package pairing

import (
	"bytes"
	"crypto/tls"
	"crypto/x509"
	"encoding/json"
	"encoding/pem"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/http/cookiejar"
	"net/url"
	"runtime"

	"go.uber.org/zap"

	"github.com/status-im/status-go/api"
	gocommon "github.com/status-im/status-go/common"
	"github.com/status-im/status-go/logutils"
	"github.com/status-im/status-go/server"
	"github.com/status-im/status-go/signal"
	"github.com/status-im/status-go/timesource"
)

/*
|--------------------------------------------------------------------------
| BaseClient
|--------------------------------------------------------------------------
|
|
|
*/

// BaseClient is responsible for lower level pairing.Client functionality common to dependent Client types
type BaseClient struct {
	*http.Client
	serverCert     *x509.Certificate
	baseAddress    *url.URL
	challengeTaker *ChallengeTaker
}

func findServerCert(c *ConnectionParams, reachableIPs []net.IP) (*url.URL, *x509.Certificate, error) {
	var baseAddress *url.URL
	var serverCert *x509.Certificate

	type connectionError struct {
		ip  net.IP
		err error
	}
	errCh := make(chan connectionError, len(reachableIPs))

	type result struct {
		u    *url.URL
		cert *x509.Certificate
	}
	successCh := make(chan result, 1) // as we close on the first success

	for _, ip := range reachableIPs {
		go func(ip net.IP) {
			defer gocommon.LogOnPanic()
			u := c.BuildURL(ip)
			cert, err := getServerCert(u)
			if err != nil {
				errCh <- connectionError{ip: ip, err: fmt.Errorf("connecting to '%s' failed: %s", u, err.Error())}
				return
			}
			// If no error, send the results to the success channel
			successCh <- result{u: u, cert: cert}
		}(ip)
	}

	// Keep track of error counts
	errorCount := 0
	var combinedErrors string
	for {
		select {
		case success := <-successCh:
			baseAddress = success.u
			serverCert = success.cert
			return baseAddress, serverCert, nil
		case ipErr := <-errCh:
			errorCount++
			combinedErrors += fmt.Sprintf("IP %s: %s; ", ipErr.ip, ipErr.err)
			if errorCount == len(reachableIPs) {
				return nil, nil, fmt.Errorf(combinedErrors)
			}
		}
	}
}

// NewBaseClient returns a fully qualified BaseClient from the given ConnectionParams
func NewBaseClient(c *ConnectionParams, logger *zap.Logger) (*BaseClient, error) {
	var baseAddress *url.URL
	var serverCert *x509.Certificate
	var certErrs error

	netIPs, err := server.FindReachableAddressesForPairingClient(c.netIPs)
	if err != nil {
		logger.Error("[local pair client] failed to find reachable addresses", zap.Error(err), zap.Any("netIPs", netIPs))
		signal.SendLocalPairingEvent(Event{Type: EventConnectionError, Error: err.Error(), Action: ActionConnect})
		return nil, err
	}
	// if client and server aren't on the same network, netIPs maybe empty, we should check it before invoking findServerCert
	if len(netIPs) == 0 {
		logger.Error("[local pair client] no reachable addresses found")
		signal.SendLocalPairingEvent(Event{Type: EventConnectionError, Error: "no reachable addresses found", Action: ActionConnect})
		return nil, fmt.Errorf("no reachable addresses found")
	}

	maxRetries := 3
	for i := 0; i < maxRetries; i++ {
		baseAddress, serverCert, certErrs = findServerCert(c, netIPs)
		if serverCert == nil {
			certErrs = fmt.Errorf("failed to connect to any of given addresses. %w", certErrs)
			logger.Warn("failed to connect to any of given addresses. Retrying...", zap.Error(certErrs), zap.Any("netIPs", netIPs), zap.Int("retry", i+1))
		} else {
			break
		}
	}

	if serverCert == nil {
		certErrs = fmt.Errorf("failed to connect to any of given addresses. %w", certErrs)
		signal.SendLocalPairingEvent(Event{Type: EventConnectionError, Error: certErrs.Error(), Action: ActionConnect})
		return nil, certErrs
	}

