package com.inspect.tcpserver.sip.media;

import java.util.StringTokenizer;

public class SdpParser {

    public static SdpInfo parse(String sdp) {
        SdpInfo info = new SdpInfo();

        String[] lines = sdp.split("\\r?\\n");

        for (String line : lines) {
            line = line.trim();
            if (line.isEmpty()) continue;

            // ---------- 会话级 ----------
            if (line.startsWith("c=")) {
                // c=IN IP4 192.168.1.116
                String[] parts = line.split("\\s+");
                if (parts.length >= 3) {
                    info.setRemoteIp(parts[2]);
                }
            }

            // ---------- media ----------
            else if (line.startsWith("m=video")) {
                // m=video 50000 TCP/AVP 98
                StringTokenizer st = new StringTokenizer(line);
                st.nextToken(); // m=video

                info.setMediaPort(Integer.parseInt(st.nextToken()));

                String proto = st.nextToken();
                if (proto.toUpperCase().contains("TCP")) {
                    info.setTransport(SdpInfo.Transport.RTP_TCP);
                } else {
                    info.setTransport(SdpInfo.Transport.RTP_UDP);
                }

                info.setPayloadType(Integer.parseInt(st.nextToken()));
            }

            // ---------- rtpmap ----------
            else if (line.startsWith("a=rtpmap")) {
                // a=rtpmap:98 H264/90000
                String value = line.substring("a=rtpmap:".length());
                String[] parts = value.split("\\s+");
                if (parts.length == 2) {
                    String[] codecInfo = parts[1].split("/");
                    info.setCodec(codecInfo[0]);
                    info.setClockRate(Integer.parseInt(codecInfo[1]));
                }
            }

            // ---------- setup ----------
            else if (line.startsWith("a=setup:")) {
                info.setSetup(line.substring("a=setup:".length()));
            }

            // ---------- connection ----------
            else if (line.startsWith("a=connection:")) {
                info.setConnection(line.substring("a=connection:".length()));
            }

            // ---------- fmtp ----------
            else if (line.startsWith("a=fmtp:")) {
                // 可留作扩展
                info.putAttribute("fmtp", line);
            }

            // ---------- y= (SSRC) ----------
            else if (line.startsWith("y=")) {
                // y=0700000038
                info.setSsrc(Long.parseLong(line.substring(2)));
            }

            // ---------- 其他属性 ----------
            else if (line.startsWith("a=")) {
                int idx = line.indexOf(':');
                if (idx > 0) {
                    info.putAttribute(
                            line.substring(2, idx),
                            line.substring(idx + 1)
                    );
                }
            }
        }

        return info;
    }
}