iso8601time.go

/*
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You 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 helper

import (
	"fmt"
	"reflect"
	"regexp"
	"strings"
	"time"

	"github.com/mitchellh/mapstructure"
)

/*
parse iso8601 datetime format for json.Unmarshal

declare your field type as:

type Foo struct {
	Created Iso8601Time
}

foo := &Foo{}
err := json.Unmarshal("{\"created\": \"2021-02-19T01:53:35.340+0800\"}", foo)
var time time.Time
time = foo.Created.ToTime()
*/

// DateTimeFormatItem FIXME ...
// TODO: move this to helper
type DateTimeFormatItem struct {
	Matcher *regexp.Regexp
	Format  string
}

// DateTimeFormats FIXME ...
var DateTimeFormats []DateTimeFormatItem

func init() {
	DateTimeFormats = []DateTimeFormatItem{
		{
			Matcher: regexp.MustCompile(`[+-][\d]{4}$`),
			Format:  "2006-01-02T15:04:05-0700",
		},
		{
			Matcher: regexp.MustCompile(`[\d]{3}[+-][\d]{2}:[\d]{2}$`),
			Format:  "2006-01-02T15:04:05.000-07:00",
		},
		{
			Matcher: regexp.MustCompile(`[+-][\d]{2}:[\d]{2}$`),
			Format:  "2006-01-02T15:04:05-07:00",
		},
	}
}

// Iso8601Time is type time.Time
type Iso8601Time struct {
	time   time.Time
	format string
}

func (jt *Iso8601Time) String() string {
	format := jt.format
	if format == "" {
		format = DateTimeFormats[0].Format
	}
	return jt.time.Format(format)
}

// MarshalJSON FIXME ...
func (jt Iso8601Time) MarshalJSON() ([]byte, error) {
	return []byte(fmt.Sprintf(`"%s"`, jt.String())), nil
}

// UnmarshalJSON FIXME ...
func (jt *Iso8601Time) UnmarshalJSON(b []byte) error {
	timeString := string(b)
	if timeString == "null" {
		return nil
	}
	timeString = strings.Trim(timeString, `"`)
	t, err := ConvertStringToTime(timeString)
	if err != nil {
		return err
	}
	jt.time = t
	return nil
}

// ToTime FIXME ...
func (jt *Iso8601Time) ToTime() time.Time {
	return jt.time
}

// ToNullableTime FIXME ...
func (jt *Iso8601Time) ToNullableTime() *time.Time {
	if jt == nil {
		return nil
	}
	return &jt.time
}

// ConvertStringToTime FIXME ...
func ConvertStringToTime(timeString string) (t time.Time, err error) {
	for _, formatItem := range DateTimeFormats {
		if formatItem.Matcher.MatchString(timeString) {
			return time.Parse(formatItem.Format, timeString)
		}
	}
	return time.Parse(time.RFC3339, timeString)
}

// Iso8601TimeToTime FIXME ...
func Iso8601TimeToTime(iso8601Time *Iso8601Time) *time.Time {
	if iso8601Time == nil {
		return nil
	}
	t := iso8601Time.ToTime()
	return &t
}

// DecodeMapStruct with time.Time and Iso8601Time support
func DecodeMapStruct(input map[string]interface{}, result interface{}) error {
	decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
		Metadata: nil,
		DecodeHook: mapstructure.ComposeDecodeHookFunc(
			func(f reflect.Type, t reflect.Type, data interface{}) (interface{}, error) {
				if t != reflect.TypeOf(Iso8601Time{}) && t != reflect.TypeOf(time.Time{}) {
					return data, nil
				}

				var tt time.Time
				var err error

				switch f.Kind() {
				case reflect.String:
					tt, err = ConvertStringToTime(data.(string))
				case reflect.Float64:
					tt = time.Unix(0, int64(data.(float64))*int64(time.Millisecond))
				case reflect.Int64:
					tt = time.Unix(0, data.(int64)*int64(time.Millisecond))
				}
				if err != nil {
					return data, nil
				}

				if t == reflect.TypeOf(Iso8601Time{}) {
					return Iso8601Time{time: tt}, nil
				}
				return tt, nil
			},
		),
		Result: result,
	})
	if err != nil {
		return err
	}

	if err := decoder.Decode(input); err != nil {
		return err
	}
	return err
}