	// No error on the dial out then the URL.Host is accessible
	signal.SendLocalPairingEvent(Event{Type: EventConnectionSuccess, Action: ActionConnect})

	err = verifyCert(serverCert, c.publicKey)
	if err != nil {
		return nil, err
	}

	certPem := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: serverCert.Raw})

	rootCAs, err := x509.SystemCertPool()
	if err != nil {
		return nil, err
	}
	if ok := rootCAs.AppendCertsFromPEM(certPem); !ok {
		return nil, fmt.Errorf("failed to append certPem to rootCAs")
	}

	tr := &http.Transport{
		TLSClientConfig: &tls.Config{
			MinVersion:         tls.VersionTLS12,
			InsecureSkipVerify: false, // MUST BE FALSE
			RootCAs:            rootCAs,
			Time:               timesource.GetCurrentTime,
		},
	}

	cj, err := cookiejar.New(nil)
	if err != nil {
		return nil, err
	}

	return &BaseClient{
		Client:         &http.Client{Transport: tr, Jar: cj},
		serverCert:     serverCert,
		challengeTaker: NewChallengeTaker(NewPayloadEncryptor(c.aesKey)),
		baseAddress:    baseAddress,
	}, nil
}

// getChallenge makes a call to the identified Server and receives a [32]byte challenge
func (c *BaseClient) getChallenge() error {
	c.baseAddress.Path = pairingChallenge
	resp, err := c.Get(c.baseAddress.String())
	if err != nil {
		return err
	}

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("[client] status not ok when getting challenge, received '%s'", resp.Status)
	}

	return c.challengeTaker.SetChallenge(resp)
}

/*
|--------------------------------------------------------------------------
| SenderClient
|--------------------------------------------------------------------------
|
| With AccountPayloadMounter, RawMessagePayloadMounter and InstallationPayloadMounterReceiver
|
*/

// SenderClient is responsible for sending pairing data to a ReceiverServer
type SenderClient struct {
	*BaseClient
	accountMounter      PayloadMounter
	rawMessageMounter   PayloadMounter
	installationMounter PayloadMounterReceiver
}

// NewSenderClient returns a fully qualified SenderClient created with the incoming parameters
func NewSenderClient(backend *api.GethStatusBackend, c *ConnectionParams, config *SenderClientConfig) (*SenderClient, error) {
	logger := logutils.ZapLogger().Named("SenderClient")
	pe := NewPayloadEncryptor(c.aesKey)

	bc, err := NewBaseClient(c, logger)
	if err != nil {
		return nil, err
	}

	am, rmm, imr, err := NewPayloadMounters(logger, pe, backend, config.SenderConfig)
	if err != nil {
		return nil, err
	}

	return &SenderClient{
		BaseClient:          bc,
		accountMounter:      am,
		rawMessageMounter:   rmm,
		installationMounter: imr,
	}, nil
}

func (c *SenderClient) sendAccountData() error {
	err := c.accountMounter.Mount()
	if err != nil {
		return err
	}

	c.baseAddress.Path = pairingReceiveAccount
	resp, err := c.Post(c.baseAddress.String(), "application/octet-stream", bytes.NewBuffer(c.accountMounter.ToSend()))
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingAccount})
		return err
	}

	if resp.StatusCode != http.StatusOK {
		err = fmt.Errorf("[client] status not ok when sending account data, received '%s'", resp.Status)
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingAccount})
		return err
	}

	signal.SendLocalPairingEvent(Event{Type: EventTransferSuccess, Action: ActionPairingAccount})

	c.accountMounter.LockPayload()
	return nil
}

func (c *SenderClient) sendSyncDeviceData() error {
	err := c.rawMessageMounter.Mount()
	if err != nil {
		return err
	}

	c.baseAddress.Path = pairingReceiveSyncDevice
	resp, err := c.Post(c.baseAddress.String(), "application/octet-stream", bytes.NewBuffer(c.rawMessageMounter.ToSend()))
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionSyncDevice})
		return err
	}

	if resp.StatusCode != http.StatusOK {
		err = fmt.Errorf("[client] status not okay when sending sync device data, status: %s", resp.Status)
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionSyncDevice})
		return err
	}

