package api

import (
	"context"
	"fmt"
	"net/http"
	"net/url"
	"strconv"
	"strings"

	"github.com/porter-dev/porter/internal/analytics"
	"github.com/porter-dev/porter/internal/models"
	"gorm.io/gorm"

	"github.com/go-chi/chi"
	"github.com/google/go-github/github"
	"github.com/porter-dev/porter/internal/oauth"
	"golang.org/x/oauth2"

	"github.com/porter-dev/porter/internal/models/integrations"
)

// HandleGithubOAuthStartUser starts the oauth2 flow for a user login request.
func (app *App) HandleGithubOAuthStartUser(w http.ResponseWriter, r *http.Request) {
	state := oauth.CreateRandomState()

	err := app.populateOAuthSession(w, r, state, false)

	if err != nil {
		app.handleErrorDataRead(err, w)
		return
	}

	// specify access type offline to get a refresh token
	url := app.GithubUserConf.AuthCodeURL(state, oauth2.AccessTypeOnline)

	http.Redirect(w, r, url, 302)
}

// HandleGithubOAuthStartProject starts the oauth2 flow for a project repo request.
// In this handler, the project id gets written to the session (along with the oauth
// state param), so that the correct project id can be identified in the callback.
func (app *App) HandleGithubOAuthStartProject(w http.ResponseWriter, r *http.Request) {
	state := oauth.CreateRandomState()

	err := app.populateOAuthSession(w, r, state, true)

	if err != nil {
		app.handleErrorDataRead(err, w)
		return
	}

	// specify access type offline to get a refresh token
	url := app.GithubProjectConf.AuthCodeURL(state, oauth2.AccessTypeOffline)

	http.Redirect(w, r, url, 302)
}

// HandleGithubOAuthCallback verifies the callback request by checking that the
// state parameter has not been modified, and validates the token.
// There is a difference between the oauth flow when logging a user in, and when
// linking a repository.
//
// When logging a user in, the access token gets stored in the session, and no refresh
// token is requested. We store the access token in the session because a user can be
// logged in multiple times with a single access token.
//
// NOTE: this user flow will likely be augmented with Dex, or entirely replaced with Dex.
//
// However, when linking a repository, the access token and refresh token are requested when
// the flow has started. A project also gets linked to the session. After callback, a new
// github config gets stored for the project, and the user will then get redirected to
// a URL that allows them to select their repositories they'd like to link. We require a refresh
// token because we need permanent access to the linked repository.
func (app *App) HandleGithubOAuthCallback(w http.ResponseWriter, r *http.Request) {
	session, err := app.Store.Get(r, app.ServerConf.CookieName)

	if err != nil {
		app.handleErrorDataRead(err, w)
		return
	}

	if _, ok := session.Values["state"]; !ok {
		app.sendExternalError(
			err,
			http.StatusForbidden,
			HTTPError{
				Code: http.StatusForbidden,
				Errors: []string{
					"Could not read cookie: are cookies enabled?",
				},
			},
			w,
		)

		return
	}

	if r.URL.Query().Get("state") != session.Values["state"] {
		http.Error(w, http.StatusText(http.StatusForbidden), http.StatusForbidden)
		return
	}

	token, err := app.GithubProjectConf.Exchange(oauth2.NoContext, r.URL.Query().Get("code"))

	if err != nil {
		http.Error(w, http.StatusText(http.StatusForbidden), http.StatusForbidden)
		return
	}

	if !token.Valid() {
		http.Error(w, http.StatusText(http.StatusForbidden), http.StatusForbidden)
		return
	}

	if session.Values["project_id"] != nil && session.Values["project_id"] != "" {
		userID, _ := session.Values["user_id"].(uint)
		projID, _ := session.Values["project_id"].(uint)

		app.updateProjectFromToken(projID, userID, token)
	} else {
		// otherwise, create the user if not exists
		user, err := app.upsertUserFromToken(token)

		if err != nil && strings.Contains(err.Error(), "already registered") {
			http.Redirect(w, r, "/login?error="+url.QueryEscape(err.Error()), 302)
			return
		} else if err != nil {
			http.Error(w, http.StatusText(http.StatusForbidden), http.StatusForbidden)
			return
		}

		// send to segment
		app.AnalyticsClient.Identify(analytics.CreateSegmentIdentifyUser(user))

		// log the user in
		app.Logger.Info().Msgf("New user created: %d", user.ID)

		session.Values["authenticated"] = true
		session.Values["user_id"] = user.ID
		session.Values["email"] = user.Email
		session.Values["redirect"] = ""
		session.Save(r, w)
	}

	if session.Values["query_params"] != "" {
		http.Redirect(w, r, fmt.Sprintf("/dashboard?%s", session.Values["query_params"]), 302)
	} else {
		http.Redirect(w, r, "/dashboard", 302)
	}
}

func (app *App) populateOAuthSession(w http.ResponseWriter, r *http.Request, state string, isProject bool) error {
	session, err := app.Store.Get(r, app.ServerConf.CookieName)

	if err != nil {
		return err
	}

	// need state parameter to validate when redirected
	session.Values["state"] = state
	session.Values["query_params"] = r.URL.RawQuery

	if isProject {
		// read the project id and add it to the session
		projID, err := strconv.ParseUint(chi.URLParam(r, "project_id"), 0, 64)

		if err != nil || projID == 0 {
			return fmt.Errorf("could not read project id")
		}

		session.Values["project_id"] = uint(projID)
	}

	if err := session.Save(r, w); err != nil {
		app.Logger.Warn().Err(err)
	}

	return nil
}

func (app *App) upsertUserFromToken(tok *oauth2.Token) (*models.User, error) {
	// determine if the user already exists
	client := github.NewClient(app.GithubProjectConf.Client(oauth2.NoContext, tok))

	githubUser, _, err := client.Users.Get(context.Background(), "")

	if err != nil {
		return nil, err
	}

	user, err := app.Repo.User.ReadUserByGithubUserID(*githubUser.ID)

