package vcontrolsdk

import (
	"bytes"
	"context"
	"crypto/tls"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"sync"
	"time"

	"github.com/google/go-querystring/query"
	"repository.basistech.ru/BASIS/dynamix-standard-go-sdk/config"
	"repository.basistech.ru/BASIS/dynamix-standard-go-sdk/internal/constants"
	api "repository.basistech.ru/BASIS/dynamix-standard-go-sdk/pkg"
)

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

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

	var expiryTime time.Time

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

	return &VControlClient{
		URL: cfg.VControlURL,
		client: &http.Client{
			Transport: &http.Transport{
				TLSClientConfig: &tls.Config{
					InsecureSkipVerify: cfg.SSLSkipVerify,
				},
			},
		},
		cfg:        trimConfig(&cfg),
		expiryTime: expiryTime,
		mutex:      &sync.Mutex{},
	}
}

// API builder
func (ldc *VControlClient) API() *api.API {
	return api.New(ldc)
}

// ApiCall method for sending requests to the platform
func (ldc *VControlClient) ApiCall(ctx context.Context, method, url string, params interface{}) ([]byte, error) {
	// get token
	if err := ldc.getToken(ctx); err != nil {
		return nil, err
	}

	var body *bytes.Buffer

	byteSlice, ok := params.([]byte)
	if ok {
		body = bytes.NewBuffer(byteSlice)
	} else {
		values, err := query.Values(params)
		if err != nil {
			return nil, err
		}
		body = bytes.NewBufferString(values.Encode())
	}

	req, err := http.NewRequestWithContext(ctx, method, ldc.URL+constants.API+url, body)
	if err != nil {
		return nil, err
	}

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

	return respBytes, err
}

func (ldc *VControlClient) getToken(ctx context.Context) error {
	ldc.mutex.Lock()
	defer ldc.mutex.Unlock()

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

	// set up request headers and body
	body := fmt.Sprintf("login=%s&password=%s", url.QueryEscape(ldc.cfg.Username), url.QueryEscape(ldc.cfg.Password))
	bodyReader := strings.NewReader(body)
	req, _ := http.NewRequestWithContext(ctx, "POST", ldc.cfg.VControlURL+constants.API+constants.APIv0+"/auth", bodyReader)

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

	var respBodyBytes []byte
	respBodyBytes, 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", respBodyBytes)
	}

	var token string
	cookies := resp.Cookies()
	for _, c := range cookies {
		if c.Name == "api_token" {
			token = c.Value
		}
	}

	// save token in config
	ldc.cfg.Token = token
	ldc.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 (ldc *VControlClient) do(req *http.Request) ([]byte, error) {

	req.Header.Set("Cookie", fmt.Sprintf("api_token=%s", ldc.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 := ldc.client.Do(req)
	if resp != nil {
		defer resp.Body.Close()
	}

	// 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)
}

func trimConfig(cfg *config.Config) config.Config {
	cfg.VControlURL = strings.TrimSuffix(cfg.VControlURL, "/")
	return *cfg
}