// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package fedi

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

	"github.com/superseriousbusiness/activity/streams/vocab"
	"github.com/superseriousbusiness/gotosocial/internal/ap"
	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
	"github.com/superseriousbusiness/gotosocial/internal/uris"
)

// UserGet handles the getting of a fedi/activitypub representation of a user/account, performing appropriate authentication
// before returning a JSON serializable interface to the caller.
func (p *Processor) UserGet(ctx context.Context, requestedUsername string, requestURL *url.URL) (interface{}, gtserror.WithCode) {
	// Get the instance-local account the request is referring to.
	requestedAccount, err := p.state.DB.GetAccountByUsernameDomain(ctx, requestedUsername, "")
	if err != nil {
		return nil, gtserror.NewErrorNotFound(fmt.Errorf("database error getting account with username %s: %s", requestedUsername, err))
	}

	var requestedPerson vocab.ActivityStreamsPerson

	if uris.IsPublicKeyPath(requestURL) {
		// if it's a public key path, we don't need to authenticate but we'll only serve the bare minimum user profile needed for the public key
		requestedPerson, err = p.tc.AccountToASMinimal(ctx, requestedAccount)
		if err != nil {
			return nil, gtserror.NewErrorInternalError(err)
		}
	} else {
		// if it's any other path, we want to fully authenticate the request before we serve any data, and then we can serve a more complete profile
		requestingAccountURI, errWithCode := p.federator.AuthenticateFederatedRequest(ctx, requestedUsername)
		if errWithCode != nil {
			return nil, errWithCode
		}

		// if we're not already handshaking/dereferencing a remote account, dereference it now
		if !p.federator.Handshaking(requestedUsername, requestingAccountURI) {
			requestingAccount, err := p.federator.GetAccountByURI(
				gtscontext.SetFastFail(ctx), requestedUsername, requestingAccountURI,
			)
			if err != nil {
				return nil, gtserror.NewErrorUnauthorized(err)
			}

			blocked, err := p.state.DB.IsEitherBlocked(ctx, requestedAccount.ID, requestingAccount.ID)
			if err != nil {
				return nil, gtserror.NewErrorInternalError(err)
			}

			if blocked {
				return nil, gtserror.NewErrorUnauthorized(fmt.Errorf("block exists between accounts %s and %s", requestedAccount.ID, requestingAccount.ID))
			}
		}

		requestedPerson, err = p.tc.AccountToAS(ctx, requestedAccount)
		if err != nil {
			return nil, gtserror.NewErrorInternalError(err)
		}
	}

	data, err := ap.Serialize(requestedPerson)
	if err != nil {
		return nil, gtserror.NewErrorInternalError(err)
	}

	return data, nil
}