import { SessionDescriptionHandlerModifier } from "../session-description-handler";

const stripPayload = (sdp: string, payload: string): string => {
  const mediaDescs: Array<any> = [];

  const lines: Array<string> = sdp.split(/\r\n/);

  let currentMediaDesc: any;
  for (let i = 0; i < lines.length;) {
    const line: string = lines[i];
    if (/^m=(?:audio|video)/.test(line)) {
      currentMediaDesc = {
        index: i,
        stripped: []
      };
      mediaDescs.push(currentMediaDesc);
    } else if (currentMediaDesc) {
      const rtpmap = /^a=rtpmap:(\d+) ([^/]+)\//.exec(line);
      if (rtpmap && payload === rtpmap[2]) {
        lines.splice(i, 1);
        currentMediaDesc.stripped.push(rtpmap[1]);
        continue; // Don't increment 'i'
      }
    }

    i++;
  }

  for (const mediaDesc of mediaDescs) {
    const mline: Array<string> = lines[mediaDesc.index].split(" ");

    // Ignore the first 3 parameters of the mline. The codec information is after that
    for (let j = 3; j < mline.length;) {
      if (mediaDesc.stripped.indexOf(mline[j]) !== -1) {
        mline.splice(j, 1);
        continue;
      }
      j++;
    }

    lines[mediaDesc.index] = mline.join(" ");
  }

  return lines.join("\r\n");
};

const stripMediaDescription = (sdp: string, description: string): string => {
  const descriptionRegExp = new RegExp("m=" + description + ".*$", "gm");
  const groupRegExp = new RegExp("^a=group:.*$", "gm");

  if (descriptionRegExp.test(sdp)) {
    let midLineToRemove;
    sdp = sdp.split(/^m=/gm).filter((section) => {
      if (section.substr(0, description.length) === description) {
        midLineToRemove = section.match(/^a=mid:.*$/gm);
        if (midLineToRemove) {
          const step = midLineToRemove[0].match(/:.+$/g);
          if (step) {
            midLineToRemove = step[0].substr(1);
          }
        }
        return false;
      }
      return true;
    }).join("m=");
    const groupLine = sdp.match(groupRegExp);
    if (groupLine && groupLine.length === 1) {
      let groupLinePortion = groupLine[0];
      const groupRegExpReplace = new RegExp("\ *" + midLineToRemove + "[^\ ]*", "g");
      groupLinePortion = groupLinePortion.replace(groupRegExpReplace, "");
      sdp = sdp.split(groupRegExp).join(groupLinePortion);
    }
  }
  return sdp;
};

export function stripTcpCandidates(description: RTCSessionDescriptionInit): Promise<RTCSessionDescriptionInit> {
  description.sdp = (description.sdp || "").replace(/^a=candidate:\d+ \d+ tcp .*?\r\n/img, "");
  return Promise.resolve(description);
}

export function stripTelephoneEvent(description: RTCSessionDescriptionInit): Promise<RTCSessionDescriptionInit> {
  description.sdp = stripPayload(description.sdp || "", "telephone-event");
  return Promise.resolve(description);
}

export function cleanJitsiSdpImageattr(description: RTCSessionDescriptionInit): Promise<RTCSessionDescriptionInit> {
  description.sdp = (description.sdp || "").replace(/^(a=imageattr:.*?)(x|y)=\[0-/gm, "$1$2=[1:");
  return Promise.resolve(description);
}

export function stripG722(description: RTCSessionDescriptionInit): Promise<RTCSessionDescriptionInit> {
  description.sdp = stripPayload(description.sdp || "", "G722");
  return Promise.resolve(description);
}

export function stripRtpPayload(payload: string): SessionDescriptionHandlerModifier {
  return (description: RTCSessionDescriptionInit): Promise<RTCSessionDescriptionInit> => {
    description.sdp = stripPayload(description.sdp || "", payload);
    return Promise.resolve(description);
  };
}

export function stripVideo(description: RTCSessionDescriptionInit): Promise<RTCSessionDescriptionInit> {
  description.sdp = stripMediaDescription(description.sdp || "", "video");
  return Promise.resolve(description);
}

export function addMidLines(description: RTCSessionDescriptionInit): Promise<RTCSessionDescriptionInit> {
  let sdp = description.sdp || "";
  if (sdp.search(/^a=mid.*$/gm) === -1) {
    const mlines = sdp.match(/^m=.*$/gm);
    const sdpArray = sdp.split(/^m=.*$/gm);
    if (mlines) {
      mlines.forEach((elem, idx) => {
        mlines[idx] = elem + "\na=mid:" + idx;
      });
    }
    sdpArray.forEach((elem, idx) => {
      if (mlines && mlines[idx]) {
        sdpArray[idx] = elem + mlines[idx];
      }
    });
    sdp = sdpArray.join("");
    description.sdp = sdp;
  }
  return Promise.resolve(description);
}