// Copyright (C) 2017 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.

package com.googlesource.gerrit.plugins.analytics.common

import com.googlesource.gerrit.plugins.analytics.common.ManagedResource.use
import org.eclipse.jgit.api.Git
import org.eclipse.jgit.lib.{Constants, ObjectId, Repository}
import org.eclipse.jgit.revwalk.RevWalk
import org.eclipse.jgit.revwalk.filter.CommitTimeRevFilter

import scala.collection.JavaConversions._
import scala.collection.mutable

class CommitsBranches(repo: Repository, from: Option[Long] = None,
                      to: Option[Long] = None) {

  def forCommits(objectIds: TraversableOnce[ObjectId]): Set[String] = {
    val commitToBranchesMap = new mutable.HashMap[String, mutable.Set[String]]
      with mutable.MultiMap[String, String]
    use(new Git(repo)) { git =>
      val refs = git.branchList.call
      for (ref <- refs) {
        val branchName = ref.getName.drop(Constants.R_HEADS.length)
        use(new RevWalk(repo)) { rw: RevWalk =>
          from.foreach(d1 => rw.setRevFilter(CommitTimeRevFilter.after(d1)))
          to.foreach(d2 => rw.setRevFilter(CommitTimeRevFilter.before(d2)))
          rw.markStart(rw.parseCommit(ref.getObjectId))
          rw.foreach { rev =>
            val sha1 = rev.getName
            commitToBranchesMap.addBinding(sha1, branchName)
          }
        }
      }
      objectIds.foldLeft(Set.empty[String]) {
        (branches, objectId) => {
          branches ++ commitToBranchesMap(objectId.getName)
        }
      }.filter(_.nonEmpty)
    }
  }
}