package repo_manager

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"os/user"
	"path"
	"regexp"
	"sort"
	"strings"

	"go.skia.org/infra/autoroll/go/codereview"
	"go.skia.org/infra/autoroll/go/revision"
	"go.skia.org/infra/autoroll/go/strategy"
	"go.skia.org/infra/go/android_skia_checkout"
	"go.skia.org/infra/go/common"
	"go.skia.org/infra/go/exec"
	"go.skia.org/infra/go/gerrit"
	"go.skia.org/infra/go/sklog"
	"go.skia.org/infra/go/util"
)

const (
	UPSTREAM_REMOTE_NAME    = "remote"
	REPO_BRANCH_NAME        = "merge"
	TMPL_COMMIT_MSG_ANDROID = `Roll {{.ChildPath}} {{.RollingFrom.String}}..{{.RollingTo.String}} ({{len .Revisions}} commits)

{{.ChildRepo}}/+log/{{.RollingFrom.String}}..{{.RollingTo.String}}

{{if .IncludeLog}}
{{range .Revisions}}{{.Timestamp.Format "2006-01-02"}} {{.Author}} {{.Description}}
{{end}}{{end}}

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
{{.ServerURL}}
Please CC {{stringsJoin .Reviewers ","}} on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

Test: Presubmit checks will test this change.
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.

{{range .Bugs}}Bug: {{.}}
{{end}}{{range .Tests}}{{.}}
{{end}}
`
)

var (
	// Use this function to instantiate a NewAndroidRepoManager. This is able to be
	// overridden for testing.
	NewAndroidRepoManager func(context.Context, *AndroidRepoManagerConfig, string, gerrit.GerritInterface, string, string, *http.Client, codereview.CodeReview, bool) (RepoManager, error) = newAndroidRepoManager

	// Files which exist in Skia but do not exist in Android.
	DELETE_MERGE_CONFLICT_FILES = []string{android_skia_checkout.SkUserConfigRelPath}
	// Files which exist in Android but do not exist in Skia.
	IGNORE_MERGE_CONFLICT_FILES = []string{android_skia_checkout.SkUserConfigAndroidRelPath, android_skia_checkout.SkUserConfigLinuxRelPath, android_skia_checkout.SkUserConfigMacRelPath, android_skia_checkout.SkUserConfigWinRelPath}
	FILES_GENERATED_BY_GN_TO_GP = []string{android_skia_checkout.SkUserConfigAndroidRelPath, android_skia_checkout.SkUserConfigLinuxRelPath, android_skia_checkout.SkUserConfigMacRelPath, android_skia_checkout.SkUserConfigWinRelPath, android_skia_checkout.AndroidBpRelPath}

	AUTHOR_EMAIL_RE = regexp.MustCompile(".* \\((.*)\\)")
)

// AndroidRepoManagerConfig provides configuration for the Android RepoManager.
type AndroidRepoManagerConfig struct {
	CommonRepoManagerConfig
}

// See documentation for RepoManagerConfig interface.
func (r *AndroidRepoManagerConfig) ValidStrategies() []string {
	return []string{
		strategy.ROLL_STRATEGY_BATCH,
		strategy.ROLL_STRATEGY_N_BATCH,
	}
}

// androidRepoManager is a struct used by Android AutoRoller for managing checkouts.
type androidRepoManager struct {
	*commonRepoManager
	repoUrl      string
	repoToolPath string
}

func newAndroidRepoManager(ctx context.Context, c *AndroidRepoManagerConfig, workdir string, g gerrit.GerritInterface, serverURL, serviceAccount string, client *http.Client, cr codereview.CodeReview, local bool) (RepoManager, error) {
	if err := c.Validate(); err != nil {
		return nil, err
	}
	user, err := user.Current()
	if err != nil {
		return nil, err
	}
	repoToolDir := path.Join(user.HomeDir, "bin")
	repoToolPath := path.Join(repoToolDir, "repo")
	if _, err := os.Stat(repoToolDir); err != nil {
		if err := os.MkdirAll(repoToolDir, 0755); err != nil {
			return nil, err
		}
	}
	if _, err := os.Stat(repoToolPath); err != nil {
		// Download the repo tool.
		if _, err := exec.RunCwd(ctx, repoToolDir, "wget", "https://storage.googleapis.com/git-repo-downloads/repo", "-O", repoToolPath); err != nil {
			return nil, err
		}
		// Make the repo tool executable.
		if _, err := exec.RunCwd(ctx, repoToolDir, "chmod", "a+x", repoToolPath); err != nil {
			return nil, err
		}
	}

	wd := path.Join(workdir, "android_repo")

	if c.CommitMsgTmpl == "" {
		c.CommitMsgTmpl = TMPL_COMMIT_MSG_ANDROID
	}
	crm, err := newCommonRepoManager(ctx, c.CommonRepoManagerConfig, wd, serverURL, g, client, cr, local)
	if err != nil {
		return nil, err
	}
	r := &androidRepoManager{
		commonRepoManager: crm,
		repoUrl:           g.GetRepoUrl(),
		repoToolPath:      repoToolPath,
	}
	return r, nil
}

