"use client";

import { useEffect, useState, useCallback, useRef } from "react";
import { createPortal } from "react-dom";
import Link from "next/link";
import Image from "next/image";
import {
  FiUsers, FiArrowLeft, FiShield, FiUser, FiLoader,
  FiChevronDown, FiCalendar, FiHash, FiUserCheck, FiUserX,
} from "react-icons/fi";
import { MdAdminPanelSettings } from "react-icons/md";
import "../styles/AdminDashboard.css";
import "./AdminUsers.css";

const PAGE_LIMIT = 12;

function RoleBadge({ role }) {
  if (role === "superadmin")
    return <span className="au-role-badge au-role-superadmin"><FiShield size={11} /> Super Admin</span>;
  if (role === "admin")
    return <span className="au-role-badge au-role-admin"><MdAdminPanelSettings size={11} /> Admin</span>;
  return <span className="au-role-badge au-role-user"><FiUser size={11} /> User</span>;
}

function formatDate(dateStr) {
  if (!dateStr) return "—";
  return new Date(dateStr).toLocaleDateString("en-IN", {
    day: "2-digit", month: "short", year: "numeric",
  });
}

export default function AdminUsers() {
  const [myRole, setMyRole]           = useState(null);
  const [token, setToken]             = useState("");
  const [myUsn, setMyUsn]             = useState("");
  const [isLoaded, setIsLoaded]       = useState(false);

  const [users, setUsers]             = useState([]);
  const [total, setTotal]             = useState(0);
  const [page, setPage]               = useState(1);
  const [totalPages, setTotalPages]   = useState(1);
  const [loading, setLoading]         = useState(false);
  const [loadingMore, setLoadingMore] = useState(false);
  const [error, setError]             = useState("");

  const [changingRole, setChangingRole] = useState({});
  const [roleMsg, setRoleMsg]           = useState({});

  const [openConfirmUsn, setOpenConfirmUsn] = useState(null);
  const [confirmAction, setConfirmAction]   = useState(null);
  const [dropdownPos, setDropdownPos]       = useState({ top: 0, left: 0 });

  const confirmRef = useRef(null);
  const btnRefs    = useRef({});

  // ── bootstrap ──
  useEffect(() => {
    const r = localStorage.getItem("role")  || "";
    const t = localStorage.getItem("token") || "";
    const u = localStorage.getItem("usn")   || "";
    setMyRole(r); setToken(t); setMyUsn(u);
    setTimeout(() => setIsLoaded(true), 100);
  }, []);

  // ── fetch users ──
  const fetchUsers = useCallback(async (pageNum, append = false) => {
    if (!token) return;
    append ? setLoadingMore(true) : setLoading(true);
    setError("");
    try {
      const res  = await fetch(`/api/admin/users?page=${pageNum}&limit=${PAGE_LIMIT}`, {
        headers: { Authorization: `Bearer ${token}` },
      });
      const data = await res.json();
      if (!res.ok) { setError(data.error || "Failed to fetch users"); return; }
      append ? setUsers(prev => [...prev, ...data.users]) : setUsers(data.users);
      setTotal(data.total);
      setPage(data.page);
      setTotalPages(data.totalPages);
    } catch {
      setError("Network error. Please try again.");
    } finally {
      setLoading(false); setLoadingMore(false);
    }
  }, [token]);

  useEffect(() => {
    if (token && (myRole === "admin" || myRole === "superadmin")) fetchUsers(1, false);
  }, [token, myRole, fetchUsers]);

  const handleViewMore = () => fetchUsers(page + 1, true);

  // ── inline confirm helpers ──
  const openConfirm = (user, newRole, usn) => {
    const btn = btnRefs.current[usn];
    if (btn) {
      const rect       = btn.getBoundingClientRect();
      const dropH      = 190;
      const dropW      = 230;
      const spaceBelow = window.innerHeight - rect.bottom;
      const top  = spaceBelow > dropH ? rect.bottom + 8 : rect.top - dropH - 8;
      const spaceRight = window.innerWidth - rect.left;
      const left = spaceRight > dropW  ? rect.left : rect.right - dropW;
      setDropdownPos({ top, left });
    }
    setOpenConfirmUsn(user.usn);
    setConfirmAction({ user, newRole });
  };

  const closeConfirm    = () => { setOpenConfirmUsn(null); setConfirmAction(null); };
  const handleConfirmed = () => {
    if (!confirmAction) return;
    handleRoleChange(confirmAction.user, confirmAction.newRole);
    closeConfirm();
  };

