/*
 * 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.petstore.console.dev;

import static java.nio.charset.StandardCharsets.*;

import java.io.*;
import java.time.*;
import java.time.format.*;
import java.time.temporal.*;
import java.util.*;
import java.util.stream.*;

import org.apache.juneau.http.*;
import org.apache.juneau.http.response.*;
import org.apache.juneau.petstore.console.*;
import org.apache.juneau.petstore.console.pages.*;
import org.apache.juneau.rest.server.*;
import org.apache.juneau.console.data.*;
import org.apache.juneau.rest.server.view.*;

/**
 * Data sources: a demo page built with {@link DevPageBuilders#data()} only (it has no template twin).
 *
 * <p>
 * {@code /orders} streams one CSV row per UTC hour in {@code [start, end)} with {@link SeriesSource}.  The browser
 * requests it once per UTC day chunk and caches closed days in IndexedDB.
 *
 * <h5 class='section'>Example:</h5>
 * <p class='bcode'>
 *    GET /console/dev/data
 *    GET /console/dev/data/orders?start=2026-10-01T00:00:00Z&amp;end=2026-10-02T00:00:00Z
 * </p>
 */
@Rest(path="/data", title="Data sources")
@SuppressWarnings({
   "java:S110", // Inheritance depth comes from the BasicRestServlet hierarchy, not this page.
   "resource" // The response writer is owned by the servlet container; Eclipse JDT @Owning warning is by design.
})
public class DataRest extends PetstoreConsolePage {

   private static final long serialVersionUID = 1L;

   /** The longest window {@code /orders} serves. */
   static final Duration MAX_WINDOW = Duration.ofDays(31);

   /**
    * Renders the Data sources page.
    *
    * @param req The request.
    * @return The page.
    */
   @RestGet(path="/")
   public View page(RestRequest req) {
      return twin(req, DevPageBuilders.data());
   }

   /**
    * Hourly order counts in the window.
    *
    * <p>
    * Writes one row for each UTC hour whose start falls in {@code [floor(start), end)}, where {@code floor(start)} is
    * {@code start} rounded down to the hour.  So {@code start=00:30&end=02:30} writes the 00:00, 01:00 and 02:00 rows.
    * A window with {@code end} before {@code start}, or longer than 31 days, is a 400.
    *
    * @param start The window start, ISO-8601.
    * @param end The window end, ISO-8601, exclusive.
    * @param res The response.
    * @throws IOException If the response can't be written.
    */
   @RestGet(path="/orders")
   public void orders(@Query("start") String start, @Query("end") String end, RestResponse res) throws IOException {
      var from = instant("start", start);
      var to = instant("end", end);
      if (to.isBefore(from))
         throw new BadRequest("Window end '%s' is before start '%s'", end, start);
      if (Duration.between(from, to).compareTo(MAX_WINDOW) > 0)
         throw new BadRequest("Window '%s' to '%s' is longer than %s days", start, end, MAX_WINDOW.toDays());
      var first = from.truncatedTo(ChronoUnit.HOURS);
      SeriesSource.csv(res).columns("t", "placed").write(
         Stream.iterate(first, t -> t.isBefore(to), t -> t.plus(1, ChronoUnit.HOURS))
            .map(t -> SeriesSource.Row.of(Map.of("t", t, "placed", placed(t)))));
   }

   /**
    * Serves the page-local script.
    *
    * @param res The response.
    * @throws IOException If the bundled script can't be read.
    */
   @RestGet(path="/data.js")
   public void script(RestResponse res) throws IOException {
      try (var in = DataRest.class.getResourceAsStream("data.js")) {
         if (in == null)
            throw new IllegalStateException(
               "Missing classpath resource 'data.js' beside " + DataRest.class.getName());
         res.setContentType("text/javascript;charset=utf-8");
         res.getWriter().write(new String(in.readAllBytes(), UTF_8));
      }
   }

   static long placed(Instant t) {
      return (t.getEpochSecond() / 3600 * 7) % 10 + 1;
   }

   private static Instant instant(String name, String value) {
      if (value == null)
         throw new BadRequest("Missing query parameter '%s'", name);
      try {
         return Instant.parse(value);
      } catch (DateTimeParseException x) {
         throw new BadRequest("Query parameter '%s' is not an ISO-8601 instant", name);
      }
   }
}