package main

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

import (
	"fmt"
	"path"

	"github.com/opentracing/opentracing-go/log"
	"src.opensuse.org/autogits/common"
	"src.opensuse.org/autogits/common/gitea-generated/models"
)

func prGitBranchNameForPR(req *common.PullRequestWebhookEvent) string {
	return fmt.Sprintf("PR_%s#%d", req.Pull_Request.Base.Repo.Name, req.Pull_Request.Number)
}

func verifyRepositoryConfiguration(repo *models.Repository) error {
	if repo.AutodetectManualMerge && repo.AllowManualMerge {
		return nil
	}

	// modify repo to allow above
	common.LogDebug("Adjusting repo to accept manual merges:", repo.Owner.UserName+"/"+repo.Name)
	_, err := Gitea.SetRepoOptions(repo.Owner.UserName, repo.Name, true)
	if err != nil {
		common.LogError("Failed to set repo to manual merges:", err)
	}
	return err
}

func updateSubmoduleInPR(req *common.PullRequestWebhookEvent, git common.Git) {
	common.LogDebug(req, git)
	submoduleName := req.Pull_Request.Base.Repo.Name
	commitID := req.Pull_Request.Head.Sha
	common.PanicOnError(git.GitExec(common.DefaultGitPrj, "submodule", "update", "--init", "--checkout", "--depth", "1", submoduleName))
	common.PanicOnError(git.GitExec(path.Join(common.DefaultGitPrj, submoduleName), "fetch", "--depth", "1", "origin", commitID))
	common.PanicOnError(git.GitExec(path.Join(common.DefaultGitPrj, submoduleName), "checkout", commitID))
}

type PRProcessor struct {
	config *common.AutogitConfig
	git    common.Git
}

func AllocatePRProcessor(req *common.PullRequestWebhookEvent, configs common.AutogitConfigs) (*PRProcessor, error) {
	org := req.Pull_Request.Base.Repo.Owner.Username
	repo := req.Pull_Request.Base.Repo.Name
	id := req.Pull_Request.Number

	branch := req.Pull_Request.Base.Ref
	assumed_git_project_name := org + "/" + repo + "#" + branch

	PRstr := fmt.Sprintf("%s/%s#%d", org, repo, id)
	common.LogInfo("*** Starting processing PR:", PRstr)

	c := configs.GetPrjGitConfig(org, repo, branch)
	if c == nil {
		if req.Pull_Request.Base.Repo.Default_Branch == branch {
			c = configs.GetPrjGitConfig(org, repo, "")
		}
	}
	if c == nil {
		common.LogError("Cannot find config for PR.")
		return nil, fmt.Errorf("Cannot find config for PR")
	}

	var config *common.AutogitConfig
	for _, c := range configs {
		if c.GitProjectName == assumed_git_project_name {
			config = c
			break
		}

		if c.Organization == org {
			// default branch *or* match branch
			if (c.Branch == "" && branch == req.Pull_Request.Base.Repo.Default_Branch) ||
				(c.Branch != "" && c.Branch == branch) {
				config = c
				break
			}
		}
	}
	common.LogDebug("found config", config)
	if config == nil {
		common.LogError("Cannot find config for branch '%s'", req.Pull_Request.Base.Ref)
		return nil, fmt.Errorf("Cannot find config for branch '%s'", req.Pull_Request.Base.Ref)
	}

	git, err := GitHandler.CreateGitHandler(branch)
	if err != nil {
		common.LogError("Cannot allocate GitHandler:", err)
		return nil, fmt.Errorf("Error allocating GitHandler. Err: %w", err)
	}
	common.LogDebug("git path:", git.GetPath())

	return &PRProcessor{
		config: config,
		git:    git,
	}, nil
}

func (pr *PRProcessor) CreateOrUpdatePrjGitPR(req *common.PullRequestWebhookEvent) error {
	config := pr.config
	git := pr.git

	branchName := prGitBranchNameForPR(req)

