package commands

import (
	"fmt"
	"os"
	"path/filepath"
	"strconv"

	"github.com/hasura/graphql-engine/cli/internal/metadatautil"

	"github.com/hasura/graphql-engine/cli"
	migrate "github.com/hasura/graphql-engine/cli/migrate"
	"github.com/pkg/errors"
	"github.com/spf13/cobra"
)

func newMigrateApplyCmd(ec *cli.ExecutionContext) *cobra.Command {
	opts := &MigrateApplyOptions{
		EC: ec,
	}
	migrateApplyCmd := &cobra.Command{
		Use:   "apply",
		Short: "Apply migrations on the database",
		Example: `  # Apply all migrations
  hasura migrate apply

  # Use with admin secret:
  hasura migrate apply --admin-secret "<admin-secret>"

  # Apply migrations on another Hasura instance:
  hasura migrate apply --endpoint "<endpoint>"

  # Mark migration as applied on the server and skip execution:
  hasura migrate apply --skip-execution

  # Apply a particular migration version only:
  hasura migrate apply --version "<version>"

  # Apply last 2 down migrations:
  hasura migrate apply --down 2

  # Apply only 2 up migrations:
  hasura migrate apply --up 2

  # Apply only a particular version
  hasura migrate apply --type up --version "<version>"
  
  # Apply all up migrations upto version 125, last applied is 100
  hasura migrate apply --goto 125
  
  # Apply all down migrations upto version 125, last applied is 150
  hasura migrate apply --goto 125

  # Rollback a particular version:
  hasura migrate apply --type down --version "<version>"

  # Rollback all migrations:
  hasura migrate apply --down all`,
		SilenceUsage: true,
		PreRunE: func(cmd *cobra.Command, args []string) error {
			return validateConfigV3Flags(cmd, ec)
		},
		RunE: func(cmd *cobra.Command, args []string) error {
			opts.Source = ec.Source
			if opts.dryRun && opts.SkipExecution {
				return errors.New("both --skip-execution and --dry-run flags cannot be used together")
			}
			if opts.allDatabases {
				opts.EC.Spin("getting lists of databases from server ")
				sourcesAndKind, err := metadatautil.GetSourcesAndKind(ec.APIClient.V1Metadata.ExportMetadata)
				opts.EC.Spinner.Stop()
				if err != nil {
					return fmt.Errorf("determing list of connected sources and kind: %w", err)
				}
				for _, source := range sourcesAndKind {
					opts.Source.Kind = source.Kind
					opts.Source.Name = source.Name
					if !opts.dryRun {
						opts.EC.Spin(fmt.Sprintf("Applying migrations on database: %s ", opts.Source.Name))
					}
					err := opts.Run()
					opts.EC.Spinner.Stop()
					if err != nil {
						if err == migrate.ErrNoChange {
							opts.EC.Logger.Infof("nothing to apply on database: %s", opts.Source.Name)
							continue
						}
						if e, ok := err.(*os.PathError); ok {
							// If Op is first, then log No migrations to apply
							if e.Op == "first" {
								opts.EC.Logger.Infof("nothing to apply on database: %s", opts.Source.Name)
								continue
							}
						}
						// check if the returned error is a directory not found error
						// ie might be because  a migrations/<source_name> directory is not found
						// if so skip this
						if e, ok := err.(*errDatabaseMigrationDirectoryNotFound); ok {
							opts.EC.Logger.Errorf("skipping applying migrations for database %s, encountered: \n%s", opts.Source.Name, e.Error())
							continue
						}
						opts.EC.Logger.Errorf("skipping applying migrations for database %s, encountered: \n%v", opts.Source.Name, err)
						continue
					}
					opts.EC.Logger.Infof("applied migrations on database: %s", opts.Source.Name)
				}
			} else {
				if !opts.dryRun {
					opts.EC.Spin("Applying migrations...")
				}
				err := opts.Run()
				opts.EC.Spinner.Stop()
				if err != nil {
					if err == migrate.ErrNoChange {
						opts.EC.Logger.Info("nothing to apply")
						return nil
					}
					// check if the returned error is a directory not found error
					// ie might be because  a migrations/<source_name> directory is not found
					// if so skip this
					if e, ok := err.(*errDatabaseMigrationDirectoryNotFound); ok {
						return fmt.Errorf("applying migrations on database %s: %w", opts.Source.Name, e)
					}
					if e, ok := err.(*os.PathError); ok {
						// If Op is first, then log No migrations to apply
						if e.Op == "first" {
							opts.EC.Logger.Info("nothing to apply")
							return nil
						}
					}
					return fmt.Errorf("apply failed\n%w", err)
				}
				if !opts.dryRun {
					opts.EC.Logger.Info("migrations applied")
				}
			}
			return nil
		},
	}
	f := migrateApplyCmd.Flags()
	f.SortFlags = false

