package main

import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"io"
	"os"
	"os/exec"
	"sort"
	"strconv"
	"strings"

	"path/filepath"
)

type Repository struct {
	path   string
	gitBin string
	gitDir string
	bare   bool
	opts   Options
}

type HistoryRecord struct {
	oid        string
	objectSize uint64
	objectName string
}

type BlobList []HistoryRecord

var Blob_size_list = make(map[string]string)

func NewRepository(path string) (*Repository, error) {
	// Find the `git` executable to be used:
	gitBin, err := findGitBin()
	if err != nil {
		return nil, fmt.Errorf(LocalPrinter().Sprintf(
			"couldn't find Git execute program: %s", err))
	}
	gitdir, err := GitDir(gitBin, path)
	if err != nil {
		return nil, err
	}

	if shallow, err := isShallow(gitBin, path); shallow {
		return nil, err
	}

	var bare bool
	if b, err := isBare(gitBin, path); b && err == nil {
		bare = true
		PrintLocalWithYellowln("bare repo warning")
	}

	version, err := gitVersion(gitBin, path)
	if err != nil {
		return nil, err
	}
	// Git version should >= 2.24.0
	if gitVersionConvert(version) < 2240 {
		return nil, fmt.Errorf(LocalPrinter().Sprintf(
			"sorry, this tool requires Git version at least 2.24.0"))
	}

	return &Repository{
		path:   path,   // working dir
		gitDir: gitdir, // .git dir
		gitBin: gitBin,
		bare:   bare,
	}, nil
}

func (repo Repository) GetBlobName(oid string) (string, error) {
	cmd := exec.Command(repo.gitBin, "-C", repo.path, "rev-list", "--objects", "--all")
	out, err := cmd.StdoutPipe()
	if err != nil {
		return "", err
	}
	cmd.Stderr = os.Stderr

	err = cmd.Start()
	if err != nil {
		return "", err
	}
	blobname := ""
	buf := bufio.NewReader(out)
	for {
		line, err := buf.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				break
			}
			return "", err
		}
		// drop LF
		line = line[:len(line)-1]

		if len(line) <= 41 {
			continue
		}
		if line[0:40] == oid {
			blobname = line[41:]
			break
		}
	}
	return blobname, nil
}

func parseBatchHeader(header string) (objectid, objecttype, objectsize string, err error) {
	// drop LF
	header = header[:len(header)-1]

	infos := strings.Split(header, " ")
	if infos[len(infos)-1] == "missing" {
		return "", "", "", errors.New("got missing object")
	}
	return infos[0], infos[1], infos[2], nil
}

func (repo Repository) GetBlobSize() error {

	cmd := exec.Command(repo.gitBin, "-C", repo.path, "cat-file", "--batch-all-objects",
		"--batch-check=%(objectname) %(objecttype) %(objectsize)")
	out, err := cmd.StdoutPipe()
	if err != nil {
		return err
	}

	cmd.Stderr = os.Stderr
	err = cmd.Start()
	if err != nil {
		return err
	}

	buf := bufio.NewReader(out)
	for {
		line, err := buf.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				break
			}
			return err
		}
		objectid, objecttype, objectsize, err := parseBatchHeader(line)
		if err != nil {
			return err
		}
		if objecttype == "blob" {
			Blob_size_list[objectid] = objectsize
		}
	}
	return nil
}

func (repo Repository) ScanRepository() (BlobList, error) {

	var empty BlobList
	var blobs BlobList

	if repo.opts.verbose {
		PrintLocalWithGreenln("start scanning")
	}

	for objectid, objectsize := range Blob_size_list {
		// set bitsize to 64, means max single blob size is 4 GiB
		size, _ := strconv.ParseUint(objectsize, 10, 64)
		if repo.opts.lfs && !repo.opts.interact {
			path, err := repo.GetBlobName(objectid)
			if err != nil {
				if err != io.EOF {
					return empty, fmt.Errorf(LocalPrinter().Sprintf(
						"run GetBlobName error: %s", err))
				}
			}
			if path == "" {
				continue
			}

			limit, err := UnitConvert(repo.opts.limit)
			if err != nil {
				return empty, fmt.Errorf(LocalPrinter().Sprintf(
					"convert uint error: %s", err))
			}
			if size < limit {
				continue
			}
			if len(repo.opts.types) != 0 && repo.opts.types != "*" {
				extent := filepath.Ext(path)
				if extent != "."+repo.opts.types {
					// matched none, skip
					continue
				}
			}
			// append this record blob into slice
			blobs = append(blobs, HistoryRecord{objectid, size, path})
			// sort according by size
			sort.Slice(blobs, func(i, j int) bool {
				return blobs[i].objectSize > blobs[j].objectSize
			})
		} else {
			limit, err := UnitConvert(repo.opts.limit)
			if err != nil {
				return empty, fmt.Errorf(LocalPrinter().Sprintf(
					"convert uint error: %s", err))
			}

