package jmap

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strconv"

	"github.com/opencloud-eu/opencloud/pkg/log"
	"github.com/opencloud-eu/opencloud/pkg/version"
)

// Implementation of ApiClient, SessionClient and BlobClient that uses
// HTTP to perform JMAP operations.
type HttpJmapClient struct {
	client         *http.Client
	masterUser     string
	masterPassword string
	userAgent      string
	listener       HttpJmapApiClientEventListener
}

var (
	_ ApiClient     = &HttpJmapClient{}
	_ SessionClient = &HttpJmapClient{}
	_ BlobClient    = &HttpJmapClient{}
)

const (
	logEndpoint       = "endpoint"
	logHttpStatus     = "status"
	logHttpStatusCode = "status-code"
	logHttpUrl        = "url"
)

/*
func bearer(req *http.Request, token string) {
	req.Header.Add("Authorization", "Bearer "+base64.StdEncoding.EncodeToString([]byte(token)))
}
*/

// Record JMAP HTTP execution events that may occur, e.g. using metrics.
type HttpJmapApiClientEventListener interface {
	OnSuccessfulRequest(endpoint string, status int)
	OnFailedRequest(endpoint string, err error)
	OnFailedRequestWithStatus(endpoint string, status int)
	OnResponseBodyReadingError(endpoint string, err error)
	OnResponseBodyUnmarshallingError(endpoint string, err error)
}

type nullHttpJmapApiClientEventListener struct {
}

func (l nullHttpJmapApiClientEventListener) OnSuccessfulRequest(endpoint string, status int) {
}
func (l nullHttpJmapApiClientEventListener) OnFailedRequest(endpoint string, err error) {
}
func (l nullHttpJmapApiClientEventListener) OnFailedRequestWithStatus(endpoint string, status int) {
}
func (l nullHttpJmapApiClientEventListener) OnResponseBodyReadingError(endpoint string, err error) {
}
func (l nullHttpJmapApiClientEventListener) OnResponseBodyUnmarshallingError(endpoint string, err error) {
}

var _ HttpJmapApiClientEventListener = nullHttpJmapApiClientEventListener{}

// An implementation of HttpJmapApiClientMetricsRecorder that does nothing.
func NullHttpJmapApiClientEventListener() HttpJmapApiClientEventListener {
	return nullHttpJmapApiClientEventListener{}
}

func NewHttpJmapClient(client *http.Client, masterUser string, masterPassword string, listener HttpJmapApiClientEventListener) *HttpJmapClient {
	return &HttpJmapClient{
		client:         client,
		masterUser:     masterUser,
		masterPassword: masterPassword,
		userAgent:      "OpenCloud/" + version.GetString(),
		listener:       listener,
	}
}

func (h *HttpJmapClient) Close() error {
	h.client.CloseIdleConnections()
	return nil
}

type AuthenticationError struct {
	Err error
}

func (e AuthenticationError) Error() string {
	return fmt.Sprintf("failed to find user for authentication: %v", e.Err.Error())
}
func (e AuthenticationError) Unwrap() error {
	return e.Err
}

func (h *HttpJmapClient) auth(username string, _ *log.Logger, req *http.Request) error {
	masterUsername := username + "%" + h.masterUser
	req.SetBasicAuth(masterUsername, h.masterPassword)
	return nil
}

var (
	errNilBaseUrl = errors.New("sessionUrl is nil")
)

func (h *HttpJmapClient) GetSession(sessionUrl *url.URL, username string, logger *log.Logger) (SessionResponse, Error) {
	if sessionUrl == nil {
		logger.Error().Msg("sessionUrl is nil")
		return SessionResponse{}, SimpleError{code: JmapErrorInvalidHttpRequest, err: errNilBaseUrl}
	}
	// See the JMAP specification on Service Autodiscovery: https://jmap.io/spec-core.html#service-autodiscovery
	// There are two standardised autodiscovery methods in use for Internet protocols:
	// - DNS SRV (see [@!RFC2782], [@!RFC6186], and [@!RFC6764])
	// - .well-known/servicename (see [@!RFC8615])
	// We are currently only supporting RFC8615, using the baseurl that was configured in this HttpJmapApiClient.
	//sessionUrl := baseurl.JoinPath(".well-known", "jmap")
	sessionUrlStr := sessionUrl.String()
	endpoint := endpointOf(sessionUrl)
	logger = log.From(logger.With().Str(logEndpoint, endpoint))

