// Copyright 2016 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.

package main

import (
	"flag"
	"fmt"
	"log"
	"os"

	"github.com/google/slothfs/cookie"
	"github.com/google/slothfs/gitiles"
	"github.com/google/slothfs/manifest"

	git "github.com/libgit2/git2go"
)

func main() {
	gitilesURL := flag.String("gitiles", "", "URL for gitiles")
	branch := flag.String("branch", "master", "branch to use for manifest")
	repo := flag.String("repo", "platform/manifest", "manifest repository")
	cookieJarPath := flag.String("cookies", "", "path to cURL-style cookie jar file.")
	agent := flag.String("agent", "slothfs-expand", "gitiles User-Agent string to use.")
	flag.Parse()

	if *gitilesURL == "" {
		log.Fatal("must set --gitiles")
	}

	opts := gitiles.Options{
		UserAgent: *agent,
	}
	if *cookieJarPath != "" {
		var err error
		opts.CookieJar, err = cookie.NewJar(*cookieJarPath)
		if err != nil {
			log.Fatal(err)
		}
	}

	// SustainedQPS is a little high, but since this is a one-shot
	// program let's try to get away with it.
	service, err := gitiles.NewService(*gitilesURL, opts)
	if err != nil {
		log.Fatalf("NewService: %v", err)
	}

	mf, err := fetchManifest(service, *repo, *branch)
	if err != nil {
		log.Fatalf("fetchManifest: %v", err)
	}

	mf.Filter()

	if err := derefManifest(service, *repo, mf); err != nil {
		log.Fatalf("derefManifest: %v", err)
	}

	xml, err := mf.MarshalXML()
	if err != nil {
		log.Fatalf("MarshalXML: %v", err)
	}

	os.Stdout.Write(xml)
}

func fetchManifest(service *gitiles.Service, repo, branch string) (*manifest.Manifest, error) {
	project := service.NewRepoService(repo)

	// When checking this out, it's called "manifest.xml". Go figure.
	c, err := project.GetBlob(branch, "default.xml")
	if err != nil {
		return nil, err
	}
	mf, err := manifest.Parse(c)
	if err != nil {
		return nil, err
	}

	return mf, nil
}

func derefManifest(service *gitiles.Service, manifestRepo string, mf *manifest.Manifest) error {
	branchSet := map[string]struct{}{}

	var todoProjects []int
	for i, p := range mf.Project {
		rev := mf.ProjectRevision(&p)
		if _, err := git.NewOid(rev); err == nil {
			continue
		}

		branchSet[rev] = struct{}{}
		todoProjects = append(todoProjects, i)
	}

	var branches []string
	for k := range branchSet {
		branches = append(branches, k)
	}

	repos, err := service.List(branches)
	if err != nil {
		return err
	}
	for _, i := range todoProjects {
		p := &mf.Project[i]

		proj, ok := repos[p.Name]
		if !ok {
			return fmt.Errorf("server list doesn't mention repo %s", p.Name)
		}

		p.CloneURL = proj.CloneURL

		branch := mf.ProjectRevision(p)
		commit, ok := proj.Branches[branch]
		if !ok {
			return fmt.Errorf("branch %q for repo %s not returned.", branch, p.Name)
		}

		p.Revision = commit
	}
	return nil
}