package main

import (
	"errors"
	"fmt"
	"math/rand"
	"path"
	"runtime/debug"
	"strings"
	"time"

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

//go:generate mockgen -source=repo_check.go -destination=mock/repo_check.go -typed

type StateChecker interface {
	VerifyProjectState(configs *common.AutogitConfig) error
	CheckRepos() error
	ConsistencyCheckProcess() error
}

type DefaultStateChecker struct {
	exitCheckLoop bool
	checkOnStart  bool
	checkInterval time.Duration

	gitea     common.Gitea
	processor *RequestProcessor
	i         StateChecker
}

func CreateDefaultStateChecker(checkOnStart bool, processor *RequestProcessor, gitea common.Gitea, interval time.Duration) *DefaultStateChecker {
	var s = &DefaultStateChecker{
		gitea:         gitea,
		checkInterval: interval,
		checkOnStart:  checkOnStart,
		processor:     processor,
	}
	s.i = s
	return s
}

func (s *DefaultStateChecker) ProcessPR(git common.Git, pr *models.PullRequest, config *common.AutogitConfig) error {
	var event common.PullRequestWebhookEvent

	event.Pull_Request = common.PullRequestFromModel(pr)
	event.Action = string(pr.State)
	event.Number = pr.Index
	event.Repository = common.RepositoryFromModel(pr.Base.Repo)
	event.Sender = *common.UserFromModel(pr.User)
	event.Requested_reviewer = nil

	var err error
	switch pr.State {
	case "open":
		err = s.processor.Opened.Process(&event, git, config)
	case "closed":
		err = s.processor.Closed.Process(&event, git, config)
	default:
		return fmt.Errorf("Unhandled pull request state: '%s'. %s/%s/%d", pr.State, config.Organization, "", pr.Index)
	}

	common.LogError("   * processor error returned:", err)
	return nil
}

func (s *DefaultStateChecker) VerifyProjectState(config *common.AutogitConfig) error {
	defer func() {
		if r := recover(); r != nil {
			common.LogError("panic caught")
			if err, ok := r.(error); !ok {
				common.LogError(err)
			}
			common.LogError(string(debug.Stack()))
		}
	}()

	prjGitOrg, prjGitRepo, prjGitBranch := config.GetPrjGit()
	common.LogInfo("  checking", prjGitOrg+"/"+prjGitRepo+"#"+prjGitBranch)

	git, err := GitHandler.CreateGitHandler(prjGitOrg)
	if err != nil {
		return fmt.Errorf("Cannot create git handler: %w", err)
	}
	defer git.Close()

	repo, err := s.gitea.CreateRepositoryIfNotExist(git, prjGitOrg, prjGitRepo)
	if err != nil {
		return fmt.Errorf("Error fetching or creating '%s/%s#%s' -- aborting verifyProjectState(). Err: %w", prjGitBranch, prjGitRepo, prjGitBranch, err)
	}

	_, err = git.GitClone(config.GitProjectName, prjGitBranch, repo.SSHURL)
	common.PanicOnError(err)
	prs, err := s.gitea.GetRecentPullRequests(prjGitOrg, prjGitRepo, prjGitBranch)
	if err != nil {
		return fmt.Errorf("Error fetching PrjGit Prs for %s/%s#%s: %w", prjGitOrg, prjGitRepo, prjGitBranch, err)
	}

	for _, pr := range prs {
		s.ProcessPR(git, pr, config)
	}

	common.LogDebug("   - # of PRs to check in PrjGit:", len(prs))
	submodules, err := git.GitSubmoduleList(config.GitProjectName, "HEAD")

nextSubmodule:
	for sub, commitID := range submodules {
		common.LogDebug("  + checking", sub, commitID)
		submoduleName := sub
		if n := strings.LastIndex(sub, "/"); n != -1 {
			submoduleName = sub[n+1:]
		}

		// check if open PR have PR against project
		prs, err := s.gitea.GetRecentPullRequests(config.Organization, submoduleName, config.Branch)
		if err != nil {
			return fmt.Errorf("Error fetching pull requests for %s/%s#%s. Err: %w", config.Organization, submoduleName, config.Branch, err)
		}
		common.LogDebug("   - # of PRs to check:", len(prs))

		for _, pr := range prs {
			s.ProcessPR(git, pr, config)
		}

		// check if the commited changes are syned with branches
		commits, err := s.gitea.GetRecentCommits(config.Organization, submoduleName, config.Branch, 10)
		if err != nil {
			return fmt.Errorf("Error fetching recent commits for %s/%s. Err: %w", config.Organization, submoduleName, err)
		}

		for idx, commit := range commits {
			if commit.SHA == commitID {
				if idx != 0 {
					// commit in past ...
					common.LogError("    -", submoduleName, " is behind the branch by", idx, "This should not happen in PR workflow alone")
				}
				continue nextSubmodule
			}
		}

		// not found in past, check if we should advance the branch label ... pull the submodule
		git.GitExecOrPanic(config.GitProjectName, "submodule", "update", "--init", "--filter", "blob:none", "--", sub)
		subDir := path.Join(config.GitProjectName, sub)
		newCommits := common.SplitStringNoEmpty(git.GitExecWithOutputOrPanic(subDir, "rev-list", "^origin/"+config.Branch, commitID), "\n")

		if len(newCommits) >= 1 {
			common.LogDebug("    - updating branch", config.Branch, "to new head", commitID, " - len:", len(newCommits))
			git.GitExecOrPanic(subDir, "checkout", "-B", config.Branch, commitID)
			url := git.GitExecWithOutputOrPanic(subDir, "remote", "get-url", "origin", "--push")
			sshUrl, err := common.TranslateHttpsToSshUrl(strings.TrimSpace(url))
			if err != nil {
				return fmt.Errorf("Cannot traslate HTTPS git URL to SSH_URL. %w", err)
			}
			git.GitExecOrPanic(subDir, "remote", "set-url", "origin", "--push", sshUrl)
			git.GitExecOrPanic(subDir, "push", "origin", config.Branch)
		}
	}

	// forward any package-gits referred by the project git, but don't go back
	return nil
}

func (s *DefaultStateChecker) CheckRepos() error {
	errorList := make([]error, 0, 10)

	for org, configs := range s.processor.configuredRepos {
		for _, config := range configs {
			if s.checkInterval > 0 {
				sleepInterval := (s.checkInterval - s.checkInterval/2) + time.Duration(rand.Int63n(int64(s.checkInterval)))
				common.LogInfo(" - sleep interval", sleepInterval, "until next check")
				time.Sleep(sleepInterval)
			}

			common.LogInfo(" ++ starting verification, org:", org, "config:", config.GitProjectName)
			if err := s.i.VerifyProjectState(config); err != nil {
				common.LogError(" *** verification failed, org:", org, err)
				errorList = append(errorList, err)
			}
			common.LogInfo(" ++ verification complete, org:", org, "config:", config.GitProjectName)
		}
	}

	return errors.Join(errorList...)
}

func (s *DefaultStateChecker) ConsistencyCheckProcess() error {
	if s.checkOnStart {
		savedCheckInterval := s.checkInterval
		s.checkInterval = 0
		common.LogInfo("== Startup consistency check begin...")
		s.i.CheckRepos()
		common.LogInfo("== Startup consistency check done...")
		s.checkInterval = savedCheckInterval
	}

	for {
		if s.exitCheckLoop {
			break
		}
		s.i.CheckRepos()
	}

	return nil
}