	signal.SendLocalPairingEvent(Event{Type: EventTransferSuccess, Action: ActionSyncDevice})
	return nil
}

func (c *SenderClient) receiveInstallationData() error {
	c.baseAddress.Path = pairingSendInstallation
	req, err := http.NewRequest(http.MethodGet, c.baseAddress.String(), nil)
	if err != nil {
		return err
	}

	err = c.challengeTaker.DoChallenge(req)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingInstallation})
		return err
	}

	resp, err := c.Do(req)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingInstallation})
		return err
	}

	if resp.StatusCode != http.StatusOK {
		err = fmt.Errorf("[client] status not ok when receiving installation data, received '%s'", resp.Status)
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingInstallation})
		return err
	}

	payload, err := io.ReadAll(resp.Body)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingInstallation})
		return err
	}
	signal.SendLocalPairingEvent(Event{Type: EventTransferSuccess, Action: ActionPairingInstallation})

	err = c.installationMounter.Receive(payload)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventProcessError, Error: err.Error(), Action: ActionPairingInstallation})
		return err
	}
	signal.SendLocalPairingEvent(Event{Type: EventProcessSuccess, Action: ActionPairingInstallation})
	return nil
}

// setupSendingClient creates a new SenderClient after parsing string inputs
func setupSendingClient(backend *api.GethStatusBackend, cs, configJSON string) (*SenderClient, error) {
	ccp := new(ConnectionParams)
	err := ccp.FromString(cs)
	if err != nil {
		return nil, err
	}

	conf := NewSenderClientConfig()
	err = json.Unmarshal([]byte(configJSON), conf)
	if err != nil {
		return nil, err
	}
	err = validateAndVerifyPassword(conf, conf.SenderConfig)
	if err != nil {
		return nil, err
	}

	conf.SenderConfig.DB = backend.GetMultiaccountDB()

	return NewSenderClient(backend, ccp, conf)
}

// StartUpSendingClient creates a SenderClient and triggers all `send` calls in sequence to the ReceiverServer
func StartUpSendingClient(backend *api.GethStatusBackend, cs, configJSON string) error {
	c, err := setupSendingClient(backend, cs, configJSON)
	if err != nil {
		return err
	}
	err = c.sendAccountData()
	if err != nil {
		return err
	}
	err = c.sendSyncDeviceData()
	if err != nil {
		return err
	}
	err = c.getChallenge()
	if err != nil {
		return err
	}
	return c.receiveInstallationData()
}

/*
|--------------------------------------------------------------------------
| ReceiverClient
|--------------------------------------------------------------------------
|
| With AccountPayloadReceiver, RawMessagePayloadReceiver, InstallationPayloadMounterReceiver
|
*/

// ReceiverClient is responsible for accepting pairing data to a SenderServer
type ReceiverClient struct {
	*BaseClient

	accountReceiver      PayloadReceiver
	rawMessageReceiver   PayloadReceiver
	installationReceiver PayloadMounterReceiver
}

// NewReceiverClient returns a fully qualified ReceiverClient created with the incoming parameters
func NewReceiverClient(backend *api.GethStatusBackend, c *ConnectionParams, config *ReceiverClientConfig) (*ReceiverClient, error) {
	logger := logutils.ZapLogger().Named("ReceiverClient")

	bc, err := NewBaseClient(c, logger)
	if err != nil {
		return nil, err
	}

	pe := NewPayloadEncryptor(c.aesKey)

	ar, rmr, imr, err := NewPayloadReceivers(logger, pe, backend, config.ReceiverConfig)
	if err != nil {
		return nil, err
	}

	return &ReceiverClient{
		BaseClient:           bc,
		accountReceiver:      ar,
		rawMessageReceiver:   rmr,
		installationReceiver: imr,
	}, nil
}

func (c *ReceiverClient) receiveAccountData() error {
	c.baseAddress.Path = pairingSendAccount
	req, err := http.NewRequest(http.MethodGet, c.baseAddress.String(), nil)
	if err != nil {
		return err
	}

