/* Copyright (C) 2019, 2020, 2021, 2022, 2023, 2024, 2025 Dnote contributors
 *
 * This file is part of Dnote.
 *
 * Dnote is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Dnote is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Dnote.  If not, see <https://www.gnu.org/licenses/>.
 */

package views

import (
	"fmt"
	"time"
)

type timeDiff struct {
	text  string
	tense string
}

func pluralize(singular string, count int) string {
	var noun string
	if count == 1 {
		noun = singular
	} else {
		noun = singular + "s"
	}

	return noun
}

func abs(num int64) int64 {
	if num < 0 {
		return -num
	}

	return num
}

var (
	DAY  = 24 * time.Hour.Milliseconds()
	WEEK = 7 * DAY
)

func getTimeDiffText(interval int64, noun string) string {
	return fmt.Sprintf("%d %s", interval, pluralize(noun, int(interval)))
}

func relativeTimeDiff(t1, t2 time.Time) timeDiff {
	diff := t1.Sub(t2)
	ts := abs(diff.Milliseconds())

	var tense string
	if diff > 0 {
		tense = "past"
	} else {
		tense = "future"
	}

	interval := ts / (52 * WEEK)
	if interval >= 1 {
		return timeDiff{
			text:  getTimeDiffText(interval, "year"),
			tense: tense,
		}
	}

	interval = ts / (4 * WEEK)
	if interval >= 1 {
		return timeDiff{
			text:  getTimeDiffText(interval, "month"),
			tense: tense,
		}
	}

	interval = ts / WEEK
	if interval >= 1 {
		return timeDiff{
			text:  getTimeDiffText(interval, "week"),
			tense: tense,
		}
	}

	interval = ts / DAY
	if interval >= 1 {
		return timeDiff{
			text:  getTimeDiffText(interval, "day"),
			tense: tense,
		}
	}

	interval = ts / time.Hour.Milliseconds()
	if interval >= 1 {
		return timeDiff{
			text:  getTimeDiffText(interval, "hour"),
			tense: tense,
		}
	}

	interval = ts / time.Minute.Milliseconds()
	if interval >= 1 {
		return timeDiff{
			text:  getTimeDiffText(interval, "minute"),
			tense: tense,
		}
	}

	return timeDiff{
		text: "Just now",
	}
}