package inplace

import "../common"
import "core:bytes"
import "core:fmt"
import "core:mem"
import "core:strings"
import "core:time"
import "core:time/datetime"

format_date :: proc(
	dt: common.Date_Components,
	fmt: string,
	allocator := context.temp_allocator,
) -> string {
	b := make([]byte, len(fmt), context.temp_allocator)
	x := transmute([]byte)(fmt)
	mem.copy_non_overlapping(&b[0], &x, len(fmt))


	return string(b)
	// for i := 0; i < len(fmt); {
	// 	matched := match_token(&b, dt, fmt[i:])
	// 	if matched > 0 {
	// 		i += matched
	// 	} else {
	// 		strings.write_byte(&b, fmt[i])
	// 		i += 1
	// 	}
	// }

	// log.debugf("formatted date: '%s'", b.buf)
	// return strings.to_string(b)
}

FULL_MONTH: string : "January"

match_token :: proc(s: []byte, dt: common.Date_Components) {
	if bytes.equal(s[:len(FULL_MONTH)], transmute([]u8)FULL_MONTH) {
		mo := fmt.tprintf("%s", time.Month(dt.month))
		mem.copy_non_overlapping(&s[0], &(transmute([]u8)mo)[0], len(mo))
	}
	/*
	if strings.has_prefix(s, "Monday") {emit_weekday(b, dt, full = true); return 6}
	if strings.has_prefix(
		s,
		"2006",
	) {strings.write_string(b, fmt.tprintf("%04d", dt.year)); return 4}
	if strings.has_prefix(s, "MST") {strings.write_string(b, "UTC"); return 3}
	if strings.has_prefix(s, "Jan") {emit_month_abbr(b, dt); return 3}
	if strings.has_prefix(s, "Mon") {emit_weekday(b, dt, full = false); return 3}
	if strings.has_prefix(
		s,
		"06",
	) {strings.write_string(b, fmt.tprintf("%02d", dt.year % 100)); return 2}
	if strings.has_prefix(s, "02") {strings.write_string(b, fmt.tprintf("%02d", dt.day)); return 2}
	if strings.has_prefix(
		s,
		"15",
	) {strings.write_string(b, fmt.tprintf("%02d", dt.hour)); return 2}
	if strings.has_prefix(
		s,
		"04",
	) {strings.write_string(b, fmt.tprintf("%02d", dt.minute)); return 2}
	if strings.has_prefix(
		s,
		"05",
	) {strings.write_string(b, fmt.tprintf("%02d", dt.second)); return 2}
	if strings.has_prefix(
		s,
		"01",
	) {strings.write_string(b, fmt.tprintf("%02d", dt.month)); return 2}
	if strings.has_prefix(s, "03") {emit_hour_12(b, dt, pad = true); return 2}
	if strings.has_prefix(s, "PM") {
		strings.write_string(b, "PM" if dt.hour >= 12 else "AM")
		return 2
	}
	if strings.has_prefix(s, "pm") {
		strings.write_string(b, "pm" if dt.hour >= 12 else "am")
		return 2
	}
	if len(s) >= 1 {
		switch s[0] {
		case '2':
			strings.write_string(b, fmt.tprintf("%d", dt.day)); return 1
		case '1':
			strings.write_string(b, fmt.tprintf("%d", dt.month)); return 1
		case '4':
			strings.write_string(b, fmt.tprintf("%d", dt.minute)); return 1
		case '5':
			strings.write_string(b, fmt.tprintf("%d", dt.second)); return 1
		case '3':
			emit_hour_12(b, dt, pad = false); return 1
		case:
			return 0
		}
	}
	*/
}

emit_month_abbr :: proc(b: ^strings.Builder, dt: common.Date_Components) {
	name := fmt.tprintf("%s", time.Month(dt.month))
	strings.write_string(b, name[:3 if len(name) >= 3 else len(name)])
}

emit_weekday :: proc(b: ^strings.Builder, dt: common.Date_Components, full: bool) {
	date := datetime.Date {
		year  = i64(dt.year),
		month = i8(dt.month),
		day   = i8(dt.day),
	}
	ordinal, err := datetime.date_to_ordinal(date)
	if err != .None {
		strings.write_string(b, "???")
		return
	}
	weekday := datetime.day_of_week(ordinal)
	name := fmt.tprintf("%s", weekday)
	if full {
		strings.write_string(b, name)
	} else {
		strings.write_string(b, name[:3 if len(name) >= 3 else len(name)])
	}
}

emit_hour_12 :: proc(b: ^strings.Builder, dt: common.Date_Components, pad: bool) {
	h12 := dt.hour % 12
	if h12 == 0 {h12 = 12}
	format := "%02d" if pad else "%d"

	fmt.sbprintf(b, format, h12)
}