import React, { useMemo } from "react";
import { Separator } from "../ui/separator";

import type { Workspace, SpaceType } from "../../App";
import type { CourseDirectoryItem } from "../../lib/courseDirectory";

function gmailComposeLink(email: string, subject?: string, body?: string) {
  const to = `to=${encodeURIComponent(email)}`;
  const su = subject ? `&su=${encodeURIComponent(subject)}` : "";
  const bd = body ? `&body=${encodeURIComponent(body)}` : "";
  return `https://mail.google.com/mail/?view=cm&fs=1&${to}${su}${bd}`;
}

function norm(s: any) {
  return String(s ?? "").trim().toLowerCase();
}

function pickAny(obj: any, keys: string[]) {
  for (const k of keys) {
    const v = obj?.[k];
    if (v !== undefined && v !== null && String(v).trim() !== "") return v;
  }
  return undefined;
}

function toIntOrFallback(v: any, fb: number) {
  const n = Number(v);
  if (Number.isFinite(n) && n > 0) return Math.floor(n);
  return fb;
}

export function CourseInfoSection({
  currentWorkspaceId,
  workspaces,
  selectedCourse,
  availableCourses,
}: {
  currentWorkspaceId: string;
  workspaces: Workspace[];
  selectedCourse: string;
  availableCourses: CourseDirectoryItem[];
}) {
  const currentWorkspace = useMemo(
    () => workspaces.find((w) => w.id === currentWorkspaceId),
    [workspaces, currentWorkspaceId]
  );

  // 判断当前是否是 Group/Team（用于决定是否展示 Group Name/Number）
  const isTeamSpace = useMemo(() => {
    const ws: any = currentWorkspace as any;
    const st = String((ws?.type as SpaceType) || "").toLowerCase();
    return st === "group" || st === "team";
  }, [currentWorkspace]);

  // --------- CourseInfo resolution ---------
  const courseInfo = useMemo((): CourseDirectoryItem | null => {
    const list = Array.isArray(availableCourses) ? availableCourses : [];

    // 1) selectedCourse: 可能是 id / name（大小写/空格不一致也能匹配）
    const selRaw = (selectedCourse || "").trim();
    const sel = norm(selRaw);
    if (sel) {
      const hit =
        list.find((c: any) => norm(c.id) === sel) ||
        list.find((c: any) => norm(c.name) === sel);
      if (hit) return hit as any;
    }

    // 2) workspace.courseInfo: group workspace 的 courseInfo 可能只带 id/name
    const wsCourse = (currentWorkspace as any)?.courseInfo as
      | { id?: string; name?: string; instructor?: any; teachingAssistant?: any }
      | undefined;

    const wsId = norm(wsCourse?.id);
    if (wsId) return (list.find((c: any) => norm(c.id) === wsId) ?? (wsCourse as any)) as any;

    const wsName = norm(wsCourse?.name);
    if (wsName) return (list.find((c: any) => norm(c.name) === wsName) ?? (wsCourse as any)) as any;

    return null;
  }, [availableCourses, currentWorkspace, selectedCourse]);

  // ---------- Display fields ----------
  const courseName = useMemo(() => {
    return (courseInfo as any)?.name ?? (selectedCourse || "Course");
  }, [courseInfo, selectedCourse]);

  // --------- Group fields (read-only) ---------
  const groupName = useMemo(() => {
    const ws: any = currentWorkspace as any;
    // 优先 groupName，否则退回 workspace 的 name/title
    return String(pickAny(ws, ["groupName", "name", "title"]) || "My Group");
  }, [currentWorkspace]);

  const groupNo = useMemo(() => {
    const ws: any = currentWorkspace as any;
    const raw = ws?.groupNo ?? ws?.groupNumber ?? ws?.groupIndex ?? ws?.group_id ?? ws?.groupId ?? 1;
    return toIntOrFallback(raw, 1);
  }, [currentWorkspace]);

  // ---------- Fallback：不要静默消失 ----------
  if (!courseInfo) {
    return (
      <div className="w-full">
        <div className="px-4 pt-4 pb-3 space-y-2">
          <div className="text-xs text-red-600">COURSEINFO ACTIVE (fallback)</div>
          <div className="font-semibold text-base">No course matched</div>
          <div className="text-xs text-muted-foreground space-y-1">
            <div>
              selectedCourse: <span className="font-medium">{String(selectedCourse || "")}</span>
            </div>
            <div>
              availableCourses: <span className="font-medium">{availableCourses?.length ?? 0}</span>
            </div>
            <div>
              currentWorkspaceId: <span className="font-medium">{String(currentWorkspaceId)}</span>
            </div>
          </div>
        </div>
        <Separator className="bg-[#ECECF1]" />
      </div>
    );
  }

  const instructorName = (courseInfo as any)?.instructor?.name ?? "N/A";
  const instructorEmail = String((courseInfo as any)?.instructor?.email ?? "").trim();

  const taName = (courseInfo as any)?.teachingAssistant?.name ?? "N/A";
  const taEmail = String((courseInfo as any)?.teachingAssistant?.email ?? "").trim();

  return (
    <div className="w-full">
      <div className="px-4 pt-4 pb-3 space-y-3">
        {/* Course Title */}
        <div className="font-semibold text-base">{courseName}</div>

        {/* Group fields (read-only, no pencil) */}
        {isTeamSpace && (
          <div className="space-y-1.5">
            <div className="flex items-center justify-between text-[13px]">
              <span className="text-muted-foreground">Group Name:</span>
              <span className="font-semibold truncate max-w-[60%] text-right">{groupName}</span>
            </div>
            <div className="flex items-center justify-between text-[13px]">
              <span className="text-muted-foreground">Group Number:</span>
              <span className="font-semibold">{groupNo}</span>
            </div>
          </div>
        )}

        {/* Instructor */}
        <div className="text-sm text-muted-foreground">
          Instructor:&nbsp;
          {instructorEmail ? (
            <a
              href={gmailComposeLink(
                instructorEmail,
                `[Clare] Question about ${courseName}`,
                `Hi ${instructorName},\n\nI have a question about ${courseName}:\n\n(Write your question here)\n\nThanks,\n`
              )}
              target="_blank"
              rel="noopener noreferrer"
              className="text-primary hover:underline"
            >
              {instructorName}
            </a>
          ) : (
            <span className="text-muted-foreground/60">{instructorName}</span>
          )}
        </div>

        {/* TA */}
        <div className="text-sm text-muted-foreground">
          TA:&nbsp;
          {taEmail ? (
            <a
              href={gmailComposeLink(
                taEmail,
                `[Clare] Help request for ${courseName}`,
                `Hi ${taName},\n\nI need help with ${courseName}:\n\n(Write your question here)\n\nThanks,\n`
              )}
              target="_blank"
              rel="noopener noreferrer"
              className="text-primary hover:underline"
            >
              {taName}
            </a>
          ) : (
            <span className="text-muted-foreground/60">{taName}</span>
          )}
        </div>
      </div>

      <Separator className="bg-[#ECECF1]" />
    </div>
  );
}