package version

import (
	"sort"
)

// Migration maps provide a simple way to run functions wrapped in version constraints.
type Migration map[string]func() error

// AllVersions returns a List of all versions in the migration map.
func (m Migration) AllVersions() (List, error) {
	l := List{}
	for str := range m {
		v, err := Parse(str)
		if err != nil {
			return nil, err
		}

		l = append(l, v)
	}

	sort.Stable(l)

	return l, nil
}

// RequiredVersions returns a List of all versions in the migration map that are newer than a given (presumed current) version.
// If currentVersion is nil, this is identical to AllVersions.
func (m Migration) RequiredVersions(currentVersion *Version) (List, error) {
	l, err := m.AllVersions()
	if err != nil {
		return nil, err
	}

	if currentVersion != nil {
		c := &Constraint{
			Gt: currentVersion,
		}
		l = l.Match(c)
	}

	return l, nil
}

// Run all required migration functions in the migration map.
// If currentVersion is nil, all migrations will be run.
// If afterEachCallback is not nil, it will be called after each successful migration.
func (m Migration) Run(currentVersion *Version, afterEachCallback func(*Version)) error {
	versions, err := m.RequiredVersions(currentVersion)
	if err != nil {
		return err
	}

	for _, v := range versions {
		f := m[v.Text]
		if err := f(); err != nil {
			return err
		}

		if afterEachCallback != nil {
			afterEachCallback(v)
		}
	}

	return nil
}