"use client";

import React from "react";
import { useEffect, useState, useCallback } from "react";
import { Permission } from "../../auth-context";
import { api } from "../../api";
import { Header } from "../../components/Header";
import { useRequireAuth } from "../../hooks/useRequireAuth";
import { components } from "../../generated/api";
import { formatDateTime } from "../../utils/date";
import { getStatusDisplay } from "../../utils/appointment";

type AppointmentResponse = components["schemas"]["AppointmentResponse"];
type PaginatedAppointments = components["schemas"]["PaginatedResponse_AppointmentResponse_"];

const styles: Record<string, React.CSSProperties> = {
  main: {
    minHeight: "100vh",
    background: "linear-gradient(135deg, #0f0f23 0%, #1a1a3e 50%, #2d1b4e 100%)",
    display: "flex",
    flexDirection: "column",
  },
  loader: {
    flex: 1,
    display: "flex",
    alignItems: "center",
    justifyContent: "center",
    fontFamily: "'DM Sans', system-ui, sans-serif",
    color: "rgba(255, 255, 255, 0.5)",
  },
  content: {
    flex: 1,
    padding: "2rem",
    maxWidth: "900px",
    margin: "0 auto",
    width: "100%",
  },
  pageTitle: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    fontSize: "1.75rem",
    fontWeight: 600,
    color: "#fff",
    marginBottom: "0.5rem",
  },
  pageSubtitle: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    color: "rgba(255, 255, 255, 0.5)",
    fontSize: "0.9rem",
    marginBottom: "1.5rem",
  },
  errorBanner: {
    background: "rgba(239, 68, 68, 0.15)",
    border: "1px solid rgba(239, 68, 68, 0.3)",
    color: "#f87171",
    padding: "1rem",
    borderRadius: "8px",
    marginBottom: "1rem",
    fontFamily: "'DM Sans', system-ui, sans-serif",
    fontSize: "0.875rem",
  },
  filterRow: {
    display: "flex",
    alignItems: "center",
    gap: "0.75rem",
    marginBottom: "1.5rem",
  },
  filterLabel: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    color: "rgba(255, 255, 255, 0.6)",
    fontSize: "0.875rem",
  },
  filterSelect: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    padding: "0.5rem 1rem",
    background: "rgba(255, 255, 255, 0.05)",
    border: "1px solid rgba(255, 255, 255, 0.1)",
    borderRadius: "6px",
    color: "#fff",
    fontSize: "0.875rem",
  },
  appointmentList: {
    display: "flex",
    flexDirection: "column",
    gap: "0.75rem",
  },
  appointmentCard: {
    background: "rgba(255, 255, 255, 0.03)",
    border: "1px solid rgba(255, 255, 255, 0.08)",
    borderRadius: "12px",
    padding: "1.25rem",
    transition: "all 0.2s",
  },
  appointmentCardPast: {
    opacity: 0.6,
  },
  appointmentHeader: {
    display: "flex",
    justifyContent: "space-between",
    alignItems: "flex-start",
    gap: "1rem",
  },
  appointmentTime: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    fontSize: "1rem",
    fontWeight: 500,
    color: "#fff",
    marginBottom: "0.25rem",
  },
  appointmentUser: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    fontSize: "0.875rem",
    color: "rgba(255, 255, 255, 0.5)",
    marginBottom: "0.25rem",
  },
  appointmentNote: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    fontSize: "0.875rem",
    color: "rgba(255, 255, 255, 0.4)",
    fontStyle: "italic",
    marginBottom: "0.5rem",
  },
  statusBadge: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    fontSize: "0.75rem",
    fontWeight: 500,
    padding: "0.25rem 0.75rem",
    borderRadius: "9999px",
    display: "inline-block",
  },
  buttonGroup: {
    display: "flex",
    gap: "0.5rem",
  },
  cancelButton: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    padding: "0.35rem 0.75rem",
    fontSize: "0.75rem",
    background: "rgba(255, 255, 255, 0.05)",
    border: "1px solid rgba(255, 255, 255, 0.1)",
    borderRadius: "6px",
    color: "rgba(255, 255, 255, 0.7)",
    cursor: "pointer",
    transition: "all 0.2s",
  },
  confirmButton: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    padding: "0.35rem 0.75rem",
    fontSize: "0.75rem",
    background: "rgba(239, 68, 68, 0.2)",
    border: "1px solid rgba(239, 68, 68, 0.3)",
    borderRadius: "6px",
    color: "#f87171",
    cursor: "pointer",
    transition: "all 0.2s",
  },
  emptyState: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    color: "rgba(255, 255, 255, 0.4)",
    textAlign: "center",
    padding: "3rem",
  },
};

export default function AdminAppointmentsPage() {
  const { user, isLoading, isAuthorized } = useRequireAuth({
    requiredPermission: Permission.VIEW_ALL_APPOINTMENTS,
    fallbackRedirect: "/",
  });

