package providers

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"net/url"

	"github.com/oauth2-proxy/oauth2-proxy/pkg/apis/sessions"
	"github.com/oauth2-proxy/oauth2-proxy/pkg/requests"
)

// LinkedInProvider represents an LinkedIn based Identity Provider
type LinkedInProvider struct {
	*ProviderData
}

var _ Provider = (*LinkedInProvider)(nil)

const (
	linkedinProviderName = "LinkedIn"
	linkedinDefaultScope = "r_emailaddress r_basicprofile"
)

var (
	// Default Login URL for LinkedIn.
	// Pre-parsed URL of https://www.linkedin.com/uas/oauth2/authorization.
	linkedinDefaultLoginURL = &url.URL{
		Scheme: "https",
		Host:   "www.linkedin.com",
		Path:   "/uas/oauth2/authorization",
	}

	// Default Redeem URL for LinkedIn.
	// Pre-parsed URL of https://www.linkedin.com/uas/oauth2/accessToken.
	linkedinDefaultRedeemURL = &url.URL{
		Scheme: "https",
		Host:   "www.linkedin.com",
		Path:   "/uas/oauth2/accessToken",
	}

	// Default Profile URL for LinkedIn.
	// Pre-parsed URL of https://www.linkedin.com/v1/people/~/email-address.
	linkedinDefaultProfileURL = &url.URL{
		Scheme: "https",
		Host:   "www.linkedin.com",
		Path:   "/v1/people/~/email-address",
	}
)

// NewLinkedInProvider initiates a new LinkedInProvider
func NewLinkedInProvider(p *ProviderData) *LinkedInProvider {
	p.setProviderDefaults(providerDefaults{
		name:        linkedinProviderName,
		loginURL:    linkedinDefaultLoginURL,
		redeemURL:   linkedinDefaultRedeemURL,
		profileURL:  linkedinDefaultProfileURL,
		validateURL: linkedinDefaultProfileURL,
		scope:       linkedinDefaultScope,
	})
	return &LinkedInProvider{ProviderData: p}
}

func getLinkedInHeader(accessToken string) http.Header {
	header := make(http.Header)
	header.Set("Accept", "application/json")
	header.Set("x-li-format", "json")
	header.Set("Authorization", fmt.Sprintf("Bearer %s", accessToken))
	return header
}

// GetEmailAddress returns the Account email address
func (p *LinkedInProvider) GetEmailAddress(ctx context.Context, s *sessions.SessionState) (string, error) {
	if s.AccessToken == "" {
		return "", errors.New("missing access token")
	}

	requestURL := p.ProfileURL.String() + "?format=json"
	json, err := requests.New(requestURL).
		WithContext(ctx).
		WithHeaders(getLinkedInHeader(s.AccessToken)).
		Do().
		UnmarshalJSON()
	if err != nil {
		return "", err
	}

	email, err := json.String()
	if err != nil {
		return "", err
	}
	return email, nil
}

// ValidateSessionState validates the AccessToken
func (p *LinkedInProvider) ValidateSessionState(ctx context.Context, s *sessions.SessionState) bool {
	return validateToken(ctx, p, s.AccessToken, getLinkedInHeader(s.AccessToken))
}