package xlsx

import (
	"errors"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/leonm1/airports-go"
)

type Ticket struct {
	Sheet        string
	Passenger    string
	Title        string
	FlightNumber string
	FromCity     string
	ToCity       string
	FromAirport  string
	ToAirport    string
	FlightDate   string // (raw, expected YYYY-MM-DD; Excel text may start with ')
	FlightTime   string // (raw, expected HH-MM or HH:MM; Excel text may start with ')
	PNR          string
	Card         string
	TicketNumber string //  (may have a leading ' in Excel)
}

func (t Ticket) DateTime() (time.Time, *time.Location, error) {
	loc := t.inferLocationFromAirports()
	date := strings.TrimLeft(strings.TrimSpace(t.FlightDate), "'")
	hm := strings.TrimLeft(strings.TrimSpace(t.FlightTime), "'")
	hm = strings.ReplaceAll(hm, "-", ":")

	if date == "" || hm == "" {
		return time.Time{}, loc, errors.New("missing FlightDate or FlightTime")
	}
	ts, err := time.ParseInLocation("2006-01-02 15:04", date+" "+hm, loc)
	return ts, loc, err
}

func (t Ticket) inferLocationFromAirports() *time.Location {
	if loc := iataToLocation(t.FromAirport); loc != nil {
		return loc
	}
	if loc := iataToLocation(t.ToAirport); loc != nil {
		return loc
	}
	return time.Local
}

func iataToLocation(code string) *time.Location {
	iata := strings.ToUpper(strings.TrimSpace(code))
	if len(iata) != 3 {
		return nil
	}
	ap, err := airports.LookupIATA(iata)
	if err != nil {
		return nil
	}
	// Prefer IANA tz name
	if tz := strings.TrimSpace(ap.Tz); tz != "" && tz != `\N` {
		if loc, err := time.LoadLocation(tz); err == nil {
			return loc
		}
	}
	// Fallback: fixed offset (no DST)
	if ap.Timezone != 0 {
		sec := int(ap.Timezone * 3600.0)
		return time.FixedZone("UTC"+offsetLabel(sec), sec)
	}
	return nil
}

func offsetLabel(sec int) string {
	sign := "+"
	if sec < 0 {
		sign = "-"
		sec = -sec
	}
	h := sec / 3600
	m := (sec % 3600) / 60
	return sign + two(h) + ":" + two(m)
}
func two(x int) string {
	if x < 10 {
		return "0" + strconv.Itoa(x)
	}
	return strconv.Itoa(x)
}

func parseCardLine(s string) (prefix string, number uint64, bonus string) {
	raw := strings.TrimSpace(s)
	if raw == "" {
		return "", 0, ""
	}
	// number = last run of digits
	if m := regexp.MustCompile(`(\d{3,})\D*$`).FindStringSubmatch(raw); len(m) == 2 {
		if n, err := strconv.ParseUint(m[1], 10, 64); err == nil {
			number = n
		}
	}

	// tokens (letters with '-', '/', apostrophes)
	tokRe := regexp.MustCompile(`[A-Za-z][A-Za-z'/-]*`)
	toks := tokRe.FindAllString(s, -1)

	// prefix = first 2–3 letter all-caps-ish token
	for _, t := range toks {
		u := strings.ToUpper(t)
		if len(u) >= 2 && len(u) <= 3 && regexp.MustCompile(`^[A-Z]{2,3}$`).MatchString(u) {
			prefix = u
			break
		}
	}
	// bonus = all tokens except prefix
	words := []string{}
	for _, t := range toks {
		if strings.ToUpper(t) == prefix {
			continue
		}
		words = append(words, t)
	}
	if len(words) > 0 {
		bonus = strings.Join(words, " ")
	}
	if bonus == "" && prefix != "" {
		bonus = prefix
	}
	return
}

func firstNonEmpty(a, b string) string {
	if strings.TrimSpace(a) != "" {
		return a
	}
	return b
}