package util

import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"

	"github.com/BurntSushi/toml"
	"github.com/containers/image/types"
	"github.com/containers/libpod/pkg/rootless"
	"github.com/containers/storage"
	"github.com/containers/storage/pkg/idtools"
	"github.com/opencontainers/image-spec/specs-go/v1"
	"github.com/pkg/errors"
	"golang.org/x/crypto/ssh/terminal"
)

// Helper function to determine the username/password passed
// in the creds string.  It could be either or both.
func parseCreds(creds string) (string, string) {
	if creds == "" {
		return "", ""
	}
	up := strings.SplitN(creds, ":", 2)
	if len(up) == 1 {
		return up[0], ""
	}
	return up[0], up[1]
}

// ParseRegistryCreds takes a credentials string in the form USERNAME:PASSWORD
// and returns a DockerAuthConfig
func ParseRegistryCreds(creds string) (*types.DockerAuthConfig, error) {
	username, password := parseCreds(creds)
	if username == "" {
		fmt.Print("Username: ")
		fmt.Scanln(&username)
	}
	if password == "" {
		fmt.Print("Password: ")
		termPassword, err := terminal.ReadPassword(0)
		if err != nil {
			return nil, errors.Wrapf(err, "could not read password from terminal")
		}
		password = string(termPassword)
	}

	return &types.DockerAuthConfig{
		Username: username,
		Password: password,
	}, nil
}

// StringInSlice determines if a string is in a string slice, returns bool
func StringInSlice(s string, sl []string) bool {
	for _, i := range sl {
		if i == s {
			return true
		}
	}
	return false
}

// GetImageConfig converts the --change flag values in the format "CMD=/bin/bash USER=example"
// to a type v1.ImageConfig
func GetImageConfig(changes []string) (v1.ImageConfig, error) {
	// USER=value | EXPOSE=value | ENV=value | ENTRYPOINT=value |
	// CMD=value | VOLUME=value | WORKDIR=value | LABEL=key=value | STOPSIGNAL=value

	var (
		user       string
		env        []string
		entrypoint []string
		cmd        []string
		workingDir string
		stopSignal string
	)

	exposedPorts := make(map[string]struct{})
	volumes := make(map[string]struct{})
	labels := make(map[string]string)

	for _, ch := range changes {
		pair := strings.Split(ch, "=")
		if len(pair) == 1 {
			return v1.ImageConfig{}, errors.Errorf("no value given for instruction %q", ch)
		}
		switch pair[0] {
		case "USER":
			user = pair[1]
		case "EXPOSE":
			var st struct{}
			exposedPorts[pair[1]] = st
		case "ENV":
			env = append(env, pair[1])
		case "ENTRYPOINT":
			entrypoint = append(entrypoint, pair[1])
		case "CMD":
			cmd = append(cmd, pair[1])
		case "VOLUME":
			var st struct{}
			volumes[pair[1]] = st
		case "WORKDIR":
			workingDir = pair[1]
		case "LABEL":
			if len(pair) == 3 {
				labels[pair[1]] = pair[2]
			} else {
				labels[pair[1]] = ""
			}
		case "STOPSIGNAL":
			stopSignal = pair[1]
		}
	}

	return v1.ImageConfig{
		User:         user,
		ExposedPorts: exposedPorts,
		Env:          env,
		Entrypoint:   entrypoint,
		Cmd:          cmd,
		Volumes:      volumes,
		WorkingDir:   workingDir,
		Labels:       labels,
		StopSignal:   stopSignal,
	}, nil
}

// ParseIDMapping takes idmappings and subuid and subgid maps and returns a storage mapping
func ParseIDMapping(UIDMapSlice, GIDMapSlice []string, subUIDMap, subGIDMap string) (*storage.IDMappingOptions, error) {
	options := storage.IDMappingOptions{
		HostUIDMapping: true,
		HostGIDMapping: true,
	}
	if subGIDMap == "" && subUIDMap != "" {
		subGIDMap = subUIDMap
	}
	if subUIDMap == "" && subGIDMap != "" {
		subUIDMap = subGIDMap
	}
	if len(GIDMapSlice) == 0 && len(UIDMapSlice) != 0 {
		GIDMapSlice = UIDMapSlice
	}
	if len(UIDMapSlice) == 0 && len(GIDMapSlice) != 0 {
		UIDMapSlice = GIDMapSlice
	}
	if len(UIDMapSlice) == 0 && subUIDMap == "" && os.Getuid() != 0 {
		UIDMapSlice = []string{fmt.Sprintf("0:%d:1", os.Getuid())}
	}
	if len(GIDMapSlice) == 0 && subGIDMap == "" && os.Getuid() != 0 {
		GIDMapSlice = []string{fmt.Sprintf("0:%d:1", os.Getgid())}
	}

