// Copyright 2019 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 repository

import (
	"fmt"
	"io/ioutil"
	"os"
	"path"
	"path/filepath"
	"strings"
	"time"

	"code.gitea.io/gitea/models"
	"code.gitea.io/gitea/modules/git"
	"code.gitea.io/gitea/modules/log"
)

func generateExpansion(src string, templateRepo, generateRepo *models.Repository) string {
	return os.Expand(src, func(key string) string {
		switch key {
		case "REPO_NAME":
			return generateRepo.Name
		case "TEMPLATE_NAME":
			return templateRepo.Name
		case "REPO_DESCRIPTION":
			return generateRepo.Description
		case "TEMPLATE_DESCRIPTION":
			return templateRepo.Description
		case "REPO_OWNER":
			return generateRepo.OwnerName
		case "TEMPLATE_OWNER":
			return templateRepo.OwnerName
		case "REPO_LINK":
			return generateRepo.Link()
		case "TEMPLATE_LINK":
			return templateRepo.Link()
		case "REPO_HTTPS_URL":
			return generateRepo.CloneLink().HTTPS
		case "TEMPLATE_HTTPS_URL":
			return templateRepo.CloneLink().HTTPS
		case "REPO_SSH_URL":
			return generateRepo.CloneLink().SSH
		case "TEMPLATE_SSH_URL":
			return templateRepo.CloneLink().SSH
		default:
			return key
		}
	})
}

func checkGiteaTemplate(tmpDir string) (*models.GiteaTemplate, error) {
	gtPath := filepath.Join(tmpDir, ".gitea", "template")
	if _, err := os.Stat(gtPath); os.IsNotExist(err) {
		return nil, nil
	} else if err != nil {
		return nil, err
	}

	content, err := ioutil.ReadFile(gtPath)
	if err != nil {
		return nil, err
	}

	gt := &models.GiteaTemplate{
		Path:    gtPath,
		Content: content,
	}

	return gt, nil
}

func generateRepoCommit(repo, templateRepo, generateRepo *models.Repository, tmpDir string) error {
	commitTimeStr := time.Now().Format(time.RFC3339)
	authorSig := repo.Owner.NewGitSig()

	// Because this may call hooks we should pass in the environment
	env := append(os.Environ(),
		"GIT_AUTHOR_NAME="+authorSig.Name,
		"GIT_AUTHOR_EMAIL="+authorSig.Email,
		"GIT_AUTHOR_DATE="+commitTimeStr,
		"GIT_COMMITTER_NAME="+authorSig.Name,
		"GIT_COMMITTER_EMAIL="+authorSig.Email,
		"GIT_COMMITTER_DATE="+commitTimeStr,
	)

	// Clone to temporary path and do the init commit.
	templateRepoPath := templateRepo.RepoPath()
	if err := git.Clone(templateRepoPath, tmpDir, git.CloneRepoOptions{
		Depth: 1,
	}); err != nil {
		return fmt.Errorf("git clone: %v", err)
	}

	if err := os.RemoveAll(path.Join(tmpDir, ".git")); err != nil {
		return fmt.Errorf("remove git dir: %v", err)
	}

	// Variable expansion
	gt, err := checkGiteaTemplate(tmpDir)
	if err != nil {
		return fmt.Errorf("checkGiteaTemplate: %v", err)
	}

	if err := os.Remove(gt.Path); err != nil {
		return fmt.Errorf("remove .giteatemplate: %v", err)
	}

	// Avoid walking tree if there are no globs
	if len(gt.Globs()) > 0 {
		tmpDirSlash := strings.TrimSuffix(filepath.ToSlash(tmpDir), "/") + "/"
		if err := filepath.Walk(tmpDirSlash, func(path string, info os.FileInfo, walkErr error) error {
			if walkErr != nil {
				return walkErr
			}

			if info.IsDir() {
				return nil
			}

			base := strings.TrimPrefix(filepath.ToSlash(path), tmpDirSlash)
			for _, g := range gt.Globs() {
				if g.Match(base) {
					content, err := ioutil.ReadFile(path)
					if err != nil {
						return err
					}

					if err := ioutil.WriteFile(path,
						[]byte(generateExpansion(string(content), templateRepo, generateRepo)),
						0644); err != nil {
						return err
					}
					break
				}
			}
			return nil
		}); err != nil {
			return err
		}
	}

	if err := git.InitRepository(tmpDir, false); err != nil {
		return err
	}

	repoPath := repo.RepoPath()
	if stdout, err := git.NewCommand("remote", "add", "origin", repoPath).
		SetDescription(fmt.Sprintf("generateRepoCommit (git remote add): %s to %s", templateRepoPath, tmpDir)).
		RunInDirWithEnv(tmpDir, env); err != nil {
		log.Error("Unable to add %v as remote origin to temporary repo to %s: stdout %s\nError: %v", repo, tmpDir, stdout, err)
		return fmt.Errorf("git remote add: %v", err)
	}

	return initRepoCommit(tmpDir, repo, repo.Owner)
}

func generateGitContent(ctx models.DBContext, repo, templateRepo, generateRepo *models.Repository) (err error) {
	tmpDir, err := ioutil.TempDir(os.TempDir(), "gitea-"+repo.Name)
	if err != nil {
		return fmt.Errorf("Failed to create temp dir for repository %s: %v", repo.RepoPath(), err)
	}

	defer func() {
		if err := os.RemoveAll(tmpDir); err != nil {
			log.Error("RemoveAll: %v", err)
		}
	}()

	if err = generateRepoCommit(repo, templateRepo, generateRepo, tmpDir); err != nil {
		return fmt.Errorf("generateRepoCommit: %v", err)
	}

	// re-fetch repo
	if repo, err = models.GetRepositoryByIDCtx(ctx, repo.ID); err != nil {
		return fmt.Errorf("getRepositoryByID: %v", err)
	}

	repo.DefaultBranch = "master"
	if err = models.UpdateRepositoryCtx(ctx, repo, false); err != nil {
		return fmt.Errorf("updateRepository: %v", err)
	}

	return nil
}

// GenerateGitContent generates git content from a template repository
func GenerateGitContent(ctx models.DBContext, templateRepo, generateRepo *models.Repository) error {
	if err := generateGitContent(ctx, generateRepo, templateRepo, generateRepo); err != nil {
		return err
	}

	if err := generateRepo.UpdateSize(ctx); err != nil {
		return fmt.Errorf("failed to update size for repository: %v", err)
	}

	if err := models.CopyLFS(ctx, generateRepo, templateRepo); err != nil {
		return fmt.Errorf("failed to copy LFS: %v", err)
	}
	return nil
}

// GenerateRepository generates a repository from a template
func GenerateRepository(ctx models.DBContext, doer, owner *models.User, templateRepo *models.Repository, opts models.GenerateRepoOptions) (_ *models.Repository, err error) {
	generateRepo := &models.Repository{
		OwnerID:       owner.ID,
		Owner:         owner,
		OwnerName:     owner.Name,
		Name:          opts.Name,
		LowerName:     strings.ToLower(opts.Name),
		Description:   opts.Description,
		IsPrivate:     opts.Private,
		IsEmpty:       !opts.GitContent || templateRepo.IsEmpty,
		IsFsckEnabled: templateRepo.IsFsckEnabled,
		TemplateID:    templateRepo.ID,
	}

	if err = models.CreateRepository(ctx, doer, owner, generateRepo); err != nil {
		return nil, err
	}

	repoPath := models.RepoPath(owner.Name, generateRepo.Name)
	if err = checkInitRepository(repoPath); err != nil {
		return generateRepo, err
	}

	return generateRepo, nil
}