package webhook

import (
	"encoding/json"
	"net/http"
	"time"

	"go.fifitido.net/twitch/api/eventsub"
	"go.fifitido.net/twitch/eventsub/webhook/messages"
)

var _ http.Handler = (*Transport)(nil)

// ServeHTTP implements http.Handler.
func (t *Transport) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	timestamp, err := time.Parse(time.RFC3339, r.Header.Get("Twitch-Eventsub-Message-Timestamp"))
	if err != nil {
		http.Error(w, "failed to parse timestamp", http.StatusBadRequest)
		return
	}

	msg := &messages.Message{
		Id:        r.Header.Get("Twitch-Eventsub-Message-Id"),
		Retry:     r.Header.Get("Twitch-Eventsub-Message-Retry"),
		Type:      messages.Type(r.Header.Get("Twitch-Eventsub-Message-Type")),
		Signature: r.Header.Get("Twitch-Eventsub-Message-Signature"),
		Timestamp: timestamp,
		SubscriptionType: &eventsub.SubscriptionType{
			Name:    r.Header.Get("Twitch-Eventsub-Subscription-Type"),
			Version: r.Header.Get("Twitch-Eventsub-Subscription-Version"),
		},
	}

	switch msg.Type {
	case messages.TypeNotification:
		var payload messages.Notification
		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
			http.Error(w, "failed to parse message", http.StatusBadRequest)
			return
		}
		msg.Data = &payload

		if t.opts.EventsHandler != nil {
			if err := t.opts.EventsHandler.Handle(msg); err != nil {
				http.Error(w, "failed to handle message", http.StatusInternalServerError)
				return
			}
		}
	case messages.TypeWebhookCallbackVerification:
		var payload messages.WebhookCallbackVerification
		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
			http.Error(w, "failed to parse message", http.StatusBadRequest)
			return
		}
		msg.Data = &payload

		w.Header().Set("Content-Type", "text/plain")
		w.Write([]byte(payload.Challenge))
		w.WriteHeader(http.StatusOK)
		return
	case messages.TypeRevocation:
		var payload messages.Revocation
		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
			http.Error(w, "failed to parse message", http.StatusBadRequest)
			return
		}
		msg.Data = &payload

		if t.opts.RevocationHandler != nil {
			if err := t.opts.RevocationHandler.Handle(); err != nil {
				http.Error(w, "failed to handle message", http.StatusInternalServerError)
				return
			}
		}
	}

	w.WriteHeader(http.StatusNoContent)
}