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package org.apache.juneau.rest.arg;

import static org.apache.juneau.http.annotation.PathAnnotation.*;
import java.lang.reflect.*;

import org.apache.juneau.*;
import org.apache.juneau.collections.*;
import org.apache.juneau.common.internal.*;
import org.apache.juneau.http.annotation.*;
import org.apache.juneau.httppart.*;
import org.apache.juneau.reflect.*;
import org.apache.juneau.rest.*;
import org.apache.juneau.rest.annotation.*;
import org.apache.juneau.rest.httppart.*;
import org.apache.juneau.rest.util.*;

/**
 * Resolves method parameters and parameter types annotated with {@link Path} on {@link RestOp}-annotated Java methods.
 *
 * <p>
 * The parameter value is resolved using:
 * <p class='bjava'>
 *    <jv>opSession</jv>
 *       .{@link RestOpSession#getRequest() getRequest}()
 *       .{@link RestRequest#getPathParams() getPathParams}()
 *       .{@link RequestPathParams#get(String) get}(<jv>name</jv>)
 *       .{@link RequestPathParam#as(Class) as}(<jv>type</jv>);
 * </p>
 *
 * <p>
 * {@link HttpPartSchema schema} is derived from the {@link Path} annotation.
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="../../../../../index.html#jrs.JavaMethodParameters">Java Method Parameters</a>
 * </ul>
 */
public class PathArg implements RestOpArg {
   private final HttpPartParser partParser;
   private final HttpPartSchema schema;
   private final String name, def;
   private final Type type;

   /**
    * Static creator.
    *
    * @param paramInfo The Java method parameter being resolved.
    * @param annotations The annotations to apply to any new part parsers.
    * @param pathMatcher Path matcher for the specified method.
    * @return A new {@link PathArg}, or <jk>null</jk> if the parameter is not annotated with {@link Path}.
    */
   public static PathArg create(ParamInfo paramInfo, AnnotationWorkList annotations, UrlPathMatcher pathMatcher) {
      if (paramInfo.hasAnnotation(Path.class) || paramInfo.getParameterType().hasAnnotation(Path.class))
         return new PathArg(paramInfo, annotations, pathMatcher);
      return null;
   }

   /**
    * Constructor.
    *
    * @param paramInfo The Java method parameter being resolved.
    * @param annotations The annotations to apply to any new part parsers.
    * @param pathMatcher Path matcher for the specified method.
    */
   protected PathArg(ParamInfo paramInfo, AnnotationWorkList annotations, UrlPathMatcher pathMatcher) {
      this.name = getName(paramInfo, pathMatcher);
      this.def = findDef(paramInfo).orElse(null);
      this.type = paramInfo.getParameterType().innerType();
      this.schema = HttpPartSchema.create(Path.class, paramInfo);
      Class<? extends HttpPartParser> pp = schema.getParser();
      this.partParser = pp != null ? HttpPartParser.creator().type(pp).apply(annotations).create() : null;
   }

   private String getName(ParamInfo pi, UrlPathMatcher pathMatcher) {
      String p = findName(pi).orElse(null);
      if (p != null)
         return p;
      if (pathMatcher != null) {
         int idx = 0;
         int i = pi.getIndex();
         MethodInfo mi = pi.getMethod();

         for (int j = 0; j < i; j++)
            if (mi.getParam(i).getAnnotation(Path.class) != null)
               idx++;

         String[] vars = pathMatcher.getVars();
         if (vars.length <= idx)
            throw new ArgException(pi, "Number of attribute parameters exceeds the number of URL pattern variables");

         // Check for {#} variables.
         String idxs = String.valueOf(idx);
         for (String var : vars)
                if (StringUtils.isNumeric(var) && var.equals(idxs))
               return var;

         return pathMatcher.getVars()[idx];
      }
      throw new ArgException(pi, "@Path used without name or value");
   }

   @Override /* RestOpArg */
   public Object resolve(RestOpSession opSession) throws Exception {
      RestRequest req = opSession.getRequest();
      if (name.equals("*")) {
         JsonMap m = new JsonMap();
         req.getPathParams().stream().forEach(x -> m.put(x.getName(), x.getValue()));
         return req.getBeanSession().convertToType(m, type);
      }
      HttpPartParserSession ps = partParser == null ? req.getPartParserSession() : partParser.getPartSession();
      return req.getPathParams().get(name).parser(ps).schema(schema).def(def).as(type).orElse(null);
   }
}