package jwtutil

import (
	"net/http"
	"strings"

	"github.com/lestrrat-go/jwx/v2/jwk"
	"github.com/lestrrat-go/jwx/v2/jwt"
	"github.com/pkg/errors"
)

type TokenFinderFunc func(r *http.Request) (string, error)

type FindTokenOptions struct {
	Finders []TokenFinderFunc
}

type FindTokenOptionFunc func(*FindTokenOptions)

type GetKeySetFunc func() (jwk.Set, error)

func WithFinders(finders ...TokenFinderFunc) FindTokenOptionFunc {
	return func(opts *FindTokenOptions) {
		opts.Finders = finders
	}
}

func NewFindTokenOptions(funcs ...FindTokenOptionFunc) *FindTokenOptions {
	opts := &FindTokenOptions{
		Finders: []TokenFinderFunc{
			FindTokenFromAuthorizationHeader,
		},
	}

	for _, fn := range funcs {
		fn(opts)
	}

	return opts
}

func FindTokenFromAuthorizationHeader(r *http.Request) (string, error) {
	authorization := r.Header.Get("Authorization")

	// Retrieve token from Authorization header
	rawToken := strings.TrimPrefix(authorization, "Bearer ")

	return rawToken, nil
}

func FindTokenFromQueryString(name string) TokenFinderFunc {
	return func(r *http.Request) (string, error) {
		return r.URL.Query().Get(name), nil
	}
}

func FindTokenFromCookie(cookieName string) TokenFinderFunc {
	return func(r *http.Request) (string, error) {
		cookie, err := r.Cookie(cookieName)
		if err != nil && !errors.Is(err, http.ErrNoCookie) {
			return "", errors.WithStack(err)
		}

		if cookie == nil {
			return "", nil
		}

		return cookie.Value, nil
	}
}

func FindRawToken(r *http.Request, funcs ...FindTokenOptionFunc) (string, error) {
	opts := NewFindTokenOptions(funcs...)

	var rawToken string
	var err error

	for _, find := range opts.Finders {
		rawToken, err = find(r)
		if err != nil {
			return "", errors.WithStack(err)
		}

		if rawToken == "" {
			continue
		}

		break
	}

	if rawToken == "" {
		return "", errors.WithStack(ErrUnauthenticated)
	}

	return rawToken, nil
}

func FindToken(r *http.Request, getKeySet GetKeySetFunc, funcs ...FindTokenOptionFunc) (jwt.Token, error) {
	rawToken, err := FindRawToken(r, funcs...)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	keySet, err := getKeySet()
	if err != nil {
		return nil, errors.WithStack(err)
	}

	if keySet == nil {
		return nil, errors.WithStack(ErrNoKeySet)
	}

	token, err := Parse([]byte(rawToken), keySet)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return token, nil
}