// Copyright 2020 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package task

import (
	"fmt"

	"code.gitea.io/tea/modules/config"
	local_git "code.gitea.io/tea/modules/git"
	"code.gitea.io/tea/modules/workaround"

	"code.gitea.io/sdk/gitea"
	git_config "github.com/go-git/go-git/v5/config"
	git_plumbing "github.com/go-git/go-git/v5/plumbing"
)

// PullClean deletes local & remote feature-branches for a closed pull
func PullClean(login *config.Login, repoOwner, repoName string, index int64, ignoreSHA bool, callback func(string) (string, error)) error {
	client := login.Client()

	repo, _, err := client.GetRepo(repoOwner, repoName)
	if err != nil {
		return err
	}
	defaultBranch := repo.DefaultBranch
	if len(defaultBranch) == 0 {
		defaultBranch = "master"
	}

	// fetch PR source-repo & -branch from gitea
	pr, _, err := client.GetPullRequest(repoOwner, repoName, index)
	if err != nil {
		return err
	}
	if err := workaround.FixPullHeadSha(client, pr); err != nil {
		return err
	}

	if pr.State == gitea.StateOpen {
		return fmt.Errorf("PR is still open, won't delete branches")
	}

	// if remote head branch is already deleted, pr.Head.Ref points to "pulls/<idx>/head"
	remoteBranch := pr.Head.Ref
	remoteDeleted := remoteBranch == fmt.Sprintf("refs/pull/%d/head", pr.Index)
	if remoteDeleted {
		remoteBranch = pr.Head.Name // this still holds the original branch name
		fmt.Printf("Remote branch '%s' already deleted.\n", remoteBranch)
	}

	r, err := local_git.RepoForWorkdir()
	if err != nil {
		return err
	}

	// find a branch with matching sha or name, that has a remote matching the repo url
	var branch *git_config.Branch
	if ignoreSHA {
		branch, err = r.TeaFindBranchByName(remoteBranch, pr.Head.Repository.CloneURL)
	} else {
		branch, err = r.TeaFindBranchBySha(pr.Head.Sha, pr.Head.Repository.CloneURL)
	}
	if err != nil {
		return err
	}
	if branch == nil {
		if ignoreSHA {
			return fmt.Errorf("Remote branch %s not found in local repo", remoteBranch)
		}
		return fmt.Errorf(`Remote branch %s not found in local repo.
Either you don't track this PR, or the local branch has diverged from the remote.
If you still want to continue & are sure you don't loose any important commits,
call me again with the --ignore-sha flag`, remoteBranch)
	}

	// prepare deletion of local branch:
	headRef, err := r.Head()
	if err != nil {
		return err
	}
	if headRef.Name().Short() == branch.Name {
		fmt.Printf("Checking out '%s' to delete local branch '%s'\n", defaultBranch, branch.Name)
		ref := git_plumbing.NewBranchReferenceName(defaultBranch)
		if err = r.TeaCheckout(ref); err != nil {
			return err
		}
	}

	// remove local & remote branch
	fmt.Printf("Deleting local branch %s\n", branch.Name)
	err = r.TeaDeleteLocalBranch(branch)
	if err != nil {
		return err
	}

	if !remoteDeleted && pr.Head.Repository.Permissions.Push {
		fmt.Printf("Deleting remote branch %s\n", remoteBranch)
		url, err := r.TeaRemoteURL(branch.Remote)
		if err != nil {
			return err
		}
		auth, err := local_git.GetAuthForURL(url, login.Token, login.SSHKey, callback)
		if err != nil {
			return err
		}
		err = r.TeaDeleteRemoteBranch(branch.Remote, remoteBranch, auth)
	}
	return err
}
