package main

import (
	"flag"
	"fmt"
	"log"
	"net/url"
	"regexp"
	"runtime/debug"
	"slices"
	"strconv"
	"strings"
	"time"
	"unicode"

	"src.opensuse.org/autogits/common"
	"src.opensuse.org/autogits/common/gitea-generated/models"
)

var configs common.AutogitConfigs
var acceptRx *regexp.Regexp
var rejectRx *regexp.Regexp
var groupName string

func InitRegex(newGroupName string) {
	groupName = newGroupName
	acceptRx = regexp.MustCompile("^:\\s*(LGTM|approved?)")
	rejectRx = regexp.MustCompile("^:\\s*")
}

func ParseReviewLine(reviewText string) (bool, string) {
	line := strings.TrimSpace(reviewText)
	groupTextName := "@" + groupName
	glen := len(groupTextName)
	if len(line) < glen || line[0:glen] != groupTextName {
		return false, line
	}

	l := line[glen:]
	for idx, r := range l {
		if unicode.IsSpace(r) {
			continue
		} else if r == ':' {
			return true, l[idx:]
		} else {
			return false, line
		}
	}

	return false, line
}

func ReviewAccepted(reviewText string) bool {
	for _, line := range common.SplitStringNoEmpty(reviewText, "\n") {
		if matched, reviewLine := ParseReviewLine(line); matched {
			return acceptRx.MatchString(reviewLine)
		}
	}
	return false
}

func ReviewRejected(reviewText string) bool {
	for _, line := range common.SplitStringNoEmpty(reviewText, "\n") {
		if matched, reviewLine := ParseReviewLine(line); matched {
			if rejectRx.MatchString(reviewLine) {
				return !acceptRx.MatchString(reviewLine)
			}
		}
	}
	return false
}

/* comment types - from gitea models/issues/comment.go
var commentStrings = []string{
    "comment",
    "reopen",
    "close",
    "issue_ref",
    "commit_ref",
    "comment_ref",
    "pull_ref",
    "label",
    "milestone",
    "assignees",
    "change_title",
    "delete_branch",
    "start_tracking",
    "stop_tracking",
    "add_time_manual",
    "cancel_tracking",
    "added_deadline",
    "modified_deadline",
    "removed_deadline",
    "add_dependency",
    "remove_dependency",
    "code",
    "review",
    "lock",
    "unlock",
    "change_target_branch",
    "delete_time_manual",
    "review_request",
    "merge_pull",
    "pull_push",
    "project",
    "project_board", // FIXME: the name should be project_column
    "dismiss_review",
    "change_issue_ref",
    "pull_scheduled_merge",
    "pull_cancel_scheduled_merge",
    "pin",
    "unpin",
    "change_time_estimate",
}*/

func FindAcceptableReviewInTimeline(user string, timeline []*models.TimelineComment, reviews []*models.PullReview) *models.TimelineComment {
	for _, t := range timeline {
		if t.Type == common.TimelineCommentType_Comment && t.User.UserName == user && t.Created == t.Updated {
			if ReviewAccepted(t.Body) || ReviewRejected(t.Body) {
				return t
			}
		}
	}

	return nil
}

func FindOurLastReviewInTimeline(timeline []*models.TimelineComment) *models.TimelineComment {
	for _, t := range timeline {
		if t.Type == common.TimelineCommentType_Review && t.User.UserName == groupName && t.Created == t.Updated {
			return t
		}
	}

	return nil
}

func UnrequestReviews(gitea common.Gitea, org, repo string, id int64, users []string) {
	if err := gitea.UnrequestReview(org, repo, id, users...); err != nil {
		common.LogError("Can't remove reviewrs after a review:", err)
	}
}

func ProcessNotifications(notification *models.NotificationThread, gitea common.Gitea) {
	defer func() {
		if r := recover(); r != nil {
			common.LogInfo("panic cought --- recovered")
			common.LogError(string(debug.Stack()))
		}
	}()

	rx := regexp.MustCompile(`^/?api/v\d+/repos/(?<org>[_a-zA-Z0-9-]+)/(?<project>[_a-zA-Z0-9-]+)/(?:issues|pulls)/(?<num>[0-9]+)$`)
	subject := notification.Subject
	u, err := url.Parse(notification.Subject.URL)
	if err != nil {
		common.LogError("Invalid format of notification:", subject.URL, err)
		return
	}

	match := rx.FindStringSubmatch(u.Path)
	if match == nil {
		common.LogError("** Unexpected format of notification:", subject.URL)
		return
	}

	org := match[1]
	repo := match[2]
	id, _ := strconv.ParseInt(match[3], 10, 64)

