forked from elwinar/rambler
/
reverse.go
87 lines (70 loc) · 1.65 KB
/
reverse.go
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package main
import (
"fmt"
"github.com/bradfitz/slice"
"github.com/codegangsta/cli"
"log"
)
// Reverse available migrations based on the provided context.
func Reverse(ctx *cli.Context) {
err := reverse(service, ctx.Bool("all"))
if err != nil {
log.Println(err)
}
}
func reverse(service Servicer, all bool) error {
initialized, err := service.Initialized()
if err != nil {
return fmt.Errorf("unable to check for database state: %s", err)
}
if !initialized {
return fmt.Errorf("uninitialized database")
}
available, err := service.Available()
if err != nil {
return fmt.Errorf("unable to retrieve available migrations: %s", err)
}
applied, err := service.Applied()
if err != nil {
return fmt.Errorf("unable to retrieve applied migrations: %s", err)
}
if len(applied) == 0 {
return nil
}
var i, j = len(available) - 1, len(applied) - 1
for i >= 0 && j >= 0 && available[i].Name > applied[j].Name {
i--
}
for i >= 0 && j >= 0 {
if available[i].Name == applied[j].Name {
i--
j--
continue
}
if available[i].Name < applied[j].Name {
return fmt.Errorf("missing migration: %s", applied[j].Name)
}
if available[i].Name > applied[j].Name {
return fmt.Errorf("out of order migration: %s", available[i].Name)
}
}
if i >= 0 {
return fmt.Errorf("out of order migration: %s", available[i].Name)
}
if j >= 0 {
return fmt.Errorf("missing migration: %s", applied[j].Name)
}
slice.Sort(applied, func(i, j int) bool {
return applied[i].Name > applied[j].Name
})
for _, migration := range applied {
err := service.Reverse(migration)
if err != nil {
return err
}
if !all {
return nil
}
}
return nil
}