package oauth

import (
	"encoding/json"
	e "errors"
	"net/http"
	"net/url"
	"strings"
	"fmt"

	"extrovert/internals/router/errors"
	"extrovert/templates/pages"
)

type OAuthClient interface {
	ServeHTTP(w http.ResponseWriter, r *http.Request)
	Token(r *http.Request) (string, error)
	LoginButton() templ.Component
}

type DefaultOAuthToken struct {
	Type         string  `json:"token_type"`
	Token        string  `json:"access_token"`
	Expires      int     `json:"expires_in"`
	Scope        string  `json:"scope"`
	RefreshToken *string `json:"refresh_token"`
}

type DefaultOAuthClient struct {
	Name          string
	Id            string
	Secret        string
	AuthEndpoint  *url.URL
	TokenEndpoint *url.URL
	RedirectUri   *url.URL
}

func NewDefaultOAuthClient(u *url.URL, id string, secret string, redirect *url.URL) DefaultOAuthClient {
	auth, _ := url.Parse(u.String())

	q := auth.Query()
	q.Add("client_id", id)
	q.Add("redirect_uri", redirect.String())
	q.Add("response_type", "code")
	q.Add("scope", "read write")
	q.Add("state", "state")
	q.Add("code_challenge", "challenge")
	q.Add("code_challenge_method", "plain")
	auth.RawQuery = q.Encode()

	auth = auth.JoinPath("/oauth2/authorize")

	token, _ := url.Parse(u.String())
	token = token.JoinPath("/oauth2/token")

	return DefaultOAuthClient{
		Name:          u.Hostname(),
		Id:            id,
		Secret:        secret,
		AuthEndpoint:  auth,
		TokenEndpoint: token,
		RedirectUri:   redirect,
	}
}

templ (c DefaultOAuthClient) LoginButton() {
	<a
		role="button"
		href={ templ.SafeURL(c.AuthEndpoint.String()) }
		rel="noopener noreferrer nofollow"
	>
		Login on { c.Name }
	</a>
}

func (c DefaultOAuthClient) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	code := r.URL.Query().Get("code")
	if code == "" {
		errors.NewErrMissingParams("code").ServeHTTP(w, r)
		return
	}

	req := c.TokenEndpoint

	q := req.Query()
	q.Add("client_id", c.Id)
	q.Add("client_secret", c.Secret)
	q.Add("code", code)
	q.Add("redirect_uri", c.RedirectUri.String())
	q.Add("grant_type", "authorization_code")
	q.Add("code_verifier", "challenge")
	q.Add("challenge_method", "plain")
	req.RawQuery = q.Encode()

	res, err := http.Post(req.String(), "application/x-www-form-urlencoded", bytes.NewReader([]byte("")))
	if err != nil {
		errors.NewErrInternal(e.New("Error while trying to request token"), err).ServeHTTP(w, r)
		return
	}

	body, err := io.ReadAll(res.Body)
	if err != nil {
		errors.NewErrInternal(e.New("Error while trying to read token response body"), err).ServeHTTP(w, r)
		return
	}
	if res.StatusCode != 200 {
		errors.NewErrInternal(fmt.Errorf(
			"Unable to retrieve token, non-200 response from platform. \nStatus: %v\nBody: %s",
			res.StatusCode, string(body)),
		)
		return
	}

	var token DefaultOAuthToken
	err = json.Unmarshal(body, &token)
	if err != nil {
		errors.NewErrInternal(e.New("Error while trying to validate token response body"), err).ServeHTTP(w, r)
		return
	}

	cv, err := json.Marshal(token)
	if err != nil {
		errors.NewErrInternal(e.New("Error while trying to validate token response body"), err).ServeHTTP(w, r)
		return
	}

	http.SetCookie(w, &http.Cookie{
		Name:     "__Host-OAUTH-" + strings.ToUpper(c.Name),
		Value:    url.PathEscape(string(cv)),
		SameSite: http.SameSiteStrictMode,
		Path:     "/",
		Secure:   true,
		HttpOnly: true,
	})

	err = pages.RedirectPopUp(
		"Logged into "+c.Name+"!",
		"Your "+c.Name+" account was successfully logged into project-extrovert. "+
			"Click the button below to return to the Homepage.",
		templ.SafeURL("/"),
	).Render(r.Context(), w)

	if err != nil {
		errors.NewErrInternal(e.New("Unable to render redirect page"), err).ServeHTTP(w, r)
		return
	}

	w.WriteHeader(http.StatusOK)
}

func (c DefaultOAuthClient) Token(r *http.Request) (string, error) {
	cookie, err := r.Cookie("__Host-OAUTH-" + strings.ToUpper(c.Name))
	if err != nil {
		return "", e.Join(e.New("Unable get token cookie"), err)
	}

	j, err := url.PathUnescape(cookie.Value)
	if err != nil {
		return "", e.Join(e.New("Unable to unescape token json"), err)
	}

	var token DefaultOAuthToken
	err = json.Unmarshal([]byte(j), &token)
	if err != nil {
		return "", e.Join(e.New("Unable to parse token json"), err)
	}

	return token.Token, nil
}