package at.gv.egiz.eaaf.modules.auth.sl20.utils;

import java.util.ArrayList;
import java.util.Base64;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ObjectNode;

import at.gv.egiz.eaaf.modules.auth.sl20.data.VerificationResult;
import at.gv.egiz.eaaf.modules.auth.sl20.exceptions.SL20Exception;
import at.gv.egiz.eaaf.modules.auth.sl20.exceptions.SlCommandoParserException;

public class SL20JsonExtractorUtils {
  private static final Logger log = LoggerFactory.getLogger(SL20JsonExtractorUtils.class);
  private static JsonMapper mapper = new JsonMapper();

  /**
   * Extract String value from JSON.
   *
   * @param input      JSON
   * @param keyID      Element identifier
   * @param isRequired true, if the element must not null
   * @return Value of this element
   * @throws SlCommandoParserException In case an error
   */
  public static String getStringValue(final JsonNode input, final String keyID, final boolean isRequired)
      throws SlCommandoParserException {
    try {
      final JsonNode internal = getAndCheck(input, keyID, isRequired);

      if (internal != null) {
        return internal.asText();
      } else {
        return null;
      }

    } catch (final SlCommandoParserException e) {
      throw e;

    } catch (final Exception e) {
      throw new SlCommandoParserException("Can not extract String value with keyId: " + keyID, e);

    }
  }

  /**
   * Extract Boolean value from JSON.
   *
   * @param input      JSON
   * @param keyID      Element identifier
   * @param isRequired true, if the element must not null
   * @param defaultValue in case of no existing element with key
   * @return Boolean
   * @throws SlCommandoParserException In case of an error
   */
  public static boolean getBooleanValue(final ObjectNode input, final String keyID, final boolean isRequired,
      final boolean defaultValue) throws SlCommandoParserException {
    try {
      final JsonNode internal = getAndCheck(input, keyID, isRequired);

      if (internal != null) {
        return internal.asBoolean();
      } else {
        return defaultValue;
      }

    } catch (final SlCommandoParserException e) {
      throw e;

    } catch (final Exception e) {
      throw new SlCommandoParserException("Can not extract Boolean value with keyId: " + keyID, e);

    }
  }

  /**
   * Extract JSONObject value from JSON.
   *
   * @param input      JSON
   * @param keyID      Element identifier
   * @param isRequired true, if the element must not null
   * @return JSON node
   * @throws SlCommandoParserException In case of an error
   */
  public static JsonNode getJsonObjectValue(final JsonNode input, final String keyID, final boolean isRequired)
      throws SlCommandoParserException {
    try {
      final JsonNode internal = getAndCheck(input, keyID, isRequired);

      if (internal != null) {
        return internal;
      } else {
        return null;
      }

    } catch (final SlCommandoParserException e) {
      throw e;

    } catch (final Exception e) {
      throw new SlCommandoParserException("Can not extract Boolean value with keyId: " + keyID, e);

    }
  }

  /**
   * Extract a List of String elements from a JSON element.
   *
   * @param input JSON
   * @return List of Elements in this node
   * @throws SlCommandoParserException In case of an error
   */
  public static List<String> getListOfStringElements(final JsonNode input) throws SlCommandoParserException {
    final List<String> result = new ArrayList<>();
    if (input != null) {
      if (input.isArray()) {
        final Iterator<JsonNode> arrayIterator = input.iterator();
        while (arrayIterator.hasNext()) {
          final JsonNode next = arrayIterator.next();
          if (next.isTextual()) {
            result.add(next.asText());
          }
        }

      } else if (input.isTextual()) {
        result.add(input.asText());

      } else {
        log.warn("JSON Element IS NOT a JSON array or a JSON Primitive");
        throw new SlCommandoParserException("JSON Element IS NOT a JSON array or a JSON Primitive");

      }
    }

    return result;
  }

  /**
   * Extract Map of Key/Value pairs from a JSON Element.
   *
   * @param input      parent JSON object
   * @param keyID      KeyId of the child that should be parsed
   * @param isRequired true, if the element must not null
   * @return Map of element pairs
   * @throws SlCommandoParserException In case of an error
   */
  public static Map<String, String> getMapOfStringElements(final JsonNode input, final String keyID,
      final boolean isRequired) throws SlCommandoParserException {
    final JsonNode internal = getAndCheck(input, keyID, isRequired);
    return getMapOfStringElements(internal);

  }

  /**
   * Extract Map of Key/Value pairs from a JSON Element.
   *
   * @param input JSON
   * @return Map of element pairs
   * @throws SlCommandoParserException in case of an error
   */
  public static Map<String, String> getMapOfStringElements(final JsonNode input) throws SlCommandoParserException {
    final Map<String, String> result = new HashMap<>();

    if (input != null) {
      if (input.isArray()) {
        final Iterator<JsonNode> arrayIterator = input.iterator();
        while (arrayIterator.hasNext()) {
          final JsonNode next = arrayIterator.next();
          final Iterator<Entry<String, JsonNode>> entry = next.fields();
          entitySetToMap(result, entry);