	err = c.challengeTaker.DoChallenge(req)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingAccount})
		return err
	}

	resp, err := c.Do(req)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingAccount})
		return err
	}

	if resp.StatusCode != http.StatusOK {
		err = fmt.Errorf("[client] status not ok when receiving account data, received '%s'", resp.Status)
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingAccount})
		return err
	}

	payload, err := io.ReadAll(resp.Body)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingAccount})
		return err
	}
	signal.SendLocalPairingEvent(Event{Type: EventTransferSuccess, Action: ActionPairingAccount})

	err = c.accountReceiver.Receive(payload)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventProcessError, Error: err.Error(), Action: ActionPairingAccount})
		return err
	}
	signal.SendLocalPairingEvent(Event{Type: EventProcessSuccess, Action: ActionPairingAccount})
	return nil
}

func (c *ReceiverClient) receiveSyncDeviceData() error {
	c.baseAddress.Path = pairingSendSyncDevice
	req, err := http.NewRequest(http.MethodGet, c.baseAddress.String(), nil)
	if err != nil {
		return err
	}

	err = c.challengeTaker.DoChallenge(req)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionSyncDevice})
		return err
	}

	resp, err := c.Do(req)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionSyncDevice})
		return err
	}

	if resp.StatusCode != http.StatusOK {
		err = fmt.Errorf("[client] status not ok when receiving sync device data, received '%s'", resp.Status)
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionSyncDevice})
		return err
	}

	payload, err := io.ReadAll(resp.Body)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionSyncDevice})
		return err
	}
	signal.SendLocalPairingEvent(Event{Type: EventTransferSuccess, Action: ActionSyncDevice})

	err = c.rawMessageReceiver.Receive(payload)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventProcessError, Error: err.Error(), Action: ActionSyncDevice})
		return err
	}
	signal.SendLocalPairingEvent(Event{Type: EventProcessSuccess, Action: ActionSyncDevice})
	return nil
}

func (c *ReceiverClient) sendInstallationData() error {
	err := c.installationReceiver.Mount()
	if err != nil {
		return err
	}

	c.baseAddress.Path = pairingReceiveInstallation
	req, err := http.NewRequest(http.MethodPost, c.baseAddress.String(), bytes.NewBuffer(c.installationReceiver.ToSend()))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/octet-stream")

	err = c.challengeTaker.DoChallenge(req)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingInstallation})
		return err
	}

	resp, err := c.Do(req)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingInstallation})
		return err
	}

	if resp.StatusCode != http.StatusOK {
		err = fmt.Errorf("[client] status not okay when sending installation data, status: %s", resp.Status)
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionPairingInstallation})
		return err
	}

	signal.SendLocalPairingEvent(Event{Type: EventTransferSuccess, Action: ActionPairingInstallation})
	return nil
}

// setupReceivingClient creates a new ReceiverClient after parsing string inputs
func setupReceivingClient(backend *api.GethStatusBackend, cs, configJSON string) (*ReceiverClient, error) {
	ccp := new(ConnectionParams)
	err := ccp.FromString(cs)
	if err != nil {
		return nil, err
	}

	conf := NewReceiverClientConfig()
	err = json.Unmarshal([]byte(configJSON), conf)
	if err != nil {
		return nil, err
	}

	// This is a temporal solution to allow clients not to pass DeviceType.
	// Check DeviceType deprecation reason for more info.
	conf.ReceiverConfig.DeviceType = runtime.GOOS

	err = validateReceiverConfig(conf, conf.ReceiverConfig)
	if err != nil {
		return nil, err
	}

	// ignore err because we allow no active account here
	activeAccount, _ := backend.GetActiveAccount()
	if activeAccount != nil {
		conf.ReceiverConfig.LoggedInKeyUID = activeAccount.KeyUID
	}

	conf.ReceiverConfig.DB = backend.GetMultiaccountDB()

	return NewReceiverClient(backend, ccp, conf)
}

// StartUpReceivingClient creates a ReceiverClient and triggers all `receive` calls in sequence to the SenderServer
func StartUpReceivingClient(backend *api.GethStatusBackend, cs, configJSON string) error {
	c, err := setupReceivingClient(backend, cs, configJSON)
	if err != nil {
		return err
	}

	err = c.getChallenge()
	if err != nil {
		return err
	}
	err = c.receiveAccountData()
	if err != nil {
		return err
	}

	err = c.getChallenge()
	if err != nil {
		return err
	}
	err = c.receiveSyncDeviceData()
	if err != nil {
		return err
	}

	err = c.getChallenge()
	if err != nil {
		return err
	}
	return c.sendInstallationData()
}

