// Vikunja is a to-do list application to facilitate your life.
// Copyright 2018-2021 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 Affero General Public Licensee 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 Licensee for more details.
//
// You should have received a copy of the GNU Affero General Public Licensee
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package models

import (
	"time"

	"code.vikunja.io/api/pkg/log"
	"code.vikunja.io/api/pkg/user"
	"code.vikunja.io/web"
	"xorm.io/xorm"
)

// Bucket represents a kanban bucket
type Bucket struct {
	// The unique, numeric id of this bucket.
	ID int64 `xorm:"bigint autoincr not null unique pk" json:"id" param:"bucket"`
	// The title of this bucket.
	Title string `xorm:"text not null" valid:"required" minLength:"1" json:"title"`
	// The list this bucket belongs to.
	ListID int64 `xorm:"bigint not null" json:"list_id" param:"list"`
	// All tasks which belong to this bucket.
	Tasks []*Task `xorm:"-" json:"tasks"`

	// How many tasks can be at the same time on this board max
	Limit int64 `xorm:"default 0" json:"limit"`
	// If this bucket is the "done bucket". All tasks moved into this bucket will automatically marked as done. All tasks marked as done from elsewhere will be moved into this bucket.
	IsDoneBucket bool `xorm:"BOOL" json:"is_done_bucket"`

	// A timestamp when this bucket was created. You cannot change this value.
	Created time.Time `xorm:"created not null" json:"created"`
	// A timestamp when this bucket was last updated. You cannot change this value.
	Updated time.Time `xorm:"updated not null" json:"updated"`

	// The user who initially created the bucket.
	CreatedBy   *user.User `xorm:"-" json:"created_by" valid:"-"`
	CreatedByID int64      `xorm:"bigint not null" json:"-"`

	// Including the task collection type so we can use task filters on kanban
	TaskCollection `xorm:"-" json:"-"`

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

// TableName returns the table name for this bucket.
func (b *Bucket) TableName() string {
	return "buckets"
}

func getBucketByID(s *xorm.Session, id int64) (b *Bucket, err error) {
	b = &Bucket{}
	exists, err := s.Where("id = ?", id).Get(b)
	if err != nil {
		return
	}
	if !exists {
		return b, ErrBucketDoesNotExist{BucketID: id}
	}
	return
}

func getDefaultBucket(s *xorm.Session, listID int64) (bucket *Bucket, err error) {
	bucket = &Bucket{}
	_, err = s.
		Where("list_id = ?", listID).
		OrderBy("id asc").
		Get(bucket)
	return
}

func getDoneBucketForList(s *xorm.Session, listID int64) (bucket *Bucket, err error) {
	bucket = &Bucket{}
	exists, err := s.
		Where("list_id = ? and is_done_bucket = ?", listID, true).
		Get(bucket)
	if err != nil {
		return nil, err
	}
	if !exists {
		bucket = nil
	}

	return
}

// ReadAll returns all buckets with their tasks for a certain list
// @Summary Get all kanban buckets of a list
// @Description Returns all kanban buckets with belong to a list including their tasks.
// @tags task
// @Accept json
// @Produce json
// @Security JWTKeyAuth
// @Param id path int true "List Id"
// @Param page query int false "The page number for tasks. Used for pagination. If not provided, the first page of results is returned."
// @Param per_page query int false "The maximum number of tasks per bucket per page. This parameter is limited by the configured maximum of items per page."
// @Param s query string false "Search tasks by task text."
// @Param filter_by query string false "The name of the field to filter by. Allowed values are all task properties. Task properties which are their own object require passing in the id of that entity. Accepts an array for multiple filters which will be chanied together, all supplied filter must match."
// @Param filter_value query string false "The value to filter for."
// @Param filter_comparator query string false "The comparator to use for a filter. Available values are `equals`, `greater`, `greater_equals`, `less`, `less_equals`, `like` and `in`. `in` expects comma-separated values in `filter_value`. Defaults to `equals`"
// @Param filter_concat query string false "The concatinator to use for filters. Available values are `and` or `or`. Defaults to `or`."
// @Param filter_include_nulls query string false "If set to true the result will include filtered fields whose value is set to `null`. Available values are `true` or `false`. Defaults to `false`."
// @Success 200 {array} models.Bucket "The buckets with their tasks"
// @Failure 500 {object} models.Message "Internal server error"
// @Router /lists/{id}/buckets [get]
func (b *Bucket) ReadAll(s *xorm.Session, auth web.Auth, search string, page int, perPage int) (result interface{}, resultCount int, numberOfTotalItems int64, err error) {

	// Get all buckets for this list
	buckets := []*Bucket{}
	err = s.Where("list_id = ?", b.ListID).Find(&buckets)
	if err != nil {
		return
	}

	// Make a map from the bucket slice with their id as key so that we can use it to put the tasks in their buckets
	bucketMap := make(map[int64]*Bucket, len(buckets))
	userIDs := make([]int64, 0, len(buckets))
	for _, bb := range buckets {
		bucketMap[bb.ID] = bb
		userIDs = append(userIDs, bb.CreatedByID)
	}

