import Button from "@/components/Low/Button";
import ProgressBar from "@/components/Low/ProgressBar";
import { Grading, Module } from "@/interfaces";
import { Assignment } from "@/interfaces/results";
import { Stat, User } from "@/interfaces/user";
import useExamStore from "@/stores/exam";
import { getExamById } from "@/utils/exams";
import { sortByModule } from "@/utils/moduleUtils";
import { calculateBandScore, getGradingLabel } from "@/utils/score";
import { getUserName } from "@/utils/users";
import axios from "axios";
import clsx from "clsx";
import { capitalize, uniqBy } from "lodash";
import moment from "moment";
import { useRouter } from "next/router";
import {
  BsBook,
  BsBuilding,
  BsChevronLeft,
  BsClipboard,
  BsHeadphones,
  BsMegaphone,
  BsPen,
} from "react-icons/bs";
import { toast } from "react-toastify";
import { futureAssignmentFilter } from "@/utils/assignments";
import { withIronSessionSsr } from "iron-session/next";
import { checkAccess, doesEntityAllow } from "@/utils/permissions";
import { mapBy, redirect, serialize } from "@/utils";
import { getAssignment } from "@/utils/assignments.be";
import { getEntityUsers, getUsers } from "@/utils/users.be";
import { getEntityWithRoles } from "@/utils/entities.be";
import { sessionOptions } from "@/lib/session";
import { EntityWithRoles } from "@/interfaces/entity";
import Head from "next/head";
import Separator from "@/components/Low/Separator";
import Link from "next/link";
import { requestUser } from "@/utils/api";
import { useEntityPermission } from "@/hooks/useEntityPermissions";
import { getGradingSystemByEntity } from "@/utils/grading.be";

export const getServerSideProps = withIronSessionSsr(
  async ({ req, res, params }) => {
    const user = await requestUser(req, res);
    if (!user) return redirect("/login");

    if (
      !checkAccess(user, [
        "admin",
        "developer",
        "corporate",
        "teacher",
        "mastercorporate",
      ])
    )
      return redirect("/assignments");

    res.setHeader(
      "Cache-Control",
      "public, s-maxage=10, stale-while-revalidate=59"
    );

    const { id } = params as { id: string };

    const assignment = await getAssignment(id);
    if (!assignment) return redirect("/assignments");

    const entity = await getEntityWithRoles(assignment.entity || "");
    if (!entity) {
      const users = await getUsers(
        {},
        0,
        {},
        {
          _id: 0,
          id: 1,
          name: 1,
          email: 1,
        }
      );
      return { props: serialize({ user, users, assignment }) };
    }

    if (!doesEntityAllow(user, entity, "view_assignments"))
      return redirect("/assignments");

    const [users, gradingSystem] = await Promise.all([
      await (checkAccess(user, ["developer", "admin"])
        ? getUsers(
            {},
            0,
            {},
            {
              _id: 0,
              id: 1,
              name: 1,
              email: 1,
            }
          )
        : getEntityUsers(
            entity.id,
            0,
            {},
            {
              _id: 0,
              id: 1,
              name: 1,
              email: 1,
            }
          )),
      getGradingSystemByEntity(entity.id),
    ]);

    return {
      props: serialize({ user, users, entity, assignment, gradingSystem }),
    };
  },
  sessionOptions
);

interface Props {
  user: User;
  users: User[];
  assignment: Assignment;
  entity?: EntityWithRoles;
  gradingSystem?: Grading;
}

export default function AssignmentView({
  user,
  users,
  entity,
  assignment,
  gradingSystem,
}: Props) {
  const canDeleteAssignment = useEntityPermission(
    user,
    entity,
    "delete_assignment"
  );
  const canStartAssignment = useEntityPermission(
    user,
    entity,
    "start_assignment"
  );

  const router = useRouter();

  const dispatch = useExamStore((state) => state.dispatch);

  const deleteAssignment = async () => {
    if (!canDeleteAssignment) return;
    if (!confirm("Are you sure you want to delete this assignment?")) return;

    axios
      .delete(`/api/assignments/${assignment?.id}`)
      .then(() =>
        toast.success(
          `Successfully deleted the assignment "${assignment?.name}".`
        )
      )
      .catch(() => toast.error("Something went wrong, please try again later."))
      .finally(() => router.push("/assignments"));
  };

  const startAssignment = () => {
    if (!canStartAssignment) return;
    if (!confirm("Are you sure you want to start this assignment?")) return;

    axios
      .post(`/api/assignments/${assignment.id}/start`)
      .then(() => {
        toast.success(
          `The assignment "${assignment.name}" has been started successfully!`
        );
        router.replace(router.asPath);
      })
      .catch((e) => {
        console.log(e);
        toast.error("Something went wrong, please try again later!");
      });
  };

