package ical

import (
	"bufio"
	"fmt"
	"log"
	"net/http"
	"strings"
	"time"

	"github.com/f4bpo/rental-manager/internal/calendar"
	"github.com/f4bpo/rental-manager/internal/property"
)

type Service struct {
	calStore  *calendar.Store
	propStore *property.Store
}

func NewService(calStore *calendar.Store, propStore *property.Store) *Service {
	return &Service{calStore: calStore, propStore: propStore}
}

// StartSync lance une goroutine qui synchronise toutes les heures
func (s *Service) StartSync() {
	go func() {
		s.syncAll()
		ticker := time.NewTicker(1 * time.Hour)
		for range ticker.C {
			s.syncAll()
		}
	}()
}

func (s *Service) SyncProperty(prop *property.Property) (int, error) {
	if prop.IcalURL == "" {
		return 0, fmt.Errorf("pas d'URL iCal pour %s", prop.Name)
	}

	req, err := http.NewRequest("GET", prop.IcalURL, nil)
	if err != nil {
		return 0, fmt.Errorf("erreur création requête iCal: %w", err)
	}
	req.Header.Set("User-Agent", "Mozilla/5.0 (compatible; RentalManager/1.0)")

	client := &http.Client{Timeout: 30 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return 0, fmt.Errorf("erreur fetch iCal: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return 0, fmt.Errorf("iCal HTTP %d pour %s", resp.StatusCode, prop.IcalURL)
	}

	events, err := parseIcal(resp, prop.ID)
	if err != nil {
		return 0, err
	}

	// Supprimer les anciens événements iCal pour repartir d'une base propre
	// (gère aussi les réservations annulées et les doublons)
	if err := s.calStore.DeleteIcalEvents(prop.ID); err != nil {
		return 0, fmt.Errorf("erreur nettoyage calendrier: %w", err)
	}

	imported := 0
	for _, e := range events {
		if err := s.calStore.InsertFromIcal(&e); err != nil {
			log.Printf("ical: erreur insert event %s: %v", e.IcalUID, err)
			continue
		}
		imported++
	}
	return imported, nil
}

type SyncResult struct {
	Property string `json:"property"`
	Imported int    `json:"imported"`
	Error    string `json:"error,omitempty"`
}

func (s *Service) SyncAll() []SyncResult {
	props, err := s.propStore.ListWithIcal()
	if err != nil {
		log.Printf("ical sync: erreur liste propriétés: %v", err)
		return []SyncResult{{Property: "system", Error: err.Error()}}
	}
	log.Printf("ical sync: %d propriété(s) avec URL iCal trouvée(s)", len(props))
	if len(props) == 0 {
		return []SyncResult{{Property: "system", Error: "aucune propriété avec URL iCal configurée"}}
	}
	var results []SyncResult
	for _, p := range props {
		n, err := s.SyncProperty(&p)
		if err != nil {
			log.Printf("ical sync [%s]: erreur: %v", p.Name, err)
			s.calStore.LogSync(p.ID, "error", 0, err.Error())
			results = append(results, SyncResult{Property: p.Name, Error: err.Error()})
		} else {
			log.Printf("ical sync [%s]: %d événements importés", p.Name, n)
			s.calStore.LogSync(p.ID, "ok", n, "")
			results = append(results, SyncResult{Property: p.Name, Imported: n})
		}
	}
	return results
}

func (s *Service) syncAll() { s.SyncAll() }

// parseIcal parse un flux iCal et retourne les événements VEVENT
func parseIcal(resp *http.Response, propertyID string) ([]calendar.Event, error) {
	// Unfold iCal lines (RFC 5545: continuation lines start with space or tab)
	lines := unfoldIcal(resp)

	var events []calendar.Event
	var current *calendar.Event

	for _, line := range lines {
		line = strings.TrimRight(line, "\r\n")
		if line == "" {
			continue
		}

		switch {
		case line == "BEGIN:VEVENT":
			current = &calendar.Event{PropertyID: propertyID, Source: "airbnb"}

		case line == "END:VEVENT" && current != nil:
			if current.IcalUID != "" && current.StartDate != "" && current.EndDate != "" {
				events = append(events, *current)
			} else {
				log.Printf("ical: VEVENT ignoré (uid=%q start=%q end=%q)", current.IcalUID, current.StartDate, current.EndDate)
			}
			current = nil

		case current != nil:
			key, value, found := strings.Cut(line, ":")
			if !found {
				continue
			}
			// Gérer les paramètres du type DTSTART;VALUE=DATE:20240601
			baseKey := strings.SplitN(key, ";", 2)[0]
			switch baseKey {
			case "UID":
				current.IcalUID = value
			case "SUMMARY":
				current.Title = unescapeIcal(value)
			case "DTSTART":
				current.StartDate = parseIcalDate(value)
			case "DTEND":
				current.EndDate = parseIcalDate(value)
			case "DESCRIPTION":
				current.Notes = unescapeIcal(value)
			}
		}
	}
	log.Printf("ical: %d événements parsés pour la propriété %s", len(events), propertyID)
	return events, nil
}

// unfoldIcal joint les lignes repliées (RFC 5545 §3.1)
func unfoldIcal(resp *http.Response) []string {
	scanner := bufio.NewScanner(resp.Body)
	scanner.Buffer(make([]byte, 1024*1024), 1024*1024) // 1MB buffer
	var lines []string
	for scanner.Scan() {
		text := scanner.Text()
		if len(lines) > 0 && len(text) > 0 && (text[0] == ' ' || text[0] == '\t') {
			// Continuation line: append to previous
			lines[len(lines)-1] += strings.TrimLeft(text, " \t")
		} else {
			lines = append(lines, text)
		}
	}
	return lines
}

func parseIcalDate(s string) string {
	// Extraire uniquement la partie date (avant tout T, +, -)
	// pour gérer : YYYYMMDD, YYYYMMDDTHHMMSSZ, YYYYMMDDTHHMMSS, YYYYMMDDTHHMMSS+HHMM, etc.
	raw := strings.SplitN(s, "T", 2)[0] // prend "YYYYMMDD" avant le T éventuel
	raw = strings.SplitN(raw, "+", 2)[0]
	raw = strings.SplitN(raw, "Z", 2)[0]

	if len(raw) == 8 {
		return fmt.Sprintf("%s-%s-%s", raw[0:4], raw[4:6], raw[6:8])
	}
	// Déjà au format YYYY-MM-DD
	if len(s) >= 10 && s[4] == '-' {
		return s[:10]
	}
	return s
}

func unescapeIcal(s string) string {
	s = strings.ReplaceAll(s, `\n`, "\n")
	s = strings.ReplaceAll(s, `\,`, ",")
	s = strings.ReplaceAll(s, `\;`, ";")
	s = strings.ReplaceAll(s, `\\`, `\`)
	return s
}