package collection

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"math/rand"
	"net/http"
	"strings"
	"time"

	"git.nutfactory.org/hoernschen/ActivityPub/config"
	"git.nutfactory.org/hoernschen/ActivityPub/entities/activity"
	"git.nutfactory.org/hoernschen/ActivityPub/entities/actor"
	"git.nutfactory.org/hoernschen/ActivityPub/entities/object"
	"git.nutfactory.org/hoernschen/ActivityPub/entities/user"
	"git.nutfactory.org/hoernschen/ActivityPub/utils"

	"github.com/cenkalti/backoff/v4"
	"github.com/gorilla/mux"
)

func PostInboxHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", utils.GetContentTypeString())
	newActivity := &activity.Activity{}
	err := utils.CheckRequest(r)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		if err := json.NewEncoder(w).Encode(err); err != nil {
			panic(err)
		}
		return
	}
	token, err := utils.GetAccessToken(r)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		if err := json.NewEncoder(w).Encode(err); err != nil {
			panic(err)
		}
		return
	}
	if token == "" {
		w.WriteHeader(http.StatusBadRequest)
		if err := json.NewEncoder(w).Encode("Missing Token"); err != nil {
			panic(err)
		}
		return
	}
	vars := mux.Vars(r)
	actorName := vars["actorName"]
	if actorName == "" {
		w.WriteHeader(http.StatusBadRequest)
		if err := json.NewEncoder(w).Encode("Missing Actor"); err != nil {
			panic(err)
		}
		return
	}
	decoder := json.NewDecoder(r.Body)
	err = decoder.Decode(&newActivity)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		if err := json.NewEncoder(w).Encode(fmt.Sprintf("Could not parse JSON: %s", err)); err != nil {
			panic(err)
		}
		return
	}

	if newActivity.Type == "Follow" {
		err = CreateCollectionObject(utils.GenerateFollowersUrl(actorName), newActivity.Actor)
		if err != nil {
			w.WriteHeader(http.StatusBadRequest)
			if err := json.NewEncoder(w).Encode(fmt.Sprintf("Database Error Creating Collection Object: %s", err)); err != nil {
				panic(err)
			}
			return
		}
		log.Printf("%s follows %s", newActivity.Actor, newActivity.To)
	} else if newActivity.Type == "Create" {
		foundObject, err := object.ReadObject(newActivity.Object.Id)
		if err != nil {
			w.WriteHeader(http.StatusBadRequest)
			if err := json.NewEncoder(w).Encode(fmt.Sprintf("Database Error Reading Object: %s", err)); err != nil {
				panic(err)
			}
			return
		}
		if foundObject == nil {
			_ = object.CreateObject(newActivity.Object)

			if err != nil {
				w.WriteHeader(http.StatusBadRequest)
				if err := json.NewEncoder(w).Encode(fmt.Sprintf("Database Error Creating Object: %s", err)); err != nil {
					panic(err)
				}
				return
			}

		}
		_ = CreateCollectionObject(utils.GenerateInboxUrl(actorName), newActivity.Object.Id)

		if err != nil {
			w.WriteHeader(http.StatusBadRequest)
			if err := json.NewEncoder(w).Encode(fmt.Sprintf("Database Error Creating Collection Object: %s", err)); err != nil {
				panic(err)
			}
			return
		}

		log.Printf("%s to %s: %s", newActivity.Actor, newActivity.To, newActivity.Object.Content)
	} else {
		w.WriteHeader(http.StatusBadRequest)
		if err := json.NewEncoder(w).Encode("Unsupported Activity Type"); err != nil {
			panic(err)
		}
		return
	}

	w.WriteHeader(http.StatusOK)
}

func PostOutboxHandler(w http.ResponseWriter, r *http.Request) {
	packetLossNumber := rand.Intn(100)
	if packetLossNumber > config.Packetloss {
		w.Header().Set("Content-Type", utils.GetContentTypeString())
		newActivity := &activity.Activity{}
		err := utils.CheckRequest(r)
		if err != nil {
			w.WriteHeader(http.StatusBadRequest)
			if err := json.NewEncoder(w).Encode(err); err != nil {
				panic(err)
			}
			return
		}
		token, err := utils.GetAccessToken(r)
		if err != nil {
			w.WriteHeader(http.StatusBadRequest)
			if err := json.NewEncoder(w).Encode(err); err != nil {
				panic(err)
			}
			return
		}
		foundUser, err := user.ReadUserFromToken(token)
		if err != nil || foundUser == nil {
			w.WriteHeader(http.StatusBadRequest)
			if err := json.NewEncoder(w).Encode(fmt.Sprintf("Unknown Token: %s", err)); err != nil {
				panic(err)
			}
			return
		}
		buf := new(bytes.Buffer)
		buf.ReadFrom(r.Body)
		err = json.Unmarshal(buf.Bytes(), newActivity)
		if err != nil || newActivity.Type == "Note" {
			postedObject := &object.Object{}
			err = json.Unmarshal(buf.Bytes(), postedObject)
			if err != nil {
				w.WriteHeader(http.StatusBadRequest)
				if err := json.NewEncoder(w).Encode(fmt.Sprintf("Could not parse JSON: %s")); err != nil {
					panic(err)
				}
				return
			}
			var newObject *object.Object
			if postedObject.Id == "" {
				err, newObject = object.New(
					postedObject.Type,
					postedObject.AttributedTo,
					postedObject.Content,
					postedObject.Published,
					postedObject.To,
					foundUser.Id,
				)
				if err != nil {
					w.WriteHeader(http.StatusBadRequest)
					if err := json.NewEncoder(w).Encode(fmt.Sprintf("Error Creating Object: %s")); err != nil {
						panic(err)
					}
					return
				}
				err = object.CreateObject(newObject)
				if err != nil {
					w.WriteHeader(http.StatusBadRequest)
					if err := json.NewEncoder(w).Encode(fmt.Sprintf("Database Error Creating Object: %s")); err != nil {
						panic(err)
					}
					return
				}
			} else {
				newObject = postedObject
			}
			newActivity = activity.New(
				newObject.Id,
				newObject.AttributedTo,
				newObject,
				foundUser.Id,
			)
		}

