// Copyright (C) 2023 The Android Open Source Project
//
// 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.

import com.google.gerrit.common.data.*
import com.google.gerrit.extensions.annotations.*
import com.google.inject.*
import com.google.gerrit.extensions.events.*
import com.google.gerrit.metrics.*
import org.kohsuke.args4j.*
import com.google.gerrit.server.git.*
import com.google.gerrit.entities.*
import org.eclipse.jgit.errors.*
import com.gerritforge.gerrit.globalrefdb.*
import org.eclipse.jgit.lib.*
import com.google.gerrit.sshd.*
import com.google.gerrit.lifecycle.*
import java.util.function.BiConsumer
import java.util.concurrent.*
import com.google.common.flogger.*
import java.util.regex.Pattern

abstract class BaseSshCommand extends SshCommand {
  void println(String msg) {
    stdout.println msg
    stdout.flush()
  }

  void error(String msg) { println("[ERROR] $msg") }
  void warning(String msg) { println("[WARNING] $msg") }
}

@Singleton
class RefDbMetrics implements LifecycleListener {
  FluentLogger log = FluentLogger.forEnclosingClass()

  @Inject
  MetricMaker metrics

  CallbackMetric1<String, Integer> numRefsMetric
  final Map<String, Integer> projectsAndNumRefs = new ConcurrentHashMap()

  void start() {
    numRefsMetric =
        metrics.newCallbackMetric(
            "localrefdb/num_refs_per_project",
            Integer.class,
            new Description("Number of local refs").setGauge(),
            Field.ofString("repository_name", { it.projectName } as BiConsumer)
                .description("The name of the repository.")
                .build())

    metrics.newTrigger(
        numRefsMetric, { ->
      if (projectsAndNumRefs.isEmpty()) {
        numRefsMetric.forceCreate("")
      } else {
        projectsAndNumRefs.each { e ->
          numRefsMetric.set(e.key, e.value)
        }
        numRefsMetric.prune()
      }
    })
  }

  void stop() {
    numRefsMetric.remove()
  }
}

@CommandMetaData(name = "count-refs", description = "Count the local number of refs, excluding user edits, and publish the value as 'num_refs' metric")
@RequiresCapability(GlobalCapability.ADMINISTRATE_SERVER)
class CountRefs extends BaseSshCommand {

  @Argument(index = 0, usage = "Project name", metaVar = "PROJECTS", required = true)
  String[] projects

  @Inject
  GitRepositoryManager repoMgr

  @Inject
  RefDbMetrics refdbMetrics

  SanitizeProjectName sanitizeProjectName = new SanitizeProjectName()

  public void run() {
    refdbMetrics.projectsAndNumRefs.clear()
    projects.each { project ->
      try {
        def projectName = Project.nameKey(project)

        repoMgr.openRepository(projectName).with { repo ->
          println "Counting refs of project $project ..."
          def filteredRefs = repo.refDatabase.refs.findAll { ref -> !(ref.name.startsWith("refs/users/.*")) && !ref.symbolic }
          println "Result: $project has ${filteredRefs.size()} refs"
          refdbMetrics.projectsAndNumRefs.put(sanitizeProjectName.sanitize(project), filteredRefs.size())
        }
      } catch (RepositoryNotFoundException e) {
        error "Project $project not found"
      }
    }
  }
}

class MetricsModule extends LifecycleModule {
  protected void configure() {
    listener().to(RefDbMetrics)
  }
}

class LocalRefDbCommandModule extends PluginCommandModule {
  protected void configureCommands() {
    command(CountRefs)
  }
}

class SanitizeProjectName {
  private static final Pattern METRIC_NAME_PATTERN = ~"[a-zA-Z0-9_-]+(/[a-zA-Z0-9_-]+)*"
  private static final Pattern INVALID_CHAR_PATTERN = ~"[^\\w-/]"
  private static final String REPLACEMENT_PREFIX = "_0x"

  static String sanitize(String name) {
    if (METRIC_NAME_PATTERN.matcher(name).matches() && !name.contains(REPLACEMENT_PREFIX)) {
      return name;
    }

    StringBuilder sanitizedName =
        new StringBuilder(name.substring(0, 1).replaceFirst("[^\\w-]", "_"))
    if (name.length() == 1) {
      return sanitizedName.toString()
    }

    String slashSanitizedName = name.substring(1).replaceAll("/[/]+", "/")
    if (slashSanitizedName.endsWith("/")) {
      slashSanitizedName = slashSanitizedName.substring(0, slashSanitizedName.length() - 1)
    }

    String replacementPrefixSanitizedName =
        slashSanitizedName.replaceAll(REPLACEMENT_PREFIX, REPLACEMENT_PREFIX + REPLACEMENT_PREFIX)

    for (int i = 0; i < replacementPrefixSanitizedName.length(); i++) {
      Character c = replacementPrefixSanitizedName.charAt(i)
      if (c.toString() ==~ INVALID_CHAR_PATTERN) {
        sanitizedName.append(REPLACEMENT_PREFIX)
        sanitizedName.append(c.toString().getBytes("UTF-8").encodeHex().toString().toUpperCase())
        sanitizedName.append('_')
      } else {
        sanitizedName.append(c)
      }
    }

    return sanitizedName.toString()
  }
}

modules = [MetricsModule, LocalRefDbCommandModule]