lib/timeutil/timeutil.go

// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Package timeutil provides utilities for working with time related objects.
package timeutil

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"regexp"
	"strconv"
	"strings"
	"time"

	"golang.org/x/text/language" /* copybara-comment */
	"github.com/golang/protobuf/ptypes" /* copybara-comment */
	"github.com/GoogleCloudPlatform/healthcare-federated-access-services/lib/srcutil" /* copybara-comment: srcutil */
	"github.com/GoogleCloudPlatform/healthcare-federated-access-services/lib/strutil" /* copybara-comment: strutil */

	glog "github.com/golang/glog" /* copybara-comment */
	dpb "github.com/golang/protobuf/ptypes/duration" /* copybara-comment */
	tspb "github.com/golang/protobuf/ptypes/timestamp" /* copybara-comment */
)

const (
	// DurationREStr is a regexp for a duration string consiting of
	// days, hours, minutess, and seconds (each one is optional).
	DurationREStr = "^([0-9]+d)?([0-9]+h)?([0-9]+m)?([0-9]+s)?$"
)

var (
	dayRE  = regexp.MustCompile(`^(.*[dhms])?([\d\.]+)d(.*)$`)
	hourRE = regexp.MustCompile(`^(.*[dhms])?([\d\.]+)h(.*)$`)

	// For performance reasons, initialize these structures as part of the startup sequence
	// so that they are always available.
	localeMap   = generateLocales()
	timeZoneMap = generateTimeZones()
)

// LocaleInfo is the descriptor for a locale.
type LocaleInfo struct {
	// Base is the base language as defined by BCP47.
	Base string `json:"base"`
	// Script is the script character set used as defined by BCP47.
	Script string `json:"script"`
	// Region is the geolocation as defined by BCP47.
	Region string `json:"region"`
	// UI contains human-friendly labels for UIs to display.
	UI map[string]string `json:"ui"`
}

// TimezoneInfo is the descriptor for a time zone.
type TimezoneInfo struct {
	// UI contains human-friendly labels for UIs to display.
	UI map[string]string `json:"ui"`
}

// ParseDuration parses the given duration string to time.Duration.
// It supports "d" for days which time.ParseDuration does not.
// Each day is 24 hours.
func ParseDuration(d string) (time.Duration, error) {
	if len(d) == 0 {
		return 0, nil
	}
	neg := time.Duration(1)
	if d[0] == '-' {
		neg = -1
		d = d[1:]
	}

	h := float64(0)
	if days := dayRE.FindStringSubmatch(d); len(days) > 3 {
		n, err := strconv.ParseFloat(days[2], 64)
		if err != nil {
			return 0, err
		}
		h += n * 24
		d = days[1] + days[3]
	}

	if hours := hourRE.FindStringSubmatch(d); len(hours) > 3 {
		n, err := strconv.ParseFloat(hours[2], 64)
		if err != nil {
			return 0, err
		}
		h += n
		d = hours[1] + hours[3]
	}
	if h > 0 {
		d = fmt.Sprintf("%0.3fh%s", h, d)
	}

	out, err := time.ParseDuration(d)
	if err != nil {
		return 0, err
	}

	return neg * out, nil
}

// ParseDurationWithDefault parses the given duration string.
// Returns the provided default if the string is empty or on error.
func ParseDurationWithDefault(d string, def time.Duration) time.Duration {
	if len(d) == 0 {
		return def
	}
	v, err := ParseDuration(d)
	if err != nil {
		return def
	}
	return v
}

// ParseSeconds returns a duration from a numeric string in seconds.
func ParseSeconds(d string) (time.Duration, error) {
	n, err := strconv.ParseInt(d, 10, 64)
	if err != nil {
		return 0, err
	}
	return time.Duration(n) * time.Second, nil
}

// TTLString removes tailing 0s, 0m, 0h for human readable.
func TTLString(ttl time.Duration) string {
	str := ttl.String()
	str = strings.TrimSuffix(str, "0s")
	str = strings.TrimSuffix(str, "0m")
	str = strings.TrimSuffix(str, "0h")
	return str
}

