/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.juneau.rest.httppart;

import static org.apache.juneau.commons.utils.Utils.*;
import static org.apache.juneau.httppart.HttpPartType.*;

import java.lang.reflect.*;
import java.time.*;
import java.util.*;
import java.util.regex.*;

import org.apache.http.*;
import org.apache.juneau.*;
import org.apache.juneau.assertions.*;
import org.apache.juneau.http.*;
import org.apache.juneau.http.part.*;
import org.apache.juneau.http.response.*;
import org.apache.juneau.httppart.*;
import org.apache.juneau.oapi.*;
import org.apache.juneau.parser.ParseException;
import org.apache.juneau.rest.*;

/**
 * Represents a single HTTP part on an HTTP request.
 *
 * Parent of the following classes:
 * <ul class='javatreec'>
 *    <li class='jc'>{@link RequestHeader}
 *    <li class='jc'>{@link RequestQueryParam}
 *    <li class='jc'>{@link RequestFormParam}
 *    <li class='jc'>{@link RequestPathParam}
 * </ul>
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/HttpParts">HTTP Parts</a>
 * </ul>
 */
public class RequestHttpPart {

   private final HttpPartType partType;
   private final String name;
   private final RestRequest request;
   private HttpPartParserSession parser;
   private HttpPartSchema schema;
   String value;

   /**
    * Constructor.
    *
    * @param partType The HTTP part type.
    * @param request The request object.
    * @param name The part name.
    * @param value The part value.
    */
   public RequestHttpPart(HttpPartType partType, RestRequest request, String name, String value) {
      this.partType = partType;
      this.request = request;
      this.name = name;
      this.value = value;
      parser(null);
   }

   /**
    * Converts this part to the specified POJO type using the request {@link HttpPartParser} and optional schema.
    *
    * <p>
    * If the specified type is an HTTP part type (extends from {@link org.apache.http.Header}/{@link NameValuePair}), then looks for
    * one of the following constructors:
    * <ul class='javatree'>
    *    <li class='jm><c><jk>public</jk> T(String <jv>value</jv>);</c>
    *    <li class='jm><c><jk>public</jk> T(String <jv>name</jv>, String <jv>value</jv>);</c>
    * </ul>
    *
    * <p>
    * If it doesn't find one of those constructors, then it parses it into the specified type using the part parser.
    *
    * @param <T> The type to convert to.
    * @param type The type to convert to.
    * @return The converted type, or {@link Optional#empty()} if the part is not present.
    * @throws BasicHttpException If value could not be parsed.
    */
   public <T> Optional<T> as(Class<T> type) throws BasicHttpException {
      return as(request.getBeanSession().getClassMeta(type));
   }

   /**
    * Converts this part to the specified POJO type using the request {@link HttpPartParser} and optional schema.
    *
    * <p>
    * If the specified type is an HTTP part type (extends from {@link org.apache.http.Header}/{@link NameValuePair}), then looks for
    * one of the following constructors:
    * <ul class='javatree'>
    *    <li class='jm><c><jk>public</jk> T(String <jv>value</jv>);</c>
    *    <li class='jm><c><jk>public</jk> T(String <jv>name</jv>, String <jv>value</jv>);</c>
    * </ul>
    *
    * <p>
    * If it doesn't find one of those constructors, then it parses it into the specified type using the part parser.
    *
    * @param <T> The type to convert to.
    * @param type The type to convert to.
    * @return The converted type, or {@link Optional#empty()} if the part is not present.
    * @throws BasicHttpException If value could not be parsed.
    */
   public <T> Optional<T> as(ClassMeta<T> type) throws BasicHttpException {
      try {
         if (HttpParts.isHttpPart(partType, type)) {
            var cc = HttpParts.getConstructor(type).orElse(null);
            if (nn(cc)) {
               if (! isPresent())
                  return opte();
               if (cc.hasParameterTypes(String.class))
                  return opt(cc.newInstance(get()));
               if (cc.hasParameterTypes(String.class, String.class))
                  return opt(cc.newInstance(getName(), get()));
            }
         }
         return opt(parser.parse(HEADER, schema, orElse(null), type));
      } catch (ParseException e) {
         throw new BadRequest(e, "Could not parse {0} parameter ''{1}''.", partType.toString().toLowerCase(), getName());
      }
   }