	f.StringVar(&opts.UpMigration, "up", "", "apply all or N up migration steps")
	f.StringVar(&opts.DownMigration, "down", "", "apply all or N down migration steps")
	f.StringVar(&opts.GotoVersion, "goto", "", "apply migration chain up to to the version specified")

	f.StringVar(&opts.VersionMigration, "version", "", "only apply this particular migration")
	f.BoolVar(&opts.SkipExecution, "skip-execution", false, "skip executing the migration action, but mark them as applied")
	f.StringVar(&opts.MigrationType, "type", "up", "type of migration (up, down) to be used with version flag")

	f.BoolVar(&opts.dryRun, "dry-run", false, "print the names of migrations which are going to be applied")
	f.BoolVar(&opts.allDatabases, "all-databases", false, "set this flag to attempt to apply migrations on all databases present on server")
	return migrateApplyCmd
}

type MigrateApplyOptions struct {
	EC *cli.ExecutionContext

	UpMigration      string
	DownMigration    string
	VersionMigration string
	MigrationType    string
	// version up to which migration chain has to be applied
	GotoVersion   string
	SkipExecution bool
	dryRun        bool
	Source        cli.Source
	allDatabases  bool
}
type errDatabaseMigrationDirectoryNotFound struct {
	message string
}

func (e *errDatabaseMigrationDirectoryNotFound) Error() string {
	return e.message
}
func (o *MigrateApplyOptions) Run() error {
	if o.EC.Config.Version >= cli.V3 {
		// check if  a migrations directory exists for source in project
		migrationDirectory := filepath.Join(o.EC.MigrationDir, o.Source.Name)
		if f, err := os.Stat(migrationDirectory); err != nil || f == nil {
			return &errDatabaseMigrationDirectoryNotFound{fmt.Sprintf("expected to find a migrations directory for database %s in %s, but encountered error: %s", o.Source.Name, o.EC.MigrationDir, err.Error())}
		}
	}
	if o.allDatabases && (len(o.GotoVersion) > 0 || len(o.VersionMigration) > 0) {
		return fmt.Errorf("cannot use --goto or --version in conjunction with --all-databases")
	}
	migrationType, step, err := getMigrationTypeAndStep(o.UpMigration, o.DownMigration, o.VersionMigration, o.MigrationType, o.GotoVersion, o.SkipExecution)
	if err != nil {
		return errors.Wrap(err, "error validating flags")
	}

	migrateDrv, err := migrate.NewMigrate(o.EC, true, o.Source.Name, o.Source.Kind)
	if err != nil {
		return err
	}
	migrateDrv.SkipExecution = o.SkipExecution
	migrateDrv.DryRun = o.dryRun

	return ExecuteMigration(migrationType, migrateDrv, step)
}

// Only one flag out of up, down and version can be set at a time. This function
// checks whether that is the case and returns an error is not
func getMigrationTypeAndStep(upMigration, downMigration, versionMigration, migrationType, gotoVersion string, skipExecution bool) (string, int64, error) {
	var flagCount = 0
	var stepString = "all"
	var migrationName = "up"
	if upMigration != "" {
		stepString = upMigration
		flagCount++
	}
	if downMigration != "" {
		migrationName = "down"
		stepString = downMigration
		flagCount++
	}
	if versionMigration != "" {
		migrationName = "version"
		stepString = versionMigration
		if migrationType == "down" {
			stepString = "-" + stepString
		}
		flagCount++
	}
	if gotoVersion != "" {
		migrationName = "gotoVersion"
		stepString = gotoVersion
		flagCount++
	}

	if flagCount > 1 {
		return "", 0, errors.New("only one migration type can be applied at a time (--up, --down or --goto)")
	}

	if migrationName != "version" && skipExecution {
		return "", 0, errors.New("--skip-execution flag can be set only with --version flag")
	}

	if stepString == "all" && migrationName != "version" {
		return migrationName, -1, nil
	}

	step, err := strconv.ParseInt(stepString, 10, 64)
	if err != nil {
		return "", 0, errors.Wrap(err, "not a valid input for steps/version")
	}
	return migrationName, step, nil
}