  const formatTimestamp = (timestamp: string) => {
    const date = moment(parseInt(timestamp));
    const formatter = "YYYY/MM/DD - HH:mm";

    return date.format(formatter);
  };

  const calculateAverageModuleScore = (module: Module) => {
    if (!assignment) return -1;

    const resultModuleBandScores = assignment.results.map((r) => {
      const moduleStats = r.stats.filter((s) => s.module === module);

      const correct = moduleStats.reduce(
        (acc, curr) => acc + curr.score.correct,
        0
      );
      const total = moduleStats.reduce(
        (acc, curr) => acc + curr.score.total,
        0
      );
      return calculateBandScore(correct, total, module, r.type);
    });

    return resultModuleBandScores.length === 0
      ? -1
      : resultModuleBandScores.reduce((acc, curr) => acc + curr, 0) /
          assignment.results.length;
  };

  const aggregateScoresByModule = (
    stats: Stat[]
  ): { module: Module; total: number; missing: number; correct: number }[] => {
    const scores: {
      [key in Module]: { total: number; missing: number; correct: number };
    } = {
      reading: {
        total: 0,
        correct: 0,
        missing: 0,
      },
      listening: {
        total: 0,
        correct: 0,
        missing: 0,
      },
      writing: {
        total: 0,
        correct: 0,
        missing: 0,
      },
      speaking: {
        total: 0,
        correct: 0,
        missing: 0,
      },
      level: {
        total: 0,
        correct: 0,
        missing: 0,
      },
    };

    stats
      .filter((x) => !x.isPractice)
      .forEach((x) => {
        scores[x.module!] = {
          total: scores[x.module!].total + x.score.total,
          correct: scores[x.module!].correct + x.score.correct,
          missing: scores[x.module!].missing + x.score.missing,
        };
      });

    return Object.keys(scores)
      .filter((x) => scores[x as Module].total > 0)
      .map((x) => ({ module: x as Module, ...scores[x as Module] }));
  };

  const levelAverage = (
    aggregatedLevels: { module: Module; level: number }[]
  ) =>
    aggregatedLevels.reduce(
      (accumulator, current) => accumulator + current.level,
      0
    ) / aggregatedLevels.length;

  const renderLevelScore = (
    stats: Stat[],
    aggregatedLevels: { module: Module; level: number }[]
  ) => {
    const defaultLevelScore = levelAverage(aggregatedLevels).toFixed(1);
    if (!stats.every((s) => s.module === "level")) return defaultLevelScore;
    if (!gradingSystem) return defaultLevelScore;

    const score = {
      correct: stats.reduce((acc, curr) => acc + curr.score.correct, 0),
      total: stats.reduce((acc, curr) => acc + curr.score.total, 0),
    };

    const level: number = calculateBandScore(
      score.correct,
      score.total,
      "level",
      user.focus
    );

    return getGradingLabel(level, gradingSystem.steps);
  };

  const customContent = (
    stats: Stat[],
    user: string,
    focus: "academic" | "general"
  ) => {
    const correct = stats.reduce(
      (accumulator, current) => accumulator + current.score.correct,
      0
    );
    const total = stats.reduce(
      (accumulator, current) => accumulator + current.score.total,
      0
    );
    const aggregatedScores = aggregateScoresByModule(stats).filter(
      (x) => x.total > 0
    );

    const aggregatedLevels = aggregatedScores.map((x) => ({
      module: x.module,
      level: calculateBandScore(x.correct, x.total, x.module, focus),
    }));

    const timeSpent = stats[0].timeSpent;

    const selectExam = () => {
      const examPromises = uniqBy(stats, "exam").map((stat) =>
        getExamById(stat.module, stat.exam)
      );

      Promise.all(examPromises).then((exams) => {
        if (exams.every((x) => !!x)) {
          dispatch({
            type: "INIT_SOLUTIONS",
            payload: {
              exams: exams.map((x) => x!).sort(sortByModule),
              modules: exams
                .map((x) => x!)
                .sort(sortByModule)
                .map((x) => x!.module),
              stats,
            },
          });
          router.push("/exam");
        }
      });
    };

    const content = (
      <>
        <div className="-md:items-center flex w-full justify-between 2xl:items-center">
          <div className="-md:gap-2 -md:items-center flex md:flex-col md:gap-1 2xl:flex-row 2xl:items-center 2xl:gap-2">
            <span className="font-medium">
              {formatTimestamp(stats[0].date.toString())}
            </span>
            {timeSpent && (
              <>
                <span className="md:hidden 2xl:flex">• </span>
                <span className="text-sm">
                  {Math.floor(timeSpent / 60)} minutes
                </span>
              </>
            )}
          </div>
          <span
            className={clsx(
              correct / total >= 0.7 && "text-mti-purple",
              correct / total >= 0.3 && correct / total < 0.7 && "text-mti-red",
              correct / total < 0.3 && "text-mti-rose"
            )}
          >
            Level {renderLevelScore(stats, aggregatedLevels)}
          </span>
        </div>