   /**
    * Converts this part to the specified POJO type using the request {@link HttpPartParser} and optional schema.
    *
    * <p>
    * See <a class="doclink" href="https://juneau.apache.org/docs/topics/ComplexDataTypes">Complex Data Types</a> for information on defining complex generic types of {@link Map Maps} and {@link Collection Collections}.
    *
    * @param <T> The type to convert to.
    * @param type The type to convert to.
    * @param args The type parameters.
    * @return The converted type, or {@link Optional#empty()} if the part is not present.
    * @throws BasicHttpException If value could not be parsed.
    */
   public <T> Optional<T> as(Type type, Type...args) throws BasicHttpException {
      return as(request.getBeanSession().getClassMeta(type, args));
   }

   /**
    * Returns the value of this parameter as a boolean.
    *
    * @return The value of this parameter as a boolean, or {@link Optional#empty()} if the parameter was not present.
    */
   public Optional<Boolean> asBoolean() {
      return asBooleanPart().asBoolean();
   }

   /**
    * Returns the value of this parameter as a {@link BasicBooleanPart}.
    *
    * @return The value of this parameter as a {@link BasicBooleanPart}, never <jk>null</jk>.
    */
   public BasicBooleanPart asBooleanPart() {
      return new BasicBooleanPart(getName(), getValue());
   }

   /**
    * Returns the value of this parameter as a list from a comma-delimited string.
    *
    * @return The value of this parameter as a list from a comma-delimited string, or {@link Optional#empty()} if the parameter was not present.
    */
   public Optional<List<String>> asCsvArray() {
      return asCsvArrayPart().asList();
   }

   /**
    * Returns the value of this parameter as a {@link BasicCsvArrayPart}.
    *
    * @return The value of this parameter as a {@link BasicCsvArrayPart}, never <jk>null</jk>.
    */
   public BasicCsvArrayPart asCsvArrayPart() {
      return new BasicCsvArrayPart(getName(), getValue());
   }

   /**
    * Returns the value of this parameter as a date.
    *
    * @return The value of this parameter as a date, or {@link Optional#empty()} if the parameter was not present.
    */
   public Optional<ZonedDateTime> asDate() {
      return asDatePart().asZonedDateTime();
   }

   /**
    * Returns the value of this parameter as a {@link BasicDatePart}.
    *
    * @return The value of this parameter as a {@link BasicDatePart}, never <jk>null</jk>.
    */
   public BasicDatePart asDatePart() {
      return new BasicDatePart(getName(), getValue());
   }

   /**
    * Returns the value of this parameter as an integer.
    *
    * @return The value of this parameter as an integer, or {@link Optional#empty()} if the parameter was not present.
    */
   public Optional<Integer> asInteger() {
      return asIntegerPart().asInteger();
   }

   /**
    * Returns the value of this parameter as a {@link BasicIntegerPart}.
    *
    * @return The value of this parameter as a {@link BasicIntegerPart}, never <jk>null</jk>.
    */
   public BasicIntegerPart asIntegerPart() {
      return new BasicIntegerPart(getName(), getValue());
   }

   /**
    * Returns the value of this parameter as a long.
    *
    * @return The value of this parameter as a long, or {@link Optional#empty()} if the parameter was not present.
    */
   public Optional<Long> asLong() {
      return asLongPart().asLong();
   }

   /**
    * Returns the value of this parameter as a {@link BasicLongPart}.
    *
    * @return The value of this parameter as a {@link BasicLongPart}, never <jk>null</jk>.
    */
   public BasicLongPart asLongPart() {
      return new BasicLongPart(getName(), getValue());
   }

   /**
    * Matches the specified pattern against this part value.
    *
    * <h5 class='section'>Example:</h5>
    * <p class='bjava'>
    *    Matcher <jv>matcher</jv> = <jv>request</jv>
    *       .getHeader(<js>"Content-Type"</js>)
    *       .asMatcher(Pattern.<jsm>compile</jsm>(<js>"application/(.*)"</js>));
    *
    * <jk>if</jk> (<jv>matcher</jv>.matches()) {
    *       String <jv>mediaType</jv> = <jv>matcher</jv>.group(1);
    *    }
    * </p>
    *
    * @param pattern The regular expression pattern to match.
    * @return The matcher.
    * @throws BasicHttpException If a connection error occurred.
    */
   public Matcher asMatcher(Pattern pattern) throws BasicHttpException {
      return pattern.matcher(orElse(""));
   }