  // close on outside click
  useEffect(() => {
    if (!openConfirmUsn) return;
    const handler = (e) => {
      if (confirmRef.current && !confirmRef.current.contains(e.target)) {
        const btns = Object.values(btnRefs.current);
        if (btns.some(b => b && b.contains(e.target))) return;
        closeConfirm();
      }
    };
    document.addEventListener("mousedown", handler);
    return () => document.removeEventListener("mousedown", handler);
  }, [openConfirmUsn]);

  // ── change role ──
  const handleRoleChange = async (user, newRole) => {
    setChangingRole(prev => ({ ...prev, [user.usn]: true }));
    setRoleMsg(prev => ({ ...prev, [user.usn]: "" }));
    try {
      const res  = await fetch("/api/admin/users/role", {
        method: "PATCH",
        headers: { "Content-Type": "application/json", Authorization: `Bearer ${token}` },
        body: JSON.stringify({ targetUsn: user.usn, newRole }),
      });
      const data = await res.json();
      if (!res.ok) { setRoleMsg(prev => ({ ...prev, [user.usn]: data.error || "Failed" })); return; }
      setUsers(prev => prev.map(u => u.usn === user.usn ? { ...u, role: data.user.role } : u));
      setRoleMsg(prev => ({
        ...prev,
        [user.usn]: newRole === "admin" ? "Made admin ✓" : "Removed admin ✓",
      }));
      setTimeout(() => setRoleMsg(prev => ({ ...prev, [user.usn]: "" })), 2500);
    } catch {
      setRoleMsg(prev => ({ ...prev, [user.usn]: "Network error" }));
    } finally {
      setChangingRole(prev => ({ ...prev, [user.usn]: false }));
    }
  };

  // ── guards ──
  if (myRole === null) return null;

  const isSuperAdmin = myRole === "superadmin";

  return (
    <div className={`adm-wrapper ${isLoaded ? "adm-loaded" : ""}`}>

      {/* ── Header ── */}
      <header className="adm-header">
        <div className="adm-header-content">
          <div className="adm-header-left">
            <Link href="/admin" className="au-back-link">
              <FiArrowLeft size={15} /> Admin Dashboard
            </Link>
            <div className="adm-role-badge" style={{ backgroundColor: "#3b82f6", marginTop: "0.75rem" }}>
              <FiUsers size={16} />
              <span>User Management</span>
            </div>
            <h1 className="adm-title">
              All <span className="adm-title-highlight">Users</span>
            </h1>
            <p className="adm-subtitle">
              Latest registered users — {total > 0 ? `${total} total` : "loading…"}
            </p>
          </div>
          <div className="adm-header-deco">
            <div className="adm-deco-circle" style={{ background: "#dbeafe", border: "2px solid #bfdbfe" }}>
              <FiUsers size={44} color="#3b82f6" />
            </div>
          </div>
        </div>
      </header>

      {/* ── Summary strip ── */}
      <section className="adm-summary">
        <div className="adm-summary-card adm-summary-blue">
          <div className="adm-summary-icon"><FiUsers size={20} /></div>
          <div>
            <div className="adm-summary-value">{total}</div>
            <div className="adm-summary-label">Total Users</div>
          </div>
        </div>
        <div className="adm-summary-card adm-summary-green">
          <div className="adm-summary-icon"><FiUserCheck size={20} /></div>
          <div>
            <div className="adm-summary-value">{users.filter(u => (u.role || "user") === "admin").length}</div>
            <div className="adm-summary-label">Admins (loaded)</div>
          </div>
        </div>
        <div className="adm-summary-card adm-summary-gray">
          <div className="adm-summary-icon"><FiUser size={20} /></div>
          <div>
            <div className="adm-summary-value">{users.filter(u => !u.role || u.role === "user").length}</div>
            <div className="adm-summary-label">Regular Users</div>
          </div>
        </div>
        <div className="adm-summary-card adm-summary-yellow">
          <div className="adm-summary-icon"><FiHash size={20} /></div>
          <div>
            <div className="adm-summary-value">{users.length}</div>
            <div className="adm-summary-label">Loaded</div>
          </div>
        </div>
      </section>

      {/* ── Error ── */}
      {error && <div className="au-error-banner">{error}</div>}

