package server

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

	peering "forge.cadoles.com/wpetit/go-http-peering"
	"forge.cadoles.com/wpetit/go-http-peering/crypto"
)

var (
	ErrInvalidAdvertisingRequest = errors.New("invalid advertising request")
	ErrInvalidUpdateRequest      = errors.New("invalid update request")
	ErrPeerRejected              = errors.New("peer rejected")
	ErrPeerIDAlreadyInUse        = errors.New("peer id already in use")
	ErrUnauthorized              = errors.New("unauthorized")
)

func AdvertiseHandler(store peering.Store, funcs ...OptionFunc) http.HandlerFunc {

	options := createOptions(funcs...)
	logger := options.Logger

	handler := func(w http.ResponseWriter, r *http.Request) {
		advertising := &peering.AdvertisingRequest{}

		decoder := json.NewDecoder(r.Body)
		if err := decoder.Decode(advertising); err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, ErrInvalidAdvertisingRequest)
			return
		}

		if !options.PeerIDValidator(advertising.ID) {
			logger.Printf("[ERROR] %s", ErrInvalidAdvertisingRequest)
			options.ErrorHandler(w, r, ErrInvalidAdvertisingRequest)
			return
		}

		if _, err := crypto.DecodePEMToPublicKey(advertising.PublicKey); err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, ErrInvalidAdvertisingRequest)
			return
		}

		peer, err := store.Get(advertising.ID)

		if err == nil {
			logger.Printf("[ERROR] %s", ErrPeerIDAlreadyInUse)
			options.ErrorHandler(w, r, ErrPeerIDAlreadyInUse)
			return
		}

		if err != peering.ErrPeerNotFound {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		attrs := filterAttributes(options.PeerAttributes, advertising.Attributes)

		peer, err = store.Create(advertising.ID, attrs)
		if err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		if err := store.UpdateLastContact(peer.ID, r.RemoteAddr, time.Now()); err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		if err := store.UpdatePublicKey(peer.ID, advertising.PublicKey); err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		w.WriteHeader(http.StatusCreated)

	}

	return handler
}

func UpdateHandler(store peering.Store, funcs ...OptionFunc) http.HandlerFunc {
	options := createOptions(funcs...)
	logger := options.Logger

	handler := func(w http.ResponseWriter, r *http.Request) {

		update := &peering.UpdateRequest{}
		decoder := json.NewDecoder(r.Body)
		if err := decoder.Decode(update); err != nil {
			options.ErrorHandler(w, r, ErrInvalidUpdateRequest)
			return
		}

		peerID, err := GetPeerID(r)
		if err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		peer, err := store.Get(peerID)
		if err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		if peer == nil {
			logger.Printf("[ERROR] %s", ErrUnauthorized)
			options.ErrorHandler(w, r, ErrUnauthorized)
			return
		}

		if peer.Status == peering.StatusRejected {
			logger.Printf("[ERROR] %s", ErrPeerRejected)
			options.ErrorHandler(w, r, ErrPeerRejected)
			return
		}

		if err := store.UpdateLastContact(peer.ID, r.RemoteAddr, time.Now()); err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		attrs := filterAttributes(options.PeerAttributes, update.Attributes)
		if err := store.UpdateAttributes(peer.ID, attrs); err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		w.WriteHeader(http.StatusNoContent)

	}

	return handler
}

func PingHandler(store peering.Store, funcs ...OptionFunc) http.HandlerFunc {
	options := createOptions(funcs...)
	logger := options.Logger

	handler := func(w http.ResponseWriter, r *http.Request) {

		update := &peering.UpdateRequest{}
		decoder := json.NewDecoder(r.Body)
		if err := decoder.Decode(update); err != nil {
			options.ErrorHandler(w, r, ErrInvalidUpdateRequest)
			return
		}

		peerID, err := GetPeerID(r)
		if err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		peer, err := store.Get(peerID)
		if err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		if peer == nil {
			logger.Printf("[ERROR] %s", ErrUnauthorized)
			options.ErrorHandler(w, r, ErrUnauthorized)
			return
		}

		if peer.Status == peering.StatusRejected {
			logger.Printf("[ERROR] %s", ErrPeerRejected)
			options.ErrorHandler(w, r, ErrPeerRejected)
			return
		}

		if err := store.UpdateLastContact(peer.ID, r.RemoteAddr, time.Now()); err != nil {
			logger.Printf("[ERROR] %s", err)
			options.ErrorHandler(w, r, err)
			return
		}

		w.WriteHeader(http.StatusNoContent)
	}

	return handler
}

func DefaultErrorHandler(w http.ResponseWriter, r *http.Request, err error) {
	switch err {
	case ErrInvalidAdvertisingRequest:
		http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
	case ErrPeerIDAlreadyInUse:
		http.Error(w, http.StatusText(http.StatusConflict), http.StatusConflict)
	case ErrUnauthorized:
		http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
	case ErrPeerRejected:
		http.Error(w, http.StatusText(http.StatusForbidden), http.StatusForbidden)
	default:
		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
	}
}

func DefaultPeerIDValidator(id peering.PeerID) bool {
	return string(id) != ""
}

func filterAttributes(filters []string, attrs peering.PeerAttributes) peering.PeerAttributes {
	filtered := peering.PeerAttributes{}
	for _, key := range filters {
		if _, exists := attrs[key]; exists {
			filtered[key] = attrs[key]
		}
	}
	return filtered
}