package pkgtools

import (
	"archive/tar"
	"bufio"
	"bytes"
	"compress/bzip2"
	"compress/gzip"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"regexp"
	"strings"

	"github.com/pkg/errors"
	"github.com/xi2/xz"
)

const (
	// InstallLockDir is used to prevent install script collisions.
	InstallLockDir = "/run/lock/pkgtools"

	// PackageInstallPath is the place for special package files.
	PackageInstallPath     = "install"
	PackageInstallScript   = "install/doinst.sh"
	PackageUninstallScript = "install/douinst.sh"
	PackageSlackDescFile   = "install/slack-desc"

	InstalledScriptPath  = "var/lib/pkgtools/scripts"
	InstalledPackagePath = "var/lib/pkgtools/packages"
	// ADMDir is the package database directories (packages, scripts).
	ADMDir = "var/lib/pkgtools"
	// Is the removed packages/scripts log files.
	TmpDir                              = "var/lib/pkgtools/setup/tmp"
	LogDir                              = "var/log/pkgtools"
	InstalledRemovedPackagePath         = "var/log/pkgtools/removed_packages"
	InstalledRemovedScriptsPath         = "var/log/pkgtools/removed_scripts"
	InstalledRemovedUninstallScriptPath = "var/log/pkgtools/removed_uninstall_scripts"
)

type PackageType string

const (
	UnsupportedPackageFormat = "unsupported package format"
	TGZ                      = "tgz"
	TBZ                      = "tbz"
	TLZ                      = "tlz"
	TXZ                      = "txz"
)

var SupportedPackageTypes = []string{
	TGZ,
	TBZ,
	TXZ,
}

func IsSlackwarePkg(fp string) bool {
	ext := filepath.Ext(filepath.Base(fp))
	for _, v := range SupportedPackageTypes {
		if "."+v == ext {
			return true
		}
	}
	return false
}

func FileLockPath(dir string, f string) string {
	return filepath.Join(dir, f) + ".lock"
}

func TargetPackagePath(root string, pkg string) string {
	return filepath.Join(root, InstalledPackagePath, pkg)
}

func TargetRemovedPackagePath(root string, pkg string) string {
	return filepath.Join(root, InstalledRemovedPackagePath, pkg)
}

func TargetRemovedUninstalllScriptPath(root string, pkg string) string {
	return filepath.Join(root, InstalledRemovedUninstallScriptPath, pkg)
}

func TargetTmpDir(root string) string {
	return filepath.Join(root, ADMDir, "setup", "tmp")
}

func TargetPackageInfoPath(root string, pkg string) string {
	return filepath.Join(root, InstalledPackagePath, pkg)
}

func TargetScriptPath(root string, pkg string) string {
	return filepath.Join(root, InstalledScriptPath, pkg)
}

func NewCompressedFileReader(
	r io.Reader,
	format PackageType,
) (io.Reader, error) {
	switch format {
	case TBZ:
		dec := bzip2.NewReader(r)
		return dec, nil
	case TGZ:
		dec, err := gzip.NewReader(r)
		return dec, err
	case TXZ:
		dec, err := xz.NewReader(r, 0)
		return dec, err
	default:
		return nil, errors.New(UnsupportedPackageFormat)
	}
}

func GetFullPackageName(
	root string,
	name string,
) (string, bool, error) {
	pkgs, err := ListPackages(root)
	if err != nil {
		return "", false, err
	}
	for _, pkg := range pkgs {
		v, err := PackageName(pkg)
		if err != nil {
			return "", false, err
		}
		if v == name {
			return pkg, true, nil
		} else if pkg == name {
			return pkg, true, nil
		}
	}
	return "", false, nil
}

func GetPackageSoftLinks(root string, pkg string) ([]string, error) {
	p := filepath.Join(root, InstalledScriptPath, pkg)
	if ok, _ := IsFile(p); !ok {
		return nil, nil
	}
	links, err := ReadPackageSoftLinks(p)
	return links, err
}

func ListPackages(
	root string,
) ([]string, error) {
	entries, err := os.ReadDir(filepath.Join(root, InstalledPackagePath))
	if err != nil {
		return nil, err
	}
	var pkgs []string
	for _, entry := range entries {
		ok, err := IsFile(filepath.Join(root, InstalledPackagePath, entry.Name()))
		if err != nil {
			return nil, err
		}
		if ok {
			pkgs = append(pkgs, entry.Name())
		}
	}

	return pkgs, nil
}

// Original from Slackware's 'removepkg'
// sed -n 's,^[ ]*( [ ]*cd[ ]* \(.*\) [ ]*; [ ]*rm [ ]*-rf[ ]* \(.*\) [ ]*)[ ]*$,\1/\2,p' </var/lib/pkgtools/scripts/acl-2.3.1-x86_64-1
var regExpSoftLinks = regexp.MustCompile("(\\s*cd\\s*(.*)\\s*; rm -rf (.*) )")