      {/* ── User list ── */}
      {loading ? (
        <div className="au-loading-state">
          <div className="au-spinner"><FiLoader size={28} /></div>
          <p>Loading users…</p>
        </div>
      ) : (
        <>
          <section className="au-users-grid">
            {users.map((user, idx) => {
              const userRole     = user.role || "user";
              const isChanging   = changingRole[user.usn];
              const msg          = roleMsg[user.usn];
              const isOwnAccount = user.usn === myUsn;
              const isOpen       = openConfirmUsn === user.usn;

              return (
                <div
                  key={user._id || idx}
                  className="au-user-card"
                  style={{ animationDelay: `${idx * 0.04}s` }}
                >
                  {/* Avatar + name row */}
                  <div className="au-card-top">
                    <div className="au-avatar-wrap">
                      <Image
                        src={user.profileimg || "https://res.cloudinary.com/dihocserl/image/upload/v1758109403/profile-blue-icon_w3vbnt.webp"}
                        alt={user.name}
                        width={48} height={48}
                        className="au-avatar"
                      />
                    </div>
                    <div className="au-card-info">
                      <p className="au-user-name">{user.name}</p>
                      <p className="au-user-usn">{user.usn}</p>
                    </div>
                    <RoleBadge role={userRole} />
                  </div>

                  {/* Meta row */}
                  <div className="au-meta-row">
                    <span className="au-meta-item">
                      <FiCalendar size={12} /> Joined {formatDate(user.createdAt)}
                    </span>
                  </div>

                  {/* Role action — superadmin only, not own account */}
                  {isSuperAdmin && !isOwnAccount && (
                    <div className="au-role-action">
                      <div className="au-confirm-wrap">
                        {userRole === "admin" ? (
                          <button
                            ref={el => { btnRefs.current[user.usn] = el; }}
                            className="au-role-btn au-role-btn-remove"
                            onClick={() => isOpen ? closeConfirm() : openConfirm(user, "user", user.usn)}
                            disabled={isChanging}
                          >
                            <FiUserX size={14} />
                            {isChanging ? "Updating…" : "Remove Admin"}
                          </button>
                        ) : (
                          <button
                            ref={el => { btnRefs.current[user.usn] = el; }}
                            className="au-role-btn au-role-btn-make"
                            onClick={() => isOpen ? closeConfirm() : openConfirm(user, "admin", user.usn)}
                            disabled={isChanging}
                          >
                            <FiUserCheck size={14} />
                            {isChanging ? "Updating…" : "Make Admin"}
                          </button>
                        )}
                      </div>
                      {msg && <span className="au-role-msg">{msg}</span>}
                    </div>
                  )}

                  {/* Own account label */}
                  {isOwnAccount && <div className="au-own-tag">You</div>}
                </div>
              );
            })}
          </section>

          {/* ── View more ── */}
          {page < totalPages && (
            <div className="au-view-more-wrap">
              <button className="au-view-more-btn" onClick={handleViewMore} disabled={loadingMore}>
                {loadingMore ? (
                  <><span className="au-dots"><span /><span /><span /></span> Loading…</>
                ) : (
                  <><FiChevronDown size={16} /> View More ({total - users.length} remaining)</>
                )}
              </button>
            </div>
          )}

          {users.length > 0 && page >= totalPages && (
            <p className="au-all-loaded">All {total} users loaded</p>
          )}

          {users.length === 0 && !loading && (
            <div className="au-empty"><FiUsers size={36} /><p>No users found</p></div>
          )}
        </>
      )}

      {/* ── Portal confirm dropdown ── renders on document.body, floats above everything ── */}
      {openConfirmUsn && confirmAction && typeof document !== "undefined" &&
        createPortal(
          <div
            ref={confirmRef}
            className="au-confirm-dropdown"
            style={{ top: dropdownPos.top, left: dropdownPos.left }}
          >
            <div className={`au-confirm-dropdown-icon ${
              confirmAction.newRole === "admin" ? "au-confirm-icon-blue" : "au-confirm-icon-red"
            }`}>
              {confirmAction.newRole === "admin" ? <FiUserCheck size={18} /> : <FiUserX size={18} />}
            </div>
            <p className="au-confirm-dropdown-title">
              {confirmAction.newRole === "admin" ? "Make Admin?" : "Remove Admin?"}
            </p>
            <p className="au-confirm-dropdown-text">
              {confirmAction.newRole === "admin"
                ? <><strong>{confirmAction.user.name}</strong> will gain admin access.</>
                : <><strong>{confirmAction.user.name}</strong> will lose admin access.</>}
            </p>
            <div className="au-confirm-dropdown-actions">
              <button className="au-confirm-dropdown-btn au-confirm-cancel" onClick={closeConfirm}>
                Cancel
              </button>
              <button
                className={`au-confirm-dropdown-btn ${
                  confirmAction.newRole === "admin" ? "au-confirm-ok-blue" : "au-confirm-ok-red"
                }`}
                onClick={handleConfirmed}
              >
                Confirm
              </button>
            </div>
          </div>,
          document.body
        )
      }

    </div>
  );
}