package com.minamp.net;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.security.SecureRandom;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Vector;

import com.minamp.bc.tls.DefaultTlsClient;
import com.minamp.bc.tls.NameType;
import com.minamp.bc.tls.ServerName;
import com.minamp.bc.tls.TlsAuthentication;
import com.minamp.bc.tls.TlsClientProtocol;
import com.minamp.bc.tls.TlsCredentials;
import com.minamp.bc.tls.TlsServerCertificate;
import com.minamp.bc.tls.TlsSession;
import com.minamp.bc.tls.CertificateRequest;
import com.minamp.bc.tls.crypto.TlsCrypto;
import com.minamp.bc.tls.crypto.impl.bc.BcTlsCrypto;

/**
 * Small HTTP/1.1 client with its own TLS 1.2/1.3 (Bouncy Castle), keep-alive pooling and
 * session resumption. Android 2.x's built-in SSL can't talk to plex.tv or *.plex.direct,
 * so every request in the app goes through here.
 */
public final class Http {

    public static final String USER_AGENT = "PlexampLite/1.0";

    /** Optional HTTP CONNECT proxy, only used when running the networking code on a desktop JVM. */
    public static String proxyHost;
    public static int proxyPort;

    private static TlsCrypto crypto;
    private static final Map<String, TlsSession> sessions = new HashMap<String, TlsSession>();
    private static final Map<String, List<Conn>> pool = new HashMap<String, List<Conn>>();
    private static final long IDLE_MS = 25000;

    private Http() {}

    private static synchronized TlsCrypto crypto() {
        if (crypto == null) crypto = new BcTlsCrypto(new SecureRandom());
        return crypto;
    }

    // ------------------------------------------------------------------ URL

    public static final class Url {
        public final boolean https;
        public final String host;
        public final int port;
        public final String path; // includes query

        public Url(String s) throws IOException {
            String lower = s.toLowerCase(Locale.US);
            int start;
            if (lower.startsWith("https://")) { https = true; start = 8; }
            else if (lower.startsWith("http://")) { https = false; start = 7; }
            else throw new IOException("Bad URL: " + s);
            int slash = s.indexOf('/', start);
            String hostPort = slash < 0 ? s.substring(start) : s.substring(start, slash);
            path = slash < 0 ? "/" : s.substring(slash);
            int colon = hostPort.lastIndexOf(':');
            if (colon > 0 && hostPort.indexOf(']') < colon) {
                host = hostPort.substring(0, colon);
                try { port = Integer.parseInt(hostPort.substring(colon + 1)); }
                catch (NumberFormatException e) { throw new IOException("Bad port in " + s); }
            } else {
                host = hostPort;
                port = https ? 443 : 80;
            }
        }

        String key() { return (https ? "s:" : "p:") + host + ":" + port; }

        String hostHeader() {
            boolean dflt = (https && port == 443) || (!https && port == 80);
            return dflt ? host : host + ":" + port;
        }
    }

    // ------------------------------------------------------------------ connection

    static final class Conn {
        final String key;
        Socket socket;
        InputStream in;
        OutputStream out;
        TlsClientProtocol tls;
        long idleSince;

        Conn(String key) { this.key = key; }

        void close() {
            try { if (tls != null) tls.close(); } catch (Exception ignored) {}
            try { if (socket != null) socket.close(); } catch (Exception ignored) {}
        }
    }

    private static Conn take(String key) {
        synchronized (pool) {
            List<Conn> list = pool.get(key);
            if (list == null) return null;
            long now = System.currentTimeMillis();
            while (!list.isEmpty()) {
                Conn c = list.remove(list.size() - 1);
                if (now - c.idleSince < IDLE_MS && !c.socket.isClosed()) return c;
                c.close();
            }
            return null;
        }
    }

    static void release(Conn c) {
        c.idleSince = System.currentTimeMillis();
        synchronized (pool) {
            List<Conn> list = pool.get(c.key);
            if (list == null) { list = new ArrayList<Conn>(); pool.put(c.key, list); }
            if (list.size() >= 4) { list.remove(0).close(); }
            list.add(c);
        }
    }

