// Copyright 2019-present Facebook Inc. All rights reserved.
// This source code is licensed under the Apache 2.0 license found
// in the LICENSE file in the root directory of this source tree.

// Code generated by ent, DO NOT EDIT.

package ent

import (
	"context"
	"errors"
	"fmt"
	"sync"

	"entgo.io/ent"
	"entgo.io/ent/examples/fs/ent/file"
)

const (
	// Operation types.
	OpCreate    = ent.OpCreate
	OpDelete    = ent.OpDelete
	OpDeleteOne = ent.OpDeleteOne
	OpUpdate    = ent.OpUpdate
	OpUpdateOne = ent.OpUpdateOne

	// Node types.
	TypeFile = "File"
)

// FileMutation represents an operation that mutates the File nodes in the graph.
type FileMutation struct {
	file.Mutation
	config
	id       *int
	done     bool
	oldValue func(context.Context) (*File, error)
}

var _ ent.Mutation = (*FileMutation)(nil)

// fileOption allows management of the mutation configuration using functional options.
type fileOption func(*FileMutation)

// newFileMutation creates new mutation for the File entity.
func newFileMutation(c config, op Op, opts ...fileOption) *FileMutation {
	m := &FileMutation{
		Mutation: *file.NewMutation(op),
		config:   c,
	}
	for _, opt := range opts {
		opt(m)
	}
	return m
}

// ID returns the ID value in the mutation. Note that the ID is only available
// if it was provided to the builder or after it was returned from the database.
func (m *FileMutation) ID() (id int, exists bool) {
	if m.id == nil {
		return
	}
	return *m.id, true
}

// withFileID sets the ID field of the mutation.
func withFileID(id int) fileOption {
	return func(m *FileMutation) {
		var (
			err   error
			once  sync.Once
			value *File
		)
		m.oldValue = func(ctx context.Context) (*File, error) {
			once.Do(func() {
				if m.done {
					err = errors.New("querying old values post mutation is not allowed")
				} else {
					value, err = m.Client().File.Get(ctx, id)
				}
			})
			return value, err
		}
		m.id = &id
	}
}

// withFile sets the old File of the mutation.
func withFile(node *File) fileOption {
	return func(m *FileMutation) {
		m.oldValue = func(context.Context) (*File, error) {
			return node, nil
		}
		m.id = &node.ID
	}
}

// Client returns a new `ent.Client` from the mutation. If the mutation was
// executed in a transaction (ent.Tx), a transactional client is returned.
func (m FileMutation) Client() *Client {
	client := &Client{config: m.config}
	client.init()
	return client
}

// Tx returns an `ent.Tx` for mutations that were executed in transactions;
// it returns an error otherwise.
func (m FileMutation) Tx() (*Tx, error) {
	if _, ok := m.driver.(*txDriver); !ok {
		return nil, errors.New("ent: mutation is not running in a transaction")
	}
	tx := &Tx{config: m.config}
	tx.init()
	return tx, nil
}

// IDs queries the database and returns the entity ids that match the mutation's predicate.
// That means, if the mutation is applied within a transaction with an isolation level such
// as sql.LevelSerializable, the returned ids match the ids of the rows that will be updated
// or updated by the mutation.
func (m *FileMutation) IDs(ctx context.Context) ([]int, error) {
	switch {
	case m.Op().Is(OpUpdateOne | OpDeleteOne):
		id, exists := m.ID()
		if exists {
			return []int{id}, nil
		}
		fallthrough
	case m.Op().Is(OpUpdate | OpDelete):
		return m.Client().File.Query().Where(m.Predicates()...).IDs(ctx)
	default:
		return nil, fmt.Errorf("IDs is not allowed on %s operations", m.Op())
	}
}

// OldName returns the old "name" field's value of the File entity.
// If the File object wasn't provided to the builder, the object is fetched from the database.
// An error is returned if the mutation operation is not UpdateOne, or the database query fails.
func (m *FileMutation) OldName(ctx context.Context) (v string, err error) {
	if !m.Op().Is(OpUpdateOne) {
		return v, errors.New("OldName is only allowed on UpdateOne operations")
	}
	if _, exists := m.ID(); !exists || m.oldValue == nil {
		return v, errors.New("OldName requires an ID field in the mutation")
	}
	oldValue, err := m.oldValue(ctx)
	if err != nil {
		return v, fmt.Errorf("querying old value for OldName: %w", err)
	}
	return oldValue.Name, nil
}

// OldDeleted returns the old "deleted" field's value of the File entity.
// If the File object wasn't provided to the builder, the object is fetched from the database.
// An error is returned if the mutation operation is not UpdateOne, or the database query fails.
func (m *FileMutation) OldDeleted(ctx context.Context) (v bool, err error) {
	if !m.Op().Is(OpUpdateOne) {
		return v, errors.New("OldDeleted is only allowed on UpdateOne operations")
	}
	if _, exists := m.ID(); !exists || m.oldValue == nil {
		return v, errors.New("OldDeleted requires an ID field in the mutation")
	}
	oldValue, err := m.oldValue(ctx)
	if err != nil {
		return v, fmt.Errorf("querying old value for OldDeleted: %w", err)
	}
	return oldValue.Deleted, nil
}

// OldParentID returns the old "parent_id" field's value of the File entity.
// If the File object wasn't provided to the builder, the object is fetched from the database.
// An error is returned if the mutation operation is not UpdateOne, or the database query fails.
func (m *FileMutation) OldParentID(ctx context.Context) (v int, err error) {
	if !m.Op().Is(OpUpdateOne) {
		return v, errors.New("OldParentID is only allowed on UpdateOne operations")
	}
	if _, exists := m.ID(); !exists || m.oldValue == nil {
		return v, errors.New("OldParentID requires an ID field in the mutation")
	}
	oldValue, err := m.oldValue(ctx)
	if err != nil {
		return v, fmt.Errorf("querying old value for OldParentID: %w", err)
	}
	return oldValue.ParentID, nil
}

// OldField returns the old value of the field from the database. An error is
// returned if the mutation operation is not UpdateOne, or the query to the
// database failed.
func (m *FileMutation) OldField(ctx context.Context, name string) (ent.Value, error) {
	switch name {
	case file.FieldName:
		return m.OldName(ctx)
	case file.FieldDeleted:
		return m.OldDeleted(ctx)
	case file.FieldParentID:
		return m.OldParentID(ctx)
	}
	return nil, fmt.Errorf("unknown File field %s", name)
}