package db

import (
	"time"

	gormigrate "github.com/go-gormigrate/gormigrate/v2"
	"github.com/google/uuid"
	"gorm.io/gorm"
)

// Gormigrate returns a Gormigrate migrator for the database.
func Gormigrate(db *gorm.DB) *gormigrate.Gormigrate {
	return gormigrate.New(db, gormigrate.DefaultOptions, []*gormigrate.Migration{
		{
			ID: "202010251337",
			Migrate: func(tx *gorm.DB) error {
				type FileUpload struct {
					ID          uint            `gorm:"primaryKey"`
					State       FileUploadState `gorm:"index"`
					PubID       uuid.UUID       `gorm:"uniqueIndex"`
					FileName    string
					ContentType string
					Checksum    uint32
					CreatedAt   time.Time
					UpdatedAt   time.Time
					DeletedAt   gorm.DeletedAt
				}
				type Paste struct {
					ID          uint       `gorm:"primaryKey"`
					Type        PasteType  `gorm:"index"`
					State       PasteState `gorm:"index"`
					Content     []byte
					Key         string `gorm:"uniqueIndex"`
					DeleteToken string
					CreatedAt   time.Time
					UpdatedAt   time.Time
					DeletedAt   gorm.DeletedAt
				}
				return tx.AutoMigrate(&FileUpload{}, &Paste{})
			},
		},
		{
			ID: "202107231722",
			Migrate: func(tx *gorm.DB) error {
				// Update the schema
				type FileUpload struct {
					ID          uint            `gorm:"primaryKey"`
					State       FileUploadState `gorm:"index"`
					PubID       uuid.UUID       `gorm:"uniqueIndex"`
					PasteID     uint
					FileName    string
					ContentType string
					Checksum    uint32
					CreatedAt   time.Time
					UpdatedAt   time.Time
					DeletedAt   gorm.DeletedAt
				}
				type Paste struct {
					ID          uint       `gorm:"primaryKey"`
					Type        PasteType  `gorm:"index"`
					State       PasteState `gorm:"index"`
					Content     []byte
					URL         string
					FileUpload  *FileUpload
					Key         string `gorm:"uniqueIndex"`
					DeleteToken string
					CreatedAt   time.Time
					UpdatedAt   time.Time
					DeletedAt   gorm.DeletedAt
				}
				err := tx.AutoMigrate(&FileUpload{}, &Paste{})
				if err != nil {
					return err
				}

				// Migrate the data
				pastes := make([]Paste, 0)
				if err := tx.Model(&Paste{}).Find(&pastes).Error; err != nil {
					return err
				}
				for _, p := range pastes {
					switch p.Type {
					case PasteTypeRedirect:
						p.URL = string(p.Content)
						tx.Model(p).Select("Content", "URL").Updates(p)
					case PasteTypeFileUpload:
						var id uuid.UUID
						var fus []FileUpload
						copy(id[:], p.Content)
						if err := db.Unscoped().Limit(1).Where("pub_id = ?", id).Find(&fus).Error; err != nil {
							return err
						}
						p.FileUpload = &fus[0]
						tx.Model(p).Select("Content", "FileUpload").Updates(p)
					default:
						continue
					}
				}

				// Currently there is a bug in GORM, which causes a nil ptr
				// dereference when you try dropping a column in an sqlite3
				// database.
				return nil
			},
		},
	})
}