			if size > limit {
				path, err := repo.GetBlobName(objectid)
				if err != nil {
					if err != io.EOF {
						return empty, fmt.Errorf(LocalPrinter().Sprintf(
							"run GetBlobName error: %s", err))
					}
				}
				if path == "" {
					continue
				}
				if len(repo.opts.types) != 0 && repo.opts.types != "*" {
					extent := filepath.Ext(path)
					if extent != "."+repo.opts.types {
						// matched none, skip
						continue
					}
				}
				// append this record blob into slice
				blobs = append(blobs, HistoryRecord{objectid, size, path})
				// sort according by size
				sort.Slice(blobs, func(i, j int) bool {
					return blobs[i].objectSize > blobs[j].objectSize
				})
				// remain first [op.number] blobs
				if len(blobs) > int(repo.opts.number) {
					blobs = blobs[:repo.opts.number]
					// break
				}
			}
		}
	}
	return blobs, nil
}

// check if the current repository is bare repo
func isBare(gitbin, path string) (bool, error) {

	cmd := exec.Command(gitbin, "-C", path, "rev-parse", "--is-bare-repository")
	out, err := cmd.Output()
	if err != nil {
		return false, fmt.Errorf(LocalPrinter().Sprintf(
			"could not run 'git rev-parse --is-bare-repository': %s", err),
		)
	}

	return string(bytes.TrimSpace(out)) == "true", nil
}

// check if the current repository is shallow repo, need Git version 2.15.0 or newer
func isShallow(gitbin, path string) (bool, error) {
	cmd := exec.Command(gitbin, "-C", path, "rev-parse", "--is-shallow-repository")
	out, err := cmd.Output()
	if err != nil {
		return false, fmt.Errorf(LocalPrinter().Sprintf(
			"could not run 'git rev-parse --is-shallow-repository': %s", err),
		)
	}
	if string(bytes.TrimSpace(out)) == "true" {
		return true, fmt.Errorf(LocalPrinter().Sprintf("could not run in a shallow repo"))
	}
	return false, nil
}

// check if the current repository is flesh clone.
func isFresh(gitbin, path string) (bool, error) {
	cmd := exec.Command(gitbin, "-C", path, "reflog", "show")
	out, err := cmd.Output()
	if err != nil {
		return false, fmt.Errorf(LocalPrinter().Sprintf(
			"could not run 'git reflog show': %s", err),
		)
	}
	return strings.Count(string(out), "\n") < 2, nil
}

// check if Git-LFS has installed in host machine
func hasLFSEnv(gitbin, path string) (bool, error) {
	cmd := exec.Command(gitbin, "lfs", "version")
	out, err := cmd.Output()
	if err != nil {
		return false, fmt.Errorf(LocalPrinter().Sprintf("could not run 'git lfs version': %s", err))
	}

	return strings.Contains(string(out), "git-lfs"), nil
}

// get git version string
func gitVersion(gitbin, path string) (string, error) {
	cmd := exec.Command(gitbin, "version")
	out, err := cmd.Output()
	if err != nil {
		return "", fmt.Errorf(LocalPrinter().Sprintf("could not run 'git version': %s", err))
	}
	matches := Match("[0-9]+.[0-9]+.[0-9]+.?[0-9]?", string(out))
	if len(matches) == 0 {
		return "", fmt.Errorf(LocalPrinter().Sprintf("match git version wrong"))
	}
	return matches[0], nil
}

// convert version string to int number for compare. e.g. convert 2.33.0 to 2330
func gitVersionConvert(version string) int {
	var vstr string
	dict := strings.Split(version, ".")
	if len(dict) == 3 {
		vstr = dict[0] + dict[1] + dict[2]
	}
	if len(dict) == 4 {
		vstr = dict[0] + dict[1] + dict[2] + dict[3]
	}
	vstr = strings.TrimSpace(vstr)
	ret, err := strconv.Atoi(vstr)
	if err != nil {
		return 0
	}
	return ret
}

// get current branch
func (repo Repository) GetCurrentBranch() (string, error) {
	cmd := exec.Command(repo.gitBin, "-C", repo.path, "symbolic-ref", "HEAD", "--short")
	out, err := cmd.Output()
	if err != nil {
		return "", fmt.Errorf(LocalPrinter().Sprintf("could not run 'git symbolic-ref HEAD --short': %s", err))
	}
	return strings.TrimSuffix(string(out), "\n"), nil
}

