package database

import (
	"net/http"

	"github.com/blang/semver"
	"github.com/fjl/go-couchdb"
)

const (
	VersionDocumentId = "version"
)

type MigrationVersionDocument struct {
	Rev     string `json:"_rev,omitempty"`
	Version semver.Version
}

type MigrationDatabase struct {
	*couchdb.DB
}

/*
GetVersion returns the current version as stored in the migration database.
If no document was found, defaults to returning "0.0.0" as semver.Version
object.
*/
func (mdb *MigrationDatabase) GetVersion() (version semver.Version, rev string, err error) {
	v := new(MigrationVersionDocument)
	err = mdb.DB.Get(VersionDocumentId, v, nil)
	if err != nil {
		isActuallyAnError := true
		if cerr, ok := err.(*couchdb.Error); ok {
			// CouchDB error
			if cerr.StatusCode == http.StatusNotFound {
				isActuallyAnError = false
			}
		}
		if isActuallyAnError {
			return
		}
		err = nil
	} else {
		rev = v.Rev
		version = v.Version
	}
	return
}

func (mdb *MigrationDatabase) PutVersion(version semver.Version, rev string) (newrev string, err error) {
	newrev, err = mdb.DB.Put(VersionDocumentId, MigrationVersionDocument{
		Version: version,
	}, rev)
	return
}