package com.lts.core.commons.utils;

import javax.net.ssl.*;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Map;
import java.util.Set;

/**
 * @author Robert HG (254963746@qq.com) on 8/21/15.
 */
public class WebUtils {

    private static final String DEFAULT_CHARSET = "UTF-8";
    private static final String METHOD_POST = "POST";
    private static final String METHOD_GET = "GET";
    private static boolean ignoreSSLCheck = true; // 忽略SSL检查

    private static class TrustAllTrustManager implements X509TrustManager {
        public X509Certificate[] getAcceptedIssuers() {
            return null;
        }

        public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
        }

        public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
        }
    }

    private WebUtils() {
    }

    public static void setIgnoreSSLCheck(boolean ignoreSSLCheck) {
        WebUtils.ignoreSSLCheck = ignoreSSLCheck;
    }

    /**
     * 执行HTTP POST请求。
     *
     * @param url    请求地址
     * @param params 请求参数
     * @return 响应字符串
     */
    public static String doPost(String url, Map<String, String> params, int connectTimeout, int readTimeout) throws IOException {
        return doPost(url, params, DEFAULT_CHARSET, connectTimeout, readTimeout);
    }

    /**
     * 执行HTTP POST请求。
     *
     * @param url     请求地址
     * @param params  请求参数
     * @param charset 字符集，如UTF-8, GBK, GB2312
     * @return 响应字符串
     */
    public static String doPost(String url, Map<String, String> params, String charset, int connectTimeout, int readTimeout) throws IOException {
        return doPost(url, params, charset, connectTimeout, readTimeout, null);
    }

    public static String doPost(String url, Map<String, String> params, String charset, int connectTimeout, int readTimeout, Map<String, String> headerMap) throws IOException {
        String ctype = "application/x-www-form-urlencoded;charset=" + charset;
        String query = buildQuery(params, charset);
        byte[] content = {};
        if (query != null) {
            content = query.getBytes(charset);
        }
        return _doPost(url, ctype, content, connectTimeout, readTimeout, headerMap);
    }

    /**
     * 执行HTTP POST请求。
     *
     * @param url     请求地址
     * @param ctype   请求类型
     * @param content 请求字节数组
     * @return 响应字符串
     */
    public static String doPost(String url, String ctype, byte[] content, int connectTimeout, int readTimeout) throws IOException {
        return _doPost(url, ctype, content, connectTimeout, readTimeout, null);
    }

    private static String _doPost(String url, String ctype, byte[] content, int connectTimeout, int readTimeout, Map<String, String> headerMap) throws IOException {
        HttpURLConnection conn = null;
        OutputStream out = null;
        String rsp = null;
        try {
            conn = getConnection(new URL(url), METHOD_POST, ctype, headerMap);
            conn.setConnectTimeout(connectTimeout);
            conn.setReadTimeout(readTimeout);
            out = conn.getOutputStream();
            out.write(content);
            rsp = getResponseAsString(conn);
        } finally {
            if (out != null) {
                out.close();
            }
            if (conn != null) {
                conn.disconnect();
            }
        }

        return rsp;
    }

    /**
     * 执行HTTP GET请求。
     *
     * @param url    请求地址
     * @param params 请求参数
     * @return 响应字符串
     */
    public static String doGet(String url, Map<String, String> params) throws IOException {
        return doGet(url, params, DEFAULT_CHARSET);
    }

    /**
     * 执行HTTP GET请求。
     *
     * @param url     请求地址
     * @param params  请求参数
     * @param charset 字符集，如UTF-8, GBK, GB2312
     * @return 响应字符串
     */
    public static String doGet(String url, Map<String, String> params, String charset) throws IOException {
        HttpURLConnection conn = null;
        String rsp = null;

        try {
            String ctype = "application/x-www-form-urlencoded;charset=" + charset;
            String query = buildQuery(params, charset);
            conn = getConnection(buildGetUrl(url, query), METHOD_GET, ctype, null);

            rsp = getResponseAsString(conn);
        } finally {
            if (conn != null) {
                conn.disconnect();
            }
        }

        return rsp;
    }

    private static HttpURLConnection getConnection(URL url, String method, String ctype, Map<String, String> headerMap) throws IOException {
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        if (conn instanceof HttpsURLConnection) {
            HttpsURLConnection connHttps = (HttpsURLConnection) conn;
            if (ignoreSSLCheck) {
                try {
                    SSLContext ctx = SSLContext.getInstance("TLS");
                    ctx.init(null, new TrustManager[]{new TrustAllTrustManager()}, new SecureRandom());
                    connHttps.setSSLSocketFactory(ctx.getSocketFactory());
                    connHttps.setHostnameVerifier(new HostnameVerifier() {
                        public boolean verify(String hostname, SSLSession session) {
                            return true;
                        }
                    });
                } catch (Exception e) {
                    throw new IOException(e);
                }
            }
            conn = connHttps;
        }