// KeyTTL retuns the ttl for a number of keys.
func KeyTTL(maxRequestedTTL time.Duration, numKeys int) time.Duration {
	offset := int(maxRequestedTTL.Seconds()) / numKeys
	return maxRequestedTTL + time.Second*time.Duration(offset+1)
}

// IsTimeZone returns true if the "name" provided is an IANA Time Zone name.
func IsTimeZone(name string) bool {
	if name == "" {
		return false
	}
	if _, ok := timeZoneMap[name]; ok {
		return true
	}
	// Fallback to environment check.
	if _, err := time.LoadLocation(name); err != nil {
		return false
	}
	return true
}

// GetTimeZones returns a map of canonical timezone names to region names.
func GetTimeZones() map[string]*TimezoneInfo {
	return timeZoneMap
}

// generateTimeZones returns a map of canonical timezone names to regional information.
// Example: {
//   "America/Los_Angeles": {
//     "ui" {
//       "label": "Los Angeles (America)",
//       "region": "America",
//       "city": "Los Angeles"
//     }
//   }
// }
// TODO: use standard time functions for other platforms if https://github.com/golang/go/issues/20629 is implemented.
func generateTimeZones() map[string]*TimezoneInfo {
	zoneDirs := []string{
		"/usr/share/zoneinfo/",
		"/usr/share/lib/zoneinfo/",
		"/usr/lib/locale/TZ/",
	}

	out := make(map[string]*TimezoneInfo)
	for _, dir := range zoneDirs {
		genZones(dir, "", out)
	}

	data, err := srcutil.LoadFile("deploy/metadata/standard_timezones.json")
	if err != nil {
		glog.Errorf("failed to load time zones: %v", err)
		return out
	}
	loaded := make(map[string]string)
	if err := json.Unmarshal([]byte(data), &loaded); err != nil {
		glog.Errorf("failed to unmarshal time zone data: %v", err)
		return out
	}
	for k := range loaded {
		out[k] = genZoneInfo(k)
	}

	return out
}

func genZoneInfo(key string) *TimezoneInfo {
	info := &TimezoneInfo{UI: map[string]string{}}
	p := strings.Split(key, "/")
	plen := len(p)
	switch plen {
	case 1:
		// Example: "EST"
		info.UI["label"] = key
	case 2:
		// Example: "America/Los_Angeles"
		info.UI["label"] = fmt.Sprintf("%s (%s)", strutil.ToTitle(p[1]), p[0])
		info.UI["region"] = p[0]
		info.UI["city"] = strutil.ToTitle(p[1])
	default:
		// Example: "America/Indiana/Indianapolis"
		info.UI["label"] = fmt.Sprintf("%s (%s, %s)", strutil.ToTitle(p[plen-1]), strutil.ToTitle(p[plen-2]), p[0])
		info.UI["region"] = p[0]
		info.UI["subregion"] = strutil.ToTitle(p[1])
		if plen > 3 {
			// Found a deep path, just dump the middle levels in "part".
			// There are no current examples of paths this deep.
			info.UI["part"] = strings.Join(p[2:plen-1], ", ")
		}
		info.UI["city"] = strutil.ToTitle(p[plen-1])
	}
	return info
}

func genZones(dir, path string, out map[string]*TimezoneInfo) {
	files, err := ioutil.ReadDir(dir + path)
	if err != nil {
		return // not all files need to be present
	}
	for _, f := range files {
		if f.Name() != strings.ToUpper(f.Name()[:1])+f.Name()[1:] {
			continue
		}
		if f.IsDir() {
			genZones(dir, path+"/"+f.Name(), out)
		} else {
			zone := (path + "/" + f.Name())[1:]
			out[zone] = genZoneInfo(zone)
		}
	}
}

// IsLocale returns true if the "name" provided is a locale name as per
// https://tools.ietf.org/html/bcp47.
func IsLocale(name string) bool {
	if _, ok := localeMap[name]; ok {
		return true
	}
	// Fallback to environment check.
	if _, err := language.Parse(name); err != nil {
		return false
	}
	return true
}