	req, err := http.NewRequest(http.MethodGet, sessionUrlStr, nil)
	if err != nil {
		logger.Error().Err(err).Msgf("failed to create GET request for %v", sessionUrl)
		return SessionResponse{}, SimpleError{code: JmapErrorInvalidHttpRequest, err: err}
	}
	h.auth(username, logger, req)
	req.Header.Add("Cache-Control", "no-cache, no-store, must-revalidate") // spec recommendation

	res, err := h.client.Do(req)
	if err != nil {
		h.listener.OnFailedRequest(endpoint, err)
		logger.Error().Err(err).Msgf("failed to perform GET %v", sessionUrl)
		return SessionResponse{}, SimpleError{code: JmapErrorInvalidHttpRequest, err: err}
	}
	if res.StatusCode < 200 || res.StatusCode > 299 {
		h.listener.OnFailedRequestWithStatus(endpoint, res.StatusCode)
		logger.Error().Str(logHttpStatus, res.Status).Int(logHttpStatusCode, res.StatusCode).Msg("HTTP response status code is not 200")
		return SessionResponse{}, SimpleError{code: JmapErrorServerResponse, err: fmt.Errorf("JMAP API response status is %v", res.Status)}
	}
	h.listener.OnSuccessfulRequest(endpoint, res.StatusCode)

	if res.Body != nil {
		defer func(Body io.ReadCloser) {
			err := Body.Close()
			if err != nil {
				logger.Error().Err(err).Msg("failed to close response body")
			}
		}(res.Body)
	}

	body, err := io.ReadAll(res.Body)
	if err != nil {
		logger.Error().Err(err).Msg("failed to read response body")
		h.listener.OnResponseBodyReadingError(endpoint, err)
		return SessionResponse{}, SimpleError{code: JmapErrorReadingResponseBody, err: err}
	}

	var data SessionResponse
	err = json.Unmarshal(body, &data)
	if err != nil {
		logger.Error().Str(logHttpUrl, sessionUrlStr).Err(err).Msg("failed to decode JSON payload from .well-known/jmap response")
		h.listener.OnResponseBodyUnmarshallingError(endpoint, err)
		return SessionResponse{}, SimpleError{code: JmapErrorDecodingResponseBody, err: err}
	}

	return data, nil
}

func (h *HttpJmapClient) Command(ctx context.Context, logger *log.Logger, session *Session, request Request) ([]byte, Error) {
	jmapUrl := session.JmapUrl.String()
	endpoint := session.JmapEndpoint
	logger = log.From(logger.With().Str(logEndpoint, endpoint))

	bodyBytes, err := json.Marshal(request)
	if err != nil {
		logger.Error().Err(err).Msg("failed to marshall JSON payload")
		return nil, SimpleError{code: JmapErrorEncodingRequestBody, err: err}
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, jmapUrl, bytes.NewBuffer(bodyBytes))
	if err != nil {
		logger.Error().Err(err).Msgf("failed to create POST request for %v", jmapUrl)
		return nil, SimpleError{code: JmapErrorCreatingRequest, err: err}
	}
	req.Header.Add("Content-Type", "application/json")
	req.Header.Add("User-Agent", h.userAgent)
	h.auth(session.Username, logger, req)

	res, err := h.client.Do(req)
	if err != nil {
		h.listener.OnFailedRequest(endpoint, err)
		logger.Error().Err(err).Msgf("failed to perform POST %v", jmapUrl)
		return nil, SimpleError{code: JmapErrorSendingRequest, err: err}
	}
	if res.StatusCode < 200 || res.StatusCode > 299 {
		h.listener.OnFailedRequestWithStatus(endpoint, res.StatusCode)
		logger.Error().Str(logEndpoint, endpoint).Str(logHttpStatus, res.Status).Msg("HTTP response status code is not 2xx")
		return nil, SimpleError{code: JmapErrorServerResponse, err: err}
	}
	if res.Body != nil {
		defer func(Body io.ReadCloser) {
			err := Body.Close()
			if err != nil {
				logger.Error().Err(err).Msg("failed to close response body")
			}
		}(res.Body)
	}
	h.listener.OnSuccessfulRequest(endpoint, res.StatusCode)

	body, err := io.ReadAll(res.Body)
	if err != nil {
		logger.Error().Err(err).Msg("failed to read response body")
		h.listener.OnResponseBodyReadingError(endpoint, err)
		return nil, SimpleError{code: JmapErrorServerResponse, err: err}
	}

	return body, nil
}

func (h *HttpJmapClient) UploadBinary(ctx context.Context, logger *log.Logger, session *Session, uploadUrl string, endpoint string, contentType string, body io.Reader) (UploadedBlob, Error) {
	logger = log.From(logger.With().Str(logEndpoint, endpoint))