// get current status
func GetCurrentStatus(gitbin, path string) error {
	cmd := exec.Command(gitbin, "-C", path, "status", "-s")
	out, err := cmd.Output()
	if err != nil {
		return fmt.Errorf("could not run 'git status'")
	}
	st := string(out)
	if st == "" {
		return nil
	}
	list := strings.Split(st, "\n")
	for _, ele := range list {
		if strings.HasPrefix(ele, "M ") || strings.HasPrefix(ele, " M") || strings.HasPrefix(ele, "A ") {
			return fmt.Errorf("there's some changes to be committed, please commit them first.")
		}
	}
	return nil
}

// get git objects data size
func (repo Repository) GetDatabaseSize() string {
	var path string
	if repo.bare {
		path = filepath.Join(repo.path, ".")
	} else {
		path = filepath.Join(repo.path, ".git/objects")
	}
	cmd := exec.Command("du", "-hs", path)
	out, err := cmd.Output()
	if err != nil {
		PrintLocalWithRedln("could not run 'du -hs'")
	}
	return strings.TrimSuffix(string(out), "\n")
}

// get lfs objects data size
func (repo Repository) GetLFSObjSize() string {
	path := filepath.Join(repo.path, ".git/lfs")
	if _, err := os.Stat(path); err == nil {
		cmd := exec.Command("du", "-hs", path)
		out, err := cmd.Output()
		if err != nil {
			PrintLocalWithRedln("could not run 'du -hs .git/lfs/'")
		}
		return strings.TrimSuffix(string(out), "\n")
	}
	return ""
}

// get repo GC url if the repo is hosted on Gitee.com
func (repo Repository) GetGiteeGCWeb() string {
	cmd := exec.Command(repo.gitBin, "-C", repo.path, "config", "--get", "remote.origin.url")
	out, err := cmd.Output()
	if err != nil {
		return ""
	}
	url := string(out)
	if url == "" {
		return ""
	}
	if strings.Contains(url, "gitee.com") {
		if strings.HasPrefix(url, "git@") {
			url = strings.TrimPrefix(url, "git@")
			url = "https://" + strings.Replace(url, ":", "/", 1)
		}
		url = strings.TrimSuffix(url, ".git\n") + "/settings#git-gc"
	} else {
		return ""
	}
	return url
}

func getRepoPath(gitbin, path string) string {
	cmd := exec.Command(gitbin, "-C", path, "worktree", "list")
	out, err := cmd.Output()
	if err != nil {
		return ""
	}
	repopath := strings.Split(string(out), " ")[0]
	return repopath
}

func (repo Repository) BackUp() {
	repo_path := getRepoPath(repo.gitBin, repo.path)
	dst := repo_path + ".bak"
	// check if the same directory exist
	_, err := os.Stat(dst)
	if err == nil {
		ok := AskForOverride()
		if !ok {
			PrintLocalWithYellowln("backup canceled")
			return
		} else {
			os.RemoveAll(dst)
		}
	}
	PrintLocalWithGreenln("start backup")
	cmd := exec.Command(repo.gitBin, "-C", repo.path, "clone", "--no-local", repo.path, dst)
	_, err = cmd.Output()
	if err != nil {
		PrintLocalWithRedln("clone error")
		return
	}
	abs_path, err := filepath.Abs(dst)
	if err != nil {
		PrintLocalWithRedln("run filepach.Abs error")
	}
	ft := LocalPrinter().Sprintf("backup done! Backup file path is: %s", abs_path)
	PrintGreenln(ft)
}

func (repo Repository) PushRepo() error {
	cmd := exec.Command(repo.gitBin, "-C", repo.path, "push", "origin", "--all", "--force", "--porcelain")
	out1, err := cmd.Output()
	if err != nil {
		PrintLocalWithRedln("Push failed")
		return err
	}
	PrintYellowln(strings.TrimSuffix(string(out1), "\n"))

	cmd2 := exec.Command(repo.gitBin, "-C", repo.path, "push", "origin", "--tags", "--force")
	out2, err := cmd2.Output()
	if err != nil {
		PrintLocalWithRedln("Push failed")
		return err
	}
	PrintYellowln(strings.TrimSuffix(string(out2), "\n"))
	PrintLocalWithYellowln("Done")
	return nil
}

