// Retrieves a document that matches a query filter by using the Go driver
package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"os"

	"github.com/joho/godotenv"
	"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"
)

// start-restaurant-struct
type Restaurant struct {
	ID           primitive.ObjectID `bson:"_id"`
	Name         string
	RestaurantId string `bson:"restaurant_id"`
	Cuisine      string
	Address      interface{}
	Borough      string
	Grades       []interface{}
}

// end-restaurant-struct

func main() {
	if err := godotenv.Load(); err != nil {
		log.Println("No .env file found")
	}

	var uri string
	if uri = os.Getenv("MONGODB_URI"); uri == "" {
		log.Fatal("You must set your 'MONGODB_URI' environment variable. See\n\t https://www.mongodb.com/docs/drivers/go/current/usage-examples/#environment-variable")
	}

	client, err := mongo.Connect(options.Client().ApplyURI(uri))
	if err != nil {
		panic(err)
	}
	defer func() {
		if err = client.Disconnect(context.TODO()); err != nil {
			panic(err)
		}
	}()

	// begin findOne
	coll := client.Database("sample_restaurants").Collection("restaurants")

	// Creates a query filter to match documents in which the "name" is
	// "Bagels N Buns"
	filter := bson.D{{"name", "Bagels N Buns"}}

	// Retrieves the first matching document
	var result Restaurant
	err = coll.FindOne(context.TODO(), filter).Decode(&result)

	// Prints a message if no documents are matched or if any
	// other errors occur during the operation
	if err != nil {
		if err == mongo.ErrNoDocuments {
			return
		}
		panic(err)
	}
	// end findOne

	output, err := json.MarshalIndent(result, "", "    ")
	if err != nil {
		panic(err)
	}
	fmt.Printf("%s\n", output)
}