package decortsdk

import (
	"bytes"
	"context"
	"crypto/tls"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"reflect"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/google/go-querystring/query"
	"repository.basistech.ru/BASIS/decort-golang-sdk/config"
	"repository.basistech.ru/BASIS/decort-golang-sdk/internal/constants"
	"repository.basistech.ru/BASIS/decort-golang-sdk/pkg/cloudapi"
	"repository.basistech.ru/BASIS/decort-golang-sdk/pkg/cloudbroker"
)

// DecortClient is HTTP-client for platform
type DecortClient struct {
	decortURL  string
	client     *http.Client
	cfg        config.Config
	expiryTime time.Time
	mutex      *sync.Mutex
}

// Сlient builder
func New(cfg config.Config) *DecortClient {
	if cfg.Retries == 0 {
		cfg.Retries = 5
	}

	var expiryTime time.Time

	if cfg.Token != "" {
		expiryTime = time.Now().AddDate(0, 0, 1)
	}

	return &DecortClient{
		decortURL: cfg.DecortURL,
		client: &http.Client{
			Transport: &http.Transport{
				TLSClientConfig: &tls.Config{
					//nolint:gosec
					InsecureSkipVerify: cfg.SSLSkipVerify,
				},
			},
		},
		cfg:        cfg,
		expiryTime: expiryTime,
		mutex:      &sync.Mutex{},
	}
}

// CloudAPI builder
func (dc *DecortClient) CloudAPI() *cloudapi.CloudAPI {
	return cloudapi.New(dc)
}

// CloudBroker builder
func (dc *DecortClient) CloudBroker() *cloudbroker.CloudBroker {
	return cloudbroker.New(dc)
}

// DecortApiCall method for sending requests to the platform
func (dc *DecortClient) DecortApiCall(ctx context.Context, method, url string, params interface{}) ([]byte, error) {
	values, err := query.Values(params)
	if err != nil {
		return nil, err
	}

	body := bytes.NewBufferString(values.Encode())

	req, err := http.NewRequestWithContext(ctx, method, dc.decortURL+constants.Restmachine+url, body)
	if err != nil {
		return nil, err
	}

	// get token
	if err = dc.getToken(ctx); err != nil {
		return nil, err
	}

	// perform request
	respBytes, err := dc.do(req, "")
	if err != nil {
		return nil, err
	}

	return respBytes, err
}

// DecortApiCallMP method for sending requests to the platform
func (dc *DecortClient) DecortApiCallMP(ctx context.Context, method, url string, params interface{}) ([]byte, error) {
	body, ctype, err := multiPartReq(params)
	if err != nil {
		return nil, err
	}

	req, err := http.NewRequestWithContext(ctx, method, dc.decortURL+constants.Restmachine+url, body)
	if err != nil {
		return nil, err
	}

	// get token
	if err = dc.getToken(ctx); err != nil {
		return nil, err
	}

	// perform request
	respBytes, err := dc.do(req, ctype)
	if err != nil {
		return nil, err
	}

	return respBytes, err
}

func (dc *DecortClient) getToken(ctx context.Context) error {
	dc.mutex.Lock()
	defer dc.mutex.Unlock()

	// new token is not needed
	if dc.cfg.Token != "" && !time.Now().After(dc.expiryTime) {
		return nil
	}

	// set up request headers and body
	body := fmt.Sprintf("grant_type=client_credentials&client_id=%s&client_secret=%s&response_type=id_token", dc.cfg.AppID, dc.cfg.AppSecret)
	bodyReader := strings.NewReader(body)

	dc.cfg.SSOURL = strings.TrimSuffix(dc.cfg.SSOURL, "/")

	req, _ := http.NewRequestWithContext(ctx, "POST", dc.cfg.SSOURL+"/v1/oauth/access_token", bodyReader)
	req.Header.Add("Content-Type", "application/x-www-form-urlencoded")

	// request token
	resp, err := dc.client.Do(req)
	if err != nil || resp == nil {
		return fmt.Errorf("cannot get token: %w", err)
	}
	defer resp.Body.Close()

	var tokenBytes []byte
	tokenBytes, err = io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("cannot get token: %w", err)
	}

	if resp.StatusCode != 200 {
		return fmt.Errorf("cannot get token: %s", tokenBytes)
	}