	common.LogInfo("processing:", fmt.Sprintf("%s/%s!%d", org, repo, id))
	pr, err := gitea.GetPullRequest(org, repo, id)
	if err != nil {
		common.LogError("  ** Cannot fetch PR associated with review:", subject.URL, "Error:", err)
		return
	}

	if err := ProcessPR(pr); err == nil && !common.IsDryRun {
		if err := gitea.SetNotificationRead(notification.ID); err != nil {
			common.LogDebug("  Cannot set notification as read", err)
		}
	} else if err != nil && err != ReviewNotFinished {
		common.LogError(err)
	}
}

var ReviewNotFinished = fmt.Errorf("Review is not finished")

func ProcessPR(pr *models.PullRequest) error {
	org := pr.Base.Repo.Owner.UserName
	repo := pr.Base.Repo.Name
	id := pr.Index

	found := false
	for _, reviewer := range pr.RequestedReviewers {
		if reviewer != nil && reviewer.UserName == groupName {
			found = true
			break
		}
	}
	if !found {
		common.LogInfo("   review is not requested for", groupName)
		return nil
	}

	config := configs.GetPrjGitConfig(org, repo, pr.Base.Name)
	if config == nil {
		return fmt.Errorf("Cannot find config for: %s", pr.URL)
	}
	if pr.State == "closed" {
		// dismiss the review
		common.LogInfo("  -- closed request, so nothing to review")
		return nil
	}

	reviews, err := gitea.GetPullRequestReviews(org, repo, id)
	if err != nil {
		return fmt.Errorf("Failed to fetch reviews for: %v: %w", pr.URL, err)
	}

	timeline, err := common.FetchTimelineSinceReviewRequestOrPush(gitea, groupName, pr.Head.Sha, org, repo, id)
	if err != nil {
		return fmt.Errorf("Failed to fetch timeline to review. %w", err)
	}

	groupConfig, err := config.GetReviewGroup(groupName)
	if err != nil {
		return fmt.Errorf("Failed to fetch review group. %w", err)
	}

	// submitter cannot be reviewer
	requestReviewers := groupConfig.Reviewers
	requestReviewers = slices.DeleteFunc(requestReviewers, func(u string) bool { return u == pr.User.UserName })
	//	pr.Head.Sha

	for _, reviewer := range requestReviewers {
		if review := FindAcceptableReviewInTimeline(reviewer, timeline, reviews); review != nil {
			if ReviewAccepted(review.Body) {
				if !common.IsDryRun {
					text := reviewer + " approved a review on behalf of " + groupName
					if review := FindOurLastReviewInTimeline(timeline); review == nil || review.Body != text {
						_, err := gitea.AddReviewComment(pr, common.ReviewStateApproved, text)
						if err != nil {
							common.LogError("    -> failed to write approval comment", err)
						}
						UnrequestReviews(gitea, org, repo, id, requestReviewers)
					}
				}
				common.LogInfo("  -> approved by", reviewer)
				common.LogInfo("     review at", review.Created)
				return nil
			} else if ReviewRejected(review.Body) {
				if !common.IsDryRun {
					text := reviewer + " requested changes on behalf of " + groupName + ". See " + review.HTMLURL
					if review := FindOurLastReviewInTimeline(timeline); review == nil || review.Body != text {
						_, err := gitea.AddReviewComment(pr, common.ReviewStateRequestChanges, "Changes requested. See review by: "+reviewer)
						if err != nil {
							common.LogError("    -> failed to write rejecting comment", err)
						}
						UnrequestReviews(gitea, org, repo, id, requestReviewers)
					}
				}
				common.LogInfo("  -> declined by", reviewer)
				return nil
			}
		}
	}

	// request group member reviews, if missing
	common.LogDebug("  Review incomplete...")
	if !groupConfig.Silent && len(requestReviewers) > 0 {
		common.LogDebug("  Requesting reviews for:", requestReviewers)
		if !common.IsDryRun {
			if _, err := gitea.RequestReviews(pr, requestReviewers...); err != nil {
				common.LogDebug("   -> err:", err)
			}
		} else {
			common.LogDebug("   ^^^ not done")
		}
	} else {
		common.LogDebug("  Not requesting additional reviewers")
	}

