// Vikunja is a to-do list application to facilitate your life.
// Copyright 2018-2020 Vikunja and contributors. All rights reserved.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package models

import (
	"code.vikunja.io/web"
)

// ListDuplicate holds everything needed to duplicate a list
type ListDuplicate struct {
	// The list id of the list to duplicate
	ListID int64 `json:"list_id"`
	// The target namespace
	NamespaceID int64 `json:"namespace_id"`

	List *List `json:"-"`

	web.Rights   `json:"-"`
	web.CRUDable `json:"-"`
}

// CanCreate checks if a user has the right to duplicate a list
func (ld *ListDuplicate) CanCreate(a web.Auth) (canCreate bool, err error) {
	// List Exists + user has read access to list
	ld.List = &List{ID: ld.ListID}
	canRead, err := ld.List.CanRead(a)
	if err != nil || !canRead {
		return canRead, err
	}

	// Namespace exists + user has write access to is (-> can create new lists)
	ld.List.NamespaceID = ld.NamespaceID
	return ld.List.CanCreate(a)
}

// Create duplicates a list
func (ld *ListDuplicate) Create(a web.Auth) (err error) {

	ld.List.ID = 0
	ld.List.Identifier = "" // Reset the identifier to trigger regenerating a new one
	// Set the owner to the current user
	ld.List.OwnerID = a.GetID()
	if err := CreateOrUpdateList(ld.List); err != nil {
		return err
	}

	// Duplicate kanban buckets
	// Old bucket ID as key, new id as value
	// Used to map the newly created tasks to their new buckets
	bucketMap := make(map[int64]int64)
	buckets := []*Bucket{}
	err = x.Where("list_id = ?", ld.ListID).Find(&buckets)
	if err != nil {
		return
	}
	for _, b := range buckets {
		oldID := b.ID
		b.ID = 0
		b.ListID = ld.List.ID
		if err := b.Create(a); err != nil {
			return err
		}
		bucketMap[oldID] = b.ID
	}

	// Get all tasks + all task details
	tasks, _, _, err := getTasksForLists([]*List{{ID: ld.ListID}}, &taskOptions{})
	if err != nil {
		return err
	}

	taskMap := make(map[int64]int64)
	// Create + update all tasks
	oldTaskIDs := make([]int64, len(tasks))
	for _, t := range tasks {
		oldID := t.ID
		t.ID = 0
		t.ListID = ld.List.ID
		t.BucketID = bucketMap[t.ID]
		t.UID = ""
		err := createTask(t, a, false)
		if err != nil {
			return err
		}
		taskMap[oldID] = t.ID
		oldTaskIDs = append(oldTaskIDs, oldID)
	}

	// Save all attachments
	// We also duplicate all underlying files since they could be modified in one list which would result in
	// file changes in the other list which is not something we want.
	attachments, err := getTaskAttachmentsByTaskIDs(oldTaskIDs)
	if err != nil {
		return err
	}

	for _, attachment := range attachments {
		attachment.TaskID = oldTaskIDs[attachment.TaskID]
		if err := attachment.File.LoadFileByID(); err != nil {
			return err
		}

		err := attachment.NewAttachment(attachment.File.File, attachment.File.Name, attachment.File.Size, a)
		if err != nil {
			return err
		}

		_ = attachment.File.File.Close()
	}

	// Copy label tasks (not the labels)
	labelTasks := []*LabelTask{}
	err = x.In("task_id", oldTaskIDs).Find(&labelTasks)
	if err != nil {
		return
	}

	for _, lt := range labelTasks {
		lt.ID = 0
		lt.TaskID = taskMap[lt.TaskID]
		if _, err := x.Insert(lt); err != nil {
			return err
		}
	}

	//	* assignees
	//	* comments
	//	* relations in that list
	//	* reminders
	//  * Background files + unsplash info

	//	* rights / shares
	//  * Generate new link shares if any are available
	return
}