        }

      } else if (input.isObject()) {
        final Iterator<Entry<String, JsonNode>> objectKeys = input.fields();
        entitySetToMap(result, objectKeys);

      } else {
        throw new SlCommandoParserException("JSON Element IS NOT a JSON array or a JSON object");
      }

    }

    return result;
  }

  private static void entitySetToMap(final Map<String, String> result, final Iterator<Entry<String, JsonNode>> entry) {
    while (entry.hasNext()) {
      final Entry<String, JsonNode> el = entry.next();
      if (result.containsKey(el.getKey())) {
        log.info("Attr. Map already contains Element with Key: " + el.getKey() + ". Overwrite element ... ");
      }

      result.put(el.getKey(), el.getValue().asText());

    }

  }

  /**
   * Extract Security-Layer 2.0 result from response object.
   *
   * @param command         SL2.0 command
   * @param decrypter       JWS decrypter implementation
   * @param mustBeEncrypted if <code>true</code>, the result must be encrypted
   * @return decrypted JSON
   * @throws SL20Exception In case of an error
   */
  public static JsonNode extractSL20Result(final JsonNode command, final IJoseTools decrypter,
      final boolean mustBeEncrypted) throws SL20Exception {
    final JsonNode result = command.get(SL20Constants.SL20_COMMAND_CONTAINER_RESULT);
    final JsonNode encryptedResult = command.get(SL20Constants.SL20_COMMAND_CONTAINER_ENCRYPTEDRESULT);

    if (result == null && encryptedResult == null) {
      throw new SlCommandoParserException("NO result OR encryptedResult FOUND.");
    } else if (encryptedResult == null && mustBeEncrypted) {
      throw new SlCommandoParserException("result MUST be encrypted.");
    } else if (encryptedResult != null && encryptedResult.isTextual()) {
      try {
        return decrypter.decryptPayload(encryptedResult.asText());

      } catch (final Exception e) {
        log.info("Can NOT decrypt SL20 result. Reason:" + e.getMessage());
        if (!mustBeEncrypted) {
          log.warn("Decrypted results are disabled by configuration. Parse result in plain if it is possible");

          // dummy code
          try {
            final String[] signedPayload = encryptedResult.toString().split("\\.");
            final JsonNode payLoad = mapper.getMapper()
                .readTree(new String(Base64.getUrlDecoder().decode(signedPayload[1]), "UTF-8"));
            return payLoad;

          } catch (final Exception e1) {
            log.debug("DummyCode FAILED, Reason: " + e1.getMessage() + " Ignore it ...");
            throw new SL20Exception(e.getMessage(), null, e);

          }

        } else {
          throw e;
        }

      }

    } else if (result != null) {
      return result;

    } else {
      throw new SlCommandoParserException("Internal build error");
    }

  }

  /**
   * Extract payLoad from generic transport container.
   *
   * @param container JSON
   * @param joseTools JWS implementation
   * @param mustBeSigned Throw an error if the result was not signed
   * @return Signature verification result that contains the payLoad
   * @throws SlCommandoParserException In case of an error
   */
  public static VerificationResult extractSL20PayLoad(final JsonNode container, final IJoseTools joseTools,
      final boolean mustBeSigned) throws SL20Exception {

    final JsonNode sl20Payload = container.get(SL20Constants.SL20_PAYLOAD);
    final JsonNode sl20SignedPayload = container.get(SL20Constants.SL20_SIGNEDPAYLOAD);

    if (mustBeSigned && joseTools == null) {
      throw new SlCommandoParserException("'joseTools' MUST be set if 'mustBeSigned' is 'true'");
    }

    if (sl20Payload == null && sl20SignedPayload == null) {
      throw new SlCommandoParserException("NO payLoad OR signedPayload FOUND.");
    } else if (sl20SignedPayload == null && mustBeSigned) {
      throw new SlCommandoParserException("payLoad MUST be signed.");
    } else if (joseTools != null && sl20SignedPayload != null && sl20SignedPayload.isTextual()) {
      return joseTools.validateSignature(sl20SignedPayload.asText());

    } else if (sl20Payload != null) {
      return new VerificationResult(sl20Payload);
    } else {
      throw new SlCommandoParserException("Internal build error");
    }

  }

  private static JsonNode getAndCheck(final JsonNode input, final String keyID, final boolean isRequired)
      throws SlCommandoParserException {
    final JsonNode internal = input.get(keyID);

    if (internal == null && isRequired) {
      throw new SlCommandoParserException("REQUIRED Element with keyId: " + keyID + " does not exist");
    }

    return internal;

  }
}