   /**
    * Matches the specified pattern against this part value.
    *
    * <h5 class='section'>Example:</h5>
    * <p class='bjava'>
    *    Matcher <jv>matcher</jv> = <jv>request</jv>
    *       .getHeader(<js>"Content-Type"</js>)
    *       .asMatcher(<js>"application/(.*)"</js>);
    *
    *    <jk>if</jk> (<jv>matcher</jv>.matches()) {
    *       String <jv>mediaType</jv> = <jv>matcher</jv>.group(1);
    *    }
    * </p>
    *
    * @param regex The regular expression pattern to match.
    * @return The matcher.
    * @throws BasicHttpException If a connection error occurred.
    */
   public Matcher asMatcher(String regex) throws BasicHttpException {
      return asMatcher(regex, 0);
   }

   /**
    * Matches the specified pattern against this part value.
    *
    * <h5 class='section'>Example:</h5>
    * <p class='bjava'>
    *    Matcher <jv>matcher</jv> = <jv>request</jv>
    *       .getHeader(<js>"Content-Type"</js>)
    *       .asMatcher(<js>"application/(.*)"</js>, <jsf>CASE_INSENSITIVE</jsf>);
    *
    *    <jk>if</jk> (<jv>matcher</jv>.matches()) {
    *       String <jv>mediaType</jv> = <jv>matcher</jv>.group(1);
    *    }
    * </p>
    *
    * @param regex The regular expression pattern to match.
    * @param flags Pattern match flags.  See {@link Pattern#compile(String, int)}.
    * @return The matcher.
    * @throws BasicHttpException If a connection error occurred.
    */
   public Matcher asMatcher(String regex, int flags) throws BasicHttpException {
      return asMatcher(Pattern.compile(regex, flags));
   }

   /**
    * Provides the ability to perform fluent-style assertions on comma-separated string parameters.
    *
    * <h5 class='section'>Examples:</h5>
    * <p class='bjava'>
    *    <jv>request</jv>
    *       .getQueryParam(<js>"allow"</js>)
    *       .assertCsvArray().contains(<js>"GET"</js>);
    * </p>
    *
    * @return A new fluent assertion object.
    */
   public FluentListAssertion<String,RequestHttpPart> assertCsvArray() {
      return new FluentListAssertion<>(asCsvArrayPart().asList().orElse(null), this);
   }

   /**
    * Provides the ability to perform fluent-style assertions on a date parameter.
    *
    * <h5 class='section'>Examples:</h5>
    * <p class='bjava'>
    *    <jv>request</jv>
    *       .getQueryParam(<js>"time"</js>)
    *       .assertDate().isAfterNow();
    * </p>
    *
    * @return A new fluent assertion object.
    */
   public FluentZonedDateTimeAssertion<RequestHttpPart> assertDate() {
      return new FluentZonedDateTimeAssertion<>(asDatePart().asZonedDateTime().orElse(null), this);
   }

   /**
    * Provides the ability to perform fluent-style assertions on an integer parameter.
    *
    * <h5 class='section'>Examples:</h5>
    * <p class='bjava'>
    *    <jv>request</jv>
    *       .getQueryParam(<js>"age"</js>)
    *       .assertInteger().isGreaterThan(1);
    * </p>
    *
    * @return A new fluent assertion object.
    */
   public FluentIntegerAssertion<RequestHttpPart> assertInteger() {
      return new FluentIntegerAssertion<>(asIntegerPart().asInteger().orElse(null), this);
   }

   /**
    * Provides the ability to perform fluent-style assertions on a long parameter.
    *
    * <h5 class='section'>Examples:</h5>
    * <p class='bjava'>
    *    <jv>request</jv>
    *       .getQueryParam(<js>"length"</js>)
    *       .assertLong().isLessThan(100000);
    * </p>
    *
    * @return A new fluent assertion object.
    */
   public FluentLongAssertion<RequestHttpPart> assertLong() {
      return new FluentLongAssertion<>(asLongPart().asLong().orElse(null), this);
   }

