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ExifDateTime.ts
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ExifDateTime.ts
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import {
DateTime,
DateTimeJSOptions,
DurationLike,
ToISOTimeOptions,
Zone,
ZoneOptions,
} from "luxon"
import { MinuteMs, dateTimeToExif } from "./DateTime"
import { Maybe, denull } from "./Maybe"
import { omit } from "./Object"
import { blank, notBlank } from "./String"
import {
TimeFormatMeta,
parseDateTime,
setZone,
timeFormats,
} from "./TimeParsing"
import {
UnsetZone,
UnsetZoneName,
UnsetZoneOffsetMinutes,
getZoneName,
} from "./Timezones"
/**
* Encodes an ExifDateTime with an optional tz offset in minutes.
*/
export class ExifDateTime {
static from(
exifOrIso: Maybe<string | ExifDateTime>,
defaultZone?: Maybe<string>
): Maybe<ExifDateTime> {
return exifOrIso instanceof ExifDateTime
? exifOrIso // already an ExifDateTime
: blank(exifOrIso)
? undefined // in order of strictness:
: (this.fromExifStrict(exifOrIso, defaultZone) ??
this.fromISO(exifOrIso, defaultZone) ??
this.fromExifLoose(exifOrIso, defaultZone))
}
static fromISO(
iso: string,
defaultZone?: Maybe<string>
): Maybe<ExifDateTime> {
if (blank(iso) || null != iso.match(/^\d+$/)) return undefined
// Unfortunately, DateTime.fromISO() is happy to parse a date with no time,
// so we have to do this ourselves:
return this.#fromPatterns(
iso,
timeFormats({
formatPrefixes: ["y-MM-dd'T'", "y-MM-dd ", "y-M-d "],
defaultZone,
})
)
}
/**
* Try to parse a date-time string from EXIF. If there is not both a date
* and a time component, returns `undefined`.
*
* @param text from EXIF metadata
* @param defaultZone a "zone name" to use as a backstop, or default, if
* `text` doesn't specify a zone. This may be IANA-formatted, like
* "America/Los_Angeles", or an offset, like "UTC-3". See
* `offsetMinutesToZoneName`.
*/
static fromEXIF(
text: string,
defaultZone?: Maybe<string>
): Maybe<ExifDateTime> {
if (blank(text)) return undefined
return (
// .fromExifStrict() uses .fromISO() as a backstop
this.fromExifStrict(text, defaultZone) ??
this.fromExifLoose(text, defaultZone)
)
}
static #fromPatterns(
text: string,
fmts: Iterable<TimeFormatMeta>
): Maybe<ExifDateTime> {
const result = parseDateTime(text, fmts)
return result == null
? undefined
: ExifDateTime.fromDateTime(result.dt, {
rawValue: text,
unsetMilliseconds: result.unsetMilliseconds,
inferredZone: result.inferredZone,
})
}
/**
* Parse the given date-time string, EXIF-formatted.
*
* @param text from EXIF metadata, in `y:M:d H:m:s` format (with optional
* sub-seconds and/or timezone)
* @param defaultZone a "zone name" to use as a backstop, or default, if
* `text` doesn't specify a zone. This may be IANA-formatted, like
* "America/Los_Angeles", or an offset, like "UTC-3". See
* `offsetMinutesToZoneName`.
*/
static fromExifStrict(
text: Maybe<string>,
defaultZone?: Maybe<string>
): Maybe<ExifDateTime> {
if (blank(text)) return undefined
return (
this.#fromPatterns(
text,
timeFormats({ formatPrefixes: ["y:MM:dd ", "y:M:d "], defaultZone })
) ??
// Not found yet? Maybe it's in ISO format? See
// https://github.com/photostructure/exiftool-vendored.js/issues/71
this.fromISO(text, defaultZone)
)
}
static *#looseExifFormats(defaultZone?: Maybe<string>) {
// The following are from actual datestamps seen in the wild (!!)
const formats = [
"MMM d y HH:mm:ss",
"MMM d y, HH:mm:ss",
// Thu Oct 13 00:12:27 2016:
"ccc MMM d HH:mm:ss y",
]
const zone = notBlank(defaultZone) ? defaultZone : UnsetZone
for (const fmt of formats) {
yield { fmt: fmt, zone, inferredZone: true }
}
}
static fromExifLoose(
text: Maybe<string>,
defaultZone?: Maybe<string>
): Maybe<ExifDateTime> {
return blank(text)
? undefined
: this.#fromPatterns(text, this.#looseExifFormats(defaultZone))
}
static fromDateTime(
dt: Maybe<DateTime>,
opts?: {
rawValue?: Maybe<string>
unsetMilliseconds?: boolean
inferredZone?: Maybe<boolean>
}
): Maybe<ExifDateTime> {
if (dt == null || !dt.isValid || dt.year === 0 || dt.year === 1) {
return undefined
}
return new ExifDateTime(
dt.year,
dt.month,
dt.day,
dt.hour,
dt.minute,
dt.second,
dt.millisecond === 0 && true === opts?.unsetMilliseconds
? undefined
: dt.millisecond,
dt.offset === UnsetZoneOffsetMinutes ? undefined : dt.offset,
opts?.rawValue,
dt.zoneName == null || dt.zone?.name === UnsetZone.name
? undefined
: dt.zoneName,
opts?.inferredZone
)
}
/**
* Create an ExifDateTime from a number of milliseconds since the epoch
* (meaning since 1 January 1970 00:00:00 UTC). Uses the default zone.