/*
|--------------------------------------------------------------------------
| ReceiverClient
|--------------------------------------------------------------------------
*/

type KeystoreFilesReceiverClient struct {
	*BaseClient

	keystoreFilesReceiver PayloadReceiver
}

func NewKeystoreFilesReceiverClient(backend *api.GethStatusBackend, c *ConnectionParams, config *KeystoreFilesReceiverClientConfig) (*KeystoreFilesReceiverClient, error) {
	logger := logutils.ZapLogger().Named("ReceiverClient")
	bc, err := NewBaseClient(c, logger)
	if err != nil {
		return nil, err
	}
	pe := NewPayloadEncryptor(c.aesKey)

	kfrc, err := NewKeystoreFilesPayloadReceiver(backend, pe, config.ReceiverConfig, logger)
	if err != nil {
		return nil, err
	}

	return &KeystoreFilesReceiverClient{
		BaseClient:            bc,
		keystoreFilesReceiver: kfrc,
	}, nil
}

func (c *KeystoreFilesReceiverClient) receiveKeystoreFilesData() error {
	c.baseAddress.Path = pairingSendAccount
	req, err := http.NewRequest(http.MethodGet, c.baseAddress.String(), nil)
	if err != nil {
		return err
	}

	err = c.challengeTaker.DoChallenge(req)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionKeystoreFilesTransfer})
		return err
	}

	resp, err := c.Do(req)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionKeystoreFilesTransfer})
		return err
	}

	if resp.StatusCode != http.StatusOK {
		err = fmt.Errorf("[client] status not ok when receiving account data, received '%s'", resp.Status)
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionKeystoreFilesTransfer})
		return err
	}

	payload, err := io.ReadAll(resp.Body)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventTransferError, Error: err.Error(), Action: ActionKeystoreFilesTransfer})
		return err
	}
	signal.SendLocalPairingEvent(Event{Type: EventTransferSuccess, Action: ActionKeystoreFilesTransfer})

	err = c.keystoreFilesReceiver.Receive(payload)
	if err != nil {
		signal.SendLocalPairingEvent(Event{Type: EventProcessError, Error: err.Error(), Action: ActionKeystoreFilesTransfer})
		return err
	}
	signal.SendLocalPairingEvent(Event{Type: EventProcessSuccess, Action: ActionKeystoreFilesTransfer})
	return nil
}

// setupKeystoreFilesReceivingClient creates a new ReceiverClient after parsing string inputs
func setupKeystoreFilesReceivingClient(backend *api.GethStatusBackend, cs, configJSON string) (*KeystoreFilesReceiverClient, error) {
	ccp := new(ConnectionParams)
	err := ccp.FromString(cs)
	if err != nil {
		return nil, err
	}

	conf := NewKeystoreFilesReceiverClientConfig()
	err = json.Unmarshal([]byte(configJSON), conf)
	if err != nil {
		return nil, err
	}
	err = validateKeystoreFilesConfig(backend, conf)
	if err != nil {
		return nil, err
	}

	return NewKeystoreFilesReceiverClient(backend, ccp, conf)
}

// StartUpKeystoreFilesReceivingClient creates a KeystoreFilesReceiverClient and triggers all `receive` calls in sequence to the KeystoreFilesSenderServer
func StartUpKeystoreFilesReceivingClient(backend *api.GethStatusBackend, cs, configJSON string) error {
	c, err := setupKeystoreFilesReceivingClient(backend, cs, configJSON)
	if err != nil {
		return err
	}

	err = c.getChallenge()
	if err != nil {
		return err
	}

	return c.receiveKeystoreFilesData()
}