package cache

import (
	"errors"
	"fmt"

	"golang.org/x/mod/semver"
)

type migrationFunc func(c *Cache) error

// Registry of migrations by version
var migrations = map[string]map[string]migrationFunc{
	"v0.1.0": {
		"Make Aliases Unique": v010_aliases,
	},
}

// Performs any required updates based on version
// of cache read from disk.
// Does not check to ensure migrations were successful,
// only checks if a version has been achieved
func (c *Cache) DoMigrations() error {
	c.lock.Lock()
	defer c.lock.Unlock()
	return c.doMigrations()
}

func (c *Cache) doMigrations() error {
	var errs error
	for version, migrationFuncs := range migrations {
		if semver.Compare(c.CacheVersion, version) < 0 {
			for name, migration := range migrationFuncs {
				err := migration(c)
				if err != nil {
					errs = errors.Join(
						errs,
						fmt.Errorf("%s - %s: %w", version, name, err),
					)
				}
			}

			// We've reached a cache version, update the CacheVersion
			// and write to disk
			if errs == nil {
				c.CacheVersion = version
				c.write()
			}
		}
	}

	return errs
}

func v010_aliases(c *Cache) error {
	return errors.New("unimplemented migration")
}