/**
 * Copyright 2015 CANAL+ Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import { assertUnreachable } from "../../../../utils/assert";
import { parseXml } from "../../../../utils/xml-parser";
import type { IIrParserResponse, ILoadedXlinkData, IMPDParserArguments } from "../common";
import parseMpdIr from "../common";
import type { IPeriodIntermediateRepresentation } from "../node_parser_types";
import type { IDashParserResponse, ILoadedResource } from "../parsers_types";
import { createMPDIntermediateRepresentation } from "./node_parsers/MPD";
import { createPeriodIntermediateRepresentation } from "./node_parsers/Period";

/**
 * Parse MPD through the Fast JS parser.
 * @param {string} xml - MPD under a string format
 * @param {Object} args - Various parsing options and information.
 * @returns {Object} - Response returned by the DASH-JS parser.
 */
export default function parseFromString(
  xml: string,
  args: IMPDParserArguments,
): IDashParserResponse<string> {
  const root = parseXml(xml);
  const lastChild = root[root.length - 1];
  if (
    lastChild === undefined ||
    typeof lastChild === "string" ||
    lastChild.tagName !== "MPD"
  ) {
    throw new Error("DASH Parser: document root should be MPD");
  }

  const [mpdIR, warnings] = createMPDIntermediateRepresentation(lastChild, xml);
  const ret = parseMpdIr(mpdIR, args, warnings);
  return processReturn(ret);

  /**
   * Handle `parseMpdIr` return values, asking for resources if they are needed
   * and pre-processing them before continuing parsing.
   *
   * @param {Object} initialRes
   * @returns {Object}
   */
  function processReturn(initialRes: IIrParserResponse): IDashParserResponse<string> {
    if (initialRes.type === "done") {
      return initialRes;
    } else if (initialRes.type === "needs-clock") {
      return {
        type: "needs-resources",
        value: {
          urls: [initialRes.value.url],
          format: "string",
          continue(
            loadedClock: Array<ILoadedResource<string>>,
          ): IDashParserResponse<string> {
            if (loadedClock.length !== 1) {
              throw new Error("DASH parser: wrong number of loaded ressources.");
            }
            const newRet = initialRes.value.continue(loadedClock[0].responseData);
            return processReturn(newRet);
          },
        },
      };
    } else if (initialRes.type === "needs-xlinks") {
      return {
        type: "needs-resources",
        value: {
          urls: initialRes.value.xlinksUrls,
          format: "string",
          continue(
            loadedXlinks: Array<ILoadedResource<string>>,
          ): IDashParserResponse<string> {
            const resourceInfos: ILoadedXlinkData[] = [];
            for (let i = 0; i < loadedXlinks.length; i++) {
              const {
                responseData: xlinkResp,
                receivedTime,
                sendingTime,
                url,
              } = loadedXlinks[i];
              if (!xlinkResp.success) {
                throw xlinkResp.error;
              }
              const wrappedData = "<root>" + xlinkResp.data + "</root>";
              const dataAsXML = parseXml(wrappedData);
              const innerParsed = dataAsXML[dataAsXML.length - 1];
              if (innerParsed === undefined || typeof innerParsed === "string") {
                throw new Error("DASH parser: Invalid external ressources");
              }
              const periods = innerParsed.children;
              const periodsIR: IPeriodIntermediateRepresentation[] = [];
              const periodsIRWarnings: Error[] = [];
              for (let j = 0; j < periods.length; j++) {
                const period = periods[j];
                if (typeof period === "string" || period.tagName !== "Period") {
                  continue;
                }
                const [periodIR, periodWarnings] = createPeriodIntermediateRepresentation(
                  period,
                  wrappedData,
                );
                periodsIRWarnings.push(...periodWarnings);
                periodsIR.push(periodIR);
              }
              resourceInfos.push({
                url,
                receivedTime,
                sendingTime,
                parsed: periodsIR,
                warnings: periodsIRWarnings,
              });
            }
            const newRet = initialRes.value.continue(resourceInfos);
            return processReturn(newRet);
          },
        },
      };
    } else {
      assertUnreachable(initialRes);
    }
  }
}