*
* @param millis - a number of milliseconds since 1970 UTC
*
* @param options.rawValue - the original parsed string input
* @param options.zone - the zone to place the DateTime into. Defaults to 'local'.
* @param options.locale - a locale to set on the resulting DateTime instance
* @param options.outputCalendar - the output calendar to set on the resulting DateTime instance
* @param options.numberingSystem - the numbering system to set on the resulting DateTime instance
*/
static fromMillis(
millis: number,
options: DateTimeJSOptions & { rawValue?: string } = {}
) {
if (
options.zone == null ||
[UnsetZoneName, UnsetZone].includes(options.zone)
) {
delete options.zone
}
let dt = DateTime.fromMillis(millis, {
...omit(options, "rawValue"),
})
if (options.zone == null) {
dt = dt.setZone(UnsetZone, { keepLocalTime: true })
}
// TODO: is there a way to provide an invalid millisecond value?
// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
return this.fromDateTime(dt, { rawValue: options.rawValue })!
}
static now(
opts: DateTimeJSOptions & { rawValue?: string } = {}
): ExifDateTime {
return this.fromMillis(Date.now(), opts)
}
#dt?: DateTime
readonly zone: Maybe<string>
constructor(
readonly year: number,
readonly month: number,
readonly day: number,
readonly hour: number,
readonly minute: number,
readonly second: number,
readonly millisecond?: number,
readonly tzoffsetMinutes?: number,
readonly rawValue?: string,
readonly zoneName?: string,
readonly inferredZone?: boolean
) {
this.zone = getZoneName({ zoneName, tzoffsetMinutes })
}
get millis() {
return this.millisecond
}
get hasZone(): boolean {
return this.zone != null
}
get unsetMilliseconds(): boolean {
return this.millisecond == null
}
setZone(
zone: string | Zone,
opts?: ZoneOptions & { inferredZone?: boolean }
): Maybe<ExifDateTime> {
const dt = setZone({
zone,
src: this.toDateTime(),
srcHasZone: this.hasZone,
opts,
})
return ExifDateTime.fromDateTime(dt, {
rawValue: this.rawValue,
unsetMilliseconds: this.millisecond == null,
inferredZone: opts?.inferredZone ?? true,
})
}
/**
* CAUTION: This instance will inherit the system timezone if this instance
* has an unset zone (as Luxon doesn't support "unset" timezones)
*/
toDateTime(overrideZone?: Maybe<string>): DateTime {
return (this.#dt ??= DateTime.fromObject(
{
year: this.year,
month: this.month,
day: this.day,
hour: this.hour,
minute: this.minute,
second: this.second,
millisecond: this.millisecond,
},
{
zone: overrideZone ?? this.zone,
}
))
}
toEpochSeconds(overrideZone?: Maybe<string>) {
return this.toDateTime(overrideZone).toUnixInteger()
}
toDate(): Date {
return this.toDateTime().toJSDate()
}
toISOString(options: ToISOTimeOptions = {}): Maybe<string> {
return denull(
this.toDateTime().toISO({
suppressMilliseconds:
options.suppressMilliseconds ?? this.millisecond == null,
includeOffset: this.hasZone && options.includeOffset !== false,
})
)
}
toExifString() {
return dateTimeToExif(this.toDateTime(), {
includeOffset: this.hasZone,
includeMilliseconds: this.millisecond != null,
})
}
toString() {
return this.toISOString()
}
/**
* @return the epoch milliseconds of this
*/
toMillis() {
return this.toDateTime().toMillis()
}
get isValid() {
return this.toDateTime().isValid
}
toJSON() {
return {
_ctor: "ExifDateTime",
year: this.year,
month: this.month,
day: this.day,
hour: this.hour,
minute: this.minute,
second: this.second,
millisecond: this.millisecond,
tzoffsetMinutes: this.tzoffsetMinutes,
rawValue: this.rawValue,
zoneName: this.zoneName,
inferredZone: this.inferredZone,
}
}
/**
* @return a new ExifDateTime from the given JSON. Note that this instance **may not be valid**.
*/
static fromJSON(
json: Omit<ReturnType<ExifDateTime["toJSON"]>, "_ctor">
): ExifDateTime {
return new ExifDateTime(
json.year,
json.month,
json.day,
json.hour,
json.minute,
json.second,
json.millisecond,
json.tzoffsetMinutes,
json.rawValue,
json.zoneName,
json.inferredZone
)
}
maybeMatchZone(
target: ExifDateTime,
maxDeltaMs = 14 * MinuteMs
): Maybe<ExifDateTime> {
const targetZone = target.zone
if (targetZone == null || !target.hasZone) return
return (
this.setZone(targetZone, { keepLocalTime: false })?.ifClose(
target,
maxDeltaMs
) ??
this.setZone(targetZone, { keepLocalTime: true })?.ifClose(
target,
maxDeltaMs
)
)
}
private ifClose(
target: ExifDateTime,
maxDeltaMs = 14 * MinuteMs
): Maybe<ExifDateTime> {
const ts = this.toMillis()
const targetTs = target.toMillis()
return Math.abs(ts - targetTs) <= maxDeltaMs ? this : undefined
}
plus(duration: DurationLike) {
let dt = this.toDateTime().plus(duration)
if (!this.hasZone) {
dt = dt.setZone(UnsetZone, { keepLocalTime: true })
}
return ExifDateTime.fromDateTime(dt, this)
}
}