	parseTriple := func(spec []string) (container, host, size int, err error) {
		cid, err := strconv.ParseUint(spec[0], 10, 32)
		if err != nil {
			return 0, 0, 0, fmt.Errorf("error parsing id map value %q: %v", spec[0], err)
		}
		hid, err := strconv.ParseUint(spec[1], 10, 32)
		if err != nil {
			return 0, 0, 0, fmt.Errorf("error parsing id map value %q: %v", spec[1], err)
		}
		sz, err := strconv.ParseUint(spec[2], 10, 32)
		if err != nil {
			return 0, 0, 0, fmt.Errorf("error parsing id map value %q: %v", spec[2], err)
		}
		return int(cid), int(hid), int(sz), nil
	}
	parseIDMap := func(spec []string) (idmap []idtools.IDMap, err error) {
		for _, uid := range spec {
			splitmap := strings.SplitN(uid, ":", 3)
			if len(splitmap) < 3 {
				return nil, fmt.Errorf("invalid mapping requires 3 fields: %q", uid)
			}
			cid, hid, size, err := parseTriple(splitmap)
			if err != nil {
				return nil, err
			}
			pmap := idtools.IDMap{
				ContainerID: cid,
				HostID:      hid,
				Size:        size,
			}
			idmap = append(idmap, pmap)
		}
		return idmap, nil
	}
	if subUIDMap != "" && subGIDMap != "" {
		mappings, err := idtools.NewIDMappings(subUIDMap, subGIDMap)
		if err != nil {
			return nil, err
		}
		options.UIDMap = mappings.UIDs()
		options.GIDMap = mappings.GIDs()
	}
	parsedUIDMap, err := parseIDMap(UIDMapSlice)
	if err != nil {
		return nil, err
	}
	parsedGIDMap, err := parseIDMap(GIDMapSlice)
	if err != nil {
		return nil, err
	}
	options.UIDMap = append(options.UIDMap, parsedUIDMap...)
	options.GIDMap = append(options.GIDMap, parsedGIDMap...)
	if len(options.UIDMap) > 0 {
		options.HostUIDMapping = false
	}
	if len(options.GIDMap) > 0 {
		options.HostGIDMapping = false
	}
	return &options, nil
}

// GetRootlessRuntimeDir returns the runtime directory when running as non root
func GetRootlessRuntimeDir() (string, error) {
	runtimeDir := os.Getenv("XDG_RUNTIME_DIR")
	uid := fmt.Sprintf("%d", rootless.GetRootlessUID())
	if runtimeDir == "" {
		tmpDir := filepath.Join("/run", "user", uid)
		os.MkdirAll(tmpDir, 0700)
		st, err := os.Stat(tmpDir)
		if err == nil && int(st.Sys().(*syscall.Stat_t).Uid) == os.Getuid() && st.Mode().Perm() == 0700 {
			runtimeDir = tmpDir
		}
	}
	if runtimeDir == "" {
		tmpDir := filepath.Join(os.TempDir(), "user", uid)
		os.MkdirAll(tmpDir, 0700)
		st, err := os.Stat(tmpDir)
		if err == nil && int(st.Sys().(*syscall.Stat_t).Uid) == os.Getuid() && st.Mode().Perm() == 0700 {
			runtimeDir = tmpDir
		}
	}
	if runtimeDir == "" {
		home := os.Getenv("HOME")
		if home == "" {
			return "", fmt.Errorf("neither XDG_RUNTIME_DIR nor HOME was set non-empty")
		}
		resolvedHome, err := filepath.EvalSymlinks(home)
		if err != nil {
			return "", errors.Wrapf(err, "cannot resolve %s", home)
		}
		runtimeDir = filepath.Join(resolvedHome, "rundir")
	}
	return runtimeDir, nil
}

// GetRootlessStorageOpts returns the storage ops for containers running as non root
func GetRootlessStorageOpts() (storage.StoreOptions, error) {
	var opts storage.StoreOptions

	rootlessRuntime, err := GetRootlessRuntimeDir()
	if err != nil {
		return opts, err
	}
	opts.RunRoot = rootlessRuntime

	dataDir := os.Getenv("XDG_DATA_HOME")
	if dataDir == "" {
		home := os.Getenv("HOME")
		if home == "" {
			return opts, fmt.Errorf("neither XDG_DATA_HOME nor HOME was set non-empty")
		}
		// runc doesn't like symlinks in the rootfs path, and at least
		// on CoreOS /home is a symlink to /var/home, so resolve any symlink.
		resolvedHome, err := filepath.EvalSymlinks(home)
		if err != nil {
			return opts, errors.Wrapf(err, "cannot resolve %s", home)
		}
		dataDir = filepath.Join(resolvedHome, ".local", "share")
	}
	opts.GraphRoot = filepath.Join(dataDir, "containers", "storage")
	if path, err := exec.LookPath("fuse-overlayfs"); err == nil {
		opts.GraphDriverName = "overlay"
		opts.GraphDriverOptions = []string{fmt.Sprintf("overlay.mount_program=%s", path)}
	} else {
		opts.GraphDriverName = "vfs"
	}
	return opts, nil
}

// GetDefaultStoreOptions returns the storage ops for containers
func GetDefaultStoreOptions() (storage.StoreOptions, error) {
	storageOpts := storage.DefaultStoreOptions
	if rootless.IsRootless() {
		var err error
		storageOpts, err = GetRootlessStorageOpts()
		if err != nil {
			return storageOpts, err
		}

		storageConf := filepath.Join(os.Getenv("HOME"), ".config/containers/storage.conf")
		if _, err := os.Stat(storageConf); err == nil {
			storage.ReloadConfigurationFile(storageConf, &storageOpts)
		} else if os.IsNotExist(err) {
			os.MkdirAll(filepath.Dir(storageConf), 0755)
			file, err := os.OpenFile(storageConf, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0666)
			if err != nil {
				return storageOpts, errors.Wrapf(err, "cannot open %s", storageConf)
			}

			defer file.Close()
			enc := toml.NewEncoder(file)
			if err := enc.Encode(storageOpts); err != nil {
				os.Remove(storageConf)
			}
		}
	}
	return storageOpts, nil
}