    /** Forget resumable TLS sessions (next connection to each host does a full, verified handshake). */
    static void forgetSessions() {
        synchronized (sessions) { sessions.clear(); }
        evictAll();
    }

    /** Drop all pooled connections (e.g. after the network changed). */
    public static void evictAll() {
        final List<Conn> doomed = new ArrayList<Conn>();
        synchronized (pool) {
            for (Iterator<List<Conn>> it = pool.values().iterator(); it.hasNext();) doomed.addAll(it.next());
            pool.clear();
        }
        if (doomed.isEmpty()) return;
        // closing TLS sends an encrypted alert: keep that off the (small-stack) caller thread
        Threads.start(new Runnable() {
            public void run() { for (int i = 0; i < doomed.size(); i++) doomed.get(i).close(); }
        }, "http-evict");
    }

    private static Conn connect(final Url u, int timeoutMs) throws IOException {
        Conn c = new Conn(u.key());
        Socket s = new Socket();
        boolean ok = false;
        try {
            if (proxyHost != null) {
                s.connect(new InetSocketAddress(proxyHost, proxyPort), timeoutMs);
                s.setSoTimeout(timeoutMs);
                OutputStream po = s.getOutputStream();
                String req = "CONNECT " + u.host + ":" + u.port + " HTTP/1.1\r\nHost: " + u.host + ":" + u.port + "\r\n\r\n";
                po.write(req.getBytes("ISO-8859-1"));
                po.flush();
                InputStream pi = s.getInputStream();
                String status = readLine(pi);
                if (status == null || status.indexOf(" 200") < 0) throw new IOException("Proxy refused: " + status);
                String line;
                while ((line = readLine(pi)) != null && line.length() > 0) { /* skip headers */ }
            } else {
                s.connect(new InetSocketAddress(u.host, u.port), timeoutMs);
                s.setSoTimeout(timeoutMs);
            }
            s.setTcpNoDelay(true);
            c.socket = s;
            if (u.https) {
                TlsClientProtocol proto = new TlsClientProtocol(s.getInputStream(), s.getOutputStream());
                proto.connect(new Client(crypto(), u.host, u.key()));
                c.tls = proto;
                c.in = new BufferedInputStream(proto.getInputStream(), 8192);
                c.out = new BufferedOutputStream(proto.getOutputStream(), 4096);
            } else {
                c.in = new BufferedInputStream(s.getInputStream(), 8192);
                c.out = new BufferedOutputStream(s.getOutputStream(), 4096);
            }
            ok = true;
            return c;
        } finally {
            if (!ok) { try { s.close(); } catch (Exception ignored) {} }
        }
    }

    private static final class Client extends DefaultTlsClient {
        private final String host;
        private final String sessionKey;

        private final long started = System.currentTimeMillis();

        Client(TlsCrypto crypto, String host, String sessionKey) {
            super(crypto);
            this.host = host;
            this.sessionKey = sessionKey;
        }

        @Override
        protected Vector getSNIServerNames() {
            if (CertVerifier.isIpLiteral(host)) return null;
            Vector v = new Vector();
            try {
                v.addElement(new ServerName(NameType.host_name, host.getBytes("US-ASCII")));
            } catch (java.io.UnsupportedEncodingException e) {
                return null;
            }
            return v;
        }

        /**
         * TLS 1.2 only: this TLS stack can resume 1.2 sessions but not 1.3 ones, and on a 600 MHz
         * phone a resumed handshake (no key exchange, no signature checks) is the difference
         * between ~10 s and well under a second for every new connection.
         */
        @Override
        protected com.minamp.bc.tls.ProtocolVersion[] getSupportedVersions() {
            return com.minamp.bc.tls.ProtocolVersion.TLSv12.only();
        }

        @Override
        public TlsSession getSessionToResume() {
            synchronized (sessions) { return sessions.get(sessionKey); }
        }