	// add a helpful comment, if not yet added
	found_help_comment := false
	for _, t := range timeline {
		if t.Type == common.TimelineCommentType_Comment && t.User != nil && t.User.UserName == groupName {
			found_help_comment = true
			break
		}
	}

	if !found_help_comment && !common.IsDryRun {
		helpComment := fmt.Sprintln("Review by", groupName, "represents a group of reviewers:", strings.Join(requestReviewers, ", "), ".\n\n"+
			"Do **not** use standard review interface to review on behalf of the group.\n"+
			"To accept the review on behalf of the group, create the following comment: `@"+groupName+": approve`.\n"+
			"To request changes on behalf of the group, create the following comment: `@"+groupName+": decline` followed with lines justifying the decision.\n"+
			"Future edits of the comments are ignored, a new comment is required to change the review state.")
		if slices.Contains(groupConfig.Reviewers, pr.User.UserName) {
			helpComment = helpComment + "\n\n" +
				"Submitter is member of this review group, hence they are excluded from being one of the reviewers here"
		}
		gitea.AddComment(pr, helpComment)
	}

	return ReviewNotFinished
}

func PeriodReviewCheck() {
	notifications, err := gitea.GetNotifications(common.GiteaNotificationType_Pull, nil)
	if err != nil {
		common.LogError("   Error fetching unread notifications: %w", err)
		return
	}

	for _, notification := range notifications {
		ProcessNotifications(notification, gitea)
	}
}

var gitea common.Gitea

func main() {
	giteaUrl := flag.String("gitea-url", "https://src.opensuse.org", "Gitea instance used for reviews")
	rabbitMqHost := flag.String("rabbit-url", "amqps://rabbit.opensuse.org", "RabbitMQ instance where Gitea webhook notifications are sent")
	interval := flag.Int64("interval", 10, "Notification polling interval in minutes (min 1 min)")
	configFile := flag.String("config", "", "PrjGit listing config file")
	logging := flag.String("logging", "info", "Logging level: [none, error, info, debug]")
	flag.BoolVar(&common.IsDryRun, "dry", false, "Dry run, no effect. For debugging")
	flag.Parse()

	args := flag.Args()
	if len(args) != 1 {
		log.Println("  syntax:")
		log.Println("      group-review [OPTIONS] <review-group-name>")
		log.Println()
		flag.Usage()
		return
	}
	groupName = args[0]

	if *configFile == "" {
		common.LogError("Missing config file")
		return
	}

	configData, err := common.ReadConfigFile(*configFile)
	if err != nil {
		common.LogError("Failed to read config file", err)
		return
	}

	if err := common.RequireGiteaSecretToken(); err != nil {
		common.LogError(err)
		return
	}

	if err := common.RequireRabbitSecrets(); err != nil {
		common.LogError(err)
		return
	}

	gitea = common.AllocateGiteaTransport(*giteaUrl)
	configs, err = common.ResolveWorkflowConfigs(gitea, configData)
	if err != nil {
		common.LogError("Cannot parse workflow configs:", err)
		return
	}

	reviewer, err := gitea.GetCurrentUser()
	if err != nil {
		common.LogError("Cannot fetch review user:", err)
		return
	}

	if err := common.SetLoggingLevelFromString(*logging); err != nil {
		common.LogError(err.Error())
		return
	}

	if *interval < 1 {
		*interval = 1
	}

	InitRegex(groupName)

	common.LogInfo(" ** processing group reviews for group:", groupName)
	common.LogInfo(" ** username in Gitea:", reviewer.UserName)
	common.LogInfo(" ** polling interval:", *interval, "min")
	common.LogInfo(" ** connecting to RabbitMQ:", *rabbitMqHost)

	if groupName != reviewer.UserName {
		common.LogError(" ***** Reviewer does not match group name. Aborting. *****")
		return
	}

	u, err := url.Parse(*rabbitMqHost)
	if err != nil {
		common.LogError("Cannot parse RabbitMQ host:", err)
		return
	}

	config_update := ConfigUpdatePush{
		config_modified: make(chan *common.AutogitConfig),
	}

	process_issue_pr := IssueCommentProcessor{}

	configUpdates := &common.RabbitMQGiteaEventsProcessor{
		Orgs: []string{},
		Handlers: map[string]common.RequestProcessor{
			common.RequestType_Push:         &config_update,
			common.RequestType_IssueComment: &process_issue_pr,
		},
	}
	configUpdates.Connection().RabbitURL = u
	for _, c := range configs {
		if org, _, _ := c.GetPrjGit(); !slices.Contains(configUpdates.Orgs, org) {
			configUpdates.Orgs = append(configUpdates.Orgs, org)
		}
	}
	go common.ProcessRabbitMQEvents(configUpdates)

	for {
	config_update_loop:
		for {
			select {
			case configTouched, ok := <-config_update.config_modified:
				if ok {
					for idx, c := range configs {
						if c == configTouched {
							org, repo, branch := c.GetPrjGit()
							prj := fmt.Sprintf("%s/%s#%s", org, repo, branch)
							common.LogInfo("Detected config update for", prj)

							new_config, err := common.ReadWorkflowConfig(gitea, prj)
							if err != nil {
								common.LogError("Failed parsing Project config for", prj, err)
							} else {
								configs[idx] = new_config
							}
						}
					}
				}
			default:
				break config_update_loop
			}
		}

		PeriodReviewCheck()
		time.Sleep(time.Duration(*interval * int64(time.Minute)))
	}
}