"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";

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; bgColor: string; textColor: string } {
  switch (status) {
    case "booked":
      return { text: "Booked", bgColor: "rgba(34, 197, 94, 0.2)", textColor: "#4ade80" };
    case "cancelled_by_user":
      return { text: "Cancelled by you", bgColor: "rgba(239, 68, 68, 0.2)", textColor: "#f87171" };
    case "cancelled_by_admin":
      return { text: "Cancelled by admin", bgColor: "rgba(239, 68, 68, 0.2)", textColor: "#f87171" };
    default:
      return { text: status, bgColor: "rgba(255,255,255,0.1)", textColor: "rgba(255,255,255,0.6)" };
  }
}

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: "800px",
    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",
  },
  section: {
    marginBottom: "2rem",
  },
  sectionTitle: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    fontSize: "1.1rem",
    fontWeight: 500,
    color: "#fff",
    marginBottom: "1rem",
  },
  sectionTitleMuted: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    fontSize: "1.1rem",
    fontWeight: 500,
    color: "rgba(255, 255, 255, 0.5)",
    marginBottom: "1rem",
  },
  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,
    background: "rgba(255, 255, 255, 0.01)",
  },
  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",
  },
  appointmentNote: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    fontSize: "0.875rem",
    color: "rgba(255, 255, 255, 0.5)",
    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",
  },
  emptyStateLink: {
    color: "#a78bfa",
    textDecoration: "none",
  },
};

export default function AppointmentsPage() {
  const { user, isLoading, isAuthorized } = useRequireAuth({
    requiredPermission: Permission.VIEW_OWN_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 fetchAppointments = useCallback(async () => {
    try {
      const data = await api.get<AppointmentResponse[]>("/api/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/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 upcomingAppointments = appointments.filter(
    (apt) => apt.status === "booked" && new Date(apt.slot_start) > new Date()
  );
  const pastOrCancelledAppointments = appointments.filter(
    (apt) => apt.status !== "booked" || new Date(apt.slot_start) <= new Date()
  );

  return (
    <main style={styles.main}>
      <Header currentPage="appointments" />
      <div style={styles.content}>
        <h1 style={styles.pageTitle}>My Appointments</h1>
        <p style={styles.pageSubtitle}>
          View and manage your booked appointments
        </p>

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

        {isLoadingAppointments ? (
          <div style={styles.emptyState}>Loading appointments...</div>
        ) : appointments.length === 0 ? (
          <div style={styles.emptyState}>
            <p>You don&apos;t have any appointments yet.</p>
            <a href="/booking" style={styles.emptyStateLink}>Book an appointment</a>
          </div>
        ) : (
          <>
            {/* Upcoming Appointments */}
            {upcomingAppointments.length > 0 && (
              <div style={styles.section}>
                <h2 style={styles.sectionTitle}>
                  Upcoming ({upcomingAppointments.length})
                </h2>
                <div style={styles.appointmentList}>
                  {upcomingAppointments.map((apt) => {
                    const status = getStatusDisplay(apt.status);
                    return (
                      <div key={apt.id} style={styles.appointmentCard}>
                        <div style={styles.appointmentHeader}>
                          <div>
                            <div style={styles.appointmentTime}>
                              {formatDateTime(apt.slot_start)}
                            </div>
                            {apt.note && (
                              <div style={styles.appointmentNote}>
                                {apt.note}
                              </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>
            )}

            {/* Past/Cancelled Appointments */}
            {pastOrCancelledAppointments.length > 0 && (
              <div style={styles.section}>
                <h2 style={styles.sectionTitleMuted}>
                  Past & Cancelled ({pastOrCancelledAppointments.length})
                </h2>
                <div style={styles.appointmentList}>
                  {pastOrCancelledAppointments.map((apt) => {
                    const status = getStatusDisplay(apt.status);
                    return (
                      <div key={apt.id} style={{...styles.appointmentCard, ...styles.appointmentCardPast}}>
                        <div style={styles.appointmentTime}>
                          {formatDateTime(apt.slot_start)}
                        </div>
                        {apt.note && (
                          <div style={styles.appointmentNote}>
                            {apt.note}
                          </div>
                        )}
                        <span style={{
                          ...styles.statusBadge,
                          background: status.bgColor,
                          color: status.textColor,
                        }}>
                          {status.text}
                        </span>
                      </div>
                    );
                  })}
                </div>
              </div>
            )}
          </>
        )}
      </div>
    </main>
  );
}