	org, prj, _ := config.GetPrjGit()
	prOrg := req.Pull_Request.Base.Repo.Owner.Username
	prRepo := req.Pull_Request.Base.Repo.Name

	if org == prOrg && prj == prRepo {
		common.LogDebug("PrjGit PR. No need to update it...")
		return nil
	}

	prjGit, err := Gitea.CreateRepositoryIfNotExist(git, org, prj)
	common.PanicOnErrorWithMsg(err, "Error creating a prjgitrepo:", err)

	common.PanicOnError(verifyRepositoryConfiguration(prjGit))

	remoteName, err := git.GitClone(common.DefaultGitPrj, config.Branch, prjGit.SSHURL)
	common.PanicOnError(err)

	// check if branch already there, and check that out if available
	if err := git.GitExec(common.DefaultGitPrj, "fetch", remoteName, branchName); err == nil {
		git.GitExecOrPanic(common.DefaultGitPrj, "checkout", "-B", branchName, remoteName+"/"+branchName)
	}

	commitMsg := fmt.Sprintf(`auto-created for %s

This commit was autocreated by %s
referencing

`+common.PrPattern,
		prRepo,
		GitAuthor,
		prOrg,
		prRepo,
		req.Pull_Request.Number,
	)

	subList, err := git.GitSubmoduleList(common.DefaultGitPrj, "HEAD")
	common.PanicOnError(err)

	if id := subList[prRepo]; id != req.Pull_Request.Head.Sha {
		updateSubmoduleInPR(req, git)
		status, err := git.GitStatus(common.DefaultGitPrj)
		common.LogDebug("status:", status)
		common.LogDebug("submodule", prRepo, " hash:", id, " -> ", req.Pull_Request.Head.Sha)
		common.PanicOnError(err)
		common.PanicOnError(git.GitExec(common.DefaultGitPrj, "commit", "-a", "-m", commitMsg))
		common.PanicOnError(git.GitExec(common.DefaultGitPrj, "push", remoteName, "+HEAD:"+branchName))
	}

	_, err = Gitea.CreatePullRequestIfNotExist(prjGit, branchName, prjGit.DefaultBranch,
		fmt.Sprintf("Forwarded PR: %s", prRepo),
		fmt.Sprintf(`This is a forwarded pull request by %s
referencing the following pull request:

`+common.PrPattern,
			GitAuthor, prOrg, prRepo, req.Pull_Request.Number),
	)

	return err
}

func (pr *PRProcessor) Process(req *common.PullRequestWebhookEvent) error {
	config := pr.config
	git := pr.git

	// requests against project are not handled here
	common.LogInfo("processing opened PR:", req.Pull_Request.Url)
	prOrg := req.Pull_Request.Base.Repo.Owner.Username
	prRepo := req.Pull_Request.Base.Repo.Name

	common.LogError(req)

	prjGitOrg, prjGitRepo, prjGitBranch := config.GetPrjGit()
	if prOrg != prjGitOrg || prRepo != prjGitRepo {
		if err := pr.CreateOrUpdatePrjGitPR(req); err != nil {
			return err
		}
	}

	prset, err := common.FetchPRSet(CurrentUser.UserName, Gitea, prOrg, prRepo, req.Number, config)
	if err != nil {
		common.LogError("Cannot fetch PRSet:", err)
		return err
	}
	common.LogInfo("fetched PRSet of size:", len(prset.PRs))

	// make sure that prjgit is consistent and only submodules that are to be *updated*
	// reset anything that changed that is not part of the prset
	// package removals/additions are *not* counted here
	if pr, err := prset.GetPrjGitPR(); err == nil {
		remote, err := git.GitClone(common.DefaultGitPrj, prjGitBranch, pr.Base.Repo.CloneURL)
		common.PanicOnError(err)
		git.GitExecOrPanic(common.DefaultGitPrj, "fetch", remote, pr.Base.Ref, pr.Head.Ref)