// BrachesChanged prints all branches that have been changed
func BrachesChanged() bool {
	branches := Branch_changed.ToSlice()
	if len(branches) != 0 {
		PrintLocalWithYellowln("branches have been changed")
		for _, branch := range branches {
			s := strings.TrimSpace(branch.(string))
			if strings.HasPrefix(s, "refs/heads/") {
				PrintYellowln(strings.TrimPrefix(s, "refs/heads/"))
			}

			if strings.HasPrefix(s, "refs/tags/") {
				PrintYellowln(strings.TrimPrefix(s, "refs/tags/"))
			}

			if strings.HasPrefix(s, "refs/remotes/") {
				PrintYellowln(strings.TrimPrefix(s, "refs/remotes/"))
			}
		}
		fmt.Println()
		return true
	}
	return false
}

func (repo Repository) CleanUp() {
	if BrachesChanged() || repo.opts.lfs {
		// clean up
		PrintLocalWithGreenln("file cleanup is complete. Start cleaning the repository")
	} else {
		// exit
		PrintLocalWithYellowln("nothing have changed, exit...")
		os.Exit(1)
	}

	if !repo.bare {
		fmt.Println("running git reset --hard")
		cmd1 := exec.Command(repo.gitBin, "-C", repo.path, "reset", "--hard")
		cmd1.Stdout = os.Stdout
		err := cmd1.Start()
		if err != nil {
			PrintRedln(fmt.Sprint(err))
		}
		err = cmd1.Wait()
		if err != nil {
			PrintRedln(fmt.Sprint(err))
		}
	}

	fmt.Println("running git reflog expire --expire=now --all")
	cmd2 := exec.Command(repo.gitBin, "-C", repo.path, "reflog", "expire", "--expire=now", "--all")
	cmd2.Stderr = os.Stderr
	cmd2.Stdout = os.Stdout
	err := cmd2.Start()
	if err != nil {
		PrintRedln(fmt.Sprint(err))
	}
	err = cmd2.Wait()
	if err != nil {
		PrintRedln(fmt.Sprint(err))
	}

	fmt.Println("running git gc --prune=now")
	cmd3 := exec.Command(repo.gitBin, "-C", repo.path, "gc", "--prune=now")
	cmd3.Stderr = os.Stderr
	cmd3.Stdout = os.Stdout
	err = cmd3.Start()
	if err != nil {
		PrintRedln(fmt.Sprint(err))
	}
	cmd3.Wait()
	if err != nil {
		PrintRedln(fmt.Sprint(err))
	}
}

func LFSPrompt() {
	FilesChanged()
	PrintLocalWithPlainln("before you push to remote, you have to do something below:")
	PrintLocalWithYellowln("1. install git-lfs")
	PrintLocalWithYellowln("2. run command: git lfs install")
	PrintLocalWithYellowln("3. edit .gitattributes file")
	PrintLocalWithYellowln("4. commit your .gitattributes file.")
}

func (repo Repository) Prompt() {
	PrintLocalWithGreenln("cleaning completed")
	PrintLocalWithPlain("current repository size")
	PrintLocalWithYellowln(repo.GetDatabaseSize())
	if lfs := repo.GetLFSObjSize(); len(lfs) > 0 {
		PrintLocalWithPlain("including LFS objects size")
		PrintLocalWithYellowln(lfs)
	}
	if repo.opts.lfs {
		LFSPrompt()
	}
	var pushed bool
	if !repo.opts.lfs {
		if AskForUpdate() {
			PrintLocalWithPlainln("execute force push")
			PrintLocalWithYellowln("git push origin --all --force")
			PrintLocalWithYellowln("git push origin --tags --force")
			err := repo.PushRepo()
			if err == nil {
				pushed = true
			}
		}
	}
	PrintLocalWithPlainln("suggest operations header")
	if pushed {
		PrintLocalWithGreenln("1. (Done!)")
		fmt.Println()
	} else {
		PrintLocalWithRedln("1. (Undo)")
		PrintLocalWithRedln("    git push origin --all --force")
		PrintLocalWithRedln("    git push origin --tags --force")
		fmt.Println()
	}
	PrintLocalWithRedln("2. (Undo)")
	url := repo.GetGiteeGCWeb()
	if url != "" {
		PrintLocalWithRed("gitee GC page link")
		PrintYellowln(url)
	}
	fmt.Println()
	PrintLocalWithRedln("3. (Undo)")
	PrintLocalWithRed("for detailed documentation, see")
	PrintYellowln("https://gitee.com/oschina/git-repo-clean/blob/main/docs/repo-update.md")
	fmt.Println()
	PrintLocalWithPlainln("suggest operations done")
	PrintLocalWithPlainln("introduce GIT LFS")
	PrintLocalWithPlain("for the use of Gitee LFS, see")
	PrintYellowln("https://gitee.com/help/articles/4235")
}