Refactor lookup providers

- Create lookup strategy object to handle several provider
- New root ID server provider
- Refactor code into appropriate classes

src/main/groovy/io/kamax/mxisd/lookup/LdapProvider.groovy

@@ -0,0 +1,56 @@
+package io.kamax.mxisd.lookup
+
+import io.kamax.mxisd.api.ThreePidType
+import io.kamax.mxisd.config.LdapConfig
+import org.apache.directory.api.ldap.model.cursor.EntryCursor
+import org.apache.directory.api.ldap.model.entry.Attribute
+import org.apache.directory.api.ldap.model.message.SearchScope
+import org.apache.directory.ldap.client.api.LdapConnection
+import org.apache.directory.ldap.client.api.LdapNetworkConnection
+import org.springframework.beans.factory.annotation.Autowired
+import org.springframework.stereotype.Component
+
+@Component
+class LdapProvider implements ThreePidProvider {
+
+    @Autowired
+    private LdapConfig ldapCfg
+
+    @Override
+    int getPriority() {
+        return 20
+    }
+
+    @Override
+    Optional<?> find(ThreePidType type, String threePid) {
+        LdapConnection conn = new LdapNetworkConnection(ldapCfg.getHost(), ldapCfg.getPort())
+        try {
+            conn.bind(ldapCfg.getBindDn(), ldapCfg.getBindPassword())
+
+            String searchQuery = ldapCfg.getQuery().replaceAll("%3pid", threePid)
+            EntryCursor cursor = conn.search(ldapCfg.getBaseDn(), searchQuery, SearchScope.SUBTREE, ldapCfg.getAttribute())
+            try {
+                if (cursor.next()) {
+                    Attribute attribute = cursor.get().get(ldapCfg.getAttribute())
+                    if (attribute != null) {
+                        return Optional.of([
+                                address   : threePid,
+                                medium    : type,
+                                mxid      : attribute.get().toString(),
+                                not_before: 0,
+                                not_after : 9223372036854775807,
+                                ts        : 0
+                        ])
+                    }
+                }
+            } finally {
+                cursor.close()
+            }
+        } finally {
+            conn.close()
+        }
+
+        return Optional.empty()
+    }
+
+}