import router from "@/router";
import { userService } from "@/services/user.service";

// TODO: Do I need this file?
/**
 * Contains a bunch of path helper functions.
 */
export const pathService = {
  /**
   * Redirects to the not found page.
   *
   * @param {*} reason Optional: A reason to explain to the user, why they got redirected
   * @param {*} sourceRoute Optional: Adds additional information from the source route to the query
   */
  notFound(reason, sourceRoute) {
    var payload = {};

    if (reason !== undefined) {
      payload.reason = reason;
    }

    if (sourceRoute !== undefined) {
      payload.source = sourceRoute.path;
    }

    router.push({
      path: "/404",
      query: payload
    });
  },

  /**
   * Validates and gets all data to a path of the form /dashboard/:sem:-sem
   *
   * @param {*} route Object that describes the current path and its parameters
   *
   * @returns A promise of the form ({semester: semester})
   */
  validateSemPath(route) {
    var semesterNr = this.getSemesterNrFromParam(route.params.semesterName);

    // Invalid path?
    if (semesterNr === undefined) {
      this.notFound("Invalid URL", route);
    }

    // Gather more data
    return userService
      .getSemester(semesterNr)
      .then(semester => {
        return { semester: semester.data };
      })
      .catch(() => {
        // Semester could not be found
        this.notFound(semesterNr + ". semester not found", route);
      });
  },

  /**
   * Validates and gets all data to a path of the form /dashboard/:sem:-sem/:module:
   *
   * @param {*} route Object that describes the current path and its parameters
   *
   * @returns A promise of the form ({semester: semester, module: module})
   */
  validateSemModulePath(route) {
    // First evaluate semester and than the module
    return this.validateSemPath(route).then(obj => {
      var moduleName = route.params.moduleName;

      // Gather more data
      return userService
        .getModule(obj.semester.nr, moduleName)
        .then(module => {
          return { semester: obj.semester, module: module.data };
        })
        .catch(() => {
          // Module could not be found
          this.notFound('"' + moduleName + '" module not found', route);
        });
    });
  },

  /**
   * Extracts the semester nr based on the url parameter in the format ":semesterNr:-sem".
   *
   * @param {*} semesterParam In the format ":semesterNr:-sem"
   *
   * @returns Semester Nr. if valid, otherwise undefined
   */
  getSemesterNrFromParam(semesterParam) {
    let re = new RegExp("^([1-9][0-9]*)-sem$");
    var res = semesterParam.match(re);

    // Found a match?
    if (res === null) {
      return undefined; // No
    } else {
      // First group is semester nr
      return res[1];
    }
  },

  getBreadcrumbs(route) {
    let sites = route.path.split("/");
    let siteCount = sites.length;

    return sites.reduce((crumbs, current, index) => {
      // Ignore empty parts
      if (current.length <= 0) {
        return crumbs;
      }

      var name = current;
      // Handle semester name
      var semNr = this.getSemesterNrFromParam(current);
      if (semNr !== undefined) {
        name = semNr + ". Semester";
      }
      // Handle decoding and capitalization
      name = decodeURIComponent(name);
      name = name.charAt(0).toUpperCase() + name.slice(1);

      let part = {
        text: name
      };

      let isActive = index + 1 == siteCount;
      if (isActive) {
        part.active = true;
      } else {
        part.to = crumbs[crumbs.length - 1]
          ? crumbs[crumbs.length - 1].to + "/" + current
          : "/" + current;
      }

      crumbs.push(part);
      return crumbs;
    }, []);
  }
};