"use client";

import { useEffect, useState, useCallback } from "react";
import { Permission } from "../../auth-context";
import { api } from "../../api";
import { sharedStyles } from "../../styles/shared";
import { Header } from "../../components/Header";
import { useRequireAuth } from "../../hooks/useRequireAuth";
import { components } from "../../generated/api";

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

// Helper to format datetime
function formatDateTime(isoString: string): string {
  const d = new Date(isoString);
  return d.toLocaleString("en-US", {
    weekday: "short",
    month: "short",
    day: "numeric",
    hour: "2-digit",
    minute: "2-digit",
    hour12: false,
  });
}

// Helper to get status display
function getStatusDisplay(status: string): { text: string; color: string } {
  switch (status) {
    case "booked":
      return { text: "Booked", color: "#28a745" };
    case "cancelled_by_user":
      return { text: "Cancelled by user", color: "#dc3545" };
    case "cancelled_by_admin":
      return { text: "Cancelled by admin", color: "#dc3545" };
    default:
      return { text: status, color: "#666" };
  }
}

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 {
      const data = await api.get<AppointmentResponse[]>("/api/admin/appointments");
      setAppointments(data);
    } 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 (
      <div style={sharedStyles.pageContainer}>
        <Header currentPage="admin-appointments" />
        <main style={sharedStyles.mainContent}>
          <p>Loading...</p>
        </main>
      </div>
    );
  }

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

  return (
    <div style={sharedStyles.pageContainer}>
      <Header currentPage="admin-appointments" />
      <main style={sharedStyles.mainContent}>
        <h1 style={{ marginBottom: "0.5rem" }}>All Appointments</h1>
        <p style={{ color: "#666", marginBottom: "1.5rem" }}>
          View and manage all user appointments
        </p>

        {error && (
          <div style={{
            background: "#f8d7da",
            border: "1px solid #f5c6cb",
            color: "#721c24",
            padding: "1rem",
            borderRadius: "8px",
            marginBottom: "1rem",
          }}>
            {error}
          </div>
        )}

        {/* Status Filter */}
        <div style={{ marginBottom: "1rem", display: "flex", gap: "0.5rem", alignItems: "center" }}>
          <label style={{ fontWeight: 500 }}>Filter:</label>
          <select
            value={statusFilter}
            onChange={(e) => setStatusFilter(e.target.value)}
            style={{
              padding: "0.5rem",
              border: "1px solid #ddd",
              borderRadius: "4px",
            }}
          >
            <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 ? (
          <p>Loading appointments...</p>
        ) : appointments.length === 0 ? (
          <p style={{ color: "#666" }}>No appointments yet.</p>
        ) : filteredAppointments.length === 0 ? (
          <p style={{ color: "#666" }}>No appointments match the filter.</p>
        ) : (
          <div style={{ display: "flex", flexDirection: "column", gap: "0.75rem" }}>
            {filteredAppointments.map((apt) => {
              const status = getStatusDisplay(apt.status);
              const isPast = new Date(apt.slot_start) <= new Date();
              return (
                <div
                  key={apt.id}
                  style={{
                    border: "1px solid #ddd",
                    borderRadius: "8px",
                    padding: "1rem",
                    background: isPast ? "#fafafa" : "#fff",
                    opacity: isPast && apt.status !== "booked" ? 0.7 : 1,
                  }}
                >
                  <div style={{ display: "flex", justifyContent: "space-between", alignItems: "flex-start" }}>
                    <div>
                      <div style={{ fontWeight: 500, marginBottom: "0.25rem" }}>
                        {formatDateTime(apt.slot_start)}
                      </div>
                      <div style={{ color: "#666", fontSize: "0.875rem", marginBottom: "0.25rem" }}>
                        User: {apt.user_email}
                      </div>
                      {apt.note && (
                        <div style={{ color: "#888", fontSize: "0.875rem", marginBottom: "0.5rem", fontStyle: "italic" }}>
                          &quot;{apt.note}&quot;
                        </div>
                      )}
                      <span style={{
                        color: status.color,
                        fontSize: "0.75rem",
                        fontWeight: 500,
                      }}>
                        {status.text}
                      </span>
                    </div>
                    
                    {apt.status === "booked" && (
                      <div>
                        {confirmCancelId === apt.id ? (
                          <div style={{ display: "flex", gap: "0.5rem" }}>
                            <button
                              onClick={() => handleCancel(apt.id)}
                              disabled={cancellingId === apt.id}
                              style={{
                                padding: "0.25rem 0.75rem",
                                background: "#dc3545",
                                color: "#fff",
                                border: "none",
                                borderRadius: "4px",
                                cursor: cancellingId === apt.id ? "not-allowed" : "pointer",
                                fontSize: "0.75rem",
                              }}
                            >
                              {cancellingId === apt.id ? "..." : "Confirm"}
                            </button>
                            <button
                              onClick={() => setConfirmCancelId(null)}
                              style={{
                                padding: "0.25rem 0.75rem",
                                background: "#fff",
                                border: "1px solid #ddd",
                                borderRadius: "4px",
                                cursor: "pointer",
                                fontSize: "0.75rem",
                              }}
                            >
                              No
                            </button>
                          </div>
                        ) : (
                          <button
                            onClick={() => setConfirmCancelId(apt.id)}
                            style={{
                              padding: "0.25rem 0.75rem",
                              background: "#fff",
                              border: "1px solid #ddd",
                              borderRadius: "4px",
                              cursor: "pointer",
                              fontSize: "0.75rem",
                              color: "#666",
                            }}
                          >
                            Cancel
                          </button>
                        )}
                      </div>
                    )}
                  </div>
                </div>
              );
            })}
          </div>
        )}
      </main>
    </div>
  );
}