/*
Copyright 2013 Google Inc. 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.
*/

/*
Presubmitter polls GWT's Gerrit server and runs presubmit checks when
new changes are detected.

To use presubmitter, you need to first setup a JSON-formatted creds file
like:

    {
      "GerritUsername": "git-azurediamond.bash.org",
      "GerritPassword": "hunter2",
      "JenkinsToken": "opensesame"
    }

By default, presubmitter looks for this file at $HOME/.gwtcreds.  This
can be changed using the -creds flag.

Additionally, presubmitter expects to be run from the top-level
directory of a GWT git repository that it can use for checking out
uploaded changes.

Lastly, presubmitter expects to find the checkstyle JAR at
../tools/antlib/checkstyle-all-4.2.jar, but this can also be changed using
the -checkstylejar flag.
*/
package main

import (
	"flag"
	"log"
	"sync"
	"time"

	"gwt.googlesource.com/buildglue.git/gerrit"
	"gwt.googlesource.com/buildglue.git/jenkins"
	"gwt.googlesource.com/buildglue.git/lint"
)

const query = "(project:gwt status:open -label:Verified=1 -label:Verified=-1 -label:Code-Review=-1 -label:Code-Review=-2 ownerin:\"Jenkins Trusted\" -age:1w) OR (project:gwt status:open -label:Verified=1 -label:Verified=-1 label:Code-Review=2 -age:1w)"

const timeout = 90 * time.Minute

// Running lint mutates the current directory, so we need to ensure we serialize it.
var lintLock sync.Mutex

func main() {
	flag.Parse()

	nextRetry := make(map[string]time.Time)
	for {
		refs, err := gerrit.Query(query)
		if err != nil {
			log.Println("error querying gerrit:", err)
			time.Sleep(time.Minute)
			continue
		}
		log.Println("found refs:", refs)

		now := time.Now()
		for _, ref := range refs {
			if now.Before(nextRetry[ref]) {
				continue
			}
			// TODO(mdempsky): Exponential back off.
			nextRetry[ref] = now.Add(timeout)

			log.Println("verifying ref:", ref)
			go func(ref string) {
				lintLock.Lock()
				if err := lint.Lint(ref); err != nil {
					lintLock.Unlock()
					log.Println("lint error:", err)
					return
				}
				lintLock.Unlock()

				if err := jenkins.RunPresubmit(ref); err != nil {
					log.Println("presubmit error:", err)
					return
				}
			}(ref)
		}

		time.Sleep(time.Minute)
	}
}