        @Override
        public void notifyHandshakeComplete() throws IOException {
            super.notifyHandshakeComplete();
            boolean resumed = context.getSecurityParametersConnection().isResumedSession();
            DiagLog.log("TLS " + (resumed ? "resumed" : "full handshake") + " with " + host
                    + " in " + (System.currentTimeMillis() - started) + "ms");
            TlsSession s = context.getSession();
            if (s != null && s.isResumable()) {
                synchronized (sessions) { sessions.put(sessionKey, s); }
            }
        }

        public TlsAuthentication getAuthentication() throws IOException {
            return new TlsAuthentication() {
                public void notifyServerCertificate(TlsServerCertificate sc) throws IOException {
                    com.minamp.bc.tls.Certificate cert = sc.getCertificate();
                    List<byte[]> chain = new ArrayList<byte[]>();
                    for (int i = 0; i < cert.getLength(); i++) chain.add(cert.getCertificateAt(i).getEncoded());
                    CertVerifier.verify(chain, host);
                }

                public TlsCredentials getClientCredentials(CertificateRequest req) {
                    return null;
                }
            };
        }
    }

    // ------------------------------------------------------------------ request / response

    public static final class Response {
        public final int code;
        public final String status;
        public final Map<String, String> headers; // lower-case names
        public final InputStream body;
        public final long contentLength; // -1 if unknown
        public final boolean chunked;

        Response(int code, String status, Map<String, String> headers, InputStream body, long len, boolean chunked) {
            this.code = code; this.status = status; this.headers = headers; this.body = body;
            this.contentLength = len; this.chunked = chunked;
        }

        public String header(String name) { return headers.get(name.toLowerCase(Locale.US)); }

        public void close() {
            try { body.close(); } catch (IOException ignored) {}
        }

        public byte[] readAll() throws IOException {
            try {
                ByteArrayOutputStream bos = new ByteArrayOutputStream(contentLength > 0 && contentLength < 4000000 ? (int) contentLength : 8192);
                byte[] buf = new byte[8192];
                int n;
                while ((n = body.read(buf)) > 0) bos.write(buf, 0, n);
                return bos.toByteArray();
            } finally {
                close();
            }
        }

        public String readString() throws IOException {
            return new String(readAll(), "UTF-8");
        }
    }

    public static Response get(String url, Map<String, String> headers, int timeoutMs) throws IOException {
        return request("GET", url, headers, null, timeoutMs);
    }

    public static Response request(String method, String url, Map<String, String> headers, byte[] body, int timeoutMs) throws IOException {
        for (int redirects = 0; ; redirects++) {
            long t0 = System.currentTimeMillis();
            Response r;
            try {
                r = requestOnce(method, url, headers, body, timeoutMs);
            } catch (IOException e) {
                DiagLog.log(method + " " + DiagLog.redact(url) + " -> FAILED after " + (System.currentTimeMillis() - t0) + "ms: " + Threads.describe(e));
                throw e;
            } catch (RuntimeException e) {
                DiagLog.log(method + " " + DiagLog.redact(url) + " -> FAILED: " + Threads.describe(e));
                throw e;
            }
            if (!url.contains("/photo/:/transcode")) { // artwork would drown out everything else
                DiagLog.log(method + " " + DiagLog.redact(url) + " -> " + r.code + " (" + (System.currentTimeMillis() - t0) + "ms)");
            }
            if ((r.code == 301 || r.code == 302 || r.code == 307 || r.code == 308) && redirects < 4
                    && ("GET".equals(method) || "HEAD".equals(method))) {
                String loc = r.header("location");
                r.close();
                if (loc == null) throw new IOException("Redirect without location");
                if (loc.startsWith("/")) {
                    Url u = new Url(url);
                    loc = (u.https ? "https://" : "http://") + u.hostHeader() + loc;
                }
                url = loc;
                continue;
            }
            return r;
        }
    }

    private static Response requestOnce(String method, String url, Map<String, String> headers, byte[] body, int timeoutMs) throws IOException {
        Url u = new Url(url);
        // A pooled connection may have been closed by the server; retry once on a fresh one.
        for (int attempt = 0; attempt < 2; attempt++) {
            Conn c = take(u.key());
            boolean pooled = c != null;
            if (c == null) c = connect(u, timeoutMs);
            try {
                c.socket.setSoTimeout(timeoutMs);
                writeRequest(c, u, method, headers, body);
                return readResponse(c, method);
            } catch (IOException e) {
                c.close();
                if (!pooled) throw e;
            }
        }
        throw new IOException("Request failed");
    }