	// if the user does not exist, create new user
	if err != nil && err == gorm.ErrRecordNotFound {
		emails, _, err := client.Users.ListEmails(context.Background(), &github.ListOptions{})

		if err != nil {
			return nil, err
		}

		primary := ""
		verified := false

		// get the primary email
		for _, email := range emails {
			if email.GetPrimary() {
				primary = email.GetEmail()
				verified = email.GetVerified()
				break
			}
		}

		if primary == "" {
			return nil, fmt.Errorf("github user must have an email")
		}

		// check if a user with that email address already exists
		_, err = app.Repo.User.ReadUserByEmail(primary)

		if err == gorm.ErrRecordNotFound {
			user = &models.User{
				Email:         primary,
				EmailVerified: !app.Capabilities.Email || verified,
				GithubUserID:  githubUser.GetID(),
			}

			user, err = app.Repo.User.CreateUser(user)

			if err != nil {
				return nil, err
			}

			app.AnalyticsClient.Track(analytics.UserCreateTrack(&analytics.UserCreateTrackOpts{
				UserScopedTrackOpts: analytics.GetUserScopedTrackOpts(user.ID),
				Email:               user.Email,
			}))

			if !verified {
				// non-fatal email verification flow
				app.startEmailVerificationFlow(user)
			}
		} else if err == nil {
			return nil, fmt.Errorf("email already registered")
		} else if err != nil {
			return nil, err
		}
	} else if err != nil {
		return nil, fmt.Errorf("unexpected error occurred:%s", err.Error())
	}

	return user, nil
}

// updates a project's repository clients with the token information.
func (app *App) updateProjectFromToken(projectID uint, userID uint, tok *oauth2.Token) error {
	// get the list of repositories that this token has access to
	client := github.NewClient(app.GithubProjectConf.Client(oauth2.NoContext, tok))

	user, _, err := client.Users.Get(context.Background(), "")

	if err != nil {
		return err
	}

	oauthInt := &integrations.OAuthIntegration{
		SharedOAuthModel: integrations.SharedOAuthModel{
			AccessToken:  []byte(tok.AccessToken),
			RefreshToken: []byte(tok.RefreshToken),
		},
		Client:    integrations.OAuthGithub,
		UserID:    userID,
		ProjectID: projectID,
	}

	// create the oauth integration first
	oauthInt, err = app.Repo.OAuthIntegration.CreateOAuthIntegration(oauthInt)

	if err != nil {
		return err
	}

	// create the git repo
	gr := &models.GitRepo{
		ProjectID:          projectID,
		RepoEntity:         *user.Login,
		OAuthIntegrationID: oauthInt.ID,
	}

	gr, err = app.Repo.GitRepo.CreateGitRepo(gr)

	return err
}

// HandleGithubAppOAuthCallback handles the oauth callback from the GitHub app oauth flow
// this basically just involves generating an access token and then linking it to the current user
func (app *App) HandleGithubAppOAuthCallback(w http.ResponseWriter, r *http.Request) {
	session, err := app.Store.Get(r, app.ServerConf.CookieName)

	if err != nil {
		app.handleErrorDataRead(err, w)
		return
	}

	token, err := app.GithubAppConf.Exchange(oauth2.NoContext, r.URL.Query().Get("code"))

	if err != nil || !token.Valid() {
		if session.Values["query_params"] != "" {
			http.Redirect(w, r, fmt.Sprintf("/dashboard?%s", session.Values["query_params"]), 302)
		} else {
			http.Redirect(w, r, "/dashboard", 302)
		}
		return
	}

	fmt.Println("exchange happaned")
	fmt.Println(token.AccessToken)
	fmt.Println(token.RefreshToken)

	userID, err := app.getUserIDFromRequest(r)

	if err != nil {
		app.handleErrorInternal(err, w)
		return
	}

	user, err := app.Repo.User.ReadUser(userID)

	if err != nil {
		app.handleErrorInternal(err, w)
		return
	}

	oauthInt := &integrations.GithubAppOAuthIntegration{
		SharedOAuthModel: integrations.SharedOAuthModel{
			AccessToken:  []byte(token.AccessToken),
			RefreshToken: []byte(token.RefreshToken),
			Expiry:       token.Expiry,
		},
		UserID: user.ID,
	}

	oauthInt, err = app.Repo.GithubAppOAuthIntegration.CreateGithubAppOAuthIntegration(oauthInt)

	if err != nil {
		app.handleErrorInternal(err, w)
		return
	}

	user.GithubAppIntegrationID = oauthInt.ID

	user, err = app.Repo.User.UpdateUser(user)

	if err != nil {
		app.handleErrorInternal(err, w)
		return
	}

	app.AnalyticsClient.Track(analytics.GithubConnectionSuccessTrack(
		&analytics.GithubConnectionSuccessTrackOpts{
			UserScopedTrackOpts: analytics.GetUserScopedTrackOpts(user.ID),
		},
	))

	if session.Values["query_params"] != "" {
		http.Redirect(w, r, fmt.Sprintf("/dashboard?%s", session.Values["query_params"]), 302)
	} else {
		http.Redirect(w, r, "/dashboard", 302)
	}
}