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, uploadUrl, body)
	if err != nil {
		logger.Error().Err(err).Msgf("failed to create POST request for %v", uploadUrl)
		return UploadedBlob{}, SimpleError{code: JmapErrorCreatingRequest, err: err}
	}
	req.Header.Add("Content-Type", contentType)
	req.Header.Add("User-Agent", h.userAgent)
	h.auth(session.Username, logger, req)

	res, err := h.client.Do(req)
	if err != nil {
		h.listener.OnFailedRequest(endpoint, err)
		logger.Error().Err(err).Msgf("failed to perform POST %v", uploadUrl)
		return UploadedBlob{}, SimpleError{code: JmapErrorSendingRequest, err: err}
	}
	if res.StatusCode < 200 || res.StatusCode > 299 {
		h.listener.OnFailedRequestWithStatus(endpoint, res.StatusCode)
		logger.Error().Str(logHttpStatus, res.Status).Int(logHttpStatusCode, res.StatusCode).Msg("HTTP response status code is not 2xx")
		return UploadedBlob{}, SimpleError{code: JmapErrorServerResponse, err: err}
	}
	if res.Body != nil {
		defer func(Body io.ReadCloser) {
			err := Body.Close()
			if err != nil {
				logger.Error().Err(err).Msg("failed to close response body")
			}
		}(res.Body)
	}
	h.listener.OnSuccessfulRequest(endpoint, res.StatusCode)

	responseBody, err := io.ReadAll(res.Body)
	if err != nil {
		logger.Error().Err(err).Msg("failed to read response body")
		h.listener.OnResponseBodyReadingError(endpoint, err)
		return UploadedBlob{}, SimpleError{code: JmapErrorServerResponse, err: err}
	}

	var result UploadedBlob
	err = json.Unmarshal(responseBody, &result)
	if err != nil {
		logger.Error().Str(logHttpUrl, uploadUrl).Err(err).Msg("failed to decode JSON payload from the upload response")
		h.listener.OnResponseBodyUnmarshallingError(endpoint, err)
		return UploadedBlob{}, SimpleError{code: JmapErrorDecodingResponseBody, err: err}
	}

	return result, nil
}

func (h *HttpJmapClient) DownloadBinary(ctx context.Context, logger *log.Logger, session *Session, downloadUrl string, endpoint string) (*BlobDownload, Error) {
	logger = log.From(logger.With().Str(logEndpoint, endpoint))

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, downloadUrl, nil)
	if err != nil {
		logger.Error().Err(err).Msgf("failed to create GET request for %v", downloadUrl)
		return nil, SimpleError{code: JmapErrorCreatingRequest, err: err}
	}
	req.Header.Add("User-Agent", h.userAgent)
	h.auth(session.Username, logger, req)

	res, err := h.client.Do(req)
	if err != nil {
		h.listener.OnFailedRequest(endpoint, err)
		logger.Error().Err(err).Msgf("failed to perform GET %v", downloadUrl)
		return nil, SimpleError{code: JmapErrorSendingRequest, err: err}
	}
	if res.StatusCode == http.StatusNotFound {
		return nil, nil
	}
	if res.StatusCode < 200 || res.StatusCode > 299 {
		h.listener.OnFailedRequestWithStatus(endpoint, res.StatusCode)
		logger.Error().Str(logHttpStatus, res.Status).Int(logHttpStatusCode, res.StatusCode).Msg("HTTP response status code is not 2xx")
		return nil, SimpleError{code: JmapErrorServerResponse, err: err}
	}
	h.listener.OnSuccessfulRequest(endpoint, res.StatusCode)

	sizeStr := res.Header.Get("Content-Length")
	size := -1
	if sizeStr != "" {
		size, err = strconv.Atoi(sizeStr)
		if err != nil {
			logger.Warn().Err(err).Msgf("failed to parse Content-Length blob download response header value '%v'", sizeStr)
			size = -1
		}
	}

	return &BlobDownload{
		Body:               res.Body,
		Size:               size,
		Type:               res.Header.Get("Content-Type"),
		ContentDisposition: res.Header.Get("Content-Disposition"),
		CacheControl:       res.Header.Get("Cache-Control"),
	}, nil
}