package sprigx

import (
	`errors`
	`strconv`
	`strings`
	`time`
)

/*
tmFmt formats time t using format string fstr.

While one certainly can do the same via e.g.

	{{- $t := tmNow -}}
	{{ $t.Format $fstr }}

This takes a time.Time as the second (and last) parameter,
allowing it to work in pipelines.
*/
func tmFmt(fstr string, t time.Time) (out string) {

	out = t.Format(fstr)

	return
}

/*
tmParseMonth attempts to first try tmParseMonthInt
and then tries tmParseMonthStr if v is not "numeric".
*/
func tmParseMonth(v any) (mon time.Month, err error) {

	var s string

	if mon, err = tmParseMonthInt(v); err != nil {
		if errors.Is(err, strconv.ErrSyntax) {
			// NaN
			err = nil
		} else {
			return
		}
	}

	// If it gets here, it's a non-numeric string.
	if s, err = toString(v); err != nil {
		return
	}
	if mon, err = tmParseMonthStr(s); err != nil {
		return
	}

	return
}

/*
tmParseMonthInt parses a number representation of month n to a time.Month.
n may be any numeric type or a string representation of a number
(or a custom type derived from those).

A negative integer (or float, etc.) will be converted to a positive one (e.g. -6 => 6 => time.June).

floats are rounded to the nearest integer.

The integer should map directly to the month constants in the time module:

	* 1: January
	* 2: February
	* 3: March
	* 4: April
	* 5: May
	* 6: June
	* 7: July
	* 8: August
	* 9: September
	* 10: October
	* 11: November
	* 12: December

If n resolves to 0, mon will be the current month (as determined by time.Now).

If n resolves to > 12, err will be ErrBadMonth.
*/
func tmParseMonthInt(n any) (mon time.Month, err error) {

	var i int

	if i, _, err = toPosInt(n); err != nil {
		return
	}

	if i == 0 {
		mon = time.Now().Month()
		return
	}

	if i > 12 {
		err = ErrBadMonth
		return
	}

	mon = time.Month(i)

	return
}

/*
tmParseMonthStr parses a string representation of month s to a time.Month.

It normalizes s to lowercase and only uses the first 3 characters
(the minimum length needed to determine month name
uniqueness - "June" vs. "July", "March" vs. "May").

An empty (or whitespace-only) string will use the current month (as determined by time.Now).
*/
func tmParseMonthStr(s string) (mon time.Month, err error) {

	var i int
	var m time.Month

	if strings.TrimSpace(s) == "" {
		mon = time.Now().Month()
		return
	}

	s = strings.ToLower(strings.TrimSpace(s))[0:3]

	for i = range 12 {
		m = time.Month(i + 1)
		if strings.ToLower(m.String())[0:3] == s {
			mon = m
			return
		}
	}

	err = ErrBadMonth

	return
}