/*
 * This file is part of BlueMap, licensed under the MIT License (MIT).
 *
 * Copyright (c) Blue (Lukas Rieger) <https://bluecolored.de>
 * Copyright (c) contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package de.bluecolored.bluemap.core.webserver;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import de.bluecolored.bluemap.core.webserver.HttpConnection.ConnectionClosedException;
import de.bluecolored.bluemap.core.webserver.HttpConnection.InvalidRequestException;

public class HttpRequest {

	private static final Pattern REQUEST_PATTERN = Pattern.compile("^(\\w+) (\\S+) (.+)$");
	
	private String method;
	private String path;
	private String version;
	private Map<String, Set<String>> header;
	private Map<String, Set<String>> headerLC;
	private byte[] data;
	
	public HttpRequest(String method, String path, String version, Map<String, Set<String>> header) {
		this.method = method;
		this.path = path;
		this.version = version;
		this.header = header;
		this.headerLC = new HashMap<>();
		
		for (Entry<String, Set<String>> e : header.entrySet()){
			Set<String> values = new HashSet<>();
			for (String v : e.getValue()){
				values.add(v.toLowerCase());
			}
			
			headerLC.put(e.getKey().toLowerCase(), values);
		}
		
		this.data = new byte[0];
	}
	
	public String getMethod() {
		return method;
	}
	
	public String getPath(){
		return path;
	}

	public String getVersion() {
		return version;
	}

	public Map<String, Set<String>> getHeader() {
		return header;
	}
	
	public Map<String, Set<String>> getLowercaseHeader() {
		return header;
	}
	
	public Set<String> getHeader(String key){
		Set<String> headerValues = header.get(key);
		if (headerValues == null) return Collections.emptySet();
		return headerValues;
	}
	
	public Set<String> getLowercaseHeader(String key){
		Set<String> headerValues = headerLC.get(key.toLowerCase());
		if (headerValues == null) return Collections.emptySet();
		return headerValues;
	}
	
	public InputStream getData(){
		return new ByteArrayInputStream(data);
	}
	
	public static HttpRequest read(InputStream in) throws IOException, InvalidRequestException {
		BufferedReader reader = new BufferedReader(new InputStreamReader(in, StandardCharsets.UTF_8));
		List<String> header = new ArrayList<>(20); 
		while(header.size() < 1000){
			String headerLine = readLine(reader);
			if (headerLine.isEmpty()) break;
			header.add(headerLine);
		}
		
		if (header.isEmpty()) throw new InvalidRequestException();
		
		Matcher m = REQUEST_PATTERN.matcher(header.remove(0));
		if (!m.find()) throw new InvalidRequestException();

		String method = m.group(1);
		if (method == null) throw new InvalidRequestException();
		
		String adress = m.group(2);
		if (adress == null) throw new InvalidRequestException();
		
		String version = m.group(3);
		if (version == null) throw new InvalidRequestException();
		
		Map<String, Set<String>> headerMap = new HashMap<String, Set<String>>();
		for (String line : header){
			if (line.trim().isEmpty()) continue;
			
			String[] kv = line.split(":", 2);
			if (kv.length < 2) continue;
			
			Set<String> values = new HashSet<>();
			if (kv[0].trim().equalsIgnoreCase("If-Modified-Since")){
				values.add(kv[1].trim());
			} else {
				for(String v : kv[1].split(",")){
					values.add(v.trim());
				}
			}
			
			headerMap.put(kv[0].trim(), values);
		}
		
		HttpRequest request = new HttpRequest(method, adress, version, headerMap);

		if (request.getLowercaseHeader("Transfer-Encoding").contains("chunked")){
			try {
				ByteArrayOutputStream dataStream = new ByteArrayOutputStream();
				while (dataStream.size() < 1000000){
					String hexSize = reader.readLine();
					int chunkSize = Integer.parseInt(hexSize, 16);
					if (chunkSize <= 0) break;
					byte[] data = new byte[chunkSize];
					in.read(data);
					dataStream.write(data);
				}
				
				if (dataStream.size() >= 1000000) {
					throw new InvalidRequestException();
				}
				
				request.data = dataStream.toByteArray();
				
				return request;
			} catch (NumberFormatException ex){
				return request;
			}
		} else {
			Set<String> clSet = request.getLowercaseHeader("Content-Length");
			if (clSet.isEmpty()){
				return request;
			} else {
				try {
					int cl = Integer.parseInt(clSet.iterator().next());
					byte[] data = new byte[cl];
					in.read(data);
					request.data = data;
					return request;
				} catch (NumberFormatException ex){
					return request;
				}
			}
		}
	}
	
	private static String readLine(BufferedReader in) throws ConnectionClosedException, IOException {
		String line = in.readLine();
		if (line == null){
			throw new ConnectionClosedException();
		}
		return line;
	}
	
}