//  Vikunja is a todo-list application to facilitate your life.
//  Copyright 2018 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"
	"github.com/go-xorm/builder"
)

// LabelTask represents a relation between a label and a task
type LabelTask struct {
	// The unique, numeric id of this label.
	ID     int64 `xorm:"int(11) autoincr not null unique pk" json:"-"`
	TaskID int64 `xorm:"int(11) INDEX not null" json:"-" param:"listtask"`
	// The label id you want to associate with a task.
	LabelID int64 `xorm:"int(11) INDEX not null" json:"label_id" param:"label"`
	// A unix timestamp when this task was created. You cannot change this value.
	Created int64 `xorm:"created" json:"created"`

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

// TableName makes a pretty table name
func (LabelTask) TableName() string {
	return "label_task"
}

// Delete deletes a label on a task
// @Summary Remove a label from a task
// @Description Remove a label from a task. The user needs to have write-access to the list to be able do this.
// @tags labels
// @Accept json
// @Produce json
// @Security JWTKeyAuth
// @Param task path int true "Task ID"
// @Param label path int true "Label ID"
// @Success 200 {object} models.Label "The label was successfully removed."
// @Failure 403 {object} code.vikunja.io/web.HTTPError "Not allowed to remove the label."
// @Failure 404 {object} code.vikunja.io/web.HTTPError "Label not found."
// @Failure 500 {object} models.Message "Internal error"
// @Router /tasks/{task}/labels/{label} [delete]
func (lt *LabelTask) Delete() (err error) {
	_, err = x.Delete(&LabelTask{LabelID: lt.LabelID, TaskID: lt.TaskID})
	return err
}

// Create adds a label to a task
// @Summary Add a label to a task
// @Description Add a label to a task. The user needs to have write-access to the list to be able do this.
// @tags labels
// @Accept json
// @Produce json
// @Security JWTKeyAuth
// @Param task path int true "Task ID"
// @Param label body models.Label true "The label object"
// @Success 200 {object} models.Label "The created label relation object."
// @Failure 400 {object} code.vikunja.io/web.HTTPError "Invalid label object provided."
// @Failure 403 {object} code.vikunja.io/web.HTTPError "Not allowed to add the label."
// @Failure 404 {object} code.vikunja.io/web.HTTPError "The label does not exist."
// @Failure 500 {object} models.Message "Internal error"
// @Router /tasks/{task}/labels [put]
func (lt *LabelTask) Create(a web.Auth) (err error) {
	// Check if the label is already added
	exists, err := x.Exist(&LabelTask{LabelID: lt.LabelID, TaskID: lt.TaskID})
	if err != nil {
		return err
	}
	if exists {
		return ErrLabelIsAlreadyOnTask{lt.LabelID, lt.TaskID}
	}

	// Insert it
	_, err = x.Insert(lt)
	return
}

// ReadAll gets all labels on a task
// @Summary Get all labels on a task
// @Description Returns all labels which are assicociated with a given task.
// @tags labels
// @Accept json
// @Produce json
// @Param task path int true "Task ID"
// @Param p query int false "The page number. Used for pagination. If not provided, the first page of results is returned."
// @Param s query string false "Search labels by label text."
// @Security JWTKeyAuth
// @Success 200 {array} models.Label "The labels"
// @Failure 500 {object} models.Message "Internal error"
// @Router /tasks/{task}/labels [get]
func (lt *LabelTask) ReadAll(search string, a web.Auth, page int) (labels interface{}, err error) {
	u, err := getUserWithError(a)
	if err != nil {
		return nil, err
	}

	// Check if the user has the right to see the task
	task, err := GetListTaskByID(lt.TaskID)
	if err != nil {
		return nil, err
	}

	if !task.CanRead(a) {
		return nil, ErrNoRightToSeeTask{lt.TaskID, u.ID}
	}

	return getLabelsByTaskIDs(&LabelByTaskIDsOptions{
		User:    u,
		Search:  search,
		Page:    page,
		TaskIDs: []int64{lt.TaskID},
	})
}

// Helper struct, contains the label + its task ID
type labelWithTaskID struct {
	TaskID int64
	Label  `xorm:"extends"`
}

// LabelByTaskIDsOptions is a struct to not clutter the function with too many optional parameters.
type LabelByTaskIDsOptions struct {
	User            *User
	Search          string
	Page            int
	TaskIDs         []int64
	GetUnusedLabels bool
}

// Helper function to get all labels for a set of tasks
// Used when getting all labels for one task as well when getting all lables
func getLabelsByTaskIDs(opts *LabelByTaskIDsOptions) (ls []*labelWithTaskID, err error) {
	// Include unused labels. Needed to be able to show a list of all unused labels a user
	// has access to.
	var uidOrNil interface{}
	var requestOrNil interface{}
	if opts.GetUnusedLabels {
		uidOrNil = opts.User.ID
		requestOrNil = "label_task.label_id != null OR labels.created_by_id = ?"
	}

