package sbt
package ivyint

import org.apache.ivy.util.url.CredentialsStore
import collection.JavaConverters._

/** A key used to store credentials in the ivy credentials store. */
private[sbt] sealed trait CredentialKey
/** Represents a key in the ivy credentials store that is only specific to a host. */
private[sbt] case class Host(name: String) extends CredentialKey
/** Represents a key in the ivy credentials store that is keyed to both a host and a "realm". */
private[sbt] case class Realm(host: String, realm: String) extends CredentialKey

/**
 * Helper mechanism to improve credential related error messages.
 * 
 * This evil class exposes to us the necessary information to warn on credential failure and offer
 * spelling/typo suggestions.
 */
private[sbt] object IvyCredentialsLookup {

  /** Helper extractor for Ivy's key-value store of credentials. */
  private object KeySplit {
    def unapply(key: String): Option[(String,String)] = {
      key.indexOf('@') match {
        case -1 => None
        case n => Some(key.take(n) -> key.drop(n+1))
      }
    }
  }

  /** Here we cheat runtime private so we can look in the credentials store. 
   *
   *  TODO - Don't bomb at class load time...  
   */
  private val credKeyringField = {
    val tmp = classOf[CredentialsStore].getDeclaredField("KEYRING")
    tmp.setAccessible(true)
    tmp
  }

  /** All the keys for credentials in the ivy configuration store. */
  def keyringKeys: Set[CredentialKey] = {
    val map = credKeyringField.get(null).asInstanceOf[java.util.HashMap[String, Any]]
    // make a clone of the set...
    (map.keySet.asScala.map {
      case KeySplit(realm, host) => Realm(host, realm)
      case host => Host(host)
    })(collection.breakOut)
  }
  
  /**
   * A mapping of host -> realms in the ivy credentials store.
   */
  def realmsForHost: Map[String, Set[String]] =
    keyringKeys collect {
      case x: Realm => x
    } groupBy { realm =>
      realm.host
    } mapValues { realms =>
      realms map (_.realm)  
    }
}