package salty

import (
	"context"
	"crypto/sha256"
	"encoding/json"
	"errors"
	"fmt"
	"net"
	"net/http"
	"net/url"
	"strings"

	"github.com/keys-pub/keys"
	"github.com/sour-is/ev/internal/lg"
	"github.com/sour-is/ev/pkg/es"
	"github.com/sour-is/ev/pkg/es/event"
	"github.com/sour-is/ev/pkg/gql"
	"go.opentelemetry.io/otel/metric/instrument/syncint64"
	"go.uber.org/multierr"
)

type DNSResolver interface {
	LookupSRV(ctx context.Context, service, proto, name string) (string, []*net.SRV, error)
}

type service struct {
	baseURL string
	es      *es.EventStore
	dns     DNSResolver

	m_create_user  syncint64.Counter
	m_get_user     syncint64.Counter
	m_api_ping     syncint64.Counter
	m_api_register syncint64.Counter
	m_api_lookup   syncint64.Counter
	m_api_send     syncint64.Counter
}
type contextKey struct {
	name string
}

var saltyKey = contextKey{"salty"}

type SaltyResolver interface {
	CreateSaltyUser(ctx context.Context, nick string, pub string) (*SaltyUser, error)
	SaltyUser(ctx context.Context, nick string) (*SaltyUser, error)
	RegisterHTTP(mux *http.ServeMux)
}

func New(ctx context.Context, es *es.EventStore, baseURL string) (*service, error) {
	ctx, span := lg.Span(ctx)
	defer span.End()

	if err := event.Register(ctx, &UserRegistered{}); err != nil {
		return nil, err
	}
	if err := event.RegisterName(ctx, "domain.UserRegistered", &UserRegistered{}); err != nil {
		return nil, err
	}

	m := lg.Meter(ctx)

	svc := &service{baseURL: baseURL, es: es, dns: net.DefaultResolver}

	var err, errs error
	svc.m_create_user, err = m.SyncInt64().Counter("salty_create_user")
	errs = multierr.Append(errs, err)

	svc.m_get_user, err = m.SyncInt64().Counter("salty_get_user")
	errs = multierr.Append(errs, err)

	svc.m_api_ping, err = m.SyncInt64().Counter("salty_api_ping")
	errs = multierr.Append(errs, err)

	svc.m_api_register, err = m.SyncInt64().Counter("salty_api_register")
	errs = multierr.Append(errs, err)

	svc.m_api_lookup, err = m.SyncInt64().Counter("salty_api_lookup")
	errs = multierr.Append(errs, err)

	svc.m_api_send, err = m.SyncInt64().Counter("salty_api_send")
	errs = multierr.Append(errs, err)
	span.RecordError(err)

	return svc, errs
}

func (s *service) BaseURL() string {
	if s == nil {
		return "http://missing.context/"
	}
	return s.baseURL
}
func (s *service) RegisterHTTP(mux *http.ServeMux) {
	mux.Handle("/.well-known/salty/", lg.Htrace(s, "lookup"))
}
func (s *service) RegisterAPIv1(mux *http.ServeMux) {
	mux.HandleFunc("/ping", s.apiv1)
	mux.HandleFunc("/register", s.apiv1)
	mux.HandleFunc("/lookup/", s.apiv1)
	mux.HandleFunc("/send", s.apiv1)
}
func (s *service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	ctx, span := lg.Span(ctx)
	defer span.End()

	addr := "saltyuser-" + strings.TrimPrefix(r.URL.Path, "/.well-known/salty/")
	addr = strings.TrimSuffix(addr, ".json")

	span.AddEvent(fmt.Sprint("find ", addr))
	a, err := es.Update(ctx, s.es, addr, func(ctx context.Context, agg *SaltyUser) error { return nil })
	switch {
	case errors.Is(err, event.ErrShouldExist):
		span.RecordError(err)

		w.WriteHeader(http.StatusNotFound)
		return
	case err != nil:
		span.RecordError(err)

		w.WriteHeader(http.StatusInternalServerError)
		return
	}

	basePath, _ := url.JoinPath(s.baseURL, a.inbox.String())

	err = json.NewEncoder(w).Encode(
		struct {
			Endpoint string `json:"endpoint"`
			Key      string `json:"key"`
		}{
			Endpoint: basePath,
			Key:      a.pubkey.ID().String(),
		})
	if err != nil {
		span.RecordError(err)
	}
}
func (s *service) CreateSaltyUser(ctx context.Context, nick string, pub string) (*SaltyUser, error) {
	ctx, span := lg.Span(ctx)
	defer span.End()

	s.m_create_user.Add(ctx, 1)

	streamID := fmt.Sprintf("saltyuser-%x", sha256.Sum256([]byte(strings.ToLower(nick))))
	span.AddEvent(streamID)

	key, err := keys.NewEdX25519PublicKeyFromID(keys.ID(pub))
	if err != nil {
		span.RecordError(err)
		return nil, err
	}

	a, err := es.Create(ctx, s.es, streamID, func(ctx context.Context, agg *SaltyUser) error {
		return agg.OnUserRegister(nick, key)
	})
	switch {
	case errors.Is(err, es.ErrShouldNotExist):
		span.RecordError(err)
		return nil, fmt.Errorf("user exists")

	case err != nil:
		span.RecordError(err)
		return nil, fmt.Errorf("internal error")
	}

	return a, nil
}
func (s *service) SaltyUser(ctx context.Context, nick string) (*SaltyUser, error) {
	ctx, span := lg.Span(ctx)
	defer span.End()

	s.m_get_user.Add(ctx, 1)

	streamID := fmt.Sprintf("saltyuser-%x", sha256.Sum256([]byte(strings.ToLower(nick))))
	span.AddEvent(streamID)

	a, err := es.Update(ctx, s.es, streamID, func(ctx context.Context, agg *SaltyUser) error { return nil })
	switch {
	case errors.Is(err, es.ErrShouldExist):
		span.RecordError(err)
		return nil, fmt.Errorf("user not found")

	case err != nil:
		span.RecordError(err)
		return nil, fmt.Errorf("%w internal error", err)
	}

	return a, err
}
func (s *service) GetMiddleware() func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			r = r.WithContext(gql.ToContext(r.Context(), saltyKey, s))
			next.ServeHTTP(w, r)
		})
	}
}

func (s *service) apiv1(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	ctx, span := lg.Span(ctx)
	defer span.End()

	switch r.Method {
	case http.MethodGet:
		switch {
		case r.URL.Path == "/ping":
			w.Header().Set("Content-Type", "application/json")
			_, _ = w.Write([]byte(`{}`))

		case strings.HasPrefix(r.URL.Path, "/lookup/"):
			addr, err := s.ParseAddr(strings.TrimPrefix(r.URL.Path, "/lookup/"))
			if err != nil {
				span.RecordError(err)
				w.WriteHeader(http.StatusBadRequest)
				return
			}
			err = addr.Refresh(ctx)
			if err != nil {
				span.RecordError(err)
				w.WriteHeader(http.StatusBadRequest)
				return
			}

			json.NewEncoder(w).Encode(addr)
			return

		default:
			w.WriteHeader(http.StatusNotFound)
			return
		}

	case http.MethodPost:
		switch r.URL.Path {
		case "/register":

		case "/send":

		default:
			w.WriteHeader(http.StatusNotFound)
			return
		}
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}
}