  const [appointments, setAppointments] = useState<AppointmentResponse[]>([]);
  const [isLoadingAppointments, setIsLoadingAppointments] = useState(true);
  const [cancellingId, setCancellingId] = useState<number | null>(null);
  const [confirmCancelId, setConfirmCancelId] = useState<number | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [statusFilter, setStatusFilter] = useState<string>("all");

  const fetchAppointments = useCallback(async () => {
    try {
      // Fetch with large per_page to get all appointments for now
      const data = await api.get<PaginatedAppointments>("/api/admin/appointments?per_page=100");
      setAppointments(data.records);
    } catch (err) {
      console.error("Failed to fetch appointments:", err);
      setError("Failed to load appointments");
    } finally {
      setIsLoadingAppointments(false);
    }
  }, []);

  useEffect(() => {
    if (user && isAuthorized) {
      fetchAppointments();
    }
  }, [user, isAuthorized, fetchAppointments]);

  const handleCancel = async (appointmentId: number) => {
    setCancellingId(appointmentId);
    setError(null);
    
    try {
      await api.post<AppointmentResponse>(`/api/admin/appointments/${appointmentId}/cancel`, {});
      await fetchAppointments();
      setConfirmCancelId(null);
    } catch (err) {
      if (err instanceof Error) {
        setError(err.message);
      } else {
        setError("Failed to cancel appointment");
      }
    } finally {
      setCancellingId(null);
    }
  };

  if (isLoading) {
    return (
      <main style={styles.main}>
        <div style={styles.loader}>Loading...</div>
      </main>
    );
  }

  if (!isAuthorized) {
    return null;
  }

  const filteredAppointments = appointments.filter((apt) => {
    if (statusFilter === "all") return true;
    return apt.status === statusFilter;
  });

  const bookedCount = appointments.filter((a) => a.status === "booked").length;

  return (
    <main style={styles.main}>
      <Header currentPage="admin-appointments" />
      <div style={styles.content}>
        <h1 style={styles.pageTitle}>All Appointments</h1>
        <p style={styles.pageSubtitle}>
          View and manage all user appointments
        </p>

        {error && (
          <div style={styles.errorBanner}>{error}</div>
        )}

        {/* Status Filter */}
        <div style={styles.filterRow}>
          <span style={styles.filterLabel}>Filter:</span>
          <select
            value={statusFilter}
            onChange={(e) => setStatusFilter(e.target.value)}
            style={styles.filterSelect}
          >
            <option value="all">All ({appointments.length})</option>
            <option value="booked">Booked ({bookedCount})</option>
            <option value="cancelled_by_user">Cancelled by User</option>
            <option value="cancelled_by_admin">Cancelled by Admin</option>
          </select>
        </div>

        {isLoadingAppointments ? (
          <div style={styles.emptyState}>Loading appointments...</div>
        ) : appointments.length === 0 ? (
          <div style={styles.emptyState}>No appointments yet.</div>
        ) : filteredAppointments.length === 0 ? (
          <div style={styles.emptyState}>No appointments match the filter.</div>
        ) : (
          <div style={styles.appointmentList}>
            {filteredAppointments.map((apt) => {
              const status = getStatusDisplay(apt.status);
              const isPast = new Date(apt.slot_start) <= new Date();
              return (
                <div
                  key={apt.id}
                  style={{
                    ...styles.appointmentCard,
                    ...(isPast ? styles.appointmentCardPast : {}),
                  }}
                >
                  <div style={styles.appointmentHeader}>
                    <div>
                      <div style={styles.appointmentTime}>
                        {formatDateTime(apt.slot_start)}
                      </div>
                      <div style={styles.appointmentUser}>
                        {apt.user_email}
                      </div>
                      {apt.note && (
                        <div style={styles.appointmentNote}>
                          &quot;{apt.note}&quot;
                        </div>
                      )}
                      <span style={{
                        ...styles.statusBadge,
                        background: status.bgColor,
                        color: status.textColor,
                      }}>
                        {status.text}
                      </span>
                    </div>
                    
                    {apt.status === "booked" && (
                      <div style={styles.buttonGroup}>
                        {confirmCancelId === apt.id ? (
                          <>
                            <button
                              onClick={() => handleCancel(apt.id)}
                              disabled={cancellingId === apt.id}
                              style={styles.confirmButton}
                            >
                              {cancellingId === apt.id ? "..." : "Confirm"}
                            </button>
                            <button
                              onClick={() => setConfirmCancelId(null)}
                              style={styles.cancelButton}
                            >
                              No
                            </button>
                          </>
                        ) : (
                          <button
                            onClick={() => setConfirmCancelId(apt.id)}
                            style={styles.cancelButton}
                          >
                            Cancel
                          </button>
                        )}
                      </div>
                    )}
                  </div>
                </div>
              );
            })}
          </div>
        )}
      </div>
    </main>
  );
}