	// Get all labels associated with these labels
	var labels []*labelWithTaskID
	err = x.Table("labels").
		Select("labels.*, label_task.task_id").
		Join("LEFT", "label_task", "label_task.label_id = labels.id").
		Where(requestOrNil, uidOrNil).
		Or(builder.In("label_task.task_id", opts.TaskIDs)).
		And("labels.title LIKE ?", "%"+opts.Search+"%").
		GroupBy("labels.id").
		Limit(getLimitFromPageIndex(opts.Page)).
		Find(&labels)
	if err != nil {
		return nil, err
	}

	// Get all created by users
	var userids []int64
	for _, l := range labels {
		userids = append(userids, l.CreatedByID)
	}
	users := make(map[int64]*User)
	err = x.In("id", userids).Find(&users)
	if err != nil {
		return nil, err
	}

	// Put it all together
	for in, l := range labels {
		labels[in].CreatedBy = users[l.CreatedByID]
	}

	return labels, err
}

// Create or update a bunch of task labels
func (t *ListTask) updateTaskLabels(creator web.Auth, labels []*Label) (err error) {

	// If we don't have any new labels, delete everything right away. Saves us some hassle.
	if len(labels) == 0 && len(t.Labels) > 0 {
		_, err = x.Where("task_id = ?", t.ID).
			Delete(LabelTask{})
		return err
	}

	// If we didn't change anything (from 0 to zero) don't do anything.
	if len(labels) == 0 && len(t.Labels) == 0 {
		return nil
	}

	// Make a hashmap of the new labels for easier comparison
	newLabels := make(map[int64]*Label, len(labels))
	for _, newLabel := range labels {
		newLabels[newLabel.ID] = newLabel
	}

	// Get old labels to delete
	var found bool
	var labelsToDelete []int64
	oldLabels := make(map[int64]*Label, len(t.Labels))
	allLabels := t.Labels
	t.Labels = []*Label{} // We re-empty our labels struct here because we want it to be fully empty so we can put in all the actual labels.
	for _, oldLabel := range allLabels {
		found = false
		if newLabels[oldLabel.ID] != nil {
			found = true // If a new label is already in the list with old labels
		}

		// Put all labels which are only on the old list to the trash
		if !found {
			labelsToDelete = append(labelsToDelete, oldLabel.ID)
		} else {
			t.Labels = append(t.Labels, oldLabel)
		}

		// Put it in a list with all old labels, just using the loop here
		oldLabels[oldLabel.ID] = oldLabel
	}

	// Delete all labels not passed
	if len(labelsToDelete) > 0 {
		_, err = x.In("label_id", labelsToDelete).
			And("task_id = ?", t.ID).
			Delete(LabelTask{})
		if err != nil {
			return err
		}
	}

	// Loop through our labels and add them
	for _, l := range labels {
		// Check if the label is already added on the task and only add it if not
		if oldLabels[l.ID] != nil {
			// continue outer loop
			continue
		}

		// Add the new label
		label, err := getLabelByIDSimple(l.ID)
		if err != nil {
			return err
		}

		// Check if the user has the rights to see the label he is about to add
		if !label.hasAccessToLabel(creator) {
			user, _ := creator.(*User)
			return ErrUserHasNoAccessToLabel{LabelID: l.ID, UserID: user.ID}
		}

		// Insert it
		_, err = x.Insert(&LabelTask{LabelID: l.ID, TaskID: t.ID})
		if err != nil {
			return err
		}
		t.Labels = append(t.Labels, label)
	}
	return
}

// LabelTaskBulk is a helper struct to update a bunch of labels at once
type LabelTaskBulk struct {
	// All labels you want to update at once. Works exactly like you would update labels while updateing a list.
	Labels []*Label `json:"labels"`
	TaskID int64    `json:"-" param:"listtask"`

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

// Create updates a bunch of labels on a task at once
// @Summary Add multiple new labels to a task
// @Description Adds multiple new labels to a task.
// @tags labels
// @Accept json
// @Produce json
// @Security JWTKeyAuth
// @Param label body models.LabelTaskBulk true "The array of labels"
// @Param taskID path int true "Task ID"
// @Success 200 {object} models.LabelTaskBulk "The updated labels object."
// @Failure 400 {object} code.vikunja.io/web.HTTPError "Invalid label object provided."
// @Failure 500 {object} models.Message "Internal error"
// @Router /tasks/{taskID}/labels/bulk [post]
func (ltb *LabelTaskBulk) Create(a web.Auth) (err error) {
	task, err := GetListTaskByID(ltb.TaskID)
	if err != nil {
		return
	}
	return task.updateTaskLabels(a, task.Labels)
}