		common.LogDebug("Fetch done")
		orig_subs, err := git.GitSubmoduleList(common.DefaultGitPrj, pr.Base.Sha)
		common.PanicOnError(err)
		new_subs, err := git.GitSubmoduleList(common.DefaultGitPrj, pr.Head.Sha)
		common.PanicOnError(err)
		common.LogDebug("Submodule parse done")

		reset_submodule := func(submodule, sha string) {
			spath := path.Join(common.DefaultGitPrj, submodule)
			git.GitExecOrPanic(common.DefaultGitPrj, "submodule", "update", "--init", "--depth", "1", submodule)
			git.GitExecOrPanic(spath, "fetch", "origin", sha)
			git.GitExecOrPanic(spath, "checkout", sha)
		}

		for path, commit := range new_subs {
			if old, ok := orig_subs[path]; ok && old != commit {
				found := false
				for _, pr := range prset.PRs {
					if pr.PR.Base.Repo.Name == path && commit == pr.PR.Head.Sha {
						found = true
						break
					}
				}
				if !found {
					reset_submodule(path, old)
				}
			}
		}

		stats, err := git.GitStatus(common.DefaultGitPrj)
		common.PanicOnError(err)
		if len(stats) > 0 {
			git.GitExecOrPanic(common.DefaultGitPrj, "commit", "-a", "-m", "Sync submodule updates with PR-set")
			git.GitExecOrPanic(common.DefaultGitPrj, "submodule", "deinit", "--all", "--force")
			git.GitExecOrPanic(common.DefaultGitPrj, "push")
		}
	}

	// request build review
	PR, err := prset.GetPrjGitPR()
	if err != nil {
		common.LogError("Error fetching PrjGitPR:", err)
		return nil
	}
	common.LogDebug("  num of reviewers:", len(PR.RequestedReviewers))
	org, repo, branch := config.GetPrjGit()
	maintainers, err := common.FetchProjectMaintainershipData(Gitea, org, repo, branch)
	if err != nil {
		return err
	}

	err = prset.AssignReviewers(Gitea, maintainers)

	for _, pr := range prset.PRs {
		if err := verifyRepositoryConfiguration(pr.PR.Base.Repo); err != nil {
			common.LogError("Cannot set manual merge... aborting processing")
			return err
		}
	}

	common.LogInfo("Consistent PRSet:", prset.IsConsistent())
	common.LogInfo("Reviewed?", prset.IsApproved(Gitea, maintainers))
	if prset.IsConsistent() && prset.IsApproved(Gitea, maintainers) {
		common.LogInfo("Merging...")
		if err = prset.Merge(Gitea, git); err != nil {
			common.LogError("merge error:", err)
		}
	}

	return err
}

type PullRequestProcessor interface {
	Process(req *common.PullRequestWebhookEvent, git common.Git, config *common.AutogitConfig) error
}

type RequestProcessor struct {
	configuredRepos map[string][]*common.AutogitConfig
}

func ProcesPullRequest(req *common.PullRequestWebhookEvent, configs []*common.AutogitConfig) error {
	if len(configs) < 1 {
		// ignoring pull request against unconfigured project (could be just regular sources?)
		return nil
	}

	if req.Pull_Request.State != "open" {
		common.LogError("Can only deal with open PRs. This one is", req.Pull_Request.State)
		return nil
	}

	pr, err := AllocatePRProcessor(req, configs)
	if err != nil {
		log.Error(err)
		return err
	}
	defer pr.git.Close()

	switch req.Action {
	case "opened", "reopened", "synchronized", "edited", "closed", "reviewed":
		return pr.Process(req)
	}

	common.LogError("Unhandled pull request action:", req.Action)
	return nil
}

func (w *RequestProcessor) ProcessFunc(request *common.Request) error {
	req, ok := request.Data.(*common.PullRequestWebhookEvent)
	if !ok {
		common.LogError("*** Invalid data format for PR processing.")
		return fmt.Errorf("*** Invalid data format for PR processing.")
	}

	org := req.Repository.Owner.Username
	configs := w.configuredRepos[org]
	return ProcesPullRequest(req, configs)

}