	// Get all users
	users, err := getUsersOrLinkSharesFromIDs(s, userIDs)
	if err != nil {
		return
	}

	for _, bb := range buckets {
		bb.CreatedBy = users[bb.CreatedByID]
	}

	tasks := []*Task{}

	opts, err := getTaskFilterOptsFromCollection(&b.TaskCollection)
	if err != nil {
		return nil, 0, 0, err
	}

	opts.sortby = []*sortParam{
		{
			orderBy: orderAscending,
			sortBy:  taskPropertyPosition,
		},
	}
	opts.page = page
	opts.perPage = perPage
	opts.search = search
	opts.filterConcat = filterConcatAnd

	var bucketFilterIndex int
	for i, filter := range opts.filters {
		if filter.field == taskPropertyBucketID {
			bucketFilterIndex = i
			break
		}
	}

	if bucketFilterIndex == 0 {
		opts.filters = append(opts.filters, &taskFilter{
			field:      taskPropertyBucketID,
			value:      0,
			comparator: taskFilterComparatorEquals,
		})
		bucketFilterIndex = len(opts.filters) - 1
	}

	for id, bucket := range bucketMap {

		opts.filters[bucketFilterIndex].value = id

		ts, _, _, err := getRawTasksForLists(s, []*List{{ID: bucket.ListID}}, auth, opts)
		if err != nil {
			return nil, 0, 0, err
		}

		tasks = append(tasks, ts...)
	}

	taskMap := make(map[int64]*Task, len(tasks))
	for _, t := range tasks {
		taskMap[t.ID] = t
	}

	err = addMoreInfoToTasks(s, taskMap)
	if err != nil {
		return nil, 0, 0, err
	}

	// Put all tasks in their buckets
	// All tasks which are not associated to any bucket will have bucket id 0 which is the nil value for int64
	// Since we created a bucked with that id at the beginning, all tasks should be in there.
	for _, task := range tasks {
		// Check if the bucket exists in the map to prevent nil pointer panics
		if _, exists := bucketMap[task.BucketID]; !exists {
			log.Debugf("Tried to put task %d into bucket %d which does not exist in list %d", task.ID, task.BucketID, b.ListID)
			continue
		}
		bucketMap[task.BucketID].Tasks = append(bucketMap[task.BucketID].Tasks, task)
	}

	return buckets, len(buckets), int64(len(buckets)), nil
}

// Create creates a new bucket
// @Summary Create a new bucket
// @Description Creates a new kanban bucket on a list.
// @tags task
// @Accept json
// @Produce json
// @Security JWTKeyAuth
// @Param id path int true "List Id"
// @Param bucket body models.Bucket true "The bucket object"
// @Success 200 {object} models.Bucket "The created bucket object."
// @Failure 400 {object} web.HTTPError "Invalid bucket object provided."
// @Failure 404 {object} web.HTTPError "The list does not exist."
// @Failure 500 {object} models.Message "Internal error"
// @Router /lists/{id}/buckets [put]
func (b *Bucket) Create(s *xorm.Session, a web.Auth) (err error) {
	b.CreatedBy, err = getUserOrLinkShareUser(s, a)
	if err != nil {
		return
	}
	b.CreatedByID = b.CreatedBy.ID

	_, err = s.Insert(b)
	return
}

// Update Updates an existing bucket
// @Summary Update an existing bucket
// @Description Updates an existing kanban bucket.
// @tags task
// @Accept json
// @Produce json
// @Security JWTKeyAuth
// @Param listID path int true "List Id"
// @Param bucketID path int true "Bucket Id"
// @Param bucket body models.Bucket true "The bucket object"
// @Success 200 {object} models.Bucket "The created bucket object."
// @Failure 400 {object} web.HTTPError "Invalid bucket object provided."
// @Failure 404 {object} web.HTTPError "The bucket does not exist."
// @Failure 500 {object} models.Message "Internal error"
// @Router /lists/{listID}/buckets/{bucketID} [post]
func (b *Bucket) Update(s *xorm.Session, a web.Auth) (err error) {
	doneBucket, err := getDoneBucketForList(s, b.ListID)
	if err != nil {
		return err
	}

	if doneBucket != nil && doneBucket.IsDoneBucket && b.IsDoneBucket {
		return &ErrOnlyOneDoneBucketPerList{
			BucketID:     b.ID,
			ListID:       b.ListID,
			DoneBucketID: doneBucket.ID,
		}
	}

	_, err = s.
		Where("id = ?", b.ID).
		Cols(
			"title",
			"limit",
			"is_done_bucket",
		).
		Update(b)
	return
}

// Delete removes a bucket, but no tasks
// @Summary Deletes an existing bucket
// @Description Deletes an existing kanban bucket and dissociates all of its task. It does not delete any tasks. You cannot delete the last bucket on a list.
// @tags task
// @Accept json
// @Produce json
// @Security JWTKeyAuth
// @Param listID path int true "List Id"
// @Param bucketID path int true "Bucket Id"
// @Success 200 {object} models.Message "Successfully deleted."
// @Failure 404 {object} web.HTTPError "The bucket does not exist."
// @Failure 500 {object} models.Message "Internal error"
// @Router /lists/{listID}/buckets/{bucketID} [delete]
func (b *Bucket) Delete(s *xorm.Session, a web.Auth) (err error) {

	// Prevent removing the last bucket
	total, err := s.Where("list_id = ?", b.ListID).Count(&Bucket{})
	if err != nil {
		return
	}
	if total <= 1 {
		return ErrCannotRemoveLastBucket{
			BucketID: b.ID,
			ListID:   b.ListID,
		}
	}

	// Remove the bucket itself
	_, err = s.Where("id = ?", b.ID).Delete(&Bucket{})
	if err != nil {
		return
	}

	// Get the default bucket
	defaultBucket, err := getDefaultBucket(s, b.ListID)
	if err != nil {
		return
	}

	// Remove all associations of tasks to that bucket
	_, err = s.
		Where("bucket_id = ?", b.ID).
		Cols("bucket_id").
		Update(&Task{BucketID: defaultBucket.ID})
	return
}