SerhiiCho / 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 = []Option{}

	// conf is configuration provided by the user.

	conf = NewConfig("en", "", []LangSet{})

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

	// is currently being used.

	langSet *LangSet

)

// 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 ...Option) (string, error) {

	options = []Option{}

	langSet = nil

	var input time.Time

	var err error

	switch date := datetime.(type) {

	case int:

		input = parseTimestampIntoTime(date)

	case string:

		input, err = parseStrIntoTime(date)

	default:

		input = datetime.(time.Time)

	}

	if err != nil {

		return "", err

	}

	enableOptions(opts)

	return calculateTimeAgo(input)

}

// Configure applies the given configuration to the timeago.

func Configure(c Config) {

	if c.Language != "" {

		conf.Language = c.Language

	}

	if c.Location != "" {

		conf.Location = c.Location

	}

	if len(c.Translations) > 0 {

		conf.Translations = c.Translations

	}

}

// ClearCache removes all cached translations, options, and other

// configurations. Since Timeago caches parsed JSON files, this function

// removes all cached and resets config to default.

// It useful when you want to reload the language files without

// restarting the application or freeing up the memory.

func parseStrIntoTime(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{}, createError("%v", err)

	}

	return parsedTime, nil

}

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

	if !conf.isLocationProvided() {

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

	}

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

	if err != nil {

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

	}

	return loc, nil

}

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

	now := time.Now()

	if conf.isLocationProvided() {

		loc, err := location()

		if err != nil {

			return "", err

		}

		t = t.In(loc)

		now = now.In(loc)

	}

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

	if seconds < 0 {

		enableOption(Upcoming)

		seconds = -seconds

	}

	set, err := newLangSet()

	if err != nil {

		return "", err

	}

	langSet = set

	return generateTimeUnit(seconds)

}

func generateTimeUnit(seconds int) (string, error) {

	minutes, hours, days, weeks, months, years := getTimeCalculations(float64(seconds))

	switch {

	case optionIsEnabled("online") && seconds < 60:

		return langSet.Online, nil

	case optionIsEnabled("justNow") && seconds < 60:

		return langSet.JustNow, nil

	case seconds < 60:

		return getWords(langSet.Second, seconds)

	case minutes < 60:

		return getWords(langSet.Minute, minutes)

	case hours < 24:

		return getWords(langSet.Hour, hours)

	case days < 7:

		return getWords(langSet.Day, days)

	case weeks < 4:

		return getWords(langSet.Week, weeks)

	case months < 12:

		if months == 0 {

			months = 1

		}

		return getWords(langSet.Month, months)

	}

	return getWords(langSet.Year, years)

}

// getWords decides rather the word must be singular or plural,

// and depending on the result it adds the correct word after

// the time number.

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

	timeUnit, err := finalTimeUnit(langForm, num)

	if err != nil {

		return "", err

	}

	res := langSet.Format

	res = strings.Replace(res, "{timeUnit}", timeUnit, -1)

	res = strings.Replace(res, "{num}", strconv.Itoa(num), -1)

	if optionIsEnabled("noSuffix") || optionIsEnabled("upcoming") {

		res = strings.Replace(res, "{ago}", "", -1)

		return strings.Trim(res, " "), nil

	}

	return strings.Replace(res, "{ago}", langSet.Ago, -1), nil

}

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

	form, err := identifyTimeUnitForm(num)

	if err != nil {

		return "", err

	}

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

		return unit, nil

	}

	return langForm["other"], nil

}

func identifyTimeUnitForm(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

}

func getTimeCalculations(seconds float64) (int, int, int, int, int, int) {

	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 int(minutes), int(hours), int(days), int(weeks), int(months), int(years)

}