    private static void writeRequest(Conn c, Url u, String method, Map<String, String> headers, byte[] body) throws IOException {
        StringBuilder sb = new StringBuilder(512);
        sb.append(method).append(' ').append(u.path).append(" HTTP/1.1\r\n");
        sb.append("Host: ").append(u.hostHeader()).append("\r\n");
        boolean hasUa = false;
        if (headers != null) {
            for (Map.Entry<String, String> e : headers.entrySet()) {
                if (e.getValue() == null) continue;
                if ("user-agent".equalsIgnoreCase(e.getKey())) hasUa = true;
                sb.append(e.getKey()).append(": ").append(e.getValue()).append("\r\n");
            }
        }
        if (!hasUa) sb.append("User-Agent: ").append(USER_AGENT).append("\r\n");
        sb.append("Connection: keep-alive\r\n");
        if (body != null || "POST".equals(method) || "PUT".equals(method)) {
            sb.append("Content-Length: ").append(body == null ? 0 : body.length).append("\r\n");
        }
        sb.append("\r\n");
        c.out.write(sb.toString().getBytes("UTF-8"));
        if (body != null) c.out.write(body);
        c.out.flush();
    }

    private static Response readResponse(Conn c, String method) throws IOException {
        String statusLine = readLine(c.in);
        if (statusLine == null) throw new IOException("Connection closed");
        // HTTP/1.1 200 OK
        int sp = statusLine.indexOf(' ');
        if (sp < 0) throw new IOException("Bad status line");
        int sp2 = statusLine.indexOf(' ', sp + 1);
        int code;
        try {
            code = Integer.parseInt(sp2 < 0 ? statusLine.substring(sp + 1).trim() : statusLine.substring(sp + 1, sp2));
        } catch (NumberFormatException e) {
            throw new IOException("Bad status line");
        }
        boolean http10 = statusLine.startsWith("HTTP/1.0");
        Map<String, String> h = new LinkedHashMap<String, String>();
        String line;
        while ((line = readLine(c.in)) != null && line.length() > 0) {
            int colon = line.indexOf(':');
            if (colon <= 0) continue;
            String name = line.substring(0, colon).trim().toLowerCase(Locale.US);
            String val = line.substring(colon + 1).trim();
            String prev = h.get(name);
            h.put(name, prev == null ? val : prev + ", " + val);
        }
        String te = h.get("transfer-encoding");
        String cl = h.get("content-length");
        String conn = h.get("connection");
        boolean keepAlive = !http10 && (conn == null || conn.toLowerCase(Locale.US).indexOf("close") < 0);
        boolean chunked = te != null && te.toLowerCase(Locale.US).indexOf("chunked") >= 0;
        long len = -1;
        if (!chunked && cl != null) {
            try { len = Long.parseLong(cl.trim()); } catch (NumberFormatException ignored) {}
        }
        InputStream body;
        boolean noBody = "HEAD".equals(method) || code == 204 || code == 304 || (code >= 100 && code < 200);
        if (noBody) {
            body = new FixedStream(c, 0, keepAlive);
            len = "HEAD".equals(method) ? len : 0;
        } else if (chunked) {
            body = new ChunkedStream(c, keepAlive);
        } else if (len >= 0) {
            body = new FixedStream(c, len, keepAlive);
        } else {
            body = new EofStream(c);
        }
        return new Response(code, statusLine, h, body, len, chunked);
    }

    static String readLine(InputStream in) throws IOException {
        StringBuilder sb = new StringBuilder(64);
        int b;
        while ((b = in.read()) >= 0) {
            if (b == '\n') {
                int n = sb.length();
                if (n > 0 && sb.charAt(n - 1) == '\r') sb.setLength(n - 1);
                return sb.toString();
            }
            sb.append((char) b);
            if (sb.length() > 16384) throw new IOException("Header line too long");
        }
        return sb.length() == 0 ? null : sb.toString();
    }

    // ------------------------------------------------------------------ body streams

    private static final class FixedStream extends InputStream {
        private final Conn c; private long left; private final boolean keepAlive; private boolean closed;