// GetLocales returns a map of locale identifiers to English labels.
func GetLocales() map[string]*LocaleInfo {
	return localeMap
}

// generateLocales returns a map of canonical BCP47 locale identifiers to English labels. See IsLocale() for identifier details.
func generateLocales() map[string]*LocaleInfo {
	out := make(map[string]*LocaleInfo)
	loaded := make(map[string]string)
	data, err := srcutil.LoadFile("deploy/metadata/standard_locales.json")
	if err != nil {
		glog.Errorf("failed to load locales: %v", err)
		return out
	}
	if err := json.Unmarshal([]byte(data), &loaded); err != nil {
		glog.Errorf("failed to unmarshal locale data: %v", err)
		return out
	}
	for k, v := range loaded {
		out[k] = genLocaleInfo(k, v)
	}
	return out
}

func genLocaleInfo(key, label string) *LocaleInfo {
	info := &LocaleInfo{UI: map[string]string{"label": label}}
	p := strings.Split(key, "-")
	info.Base = p[0]
	info.UI["language"] = strings.Trim(strings.SplitN(label, "(", 2)[0], " ")
	switch len(p) {
	case 1:
		// Label Format: "<language>"
		// Label Example: "English"
		// Already captured above.
	case 2:
		// Label Format: "<language> (<region>)"
		// Label Example: "English (Canada)"
		info.Region = p[1]
		i2 := strings.Trim(leftOf(rightOf(label, "("), ")"), " ")
		switch {
		case len(p[1]) > 3:
			info.UI["script"] = i2
		default:
			info.UI["region"] = i2
		}
	case 3:
		// Label Format: "<language> (<script>, <region>)"
		// Label Example: "Serbian (Cyrillic, Serbia)"
		info.Script = p[1]
		info.Region = p[2]
		i3 := strings.Split(leftOf(rightOf(label, "("), ")"), ",")
		switch {
		case len(i3) == 1:
			// Found a misformatted string, as a safety check. Assume it is a region.
			info.UI["region"] = strings.Trim(i3[0], " ")
		default:
			info.UI["script"] = strings.Trim(i3[0], " ")
			info.UI["region"] = strings.Trim(i3[1], " ")
		}
	}
	return info
}

func leftOf(str, split string) string {
	return strings.SplitN(str, split, 2)[0]
}

func rightOf(str, split string) string {
	parts := strings.Split(str, split)
	return parts[len(parts)-1]
}

// TimestampString returns a RFC3339 date/time string for seconds sinc epoch.
func TimestampString(secs int64) string {
	return time.Unix(secs, 0).UTC().Format(time.RFC3339)
}

// RFC3339 convers a Timestamp to RFC3339 string.
// Returns "" if the timestamp is invalid.
func RFC3339(ts *tspb.Timestamp) string {
	t, err := ptypes.Timestamp(ts)
	if err != nil {
		return ""
	}
	return t.Format(time.RFC3339)
}

// ParseRFC3339 converts an RFC3339 string to time.Time.
// Returns default value of time.Time if the string is invalid.
func ParseRFC3339(s string) time.Time {
	t, err := time.Parse(time.RFC3339, s)
	if err != nil {
		return time.Time{}
	}
	return t
}

// TimestampProto returns the timestamp proto for a given time.
// Returns empty if the time is invalid.
func TimestampProto(t time.Time) *tspb.Timestamp {
	ts, err := ptypes.TimestampProto(t)
	if err != nil {
		return &tspb.Timestamp{}
	}
	return ts
}

// Time returns the time for a given timestamp.
// Returns 0 if the timestamp is invalid.
func Time(ts *tspb.Timestamp) time.Time {
	t, err := ptypes.Timestamp(ts)
	if err != nil {
		return time.Time{}
	}
	return t
}

// DurationProto returns the duration proto for a given duration.
func DurationProto(d time.Duration) *dpb.Duration {
	return ptypes.DurationProto(d)
}

// Duration returns the time for a given timestamp.
// Returns 0 if the timestamp is invalid.
func Duration(ds *dpb.Duration) time.Duration {
	d, err := ptypes.Duration(ds)
	if err != nil {
		return 0
	}
	return d
}