/*
   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 (
	"context"
	"errors"
	"fmt"
	"runtime"
	"strings"

	"codeberg.org/gruf/go-store/kv"
	"github.com/superseriousbusiness/gotosocial/internal/db"
)

// Manager provides an interface for managing media: parsing, storing, and retrieving media objects like photos, videos, and gifs.
type Manager interface {
	ProcessMedia(ctx context.Context, data []byte, accountID string) (*Media, error)
}

type manager struct {
	db      db.DB
	storage *kv.KVStore
	pool    *workerPool
}

// New returns a media manager with the given db and underlying storage.
func New(database db.DB, storage *kv.KVStore) Manager {
	workers := runtime.NumCPU() / 2

	return &manager{
		db:      database,
		storage: storage,
		pool:    newWorkerPool(workers),
	}
}

/*
	INTERFACE FUNCTIONS
*/

func (m *manager) ProcessMedia(ctx context.Context, data []byte, accountID string) (*Media, error) {
	contentType, err := parseContentType(data)
	if err != nil {
		return nil, err
	}

	split := strings.Split(contentType, "/")
	if len(split) != 2 {
		return nil, fmt.Errorf("content type %s malformed", contentType)
	}

	mainType := split[0]

	switch mainType {
	case mimeImage:
		if !supportedImage(contentType) {
			return nil, fmt.Errorf("image type %s not supported", contentType)
		}
		if len(data) == 0 {
			return nil, errors.New("image was of size 0")
		}

		return m.pool.run(func(ctx context.Context, data []byte, contentType string, accountID string) {
			m.processImage(ctx, data, contentType, accountID)
		})
	default:
		return nil, fmt.Errorf("content type %s not (yet) supported", contentType)
	}
}