package main

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"time"

	rabbitmq "github.com/rabbitmq/amqp091-go"
	"src.opensuse.org/autogits/common"
)

func failOnError(err error, msg string) {
	if err != nil {
		log.Panicf("%s: %s\n", err, msg)
	}
}

type Message struct {
	Topic string
	Body  []byte
}

var messageQueue chan Message

func PublishMessage(giteaOrg, giteaWebhookType, action string, data []byte) error {
	if messageQueue == nil {
		return fmt.Errorf("Queue not initialized")
	}

	if !json.Valid(data) {
		return errors.New("Invalid JSON in request")
	}

	var msg Message
	if len(action) > 0 {
		msg = Message{
			Topic: fmt.Sprintf("%s.%s.%s.%s.%s", topicScope, common.TopicApp, giteaOrg, giteaWebhookType, action),
			Body:  data,
		}
	} else {
		msg = Message{
			Topic: fmt.Sprintf("%s.%s.%s.%s", topicScope, common.TopicApp,  giteaOrg, giteaWebhookType),
			Body:  data,
		}
	}

	select {
	case messageQueue <- msg:
	default:
		return errors.New("Unable to queue message. Possibly queue full.")
	}
	return nil
}

func ConnectToExchangeForPublish(host, username, password string) {
	defer func() {
		if r := recover(); r != nil {
			log.Print("recovering... reconnecting...\n")
			time.Sleep(5 * time.Second)
			go ConnectToExchangeForPublish(host, username, password)
		}
	}()

	if messageQueue == nil {
		messageQueue = make(chan Message, 10240)
	}

	auth := ""
	if len(username) > 0 && len(password) > 0 {
		auth = username + ":" + password + "@"
	}

	connection, err := rabbitmq.DialTLS("amqps://"+auth+host, &tls.Config{
		ServerName: host,
	})
	failOnError(err, "Cannot connect to rabbit.opensuse.org")
	defer connection.Close()

	ch, err := connection.Channel()
	failOnError(err, "Cannot create a channel")
	defer ch.Close()

	err = ch.ExchangeDeclarePassive("pubsub", "topic", true, false, false, false, nil)
	failOnError(err, "Cannot find pubsub exchange")

	for {
		msg, ok := <-messageQueue
		if !ok {
			log.Println("Shutdown ...")
			return
		}

		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()

		err = ch.PublishWithContext(ctx, "pubsub", msg.Topic, false, false, rabbitmq.Publishing{
			ContentType:     "application/json",
			AppId:           AppName,
			Body:            []byte(msg.Body),
			Timestamp:       time.Now(),
			DeliveryMode:    2,
			ContentEncoding: "application/json",
		})

		if err != nil {
			if ch.IsClosed() || connection.IsClosed() {
				select {
				case messageQueue <- msg:
					log.Println("requeued ...")
				default:
					log.Println("queue full... message lost")
				}
				// reconnect
				log.Println("reconnecting...")
				time.Sleep(5 * time.Second)
				go ConnectToExchangeForPublish(host, username, password)
				return
			} else {
				log.Printf("Error sending request. %v\n", err)
			}
		}
	}
}