SearchLoader.java

package com.airlocksoftware.hackernews.loader;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONObject;

import android.content.Context;
import android.support.v4.content.AsyncTaskLoader;
import android.util.Log;

import com.airlocksoftware.hackernews.application.MainApplication;
import com.airlocksoftware.hackernews.data.UserPrefs;
import com.airlocksoftware.hackernews.activity.SearchActivity.SearchType;
import com.airlocksoftware.hackernews.activity.SearchActivity.SortType;
import com.airlocksoftware.hackernews.loader.SearchLoader.SearchResult;
import com.airlocksoftware.hackernews.model.Request;
import com.airlocksoftware.hackernews.model.Result;
import com.airlocksoftware.hackernews.model.SearchItem;
import com.google.gson.Gson;

public class SearchLoader extends AsyncTaskLoader<SearchResult> {

	Request mRequest;
	String mQuery;
	SortType mSort;
	SearchType mType;

	/**
	 * Which page to request search results for. Use 0 for a new search, and other positive integers as offsets from
	 * 0.
	 **/
	int mPage = 0;

	// Constants
	@SuppressWarnings("unused")
	private static final String TAG = SearchLoader.class.getSimpleName();
	private static final String START_QUERY = "https://hn.algolia.io/api/v1/";
	private static final String WEIGHTS = "&weights[title]=1.1&weights[text]=0.7&weights[domain]=2.0&weights[username]=0.1&weights[type]=0.0&boosts[fields][points]=0.15&boosts[fields][num_comments]=0.15&boosts[functions][pow(2,div(div(ms(create_ts,NOW),3600000),72))]=200.0";

	public static class SearchResult {
		public SearchResult(Result result) {
			this.result = result;
		}

		public SearchResult() {
			// default empty constructor
		}

		public Result result;
		public List<SearchItem> items;
		public int hits = -1;
		public int page = 0;
	}

	public SearchLoader(Context context, Request request, String query, SortType sort, SearchType type, int start) {
		super(context);

		mRequest = request;
		mQuery = query;
		mSort = sort;
		mType = type;
		mPage = start;
	}

	@Override
	public SearchResult loadInBackground() {
		if (mQuery == null || mSort == null || mType == null || mRequest == Request.EMPTY) {
			return new SearchResult(Result.EMPTY);
		}

		String response = performSearch();

		int hits = -1;
		List<SearchItem> items = new ArrayList<SearchItem>();
		SearchResult search = new SearchResult();

		try {
			Gson gson = new Gson();

			JSONObject obj = new JSONObject(response);

			hits = obj.getInt("nbHits");
			JSONArray results = obj.getJSONArray("hits");

			for (int i = 0; i < results.length(); i++) {
				SearchItem searchItem = gson.fromJson(
					results.getJSONObject(i).toString(),
					SearchItem.class
				);

				items.add(searchItem);
			}

		} catch (Exception e) {
			search.result = Result.FAILURE;
			e.printStackTrace();
		}

		search.items = items;
		search.hits = hits;
		search.page = mPage;
		if (search.result == null) search.result = Result.SUCCESS;
		// search.result = (items != null && hits != -1) ? Result.SUCCESS : Result.EMPTY;

		return search;
	}

	/** Builds a search url from instance variables, then performs a get of the url. Returns the result as a string. **/
	private String performSearch() {
		String searchUrl = buildSearchUrl();

		StringBuilder builder = new StringBuilder();
		HttpClient client = new DefaultHttpClient();
		HttpGet httpGet = new HttpGet(searchUrl);
//
//		UserPrefs prefs = new UserPrefs(MainApplication.getInstance().getApplicationContext());
//
//		if (prefs.getCompressData()) {
//			httpGet.addHeader("Accept-Encoding", "gzip");
//		}

		try {
			HttpResponse response = client.execute(httpGet);
			StatusLine statusLine = response.getStatusLine();
			int statusCode = statusLine.getStatusCode();

			if (statusCode == 200) {
				HttpEntity entity = response.getEntity();
				InputStream content = entity.getContent();
				BufferedReader reader = new BufferedReader(new InputStreamReader(content));
				String line;
				while ((line = reader.readLine()) != null) {
					builder.append(line);
				}
			} else {
				Log.e(searchUrl, "Failed to download file");
				// notify user of search failure
			}

		} catch (ClientProtocolException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}

		String response = builder.toString();
		return response;
	}

	private String buildSearchUrl() {

		StringBuilder builder = new StringBuilder(START_QUERY);

		String endpoint;
		String query = "";

		try {
			query = URLEncoder.encode(mQuery, "UTF-8");
		} catch (UnsupportedEncodingException e) {
			// tell user the query was invalid?
			e.printStackTrace();
		}

		switch (mSort) {
		case RELEVANCE:
			endpoint = "search";
			break;

		case DATE:
			endpoint = "search_by_date";
			break;

		// POINTS no longer a valid sort!
		// will have to sort ourselves if we want to support this
//		case POINTS:
//			endpoint = "search";
//			break;

		default:
			throw new RuntimeException("Error: didn't receive a valid SortType" + mSort.toString());
		}

		builder.append(endpoint);

		switch (mType) {
		case ALL:
			// don't append filter
			builder.append("?query=" + query);
			builder.append("&page=" + mPage);
			break;
		case STORIES:
			builder.append("?query=" + query);
			builder.append("&page=" + mPage);
			builder.append("&tags=story");
			break;
		case COMMENTS:
			builder.append("?query=" + query);
			builder.append("&page=" + mPage);
			builder.append("&tags=comment");
			break;
		case USERS:
			builder.append("?page=" + mPage);
			builder.append("&tags=author_" + query);
			break;
		default:
			throw new RuntimeException("Error: didn't receive a valid SearchType" + mType.toString());
		}

		return builder.toString();
	}

	/**
	 * Handles a request to start the Loader.
	 */
	@Override
	protected void onStartLoading() {
		forceLoad();
	}
}