        conn.setRequestMethod(method);
        conn.setDoInput(true);
        conn.setDoOutput(true);
        conn.setRequestProperty("Accept", "application/json,text/xml,text/javascript,*/*");
        conn.setRequestProperty("Content-Type", ctype);
        if (headerMap != null) {
            for (Map.Entry<String, String> entry : headerMap.entrySet()) {
                conn.setRequestProperty(entry.getKey(), entry.getValue());
            }
        }
        return conn;
    }

    private static URL buildGetUrl(String strUrl, String query) throws IOException {
        URL url = new URL(strUrl);
        if (StringUtils.isEmpty(query)) {
            return url;
        }

        if (StringUtils.isEmpty(url.getQuery())) {
            if (strUrl.endsWith("?")) {
                strUrl = strUrl + query;
            } else {
                strUrl = strUrl + "?" + query;
            }
        } else {
            if (strUrl.endsWith("&")) {
                strUrl = strUrl + query;
            } else {
                strUrl = strUrl + "&" + query;
            }
        }

        return new URL(strUrl);
    }

    public static String buildQuery(Map<String, String> params, String charset) throws IOException {
        if (params == null || params.isEmpty()) {
            return null;
        }

        StringBuilder query = new StringBuilder();
        Set<Map.Entry<String, String>> entries = params.entrySet();
        boolean hasParam = false;

        for (Map.Entry<String, String> entry : entries) {
            String name = entry.getKey();
            String value = entry.getValue();
            // 忽略参数名或参数值为空的参数
            if (StringUtils.isNotEmpty(name, value)) {
                if (hasParam) {
                    query.append("&");
                } else {
                    hasParam = true;
                }

                query.append(name).append("=").append(URLEncoder.encode(value, charset));
            }
        }

        return query.toString();
    }

    protected static String getResponseAsString(HttpURLConnection conn) throws IOException {
        String charset = getResponseCharset(conn.getContentType());
        InputStream es = conn.getErrorStream();
        if (es == null) {
            return getStreamAsString(conn.getInputStream(), charset);
        } else {
            return getStreamAsString(es, charset);
        }
    }

    private static String getStreamAsString(InputStream stream, String charset) throws IOException {
        try {
            Reader reader = new InputStreamReader(stream, charset);
            StringBuilder response = new StringBuilder();

            final char[] buff = new char[1024];
            int read = 0;
            while ((read = reader.read(buff)) > 0) {
                response.append(buff, 0, read);
            }

            return response.toString();
        } finally {
            if (stream != null) {
                stream.close();
            }
        }
    }

    private static String getResponseCharset(String ctype) {
        String charset = DEFAULT_CHARSET;

        if (!StringUtils.isEmpty(ctype)) {
            String[] params = ctype.split(";");
            for (String param : params) {
                param = param.trim();
                if (param.startsWith("charset")) {
                    String[] pair = param.split("=", 2);
                    if (pair.length == 2) {
                        if (!StringUtils.isEmpty(pair[1])) {
                            charset = pair[1].trim();
                        }
                    }
                    break;
                }
            }
        }

        return charset;
    }

    /**
     * 使用默认的UTF-8字符集反编码请求参数值。
     *
     * @param value 参数值
     * @return 反编码后的参数值
     */
    public static String decode(String value) {
        return decode(value, DEFAULT_CHARSET);
    }

    /**
     * 使用默认的UTF-8字符集编码请求参数值。
     *
     * @param value 参数值
     * @return 编码后的参数值
     */
    public static String encode(String value) {
        return encode(value, DEFAULT_CHARSET);
    }

    /**
     * 使用指定的字符集反编码请求参数值。
     *
     * @param value   参数值
     * @param charset 字符集
     * @return 反编码后的参数值
     */
    public static String decode(String value, String charset) {
        String result = null;
        if (!StringUtils.isEmpty(value)) {
            try {
                result = URLDecoder.decode(value, charset);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return result;
    }

    /**
     * 使用指定的字符集编码请求参数值。
     *
     * @param value   参数值
     * @param charset 字符集
     * @return 编码后的参数值
     */
    public static String encode(String value, String charset) {
        String result = null;
        if (!StringUtils.isEmpty(value)) {
            try {
                result = URLEncoder.encode(value, charset);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return result;
    }

}
