr;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.view.test.TestStatus.BlazeTestStatus;

import java.io.IOException;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;
import java.util.logging.Logger;

/**
 * An experimental new output stream.
 */
public class ExperimentalEventHandler extends BlazeCommandEventHandler {
  private static Logger LOG = Logger.getLogger(ExperimentalEventHandler.class.getName());
  /** Latest refresh of the progress bar, if contents other than time changed */
  static final long MAXIMAL_UPDATE_DELAY_MILLIS = 200L;
  /** Periodic update interval of a time-dependent progress bar if it can be updated in place */
  static final long SHORT_REFRESH_MILLIS = 1000L;
  /** Periodic update interval of a time-dependent progress bar if it cannot be updated in place */
  static final long LONG_REFRESH_MILLIS = 5000L;

  private final long minimalDelayMillis;
  private final boolean cursorControl;
  private final Clock clock;
  private final AnsiTerminal terminal;
  private final boolean debugAllEvents;
  private final ExperimentalStateTracker stateTracker;
  private final long minimalUpdateInterval;
  private long lastRefreshMillis;
  private int numLinesProgressBar;
  private boolean buildComplete;
  private boolean progressBarNeedsRefresh;
  private Thread updateThread;

  public final int terminalWidth;

  public ExperimentalEventHandler(
      OutErr outErr, BlazeCommandEventHandler.Options options, Clock clock) {
    super(outErr, options);
    this.cursorControl = options.useCursorControl();
    this.terminal = new AnsiTerminal(outErr.getErrorStream());
    this.terminalWidth = (options.terminalColumns > 0 ? options.terminalColumns : 80);
    this.clock = clock;
    this.debugAllEvents = options.experimentalUiDebugAllEvents;
    // If we have cursor control, we try to fit in the terminal width to avoid having
    // to wrap the progress bar. We will wrap the progress bar to terminalWidth - 1
    // characters to avoid depending on knowing whether the underlying terminal does the
    // line feed already when reaching the last character of the line, or only once an
    // additional character is written. Another column is lost for the continuation character
    // in the wrapping process.
    this.stateTracker =
        this.cursorControl
            ? new ExperimentalStateTracker(clock, this.terminalWidth - 2)
            : new ExperimentalStateTracker(clock);
    this.numLinesProgressBar = 0;
    this.minimalDelayMillis = Math.round(options.showProgressRateLimit * 1000);
    this.minimalUpdateInterval = Math.max(this.minimalDelayMillis, MAXIMAL_UPDATE_DELAY_MILLIS);
    // The progress bar has not been updated yet.
    ignoreRefreshLimitOnce();
  }

  @Override
  public synchronized void handle(Event event) {
    try {
      if (debugAllEvents) {
        // Debugging only: show all events visible to the new UI.
        clearProgressBar();
        terminal.flush();
        outErr.getOutputStream().write((event + "\n").getBytes(StandardCharsets.UTF_8));
        outErr.getOutputStream().flush();
        addProgressBar();
        terminal.flush();
      } else {
        switch (event.getKind()) {
          case STDOUT:
          case STDERR:
            if (!buildComplete) {
              clearProgressBar();
              terminal.flush();
            }
            OutputStream stream =
                event.getKind() == EventKind.STDOUT
                    ? outErr.getOutputStream()
                    : outErr.getErrorStream();
            stream.write(event.getMessageBytes());
            if (!buildComplete) {
              stream.write(new byte[] {10, 13});
            }
            stream.flush();
            if (!buildComplete) {
              if (cursorControl) {
                addProgressBar();
              }
              terminal.flush();
            }
            break;
          case ERROR:
          case WARNING:
          case INFO:
          case SUBCOMMAND:
            if (!buildComplete) {
              clearProgressBar();
            }
            setEventKindColor(event.getKind());
            terminal.writeString(event.getKind() + ": ");
            terminal.resetTerminal();
            if (event.getLocation() != null) {
              terminal.writeString(event.getLocation() + ": ");
            }
            if (event.getMessage() != null) {
              terminal.writeString(event.getMessage());
            }
            crlf();
            if (!buildComplete) {
              addProgressBar();
            }
            terminal.flush();
            break;
          case PROGRESS:
            if (stateTracker.progressBarTimeDependent()) {
              refresh();
            }
        }
      }
    } catch (IOException e) {
      LOG.warning("IO Error writing to output stream: " + e);
    }
  }

  private void setEventKindColor(EventKind kind) throws IOException {
    switch (kind) {
      case ERROR:
        terminal.textRed();
        terminal.textBold();
        break;
      case WARNING:
        terminal.textMagenta();
        break;
      case INFO:
        terminal.textGreen();
        break;
      case SUBCOMMAND:
        terminal.textBlue();
    }
  }

  @Subscribe
  public void buildStarted(BuildStartingEvent event) {
    stateTracker.buildStarted(event);
    // As a new phase started, inform immediately.
    ignoreRefreshLimitOnce();
    refresh();
  }

  @Subscribe
  public void loadingStarted(LoadingPhaseStartedEvent event) {
    stateTracker.loadingStarted(event);
    // As a new phase started, inform immediately.
    ignoreRefreshLimitOnce();
    refresh();
    startUpdateThread();
  }

  @Subscribe
  public void loadingComplete(LoadingPhaseCompleteEvent event) {
    stateTracker.loadingComplete(event);
    refresh();
  }

  @Subscribe
  public void analysisComplete(AnalysisPhaseCompleteEvent event) {
    stateTracker.analysisComplete(event);
    refresh();
  }

