package messaging

import (
	"context"
	"dev.azure.com/schwarzit/schwarzit.stackit-public/audit-go.git/log"
	"errors"
	"fmt"
	"sync"
	"time"
)

// Api is an abstraction for a messaging system that can be used to send
// audit logs to the audit log system.
type Api interface {

	// Send method will send the given data to the specified topic synchronously.
	//  Parameters:
	//  * ctx - the context object
	//  * topic - the messaging topic where to send the data to
	//  * data - the serialized data as byte array
	//  * contentType - the contentType of the serialized data
	//  * applicationProperties - properties to send with the message (i.e. cloud event headers)
	//
	// It returns technical errors for connection issues or sending problems.
	Send(ctx context.Context, topic string, data []byte, contentType string, applicationProperties map[string]any) error

	// Close the underlying connection to the messaging system.
	//  Parameters:
	//  * ctx - the context object
	//
	// It returns an error if the connection cannot be closed successfully
	Close(ctx context.Context) error
}

// AmqpApi implements Api.
type AmqpApi struct {
	config               AmqpConnectionPoolConfig
	connection           *AmqpConnection
	connectionPool       ConnectionPool
	connectionPoolHandle *ConnectionPoolHandle
	senderCache          map[string]*AmqpSenderSession
	lock                 sync.RWMutex
}

var _ Api = &AmqpApi{}

func NewAmqpApi(amqpConfig AmqpConnectionPoolConfig) (Api, error) {
	connectionPool, err := NewAmqpConnectionPool(amqpConfig, "sdk")
	if err != nil {
		return nil, fmt.Errorf("new amqp connection pool: %w", err)
	}

	amqpApi := &AmqpApi{config: amqpConfig,
		connectionPool:       connectionPool,
		connectionPoolHandle: connectionPool.NewHandle(),
		senderCache:          make(map[string]*AmqpSenderSession),
	}

	var messagingApi Api = amqpApi
	return messagingApi, nil
}

// Send implements Api.Send.
// If errors occur the connection to the messaging system will be closed and re-established.
func (a *AmqpApi) Send(_ context.Context, topic string, data []byte, contentType string, applicationProperties map[string]any) error {

	// create or get sender from cache
	var sender = a.senderFromCache(topic)
	if sender == nil {
		if err := a.newSender(topic); err != nil {
			return err
		}
		sender = a.senderFromCache(topic)
	}

	// first attempt to send
	var sendErr error
	wrappedData := [][]byte{data}
	if err := sender.Send(topic, wrappedData, contentType, applicationProperties); err != nil {
		sendErr = fmt.Errorf("send: %w", err)
	} else {
		return nil
	}

	// renew sender
	if err := a.newSender(topic); err != nil {
		return errors.Join(sendErr, err)
	}
	sender = a.senderFromCache(topic)

	// retry send
	if err := sender.Send(topic, wrappedData, contentType, applicationProperties); err != nil {
		return errors.Join(sendErr, fmt.Errorf("retry send: %w", err))
	}
	return nil
}

func (a *AmqpApi) senderFromCache(topic string) *AmqpSenderSession {
	a.lock.RLock()
	defer a.lock.RUnlock()
	return a.senderCache[topic]
}

func (a *AmqpApi) newSender(topic string) error {
	a.lock.Lock()
	defer a.lock.Unlock()

	connectionIsClosed := a.connection == nil || a.connection.IsClosed()
	if connectionIsClosed {
		connection, err := a.connectionPool.GetConnection(a.connectionPoolHandle)
		if err != nil {
			return fmt.Errorf("get connection: %w", err)
		}
		a.connection = connection
	}

	ctx, cancelFn := context.WithTimeout(context.Background(), 10*time.Second)
	sender, err := a.connection.NewSender(ctx, topic)
	cancelFn()
	if err != nil {
		return fmt.Errorf("new sender: %w", err)
	}

	a.senderCache[topic] = sender
	return nil
}

// Close implements Api.Close
func (a *AmqpApi) Close(_ context.Context) error {
	log.AuditLogger.Info("close audit amqp connection pool")

	a.lock.Lock()
	defer a.lock.Unlock()

	// cached senders
	var closeErrors []error
	for _, session := range a.senderCache {
		if err := session.Close(); err != nil {
			closeErrors = append(closeErrors, fmt.Errorf("close session: %w", err))
		}
	}
	clear(a.senderCache)

	// pool
	if err := a.connectionPool.Close(); err != nil {
		closeErrors = append(closeErrors, fmt.Errorf("close pool: %w", err))
	}

	if len(closeErrors) > 0 {
		return fmt.Errorf("close: %w", errors.Join(closeErrors...))
	}
	return nil
}