package internal

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

	"github.com/go-acme/lego/v4/providers/dns/internal/errutils"
	"github.com/go-acme/lego/v4/providers/dns/internal/useragent"
	"github.com/pquerna/otp/totp"
)

type token string

const tokenKey token = "token"

type Identifier struct {
	username string
	password string
	Secret   string

	BaseURL    *url.URL
	HTTPClient *http.Client
}

func NewIdentifier(username, password, secret string) (*Identifier, error) {
	if username == "" || password == "" {
		return nil, errors.New("credentials missing")
	}

	baseURL, _ := url.Parse(defaultBaseURL)

	return &Identifier{
		username:   username,
		password:   password,
		Secret:     secret,
		BaseURL:    baseURL,
		HTTPClient: &http.Client{Timeout: 10 * time.Second},
	}, nil
}

func (c *Identifier) Authenticate(ctx context.Context) (*Token, error) {
	endpoint := c.BaseURL.JoinPath("authenticate")

	auth := Auth{Username: c.username, Password: c.password}

	if c.Secret != "" {
		tan, err := totp.GenerateCode(c.Secret, time.Now())
		if err != nil {
			return nil, fmt.Errorf("generate TOTP: %w", err)
		}

		auth.Code, err = strconv.Atoi(tan)
		if err != nil {
			return nil, fmt.Errorf("parse TOTP: %w", err)
		}
	}

	req, err := newJSONRequest(ctx, http.MethodPost, endpoint, auth)
	if err != nil {
		return nil, err
	}

	var result APIResponse[*Token]

	err = c.do(req, &result)
	if err != nil {
		return nil, err
	}

	return result.Data, nil
}

func (c *Identifier) do(req *http.Request, result any) error {
	useragent.SetHeader(req.Header)

	resp, err := c.HTTPClient.Do(req)
	if err != nil {
		return errutils.NewHTTPDoError(req, err)
	}

	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode/100 != 2 {
		return parseError(req, resp)
	}

	if result == nil {
		return nil
	}

	raw, err := io.ReadAll(resp.Body)
	if err != nil {
		return errutils.NewReadResponseError(req, resp.StatusCode, err)
	}

	err = json.Unmarshal(raw, result)
	if err != nil {
		return errutils.NewUnmarshalError(req, resp.StatusCode, raw, err)
	}

	return nil
}

func WithContext(ctx context.Context, credential string) context.Context {
	return context.WithValue(ctx, tokenKey, credential)
}

func getToken(ctx context.Context) string {
	credential, ok := ctx.Value(tokenKey).(string)
	if !ok {
		return ""
	}

	return credential
}