package main

import (
	"context"
	"encoding/json"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"log"
	"net/http"
	"time"

	"github.com/gorilla/mux"
)

var client *mongo.Client

type Person struct {
	ID   primitive.ObjectID `bson:"_id,omitempty"`
	Name string             `bson:"name"`
}

type Debt struct {
	ID          primitive.ObjectID `bson:"_id,omitempty"`
	PersonID    primitive.ObjectID `bson:"fk_pid"`
	Amount      int                `bson:"amount"`
	Description string             `bson:"description,omitempty"`
	Datetime    time.Time          `bson:"datetime"`
}

func getDebtsForPerson(client *mongo.Client, personID string) ([]Debt, error) {
	var results []Debt

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	// Umwandlung der personID von string in primitive.ObjectID
	objID, err := primitive.ObjectIDFromHex(personID)
	if err != nil {
		return nil, err
	}

	// Verbindung zur "debts" Sammlung
	debtsCollection := client.Database("debtlist").Collection("debts")

	// Abfrage erstellen, die alle Schulden findet, deren fk_pid mit der personID übereinstimmt
	filter := bson.M{"fk_pid": objID}
	cursor, err := debtsCollection.Find(ctx, filter)
	if err != nil {
		return nil, err
	}
	defer cursor.Close(ctx)

	// Durchlaufen des Cursors und Hinzufügen der Ergebnisse zur results-Slice
	for cursor.Next(ctx) {
		var debt Debt
		if err := cursor.Decode(&debt); err != nil {
			return nil, err
		}
		results = append(results, debt)
	}

	if err := cursor.Err(); err != nil {
		return nil, err
	}

	return results, nil
}

func main() {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	var err error
	client, err = mongo.Connect(ctx, options.Client().ApplyURI("mongodb://root:example@localhost:27017"))
	if err != nil {
		panic(err)
	}

	// Router initialisieren
	r := mux.NewRouter()
	r.HandleFunc("/persons", createPerson).Methods("POST")
	r.HandleFunc("/persons/{id}", getPerson).Methods("GET")
	r.HandleFunc("/persons", getAllPersons).Methods("GET")
	r.HandleFunc("/persons/{id}", updatePerson).Methods("PUT")
	r.HandleFunc("/persons/{id}", deletePerson).Methods("DELETE")
	err = http.ListenAndServe(":3333", r)
	if err != nil {
		log.Fatal(err)
	}
}

func createPerson(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	var person Person
	json.NewDecoder(r.Body).Decode(&person)
	collection := client.Database("debtlist").Collection("persons")
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	result, err := collection.InsertOne(ctx, person)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		w.Write([]byte(`{"message": "` + err.Error() + `"}`))
		return

	}
	json.NewEncoder(w).Encode(result)
}
func updatePerson(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	var person Person
	json.NewDecoder(r.Body).Decode(&person)
	collection := client.Database("debtlist").Collection("persons")
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	filter := bson.M{"_id": person.ID}
	update := bson.M{
		"$set": bson.M{
			"name": person.Name,
		},
	}
	result, err := collection.UpdateOne(ctx, filter, update)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		w.Write([]byte(`{"message": "` + err.Error() + `"}`))
		return

	}
	json.NewEncoder(w).Encode(result)
}
func deletePerson(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	var person Person
	json.NewDecoder(r.Body).Decode(&person)
	collection := client.Database("debtlist").Collection("persons")
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	filter := bson.M{"_id": person.ID}
	result, err := collection.DeleteOne(ctx, filter)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		w.Write([]byte(`{"message": "` + err.Error() + `"}`))
		return
	}
	json.NewEncoder(w).Encode(result)
}
func getPerson(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	personID := vars["id"]
	w.Header().Set("Content-Type", "application/json")
	var person Person
	collection := client.Database("debtlist").Collection("persons")
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	pid, err := primitive.ObjectIDFromHex(personID)
	filter := bson.M{"_id": pid}
	err = collection.FindOne(ctx, filter).Decode(&person)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		w.Write([]byte(`{"message": "` + err.Error() + `"}`))
		return
	}
	json.NewEncoder(w).Encode(person)
}
func getAllPersons(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	var persons []Person
	collection := client.Database("debtlist").Collection("persons")
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	cursor, err := collection.Find(ctx, bson.M{})
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		w.Write([]byte(`{"message": "` + err.Error() + `"}`))
		return
	}
	defer cursor.Close(ctx)
	for cursor.Next(ctx) {
		var person Person
		cursor.Decode(&person)
		persons = append(persons, person)
	}
	if err := cursor.Err(); err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		w.Write([]byte(`{"message": "` + err.Error() + `"}`))
		return
	}
	json.NewEncoder(w).Encode(persons)
}