        <div className="flex w-full flex-col gap-1">
          <div className="-md:mt-2 grid w-full grid-cols-4 place-items-start gap-2">
            {aggregatedLevels.map(({ module, level }) => (
              <div
                key={module}
                className={clsx(
                  "-md:px-4 flex w-fit items-center gap-2 rounded-xl py-2 text-white md:px-2 xl:px-4",
                  module === "reading" && "bg-ielts-reading",
                  module === "listening" && "bg-ielts-listening",
                  module === "writing" && "bg-ielts-writing",
                  module === "speaking" && "bg-ielts-speaking",
                  module === "level" && "bg-ielts-level"
                )}
              >
                {module === "reading" && <BsBook className="h-4 w-4" />}
                {module === "listening" && <BsHeadphones className="h-4 w-4" />}
                {module === "writing" && <BsPen className="h-4 w-4" />}
                {module === "speaking" && <BsMegaphone className="h-4 w-4" />}
                {module === "level" && <BsClipboard className="h-4 w-4" />}
                <span className="text-sm">{level.toFixed(1)}</span>
              </div>
            ))}
          </div>
        </div>
      </>
    );

    return (
      <div className="flex flex-col gap-2">
        <span>
          {(() => {
            const student = users.find((u) => u.id === user);
            return `${student?.name} (${student?.email})`;
          })()}
        </span>
        <div
          key={user}
          className={clsx(
            "border-mti-gray-platinum -md:hidden flex cursor-pointer flex-col gap-4 rounded-xl border p-4 transition duration-300 ease-in-out",
            correct / total >= 0.7 && "hover:border-mti-purple",
            correct / total >= 0.3 &&
              correct / total < 0.7 &&
              "hover:border-mti-red",
            correct / total < 0.3 && "hover:border-mti-rose"
          )}
          onClick={selectExam}
          role="button"
        >
          {content}
        </div>
        <div
          key={user}
          className={clsx(
            "border-mti-gray-platinum -md:tooltip flex cursor-pointer flex-col gap-4 rounded-xl border p-4 transition duration-300 ease-in-out md:hidden",
            correct / total >= 0.7 && "hover:border-mti-purple",
            correct / total >= 0.3 &&
              correct / total < 0.7 &&
              "hover:border-mti-red",
            correct / total < 0.3 && "hover:border-mti-rose"
          )}
          data-tip="Your screen size is too small to view previous exams."
          role="button"
        >
          {content}
        </div>
      </div>
    );
  };

  const shouldRenderStart = () => {
    if (assignment) {
      if (futureAssignmentFilter(assignment)) {
        return true;
      }
    }

    return false;
  };

  const removeInactiveAssignees = () => {
    const mappedResults = mapBy(assignment.results, "user");
    const inactiveAssignees = assignment.assignees.filter(
      (a) => !mappedResults.includes(a)
    );
    const activeAssignees = assignment.assignees.filter((a) =>
      mappedResults.includes(a)
    );

    if (
      !confirm(
        `Are you sure you want to remove ${inactiveAssignees.length} assignees?`
      )
    )
      return;

    axios
      .patch(`/api/assignments/${assignment.id}`, {
        assignees: activeAssignees,
      })
      .then(() => {
        toast.success(
          `The assignment "${assignment.name}" has been updated successfully!`
        );
        router.replace(router.asPath);
      })
      .catch((e) => {
        console.log(e);
        toast.error("Something went wrong, please try again later!");
      });
  };

  const copyLink = async () => {
    const origin = window.location.origin;
    await navigator.clipboard.writeText(
      `${origin}/exam?assignment=${assignment.id}`
    );
    toast.success(
      "The URL to the assignment has been copied to your clipboard!"
    );
  };

