/*
   GoToSocial
   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org

   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 media

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

	"github.com/gin-gonic/gin"
	"github.com/superseriousbusiness/gotosocial/internal/api"
	"github.com/superseriousbusiness/gotosocial/internal/api/model"
	"github.com/superseriousbusiness/gotosocial/internal/config"
	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
	"github.com/superseriousbusiness/gotosocial/internal/oauth"
)

// MediaCreatePOSTHandler swagger:operation POST /api/{api_version}/media mediaCreate
//
// Upload a new media attachment.
//
//	---
//	tags:
//	- media
//
//	consumes:
//	- multipart/form-data
//
//	produces:
//	- application/json
//
//	parameters:
//	-
//		name: api_version
//		type: string
//		in: path
//		description: Version of the API to use. Must be either `v1` or `v2`.
//		required: true
//	-
//		name: description
//		in: formData
//		description: >-
//			Image or media description to use as alt-text on the attachment.
//			This is very useful for users of screenreaders!
//			May or may not be required, depending on your instance settings.
//		type: string
//	-
//		name: focus
//		in: formData
//		description: >-
//			Focus of the media file.
//			If present, it should be in the form of two comma-separated floats between -1 and 1.
//			For example: `-0.5,0.25`.
//		type: string
//		default: "0,0"
//	-
//		name: file
//		in: formData
//		description: The media attachment to upload.
//		type: file
//		required: true
//
//	security:
//	- OAuth2 Bearer:
//		- write:media
//
//	responses:
//		'200':
//			description: The newly-created media attachment.
//			schema:
//				"$ref": "#/definitions/attachment"
//		'400':
//			description: bad request
//		'401':
//			description: unauthorized
//		'422':
//			description: unprocessable
//		'500':
//			description: internal server error
func (m *Module) MediaCreatePOSTHandler(c *gin.Context) {
	authed, err := oauth.Authed(c, true, true, true, true)
	if err != nil {
		api.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGet)
		return
	}

	if _, err := api.NegotiateAccept(c, api.JSONAcceptHeaders...); err != nil {
		api.ErrorHandler(c, gtserror.NewErrorNotAcceptable(err, err.Error()), m.processor.InstanceGet)
		return
	}

	apiVersion := c.Param(APIVersionKey)
	if apiVersion != "v1" && apiVersion != "v2" {
		err := errors.New("api version must be one of v1 or v2")
		api.ErrorHandler(c, gtserror.NewErrorNotFound(err, err.Error()), m.processor.InstanceGet)
		return
	}

	form := &model.AttachmentRequest{}
	if err := c.ShouldBind(&form); err != nil {
		api.ErrorHandler(c, gtserror.NewErrorBadRequest(err, err.Error()), m.processor.InstanceGet)
		return
	}

	if err := validateCreateMedia(form); err != nil {
		api.ErrorHandler(c, gtserror.NewErrorBadRequest(err, err.Error()), m.processor.InstanceGet)
		return
	}

	apiAttachment, errWithCode := m.processor.MediaCreate(c.Request.Context(), authed, form)
	if err != nil {
		api.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
		return
	}

	if apiVersion == "v2" {
		// the mastodon v2 media API specifies that the URL should be null
		// and that the client should call /api/v1/media/:id to get the URL
		//
		// so even though we have the URL already, remove it now to comply
		// with the api
		apiAttachment.URL = nil
	}

	c.JSON(http.StatusOK, apiAttachment)
}

func validateCreateMedia(form *model.AttachmentRequest) error {
	// check there actually is a file attached and it's not size 0
	if form.File == nil {
		return errors.New("no attachment given")
	}

	maxVideoSize := config.GetMediaVideoMaxSize()
	maxImageSize := config.GetMediaImageMaxSize()
	minDescriptionChars := config.GetMediaDescriptionMinChars()
	maxDescriptionChars := config.GetMediaDescriptionMaxChars()

	// a very superficial check to see if no size limits are exceeded
	// we still don't actually know which media types we're dealing with but the other handlers will go into more detail there
	maxSize := maxVideoSize
	if maxImageSize > maxSize {
		maxSize = maxImageSize
	}

	if form.File.Size > int64(maxSize) {
		return fmt.Errorf("file size limit exceeded: limit is %d bytes but attachment was %d bytes", maxSize, form.File.Size)
	}

	if length := len([]rune(form.Description)); length > maxDescriptionChars {
		return fmt.Errorf("image description length must be between %d and %d characters (inclusive), but provided image description was %d chars", minDescriptionChars, maxDescriptionChars, length)
	}

	return nil
}
