SerhiiCho / timeago

package timeago

import (

	"math"

	"strconv"

	"strings"

	"time"

)

var (

	// cachedJsonRes saves parsed JSON translations to prevent

	// parsing the same JSON file multiple times.

	cachedJsonRes = map[string]*LangSet{}

	// options is a list of options that modify the final output.

	// Some options are noSuffix, upcoming, online, and justNow.

	options = []opt{}

	// conf is configuration provided by the user.

	conf = defaultConfig()

	// langSet is a pointer to the current language set that

	// is currently being used.

	langSet *LangSet

)

type timeNumbers struct {

	Seconds int

	Minutes int

	Hours   int

	Days    int

	Weeks   int

	Months  int

	Years   int

}

// Parse coverts privided datetime into `x time ago` format.

// The first argument can have 3 types:

// 1. int (Unix timestamp)

// 2. time.Time (Type from Go time package)

// 3. string (Datetime string in format 'YYYY-MM-DD HH:MM:SS')

func Parse(datetime interface{}, opts ...opt) (string, error) {

	options = []opt{}

	langSet = nil

	var input time.Time

	var err error

	switch date := datetime.(type) {

	case int:

		input = unixToTime(date)

	case string:

		input, err = strToTime(date)

	default:

		input = datetime.(time.Time)

	}

	if err != nil {

		return "", err

	}

	enableOptions(opts)

	return computeTimeSince(input)

}

// Configure applies the given configuration to the timeago without

// overriding the previous configuration. It will only override the

// provided configuration. If you want to override the previous

// configurations, use Reconfigure function instead.

func Configure(c Config) {

	if c.OnlineThreshold > 0 {

		conf.OnlineThreshold = c.OnlineThreshold

	}

	if c.JustNowThreshold > 0 {

		conf.JustNowThreshold = c.JustNowThreshold

	}

	if c.Language != "" {

		conf.Language = c.Language

	}

	if c.Location != "" {

		conf.Location = c.Location

	}

	if len(c.Translations) > 0 {

		conf.Translations = c.Translations

	}

}

// Reconfigure reconfigures the timeago with the provided configuration.

// It will override the previous configuration with the new one.

func Reconfigure(c Config) {

	conf = defaultConfig()

	cachedJsonRes = map[string]*LangSet{}

	Configure(c)

}

func defaultConfig() *Config {

	return NewConfig("en", "UTC", []LangSet{}, 60, 60)

}

func strToTime(datetime string) (time.Time, error) {

	if !conf.isLocationProvided() {

		parsedTime, _ := time.Parse("2006-01-02 15:04:05", datetime)

		return parsedTime, nil

	}

	loc, err := location()

	if err != nil {

		return time.Time{}, err

	}

	parsedTime, err := time.ParseInLocation("2006-01-02 15:04:05", datetime, loc)

	if err != nil {

		return time.Time{}, errorf("%v", err)

	}

	return parsedTime, nil

}

// location loads location from the time package

func location() (*time.Location, error) {

	if !conf.isLocationProvided() {

		return time.Now().Location(), nil

	}

	loc, err := time.LoadLocation(conf.Location)

	if err != nil {

		return nil, errorf("%v", err)

	}

	return loc, nil

}

func computeTimeSince(t time.Time) (string, error) {

	now := time.Now()

	var err error

	// Adjust times based on location if provided

	if t, now, err = adjustTimesForLocation(t, now); err != nil {

		return "", err

	}

	timeInSec := computeTimeDifference(t, now)

	if langSet, err = newLangSet(); err != nil {

		return "", err

	}

	if optionIsEnabled(OptOnline) && timeInSec < 60 {

		return langSet.Online, nil

	}

	if optionIsEnabled(OptJustNow) && timeInSec < 60 {

		return langSet.JustNow, nil

	}

	var timeUnit string

	langForms, timeNum := findLangForms(timeInSec)

	if timeUnit, err = computeTimeUnit(langForms, timeNum); err != nil {

		return "", err

	}

	suffix := computeSuffix()

	return mergeFinalOutput(timeNum, timeUnit, suffix)

}

// adjustTimesForLocation adjusts the given times based on the provided location.

func adjustTimesForLocation(t, now time.Time) (time.Time, time.Time, error) {

	if !conf.isLocationProvided() {

		return t, now, nil

	}

	loc, err := location()

	if err != nil {

		return t, now, err

	}

	return t.In(loc), now.In(loc), nil

}

// computeTimeDifference returns the absolute time difference in seconds.

func computeTimeDifference(t, now time.Time) int {

	timeInSec := int(now.Sub(t).Seconds())

	if timeInSec < 0 {

		enableOption(OptUpcoming)

		return -timeInSec

	}

	return timeInSec

}

func mergeFinalOutput(timeNum int, timeUnit, suffix string) (string, error) {

	replacer := strings.NewReplacer(

		"{timeUnit}", timeUnit,

		"{num}", strconv.Itoa(timeNum),

		"{ago}", suffix,

	)

	out := replacer.Replace(langSet.Format)

	return strings.TrimSpace(out), nil

}

func findLangForms(timeInSec int) (LangForms, int) {

	nums := calculateTimeNumbers(float64(timeInSec))

	switch {

	case timeInSec < 60:

		return langSet.Second, nums.Seconds

	case nums.Minutes < 60:

		return langSet.Minute, nums.Minutes

	case nums.Hours < 24:

		return langSet.Hour, nums.Hours

	case nums.Days < 7:

		return langSet.Day, nums.Days

	case nums.Weeks < 4:

		return langSet.Week, nums.Weeks

	case nums.Months < 12:

		if nums.Months == 0 {

			nums.Months = 1

		}

		return langSet.Month, nums.Months

	}

	return langSet.Year, nums.Years

}

func computeSuffix() string {

	if optionIsEnabled(OptNoSuffix) || optionIsEnabled(OptUpcoming) {

		return ""

	}

	return langSet.Ago

}

func calculateTimeNumbers(seconds float64) timeNumbers {

	minutes := math.Round(seconds / 60)

	hours := math.Round(seconds / 3600)

	days := math.Round(seconds / 86400)

	weeks := math.Round(seconds / 604800)

	months := math.Round(seconds / 2629440)

	years := math.Round(seconds / 31553280)

	return timeNumbers{

		Seconds: int(seconds),

		Minutes: int(minutes),

		Hours:   int(hours),

		Days:    int(days),

		Weeks:   int(weeks),

		Months:  int(months),

		Years:   int(years),

	}

}

func computeTimeUnit(langForm LangForms, num int) (string, error) {

	form, err := timeUnitForm(num)

	if err != nil {

		return "", err

	}

	if unit, ok := langForm[form]; ok {

		return unit, nil

	}

	return langForm["other"], nil

}

func timeUnitForm(num int) (string, error) {

	rule, err := identifyGrammarRules(num, conf.Language)

	if err != nil {

		return "", err

	}

	switch {

	case rule.Zero:

		return "zero", nil

	case rule.One:

		return "one", nil

	case rule.Few:

		return "few", nil

	case rule.Two:

		return "two", nil

	case rule.Many:

		return "many", nil

	}

	return "other", nil

}