"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";
import {
  layoutStyles,
  typographyStyles,
  bannerStyles,
  badgeStyles,
  buttonStyles,
} from "../styles/shared";

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

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) {
      setError(err instanceof Error ? err.message : "Failed to cancel appointment");
    } finally {
      setCancellingId(null);
    }
  };

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

        {error && <div style={bannerStyles.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, true);
                    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={{
                                ...badgeStyles.badge,
                                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={buttonStyles.secondaryButton}
                                  >
                                    No
                                  </button>
                                </>
                              ) : (
                                <button
                                  onClick={() => setConfirmCancelId(apt.id)}
                                  style={buttonStyles.secondaryButton}
                                >
                                  Cancel
                                </button>
                              )}
                            </div>
                          )}
                        </div>
                      </div>
                    );
                  })}
                </div>
              </div>
            )}

            {/* Past/Cancelled Appointments */}
            {pastOrCancelledAppointments.length > 0 && (
              <div style={styles.section}>
                <h2 style={typographyStyles.sectionTitleMuted}>
                  Past & Cancelled ({pastOrCancelledAppointments.length})
                </h2>
                <div style={styles.appointmentList}>
                  {pastOrCancelledAppointments.map((apt) => {
                    const status = getStatusDisplay(apt.status, true);
                    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={{
                            ...badgeStyles.badge,
                            background: status.bgColor,
                            color: status.textColor,
                          }}
                        >
                          {status.text}
                        </span>
                      </div>
                    );
                  })}
                </div>
              </div>
            )}
          </>
        )}
      </div>
    </main>
  );
}

// Page-specific styles
const styles: Record<string, React.CSSProperties> = {
  content: {
    flex: 1,
    padding: "2rem",
    maxWidth: "800px",
    margin: "0 auto",
    width: "100%",
  },
  section: {
    marginBottom: "2rem",
  },
  sectionTitle: {
    fontFamily: "'DM Sans', system-ui, sans-serif",
    fontSize: "1.1rem",
    fontWeight: 500,
    color: "#fff",
    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",
  },
  buttonGroup: {
    display: "flex",
    gap: "0.5rem",
  },
  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",
  },
};