// Helper function for updating the Android checkout.
func (r *androidRepoManager) updateAndroidCheckout(ctx context.Context) error {
	// Create the working directory if needed.
	if _, err := os.Stat(r.workdir); err != nil {
		if err := os.MkdirAll(r.workdir, 0755); err != nil {
			return err
		}
	}

	// Run repo init and sync commands.
	if _, err := exec.RunCwd(ctx, r.workdir, r.repoToolPath, "init", "-u", fmt.Sprintf("%s/a/platform/manifest", r.repoUrl), "-g", "all,-notdefault,-darwin", "-b", r.parentBranch); err != nil {
		return err
	}
	// Sync only the child path and the repohooks directory (needed to upload changes).
	if _, err := exec.RunCwd(ctx, r.workdir, r.repoToolPath, "sync", "--force-sync", r.childPath, "tools/repohooks", "-j32"); err != nil {
		return err
	}

	// Set color.ui=true so that the repo tool does not prompt during upload.
	if _, err := r.childRepo.Git(ctx, "config", "color.ui", "true"); err != nil {
		return err
	}

	// Fix the review config to a URL which will work outside prod.
	if _, err := r.childRepo.Git(ctx, "config", "remote.goog.review", fmt.Sprintf("%s/", r.repoUrl)); err != nil {
		return err
	}

	// Check to see whether there is an upstream yet.
	remoteOutput, err := r.childRepo.Git(ctx, "remote", "show")
	if err != nil {
		return err
	}
	if !strings.Contains(remoteOutput, UPSTREAM_REMOTE_NAME) {
		if _, err := r.childRepo.Git(ctx, "remote", "add", UPSTREAM_REMOTE_NAME, common.REPO_SKIA); err != nil {
			return err
		}
	}

	// Update the remote to make sure that all new branches are available.
	if _, err := r.childRepo.Git(ctx, "remote", "update", UPSTREAM_REMOTE_NAME, "--prune"); err != nil {
		return err
	}
	return nil
}

// See documentation for RepoManager interface.
func (r *androidRepoManager) Update(ctx context.Context) (*revision.Revision, *revision.Revision, []*revision.Revision, error) {
	// Sync the projects.
	r.repoMtx.Lock()
	defer r.repoMtx.Unlock()
	if err := r.updateAndroidCheckout(ctx); err != nil {
		return nil, nil, nil, err
	}

	// Get the last roll revision.
	lastRollRev, err := r.getLastRollRev(ctx)
	if err != nil {
		return nil, nil, nil, err
	}

	// Get the tip-of-tree revision.
	tipRev, err := r.getTipRev(ctx)
	if err != nil {
		return nil, nil, nil, err
	}

	// Find the not-rolled child repo commits.
	notRolledRevs, err := r.getCommitsNotRolled(ctx, lastRollRev, tipRev)
	if err != nil {
		return nil, nil, nil, err
	}

	return lastRollRev, tipRev, notRolledRevs, nil
}

// getLastRollRev returns the last-completed DEPS roll Revision.
func (r *androidRepoManager) getLastRollRev(ctx context.Context) (*revision.Revision, error) {
	output, err := r.childRepo.Git(ctx, "merge-base", fmt.Sprintf("refs/remotes/remote/%s", r.childBranch), fmt.Sprintf("refs/remotes/goog/%s", r.parentBranch))
	if err != nil {
		return nil, err
	}
	details, err := r.childRepo.Details(ctx, strings.TrimRight(output, "\n"))
	if err != nil {
		return nil, err
	}
	return revision.FromLongCommit(r.childRevLinkTmpl, details), nil
}

// abortMerge aborts the current merge in the child repo.
func (r *androidRepoManager) abortMerge(ctx context.Context) error {
	_, err := r.childRepo.Git(ctx, "merge", "--abort")
	return err
}

// abandonRepoBranch abandons the repo branch.
func (r *androidRepoManager) abandonRepoBranch(ctx context.Context) error {
	_, err := exec.RunCwd(ctx, r.childRepo.Dir(), r.repoToolPath, "abandon", REPO_BRANCH_NAME)
	return err
}