func ParsePackageSoftLinks(
	str string,
) ([]string, error) {
	var ret []string
	matches := regExpSoftLinks.FindAllStringSubmatch(str, -1)
	for _, m := range matches {
		if len(m) != 4 {
			continue
		}
		ret = append(ret, filepath.Join(
			strings.TrimSpace(m[2]),
			strings.TrimSpace(m[3]),
		))
	}
	return ret, nil
}

func ReadPackageSoftLinks(
	path string,
) ([]string, error) {
	pkgScript := filepath.Join(path)
	f, err := os.Open(pkgScript)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	buf, err := io.ReadAll(f)
	if err != nil {
		return nil, err
	}

	links, err := ParsePackageSoftLinks(string(buf))
	if err != nil {
		return nil, errors.Wrap(err, "getting package generated links")
	}
	return links, err
}

type SlackwarePkg struct {
	Format PackageType
	file   *os.File

	tarR *tar.Reader
	r    io.Reader

	uncompressedSize int64
	pkgName          string
	pkgInfo          PackageInfo
}

var _ TarReader = (*SlackwarePkg)(nil)

func OpenSlackwarePkg(fp string) (*SlackwarePkg, error) {
	var pkg SlackwarePkg
	var err error

	if v := filepath.Ext(fp); len(v) > 0 {
		pkg.Format = PackageType(filepath.Ext(fp)[1:])
	}

	pkg.file, err = os.Open(fp)
	if err != nil {
		return nil, err
	}
	r, err := NewCompressedFileReader(
		pkg.file,
		pkg.Format,
	)
	if err != nil {
		return nil, err
	}
	pkg.tarR = tar.NewReader(r)
	if err != nil {
		return nil, err
	}
	pkg.r = pkg.tarR

	pkg.pkgName, err = PackageName(fp)
	if err != nil {
		return nil, err
	}

	pkg.pkgInfo.Name = PackageBase(fp)
	pkg.pkgInfo.PackageLocation = fp

	size, err := FileSize(fp)
	if err != nil {
		return nil, err
	}
	pkg.pkgInfo.CompressedPackageSize = HumanReadableSize(size)

	return &pkg, nil
}

func (s *SlackwarePkg) PkgInfo() *PackageInfo {
	ret := s.pkgInfo
	ret.UncompressedPackageSize = HumanReadableSize(s.uncompressedSize)
	return &ret
}

func (s *SlackwarePkg) Close() error {
	return s.file.Close()
}

func (s *SlackwarePkg) Next() (*tar.Header, error) {
	h, err := s.tarR.Next()
	if err != nil {
		return nil, err
	}
	s.r = s.tarR

	s.pkgInfo.FileList = append(s.pkgInfo.FileList, h.Name)
	if h.Name == PackageSlackDescFile {
		var buf bytes.Buffer
		_, err := io.Copy(&buf, s.r)
		if err != nil {
			return nil, err
		}
		s.pkgInfo.PackageDescription = parseSlackDesc(buf.String(), s.pkgName)
		s.r = bytes.NewReader(buf.Bytes())
	}
	return h, nil
}

func (s *SlackwarePkg) Read(b []byte) (int, error) {
	n, err := s.r.Read(b)
	s.uncompressedSize += int64(n)
	return n, err
}

// PackageBase is the package's filename without the (supported) extension.
func PackageBase(fp string) string {
	filename := filepath.Base(fp)
	ext := filepath.Ext(filename)
	for _, v := range SupportedPackageTypes {
		if "."+v == ext {
			return filename[:(len(filename) - len(ext))]
		}
	}
	return filename
}

func PackageName(fp string) (string, error) {
	base := PackageBase(fp)
	strs := strings.Split(base, "-")
	if len(strs) < 4 {
		return "", errors.Errorf("badly formatted package name '%s'", fp)
	}
	name := strings.Join(strs[:(len(strs)-3)], "-")
	return name, nil
}

type PackageInfo struct {
	Name string
	// TODO: Should be size
	CompressedPackageSize   string
	UncompressedPackageSize string
	PackageLocation         string
	PackageDescription      string
	MD5Sum                  string
	FileList                []string
}

func changeExt(fp string, ext string) string {
	oldExt := filepath.Ext(fp)
	ret := fp[:(len(fp) - len(oldExt))]
	ret = ret + "." + ext
	return ret
}

func parseSlackDesc(str string, shortname string) string {
	// TODO: What does this do?
	//echo "PACKAGE DESCRIPTION:" >> $ADM_DIR/packages/$shortname
	//grep "^$packagebase:" $DESCRIPTION >> $ADM_DIR/packages/$shortname 2> /dev/null
	//if [ "$shortname" != "$packagebase" ]; then
	//  grep "^$shortname:" $DESCRIPTION >> $ADM_DIR/packages/$shortname 2> /dev/null
	//fi
	lines := strings.Split(str, "\n")
	var kept []string
	for _, l := range lines {
		if strings.HasPrefix(l, shortname) {
			kept = append(kept, l)
		}
	}
	return strings.Join(kept, "\n")
}

func GetUncompressedSize(fp string) (int64, error) {
	f, err := os.Open(fp)
	if err != nil {
		return 0, err
	}
	defer f.Close()

	ext := filepath.Ext(fp)[1:]
	r, err := NewCompressedFileReader(f, PackageType(ext))
	if err != nil {
		return 0, err
	}

	var size int64
	var buf [1024]byte
	for {
		n, err := r.Read(buf[:])
		if err == io.EOF {
			break
		} else if err != nil {
			return 0, err
		}
		size += int64(n)
	}
	return size, nil
}