  return (
    <>
      <Head>
        <title>{assignment.name} | EnCoach</title>
        <meta
          name="description"
          content="A training platform for the IELTS exam provided by the Muscat Training Institute and developed by eCrop."
        />
        <meta name="viewport" content="width=device-width, initial-scale=1" />
        <link rel="icon" href="/favicon.ico" />
      </Head>
      <>
        <div className="flex flex-col gap-4">
          <div className="w-full flex items-center justify-between">
            <div className="flex items-center gap-2">
              <Link
                href="/assignments"
                className="text-mti-purple hover:text-mti-purple-dark transition ease-in-out duration-300 text-xl"
              >
                <BsChevronLeft />
              </Link>
              <h2 className="font-bold text-2xl">{assignment.name}</h2>
            </div>
            {!!entity && (
              <span className="flex items-center gap-2">
                <BsBuilding className="text-xl" /> {entity.label}
              </span>
            )}
          </div>
          <Separator />
        </div>
        <div className="mt-4 flex w-full flex-col gap-4">
          <ProgressBar
            color="purple"
            label={`${assignment?.results.length}/${assignment?.assignees.length} assignees completed`}
            className="h-6"
            textClassName={
              (assignment?.results.length || 0) /
                (assignment?.assignees.length || 1) <
              0.5
                ? "!text-mti-gray-dim font-light"
                : "text-white"
            }
            percentage={
              ((assignment?.results.length || 0) /
                (assignment?.assignees.length || 1)) *
              100
            }
          />
          <div className="flex items-start gap-8">
            <div className="flex flex-col gap-2">
              <span>
                Start Date:{" "}
                {moment(assignment?.startDate).format("DD/MM/YY, HH:mm")}
              </span>
              <span>
                End Date:{" "}
                {moment(assignment?.endDate).format("DD/MM/YY, HH:mm")}
              </span>
            </div>
            <div className="flex flex-col gap-2">
              <span>
                Assignees:{" "}
                {users
                  .filter((u) => assignment?.assignees.includes(u.id))
                  .map((u) => `${u.name} (${u.email})`)
                  .join(", ")}
              </span>
              <span>
                Assigner:{" "}
                {getUserName(users.find((x) => x.id === assignment?.assigner))}
              </span>
            </div>
          </div>

          {assignment.assignees.length !== 0 &&
            assignment.results.length !== assignment.assignees.length && (
              <Button onClick={removeInactiveAssignees} variant="outline">
                Remove Inactive Assignees
              </Button>
            )}

          <div className="flex flex-col gap-2">
            <span className="text-xl font-bold">Average Scores</span>
            <div className="-md:mt-2 flex w-full items-center gap-4">
              {assignment &&
                uniqBy(assignment.exams, (x) => x.module).map(({ module }) => (
                  <div
                    data-tip={capitalize(module)}
                    key={module}
                    className={clsx(
                      "-md:px-4 tooltip flex w-fit items-center gap-2 rounded-xl py-2 text-white md:px-2 xl:px-4",
                      module === "reading" && "bg-ielts-reading",
                      module === "listening" && "bg-ielts-listening",
                      module === "writing" && "bg-ielts-writing",
                      module === "speaking" && "bg-ielts-speaking",
                      module === "level" && "bg-ielts-level"
                    )}
                  >
                    {module === "reading" && <BsBook className="h-4 w-4" />}
                    {module === "listening" && (
                      <BsHeadphones className="h-4 w-4" />
                    )}
                    {module === "writing" && <BsPen className="h-4 w-4" />}
                    {module === "speaking" && (
                      <BsMegaphone className="h-4 w-4" />
                    )}
                    {module === "level" && <BsClipboard className="h-4 w-4" />}
                    {calculateAverageModuleScore(module) > -1 && (
                      <span className="text-sm">
                        {calculateAverageModuleScore(module).toFixed(1)}
                      </span>
                    )}
                  </div>
                ))}
            </div>
          </div>
          <div className="flex flex-col gap-2">
            <span className="text-xl font-bold">
              Results ({assignment?.results.length}/
              {assignment?.assignees.length})
            </span>
            <div>
              {assignment && assignment?.results.length > 0 && (
                <div className="grid w-full grid-cols-1 gap-4 md:grid-cols-2 xl:grid-cols-3 xl:gap-6">
                  {assignment.results.map((r) =>
                    customContent(r.stats, r.user, r.type)
                  )}
                </div>
              )}
              {assignment && assignment?.results.length === 0 && (
                <span className="ml-1 font-semibold">No results yet...</span>
              )}
            </div>
          </div>

          <div className="flex gap-4 w-full items-center justify-end">
            <Button
              variant="outline"
              color="purple"
              className="w-full max-w-[200px]"
              onClick={copyLink}
            >
              Copy Link
            </Button>
            {assignment &&
              (assignment.results.length === assignment.assignees.length ||
                moment().isAfter(moment(assignment.endDate))) && (
                <Button
                  variant="outline"
                  color="red"
                  className="w-full max-w-[200px]"
                  onClick={deleteAssignment}
                >
                  Delete
                </Button>
              )}
            {/** if the assignment is not deemed as active yet, display start */}
            {shouldRenderStart() && (
              <Button
                variant="outline"
                color="green"
                className="w-full max-w-[200px]"
                onClick={startAssignment}
              >
                Start
              </Button>
            )}
            <Button
              onClick={() => router.push("/assignments")}
              className="w-full max-w-[200px]"
            >
              Close
            </Button>
          </div>
        </div>
      </>
    </>
  );
}