  @Subscribe
  public void progressReceiverAvailable(ExecutionProgressReceiverAvailableEvent event) {
    stateTracker.progressReceiverAvailable(event);
    // As this is the first time we have a progress message, update immediately.
    ignoreRefreshLimitOnce();
    startUpdateThread();
  }

  @Subscribe
  public void buildComplete(BuildCompleteEvent event) {
    stateTracker.buildComplete(event);
    ignoreRefreshLimitOnce();
    refresh();
    buildComplete = true;
    stopUpdateThread();
  }

  @Subscribe
  public void noBuild(NoBuildEvent event) {
    buildComplete = true;
    stopUpdateThread();
  }

  @Subscribe
  public void actionStarted(ActionStartedEvent event) {
    stateTracker.actionStarted(event);
    refresh();
  }

  @Subscribe
  public void actionCompletion(ActionCompletionEvent event) {
    stateTracker.actionCompletion(event);
    refresh();
  }

  @Subscribe
  public void testFilteringComplete(TestFilteringCompleteEvent event) {
    stateTracker.testFilteringComplete(event);
    refresh();
  }

  @Subscribe
  public synchronized void testSummary(TestSummary summary) {
    stateTracker.testSummary(summary);
    if (summary.getStatus() != BlazeTestStatus.PASSED) {
      // For failed test, write the failure to the scroll-back buffer immediately
      try {
        clearProgressBar();
        setEventKindColor(EventKind.ERROR);
        terminal.writeString("FAIL: ");
        terminal.resetTerminal();
        terminal.writeString(summary.getTarget().getLabel().toString());
        crlf();
        for (Path logPath : summary.getFailedLogs()) {
          terminal.writeString("      " + logPath.getPathString());
          crlf();
        }
        if (summary.getFailedLogs().size() > 0) {
          crlf();
        }
        if (cursorControl) {
          addProgressBar();
        }
        terminal.flush();
      } catch (IOException e) {
        LOG.warning("IO Error writing to output stream: " + e);
      }
    } else {
      refresh();
    }
  }

  private void refresh() {
    progressBarNeedsRefresh = true;
    doRefresh();
  }

  private synchronized void doRefresh() {
    long nowMillis = clock.currentTimeMillis();
    if (lastRefreshMillis + minimalDelayMillis < nowMillis) {
      try {
        if (progressBarNeedsRefresh || timeBasedRefresh()) {
          progressBarNeedsRefresh = false;
          lastRefreshMillis = nowMillis;
          clearProgressBar();
          addProgressBar();
          terminal.flush();
        }
      } catch (IOException e) {
        LOG.warning("IO Error writing to output stream: " + e);
      }
      if (!stateTracker.progressBarTimeDependent()) {
        stopUpdateThread();
      }
    } else {
      // We skipped an update due to rate limiting. If this however, turned
      // out to be the last update for a long while, we need to show it in a
      // timely manner, as it best describes the current state.
      startUpdateThread();
    }
  }

  /**
   * Decide wheter the progress bar should be redrawn only for the reason
   * that time has passed.
   */
  private synchronized boolean timeBasedRefresh () {
    if (!stateTracker.progressBarTimeDependent()) {
      return false;
    }
    long nowMillis = clock.currentTimeMillis();
    long intervalMillis = cursorControl ? SHORT_REFRESH_MILLIS : LONG_REFRESH_MILLIS;
    return lastRefreshMillis + intervalMillis < nowMillis;
  }

  private void ignoreRefreshLimitOnce() {
    // Set refresh time variables in a state such that the next progress bar
    // update will definitely be written out.
    lastRefreshMillis = clock.currentTimeMillis() - minimalDelayMillis - 1;
  }

  private synchronized void startUpdateThread() {
    if (updateThread == null) {
      final ExperimentalEventHandler eventHandler = this;
      updateThread =
          new Thread(
              new Runnable() {
                @Override
                public void run() {
                  try {
                    while (true) {
                      Thread.sleep(minimalUpdateInterval);
                      eventHandler.doRefresh();
                    }
                  } catch (InterruptedException e) {
                    // Ignore
                  }
                }
              });
      updateThread.start();
    }
  }

  private synchronized void stopUpdateThread() {
    if (updateThread != null) {
      updateThread.interrupt();
      try {
        updateThread.join();
      } catch (InterruptedException e) {
        // Ignore
      }
      updateThread = null;
    }
  }

  public void resetTerminal() {
    try {
      terminal.resetTerminal();
    } catch (IOException e) {
      LOG.warning("IO Error writing to user terminal: " + e);
    }
  }

  private void clearProgressBar() throws IOException {
    if (!cursorControl) {
      return;
    }
    for (int i = 0; i < numLinesProgressBar; i++) {
      terminal.cr();
      terminal.cursorUp(1);
      terminal.clearLine();
    }
    numLinesProgressBar = 0;
  }

  private void crlf() throws IOException {
    terminal.cr();
    terminal.writeString("\n");
  }

  private void addProgressBar() throws IOException {
    LineCountingAnsiTerminalWriter countingTerminalWriter =
        new LineCountingAnsiTerminalWriter(terminal);
    AnsiTerminalWriter terminalWriter = countingTerminalWriter;
    if (cursorControl) {
      terminalWriter = new LineWrappingAnsiTerminalWriter(terminalWriter, terminalWidth - 1);
    }
    stateTracker.writeProgressBar(terminalWriter, /* shortVersion=*/ !cursorControl);
    terminalWriter.newline();
    numLinesProgressBar = countingTerminalWriter.getWrittenLines();
  }
}