	// save token in config
	token := string(tokenBytes)
	dc.cfg.Token = token
	dc.expiryTime = time.Now().AddDate(0, 0, 1)

	return nil
}

// do method performs request and returns response as an array of bytes and nil error in case of response status code 200.
// In any other cases do returns nil response and error.
// Retries are implemented in case of connection reset errors.
func (dc *DecortClient) do(req *http.Request, ctype string) ([]byte, error) {
	// set up request headers and body
	req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
	if ctype != "" {
		req.Header.Set("Content-Type", ctype)
	}

	req.Header.Add("Authorization", "bearer "+dc.cfg.Token)
	req.Header.Set("Accept", "application/json")

	buf, err := io.ReadAll(req.Body)
	if err != nil {
		return nil, err
	}

	req.Body.Close()
	req.Body = io.NopCloser(bytes.NewBuffer(buf))

	resp, err := dc.client.Do(req)
	if resp != nil {
		defer resp.Body.Close()
	}

	// retries logic GOES HERE
	// get http response
	//var resp *http.Response
	//for i := uint64(0); i < dc.cfg.Retries; i++ {
	//	req := req.Clone(req.Context())
	//	req.Body = io.NopCloser(bytes.NewBuffer(buf))
	//
	//	if i > 0 {
	//		time.Sleep(5 * time.Second) // no time sleep for the first request
	//	}
	//
	//	resp, err = dc.client.Do(req)
	//
	//	// stop retries on success and close response body
	//	if resp != nil {
	//		defer resp.Body.Close()
	//	}
	//	if err == nil {
	//		break
	//	}
	//
	//	// retries in case of connection errors with time sleep
	//	if isConnectionError(err) {
	//		continue
	//	}
	//
	//	// return error in case of non-connection error
	//	return nil, err
	//}

	// handle http request errors
	if err != nil {
		return nil, err
	}
	if resp == nil {
		return nil, fmt.Errorf("got empty response without error")
	}

	// handle successful request
	respBytes, _ := io.ReadAll(resp.Body)
	if resp.StatusCode == 200 {
		return respBytes, nil
	}

	// handle errors with status code other than 200
	err = fmt.Errorf("%s", respBytes)
	return nil, fmt.Errorf("could not execute request: %w", err)
}

// isConnectionError checks if given error falls within specific and associated connection errors
//func isConnectionError(err error) bool {
//	if strings.Contains(err.Error(), "connection reset by peer") {
//		return true
//	}
//	if errors.Is(err, io.EOF) {
//		return true
//	}
//
//	return false
//}

// multiPartReq writes the request structure to the request body, and also returns string of the content-type
func multiPartReq(params interface{}) (*bytes.Buffer, string, error) {
	reqBody := &bytes.Buffer{}
	writer := multipart.NewWriter(reqBody)
	values := reflect.ValueOf(params)
	types := values.Type()
	defer writer.Close()
	for i := 0; i < values.NumField(); i++ {
		if !values.Field(i).IsValid() {
			continue
		}

		if values.Field(i).IsZero() {
			continue
		}

		if file, ok := constants.FileName[types.Field(i).Name]; ok {
			part, err := writer.CreateFormFile(trimString(types.Field(i)), file)
			if err != nil {
				return &bytes.Buffer{}, "", err
			}
			_, err = io.Copy(part, strings.NewReader(valueToString(values.Field(i).Interface())))
			if err != nil {
				return &bytes.Buffer{}, "", err
			}
			continue
		}

		if values.Field(i).Type().Kind() == reflect.Slice {
			switch slice := values.Field(i).Interface().(type) {
			case []string:
				for _, val := range slice {
					err := writer.WriteField(trimString(types.Field(i)), val)
					if err != nil {
						return &bytes.Buffer{}, "", err
					}
				}
			case []uint:
				for _, val := range slice {
					err := writer.WriteField(trimString(types.Field(i)), strconv.FormatUint(uint64(val), 10))
					if err != nil {
						return &bytes.Buffer{}, "", err
					}
				}
			case []uint64:
				for _, val := range slice {
					err := writer.WriteField(trimString(types.Field(i)), strconv.FormatUint(val, 10))
					if err != nil {
						return &bytes.Buffer{}, "", err
					}
				}
			default:
				return &bytes.Buffer{}, "", fmt.Errorf("unsupported slice type:%T", slice)
			}

			continue
		}

		err := writer.WriteField(trimString(types.Field(i)), valueToString(values.Field(i).Interface()))
		if err != nil {
			return &bytes.Buffer{}, "", err
		}
	}
	ct := writer.FormDataContentType()
	return reqBody, ct, nil
}

func valueToString(a any) string {
	switch str := a.(type) {
	case string:
		return str
	case uint:
		return strconv.FormatUint(uint64(str), 10)
	case uint64:
		return strconv.FormatUint(str, 10)
	case bool:
		return strconv.FormatBool(str)
	default:
		return ""
	}
}

func trimString(el reflect.StructField) string {
	return strings.TrimSuffix(el.Tag.Get("url"), ",omitempty")
}