// getChangeNumForHash returns the corresponding change number for the provided commit hash by querying Gerrit's search API.
func (r *androidRepoManager) getChangeForHash(hash string) (*gerrit.ChangeInfo, error) {
	issues, err := r.g.Search(context.TODO(), 1, false, gerrit.SearchCommit(hash))
	if err != nil {
		return nil, err
	}
	return r.g.GetIssueProperties(context.TODO(), issues[0].Issue)
}

// setTopic sets a topic using the name of the child repo and the change number.
// Example: skia_merge_1234
func (r *androidRepoManager) setTopic(changeNum int64) error {
	topic := fmt.Sprintf("%s_merge_%d", path.Base(r.childDir), changeNum)
	return r.g.SetTopic(context.TODO(), topic, changeNum)
}

// See documentation for RepoManager interface.
func (r *androidRepoManager) CreateNewRoll(ctx context.Context, from, to *revision.Revision, rolling []*revision.Revision, emails []string, cqExtraTrybots string, dryRun bool) (int64, error) {
	r.repoMtx.Lock()
	defer r.repoMtx.Unlock()

	// Update the upstream remote.
	if _, err := r.childRepo.Git(ctx, "fetch", UPSTREAM_REMOTE_NAME); err != nil {
		return 0, err
	}

	// Create the roll CL.

	// Start the merge.

	if _, err := r.childRepo.Git(ctx, "merge", to.Id, "--no-commit"); err != nil {
		// Check to see if this was a merge conflict with IGNORE_MERGE_CONFLICT_FILES.
		conflictsOutput, conflictsErr := r.childRepo.Git(ctx, "diff", "--name-only", "--diff-filter=U")
		if conflictsErr != nil || conflictsOutput == "" {
			util.LogErr(conflictsErr)
			return 0, fmt.Errorf("Failed to roll to %s. Needs human investigation: %s", to, err)
		}
		for _, conflict := range strings.Split(conflictsOutput, "\n") {
			if conflict == "" {
				continue
			}
			ignoreConflict := false
			for _, ignore := range IGNORE_MERGE_CONFLICT_FILES {
				if conflict == ignore {
					ignoreConflict = true
					sklog.Infof("Ignoring conflict in %s", conflict)
					break
				}
			}
			for _, del := range DELETE_MERGE_CONFLICT_FILES {
				if conflict == del {
					_, resetErr := r.childRepo.Git(ctx, "reset", "--", del)
					util.LogErr(resetErr)
					_, delErr := exec.RunCwd(ctx, r.childDir, "rm", del)
					util.LogErr(delErr)
					ignoreConflict = true
					sklog.Infof("Deleting %s due to merge conflict", conflict)
					break
				}
			}
			if !ignoreConflict {
				util.LogErr(r.abortMerge(ctx))
				return 0, fmt.Errorf("Failed to roll to %s. Conflicts in %s: %s", to, conflictsOutput, err)
			}
		}
	}

	if err := android_skia_checkout.RunGnToBp(ctx, r.childDir); err != nil {
		util.LogErr(r.abortMerge(ctx))
		return 0, fmt.Errorf("Error when running gn_to_bp: %s", err)
	}
	for _, genFile := range FILES_GENERATED_BY_GN_TO_GP {
		if r.parentBranch != "master" {
			if genFile != android_skia_checkout.AndroidBpRelPath {
				// Temporary hack to avoid having to cherrypick the very large
				// change https://skia-review.googlesource.com/c/skia/+/209706
				// TODO(rmistry): Remove.
				tokens := strings.Split(path.Dir(genFile), "/")
				newPath := path.Join(tokens[1:]...)
				genFile = path.Join(newPath, tokens[0], "SkUserConfig.h")
			}
		}
		if _, err := r.childRepo.Git(ctx, "add", genFile); err != nil {
			return 0, err
		}
	}

	if _, addGifErr := r.childRepo.Git(ctx, "add", android_skia_checkout.LibGifRelPath); addGifErr != nil {
		return 0, addGifErr
	}

	// Run the pre-upload steps.
	for _, s := range r.preUploadSteps {
		if err := s(ctx, nil, r.httpClient, r.workdir); err != nil {
			return 0, fmt.Errorf("Failed pre-upload step: %s", err)
		}
	}

	// Create a new repo branch.
	if _, repoBranchErr := exec.RunCwd(ctx, r.childDir, r.repoToolPath, "start", REPO_BRANCH_NAME, "."); repoBranchErr != nil {
		util.LogErr(r.abortMerge(ctx))
		return 0, fmt.Errorf("Failed to create repo branch: %s", repoBranchErr)
	}

	// If the parent branch is not master then:
	// Add all authors of merged changes to the email list. We do not do this
	// for the master branch because developers would get spammed due to multiple
	// rolls a day. Release branch rolls run rarely and developers should be
	// aware that their changes are being rolled there.
	if r.parentBranch != "master" {
		emails = make([]string, 0, len(emails)+len(rolling))
		for _, c := range rolling {
			// Extract out the email if it is a Googler.
			if strings.HasSuffix(c.Author, "@google.com") {
				emails = append(emails, c.Author)
			}
		}
		sort.Strings(emails)
	}