        FixedStream(Conn c, long len, boolean keepAlive) {
            this.c = c; this.left = len; this.keepAlive = keepAlive;
            if (len == 0) finish(true);
        }

        private void finish(boolean complete) {
            if (closed) return;
            closed = true;
            if (complete && keepAlive) release(c); else c.close();
        }

        @Override public int read() throws IOException {
            byte[] one = new byte[1];
            int n = read(one, 0, 1);
            return n <= 0 ? -1 : one[0] & 255;
        }

        @Override public int read(byte[] b, int off, int len) throws IOException {
            if (left <= 0) { finish(true); return -1; }
            if (closed) return -1;
            int n = c.in.read(b, off, (int) Math.min(len, left));
            if (n < 0) { finish(false); throw new IOException("Unexpected end of stream"); }
            left -= n;
            if (left == 0) finish(true);
            return n;
        }

        @Override public int available() throws IOException {
            if (closed) return 0;
            return (int) Math.min(c.in.available(), left);
        }

        @Override public void close() { finish(left == 0); }
    }

    private static final class ChunkedStream extends InputStream {
        private final Conn c; private final boolean keepAlive;
        private long chunkLeft = 0; private boolean eof; private boolean closed;

        ChunkedStream(Conn c, boolean keepAlive) { this.c = c; this.keepAlive = keepAlive; }

        private void finish(boolean complete) {
            if (closed) return;
            closed = true;
            if (complete && keepAlive) release(c); else c.close();
        }

        private boolean nextChunk() throws IOException {
            if (eof) return false;
            String line = readLine(c.in);
            if (line == null) throw new IOException("Unexpected end of chunked stream");
            if (line.length() == 0) { line = readLine(c.in); if (line == null) throw new IOException("Bad chunk"); }
            int semi = line.indexOf(';');
            if (semi >= 0) line = line.substring(0, semi);
            try { chunkLeft = Long.parseLong(line.trim(), 16); }
            catch (NumberFormatException e) { throw new IOException("Bad chunk size"); }
            if (chunkLeft == 0) {
                String t;
                while ((t = readLine(c.in)) != null && t.length() > 0) { /* trailers */ }
                eof = true;
                finish(true);
                return false;
            }
            return true;
        }

        @Override public int read() throws IOException {
            byte[] one = new byte[1];
            int n = read(one, 0, 1);
            return n <= 0 ? -1 : one[0] & 255;
        }

        @Override public int read(byte[] b, int off, int len) throws IOException {
            if (closed) return -1;
            if (chunkLeft == 0) {
                if (!nextChunk()) return -1;
            }
            int n = c.in.read(b, off, (int) Math.min(len, chunkLeft));
            if (n < 0) { finish(false); throw new IOException("Unexpected end of chunk"); }
            chunkLeft -= n;
            if (chunkLeft == 0) {
                // consume CRLF after chunk data
                String crlf = readLine(c.in);
                if (crlf == null) { finish(false); }
                else if (crlf.length() != 0) { finish(false); throw new IOException("Bad chunk terminator"); }
            }
            return n;
        }

        @Override public int available() throws IOException {
            if (closed) return 0;
            return (int) Math.min(c.in.available(), chunkLeft);
        }

        @Override public void close() { finish(eof); }
    }

    private static final class EofStream extends InputStream {
        private final Conn c; private boolean closed;
        EofStream(Conn c) { this.c = c; }

        @Override public int read() throws IOException {
            if (closed) return -1;
            int b = c.in.read();
            if (b < 0) close();
            return b;
        }

        @Override public int read(byte[] b, int off, int len) throws IOException {
            if (closed) return -1;
            int n = c.in.read(b, off, len);
            if (n < 0) close();
            return n;
        }

        @Override public void close() {
            if (!closed) { closed = true; c.close(); }
        }
    }

    /** Close one in-flight response's socket from another thread (used to abort streams). */
    public static void abort(Response r) {
        if (r == null) return;
        InputStream b = r.body;
        Conn c = null;
        if (b instanceof FixedStream) c = ((FixedStream) b).c;
        else if (b instanceof ChunkedStream) c = ((ChunkedStream) b).c;
        else if (b instanceof EofStream) c = ((EofStream) b).c;
        if (c != null) {
            try { c.socket.close(); } catch (Exception ignored) {}
        }
    }
}