   /**
    * Provides the ability to perform fluent-style assertions on this parameter.
    *
    * <h5 class='section'>Examples:</h5>
    * <p class='bjava'>
    *    <jv>request</jv>
    *       .getQueryParam(<js>"foo"</js>)
    *       .assertString().contains(<js>"bar"</js>);
    * </p>
    *
    * <p>
    * The assertion test returns the original object allowing you to chain multiple requests like so:
    * <p class='bjava'>
    *    String <jv>foo</jv> = <jv>request</jv>
    *       .getQueryParam(<js>"foo"</js>)
    *       .assertString().contains(<js>"bar"</js>)
    *       .asString().get();
    * </p>
    *
    * @return A new fluent assertion object.
    */
   public FluentStringAssertion<RequestHttpPart> assertString() {
      return new FluentStringAssertion<>(orElse(null), this);
   }

   /**
    * Returns the value of this part as a string.
    *
    * @return The value of this part as a string, or {@link Optional#empty()} if the part was not present.
    */
   public Optional<String> asString() {
      return opt(getValue());
   }

   /**
    * Returns the value of this parameter as a {@link BasicStringPart}.
    *
    * @return The value of this parameter as a {@link BasicStringPart}, never <jk>null</jk>.
    */
   public BasicStringPart asStringPart() {
      return new BasicStringPart(getName(), getValue());
   }

   /**
    * Returns the value of this parameter as a {@link BasicUriPart}.
    *
    * @return The value of this parameter as a {@link BasicUriPart}, never <jk>null</jk>.
    */
   public BasicUriPart asUriPart() {
      return new BasicUriPart(getName(), getValue());
   }

   /**
    * Sets a default value for this part.
    *
    * @param def The default value.
    * @return This object.
    */
   public RequestHttpPart def(String def) {
      if (value == null)
         value = def;
      return this;
   }

   /**
    * If a value is present, returns the value, otherwise throws {@link NoSuchElementException}.
    *
    * <p>
    * This is a shortened form for calling <c>asString().get()</c>.
    *
    * @return The value if present.
    */
   public String get() {
      return asString().get();
   }

   /**
    * Gets the name of this part.
    *
    * @return The name of this part, never <jk>null</jk>.
    */
   public String getName() { return name; }

   /**
    * Returns the value of this part.
    *
    * @return The value of this part.
    */
   public String getValue() { return value; }

   /**
    * Returns <jk>true</jk> if this part exists on the request.
    *
    * <p>
    * This is a shortened form for calling <c>asString().isPresent()</c>.
    *
    * @return <jk>true</jk> if this part exists on the request.
    */
   public boolean isPresent() { return asString().isPresent(); }

   /**
    * Return the value if present, otherwise return other.
    *
    * <p>
    * This is a shortened form for calling <c>asString().orElse(<jv>other</jv>)</c>.
    *
    * @param other The value to be returned if there is no value present, may be <jk>null</jk>.
    * @return The value, if present, otherwise other.
    */
   public String orElse(String other) {
      return asString().orElse(other);
   }

   /**
    * Specifies the part parser to use for this part.
    *
    * <p>
    * If not specified, uses the part parser defined on the client by calling {@link org.apache.juneau.rest.RestContext.Builder#partParser()}.
    *
    * @param value
    *    The new part parser to use for this part.
    *    <br>If <jk>null</jk>, {@link SimplePartParser#DEFAULT} will be used.
    * @return This object.
    */
   public RequestHttpPart parser(HttpPartParserSession value) {
      this.parser = value == null ? SimplePartParser.DEFAULT_SESSION : value;
      return this;
   }

   /**
    * Specifies the part schema for this part.
    *
    * <p>
    * Used by schema-based part parsers such as {@link OpenApiParser}.
    *
    * @param value
    *    The part schema.
    * @return This object.
    */
   public RequestHttpPart schema(HttpPartSchema value) {
      schema = value;
      return this;
   }

   @Override /* Overridden from Object */
   public String toString() {
      return getName() + "=" + getValue();
   }

   /**
    * Returns the request that created this part.
    *
    * @return The request that created this part.
    */
   protected RestRequest getRequest() { return request; }
}