// Use package name or package base for name
func GetPackageInfo(root string, pkgName string) (*PackageInfo, error) {
	infoPath := TargetPackageInfoPath(root, pkgName)
	info, err := ReadPackageInfo(infoPath)
	return info, errors.Wrap(err, "getting package information")
}

func ReadPackageInfo(fp string) (*PackageInfo, error) {
	f, err := os.Open(fp)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	buf, err := io.ReadAll(f)
	if err != nil {
		return nil, err
	}
	info, err := ParsePackageInfo(string(buf))
	if err != nil {
		return nil, err
	}

	return info, nil
}

func ParsePackageInfo(text string) (*PackageInfo, error) {
	keys := map[string]struct{}{
		"COMPRESSED PACKAGE SIZE":   {},
		"FILE LIST":                 {},
		"MD5SUM":                    {},
		"PACKAGE DESCRIPTION":       {},
		"PACKAGE LOCATION":          {},
		"PACKAGE NAME":              {},
		"UNCOMPRESSED PACKAGE SIZE": {},
	}

	pkg := PackageInfo{}
	scanner := bufio.NewScanner(bytes.NewBufferString(text))
	for scanner.Scan() {
		var k string

		l := scanner.Text()
		strs := strings.Split(l, ":")
		if len(strs) != 2 {
			continue
		}
		k = strings.TrimSpace(strs[0])
		v := strings.TrimSpace(strs[1])
		_ = keys

	loop:
		for {
			switch k {
			case "PACKAGE NAME":
				pkg.Name = v
			case "COMPRESSED PACKAGE SIZE":
				pkg.CompressedPackageSize = v
			case "UNCOMPRESSED PACKAGE SIZE":
				pkg.UncompressedPackageSize = v
			case "MD5SUM":
				pkg.MD5Sum = v
			case "PACKAGE LOCATION":
				pkg.PackageLocation = v
			case "PACKAGE DESCRIPTION":
				for scanner.Scan() {
					l := scanner.Text()
					strs := strings.Split(l, ":")
					if len(strs) == 2 {
						k = strings.TrimSpace(strs[0])
						v = strings.TrimSpace(strs[1])
						if _, ok := keys[k]; ok {
							break
						}
					}
					if len(pkg.PackageDescription) > 0 {
						pkg.PackageDescription += "\n"
					}
					pkg.PackageDescription += scanner.Text()
				}
				continue loop
			case "FILE LIST":
				for scanner.Scan() {
					pkg.FileList = append(pkg.FileList, scanner.Text())
				}
			default:
				return nil, fmt.Errorf("unknown key '%s'", k)
			}
			break
		}
	}
	return &pkg, nil
}

type PackageFormatKey string

type Encoder struct {
	w      io.Writer
	MD5Sum bool
}

func NewEncoder(w io.Writer) *Encoder {
	return &Encoder{w: w}
}

func (s *Encoder) EnableMD5Sum(arg bool) {
	s.MD5Sum = arg
}

func (s *Encoder) Encode(pkg *PackageInfo) error {
	_, err := s.w.Write([]byte(fmt.Sprintf("PACKAGE NAME:     %s\n", pkg.Name)))
	if err != nil {
		return err
	}
	_, err = s.w.Write([]byte(fmt.Sprintf("COMPRESSED PACKAGE SIZE:     %s\n", pkg.CompressedPackageSize)))
	if err != nil {
		return err
	}
	_, err = s.w.Write([]byte(fmt.Sprintf("UNCOMPRESSED PACKAGE SIZE:     %s\n", pkg.UncompressedPackageSize)))
	if err != nil {
		return err
	}
	_, err = s.w.Write([]byte(fmt.Sprintf("PACKAGE LOCATION: %s\n", pkg.PackageLocation)))
	if err != nil {
		return err
	}
	if s.MD5Sum {
		_, err = s.w.Write([]byte(fmt.Sprintf("PACKAGE MD5SUM: %s\n", pkg.MD5Sum)))
		if err != nil {
			return err
		}
	}

	_, err = s.w.Write([]byte(fmt.Sprintf("PACKAGE DESCRIPTION:\n%s\n", pkg.PackageDescription)))
	if err != nil {
		return err
	}
	_, err = s.w.Write([]byte("FILE LIST:\n"))
	if err != nil {
		return err
	}
	for _, f := range pkg.FileList {
		_, err = s.w.Write([]byte(f + "\n"))
		if err != nil {
			return err
		}
	}
	return nil
}