		var recipients []string
		if newActivity.Type == "Follow" {
			err = CreateCollectionObject(utils.GenerateFollowingUrl(foundUser.Id), newActivity.To)
			if err != nil {
				w.WriteHeader(http.StatusBadRequest)
				if err := json.NewEncoder(w).Encode(fmt.Sprintf("Database Error Creating Collection Object: %s")); err != nil {
					panic(err)
				}
				return
			}
			recipients = append(recipients, newActivity.To)
		} else if newActivity.Type == "Create" {
			err = CreateCollectionObject(utils.GenerateOutboxUrl(foundUser.Id), newActivity.Id)
			if err != nil {
				w.WriteHeader(http.StatusBadRequest)
				if err := json.NewEncoder(w).Encode(fmt.Sprintf("Database Error Creating Collection Object: %s")); err != nil {
					panic(err)
				}
				return
			}
			err, recipients = GetReciepientsForActivity(newActivity)
		}

		for _, recipient := range recipients {
			log.Printf("Send Activity to Recipient %s", recipient)

			operation := func() error {
				return SendActivity(newActivity, recipient, token)
			}
			notify := func(err error, duration time.Duration) {
				log.Printf("Error Sending Activity, retrying in %ss: %s", duration/1000000000, err)
			}
			backoff.RetryNotify(operation, backoff.WithMaxRetries(backoff.NewExponentialBackOff(), 16), notify)
		}

		response := OutboxResponse{
			Location: newActivity.Id,
		}

		w.WriteHeader(http.StatusOK)
		if err := json.NewEncoder(w).Encode(response); err != nil {
			panic(err)
		}
	}
}

func GetReciepientsForActivity(activityToSend *activity.Activity) (err error, recipientsWithoutDuplicates []string) {
	recipients := []string{}
	if strings.Contains(activityToSend.To, config.Homeserver) {
		var foundActor *actor.Actor
		foundActor, err = actor.ReadActor(activityToSend.To)
		if err != nil {
			return
		}
		if foundActor == nil {
			var foundCollectionObjects []string
			foundCollectionObjects, err = ReadCollectionObjects(activityToSend.To)
			if err != nil {
				return
			}
			if len(foundCollectionObjects) <= 0 {
				err = errors.New("No Recipients")
				return
			}
			recipients = append(recipients, foundCollectionObjects...)
		} else {
			recipients = append(recipients, foundActor.Id)
		}
	} else {
		// Not Implemented
	}
	recipientsWithoutDuplicates = utils.RemoveDuplicates(recipients)
	return
}

func SendActivity(activityToSend *activity.Activity, recipient string, token string) (err error) {
	if strings.Contains(recipient, config.Homeserver) {
		if activityToSend.Type == "Follow" {
			followers := fmt.Sprintf("%sfollowers/", activityToSend.To)
			err = CreateCollectionObject(followers, activityToSend.Actor)
			if err != nil {
				return
			}
			log.Printf("%s follows %s", activityToSend.Actor, activityToSend.To)
		} else if activityToSend.Type == "Create" {
			id := activityToSend.Id
			if activityToSend.Object != nil {
				id = activityToSend.Object.Id
			}
			inbox := fmt.Sprintf("%sinbox", recipient)
			err = CreateCollectionObject(inbox, id)
			if err != nil {
				return
			}
			log.Printf("%s to %s: %s", activityToSend.Actor, recipient, activityToSend.Object.Content)
		}
		if err != nil {
			return
		}
	} else {
		activityToSend.To = recipient
		var profile *actor.Actor
		err, profile = actor.GetProfile(recipient)
		if err != nil {
			return
		}
		var reqBody []byte
		reqBody, err = json.Marshal(activityToSend)
		if err != nil {
			return
		}
		client := &http.Client{Timeout: 2 * time.Second}
		var req *http.Request
		log.Printf("Inbox: %s", profile.Inbox)
		req, err = http.NewRequest(http.MethodPost, profile.Inbox, bytes.NewBuffer(reqBody))
		if err != nil {
			return
		}
		req.Header["Content-Type"] = []string{utils.GetContentTypeString()}
		req.Header["Authorization"] = []string{fmt.Sprintf("Bearer %s")}
		var res *http.Response
		res, err = client.Do(req)
		if err != nil {
			return
		}
		if res.StatusCode != http.StatusOK {
			err = utils.HandleHTTPError(res)
			return
		}
	}
	return
}