	// Create commit message.
	commitMsg, err := r.buildCommitMsg(&CommitMsgVars{
		ChildPath:   r.childPath,
		ChildRepo:   common.REPO_SKIA, // TODO(borenet): Don't hard-code.
		Reviewers:   emails,
		Revisions:   rolling,
		RollingFrom: from,
		RollingTo:   to,
		ServerURL:   r.serverURL,
	})
	if err != nil {
		return 0, err
	}

	// Temporary hack to substitute P4 for "Pixel4". See skbug.com/9595.
	commitMsg = strings.Replace(commitMsg, "Pixel4", "P4", -1)

	// Commit the change with the above message.
	if _, commitErr := r.childRepo.Git(ctx, "commit", "-m", commitMsg); commitErr != nil {
		util.LogErr(r.abandonRepoBranch(ctx))
		return 0, fmt.Errorf("Nothing to merge; did someone already merge %s..%s?: %s", from, to, commitErr)
	}

	// Bypass the repo upload prompt by setting autoupload config to true.
	// Strip "-review" from the upload URL else autoupload does not work.
	uploadUrl := strings.Replace(r.repoUrl, "-review", "", 1)
	if _, configErr := r.childRepo.Git(ctx, "config", fmt.Sprintf("review.%s/.autoupload", uploadUrl), "true"); configErr != nil {
		util.LogErr(r.abandonRepoBranch(ctx))
		return 0, fmt.Errorf("Could not set autoupload config: %s", configErr)
	}

	// Upload the CL to Gerrit.
	uploadCommand := &exec.Command{
		Name: r.repoToolPath,
		Args: []string{"upload", fmt.Sprintf("--re=%s", strings.Join(emails, ",")), "--verify"},
		Dir:  r.childDir,
		// The below is to bypass the blocking
		// "ATTENTION: You are uploading an unusually high number of commits."
		// prompt which shows up when a merge contains more than 5 commits.
		Stdin: strings.NewReader("yes"),
	}
	if _, uploadErr := exec.RunCommand(ctx, uploadCommand); uploadErr != nil {
		util.LogErr(r.abandonRepoBranch(ctx))
		return 0, fmt.Errorf("Could not upload to Gerrit: %s", uploadErr)
	}

	// Get latest hash to find Gerrit change number with.
	commitHashOutput, revParseErr := r.childRepo.Git(ctx, "rev-parse", "HEAD")
	if revParseErr != nil {
		util.LogErr(r.abandonRepoBranch(ctx))
		return 0, revParseErr
	}
	commitHash := strings.Split(commitHashOutput, "\n")[0]
	// We no longer need the local branch. Abandon the repo.
	util.LogErr(r.abandonRepoBranch(ctx))

	// Get the change number.
	change, err := r.getChangeForHash(commitHash)
	if err != nil {
		util.LogErr(r.abandonRepoBranch(ctx))
		return 0, err
	}
	// Set the topic of the merge change.
	if err := r.setTopic(change.Issue); err != nil {
		return 0, err
	}

	// Set labels.
	labels := r.g.Config().SetCqLabels
	if dryRun {
		labels = r.g.Config().SetDryRunLabels
	}
	labels = gerrit.MergeLabels(labels, r.g.Config().SelfApproveLabels)
	if err = r.g.SetReview(ctx, change, "Roller setting labels to auto-land change.", labels, emails); err != nil {
		// Only throw exception here if parentBranch is master. This is
		// because other branches will not have permissions setup for the
		// bot to run CR+2.
		if r.parentBranch != "master" {
			sklog.Warningf("Could not set labels on %d: %s", change.Issue, err)
			sklog.Warningf("Not throwing error because %s branch is not master", r.parentBranch)
		} else {
			return 0, err
		}
	}

	// Mark the change as ready for review, if necessary.
	if err := r.unsetWIP(ctx, change, 0); err != nil {
		return 0, err
	}

	return change.Issue, nil
}

func (r *androidRepoManager) getTipRev(ctx context.Context) (*revision.Revision, error) {
	output, err := r.childRepo.Git(ctx, "ls-remote", UPSTREAM_REMOTE_NAME, fmt.Sprintf("refs/heads/%s", r.childBranch), "-1")
	if err != nil {
		return nil, err
	}
	hash := strings.Split(output, "\t")[0]
	details, err := r.childRepo.Details(ctx, hash)
	if err != nil {
		return nil, err
	}
	return revision.FromLongCommit(r.childRevLinkTmpl, details), nil
}