import { call, os } from "@orpc/server";
import { z } from "zod";
import { randomUUID } from "crypto";
import { createKV } from "@/server/lib/create-kv";
import { createKV as createAvailabilityKV } from "@/server/lib/create-kv";
import { sendEmail, sendEmailWithAGB } from "@/server/lib/email";
import { renderBookingPendingHTML, renderBookingConfirmedHTML, renderBookingCancelledHTML } from "@/server/lib/email-templates";

// Helper function to convert date from yyyy-mm-dd to dd.mm.yyyy
function formatDateGerman(dateString: string): string {
  const [year, month, day] = dateString.split('-');
  return `${day}.${month}.${year}`;
}

const BookingSchema = z.object({
  id: z.string(),
  treatmentId: z.string(),
  customerName: z.string(),
  customerEmail: z.string(),
  customerPhone: z.string(),
  appointmentDate: z.string(), // ISO date string
  appointmentTime: z.string(), // HH:MM format
  status: z.enum(["pending", "confirmed", "cancelled", "completed"]),
  notes: z.string().optional(),
  createdAt: z.string(),
  slotId: z.string().optional(),
});

type Booking = z.output<typeof BookingSchema>;

const kv = createKV<Booking>("bookings");
type Availability = {
  id: string;
  date: string;
  time: string;
  durationMinutes: number;
  status: "free" | "reserved";
  reservedByBookingId?: string;
  createdAt: string;
};
const availabilityKV = createAvailabilityKV<Availability>("availability");

const create = os
  .input(BookingSchema.omit({ id: true, createdAt: true, status: true }))
  .handler(async ({ input }) => {
    // Prevent double booking: same customer email with pending/confirmed on same date
    const existing = await kv.getAllItems();
    const hasConflict = existing.some(b =>
      b.customerEmail.toLowerCase() === input.customerEmail.toLowerCase() &&
      b.appointmentDate === input.appointmentDate &&
      (b.status === "pending" || b.status === "confirmed")
    );
    if (hasConflict) {
      throw new Error("Du hast bereits eine Buchung für dieses Datum. Bitte wähle einen anderen Tag oder storniere zuerst.");
    }
    const id = randomUUID();
    const booking = { 
      id, 
      ...input, 
      status: "pending" as const,
      createdAt: new Date().toISOString()
    };
    // If a slotId is provided, tentatively reserve the slot (mark reserved but pending)
    if (booking.slotId) {
      const slot = await availabilityKV.getItem(booking.slotId);
      if (!slot) throw new Error("Availability slot not found");
      if (slot.status !== "free") throw new Error("Slot not available");
      const updatedSlot: Availability = {
        ...slot,
        status: "reserved",
        reservedByBookingId: id,
      };
      await availabilityKV.setItem(slot.id, updatedSlot);
    }
    await kv.setItem(id, booking);

    // Notify customer: request received (pending)
    void (async () => {
      const formattedDate = formatDateGerman(input.appointmentDate);
      const html = await renderBookingPendingHTML({ name: input.customerName, date: input.appointmentDate, time: input.appointmentTime });
      await sendEmail({
      to: input.customerEmail,
      subject: "Deine Terminanfrage ist eingegangen",
      text: `Hallo ${input.customerName},\n\nwir haben deine Anfrage für ${formattedDate} um ${input.appointmentTime} erhalten. Wir bestätigen deinen Termin in Kürze.\n\nLiebe Grüße\nStargirlnails Kiel`,
        html,
      cc: process.env.ADMIN_EMAIL ? [process.env.ADMIN_EMAIL] : undefined,
      }).catch(() => {});
    })();
    return booking;
  });

// Owner check reuse (simple inline version)
type Session = { id: string; userId: string; expiresAt: string; createdAt: string };
type User = { id: string; username: string; email: string; passwordHash: string; role: "customer" | "owner"; createdAt: string };
const sessionsKV = createAvailabilityKV<Session>("sessions");
const usersKV = createAvailabilityKV<User>("users");
async function assertOwner(sessionId: string): Promise<void> {
  const session = await sessionsKV.getItem(sessionId);
  if (!session) throw new Error("Invalid session");
  if (new Date(session.expiresAt) < new Date()) throw new Error("Session expired");
  const user = await usersKV.getItem(session.userId);
  if (!user || user.role !== "owner") throw new Error("Forbidden");
}

const updateStatus = os
  .input(z.object({
    sessionId: z.string(),
    id: z.string(),
    status: z.enum(["pending", "confirmed", "cancelled", "completed"])
  }))
  .handler(async ({ input }) => {
    await assertOwner(input.sessionId);
    const booking = await kv.getItem(input.id);
    if (!booking) throw new Error("Booking not found");
    
    const previousStatus = booking.status;
    const updatedBooking = { ...booking, status: input.status };
    await kv.setItem(input.id, updatedBooking);

    // Manage availability slot state transitions
    if (booking.slotId) {
      const slot = await availabilityKV.getItem(booking.slotId);
      if (slot) {
        if (input.status === "cancelled") {
          // Free the slot again
          await availabilityKV.setItem(slot.id, {
            ...slot,
            status: "free",
            reservedByBookingId: undefined,
          });
        } else if (input.status === "pending") {
          // keep reserved as pending
          if (slot.status !== "reserved") {
            await availabilityKV.setItem(slot.id, {
              ...slot,
              status: "reserved",
              reservedByBookingId: booking.id,
            });
          }
        } else if (input.status === "confirmed" || input.status === "completed") {
          // keep reserved; optionally noop
          if (slot.status !== "reserved" || slot.reservedByBookingId !== booking.id) {
            await availabilityKV.setItem(slot.id, {
              ...slot,
              status: "reserved",
              reservedByBookingId: booking.id,
            });
          }
        }
      }
    }
    // Email notifications on status changes
    try {
      if (input.status === "confirmed") {
        const formattedDate = formatDateGerman(booking.appointmentDate);
        const html = await renderBookingConfirmedHTML({ name: booking.customerName, date: booking.appointmentDate, time: booking.appointmentTime });
        await sendEmailWithAGB({
          to: booking.customerEmail,
          subject: "Dein Termin wurde bestätigt - AGB im Anhang",
          text: `Hallo ${booking.customerName},\n\nwir haben deinen Termin am ${formattedDate} um ${booking.appointmentTime} bestätigt.\n\nWichtiger Hinweis: Die Allgemeinen Geschäftsbedingungen (AGB) findest du im Anhang dieser E-Mail. Bitte lies sie vor deinem Termin durch.\n\nBis bald!\nStargirlnails Kiel`,
          html,
          cc: process.env.ADMIN_EMAIL ? [process.env.ADMIN_EMAIL] : undefined,
        });
      } else if (input.status === "cancelled") {
        const formattedDate = formatDateGerman(booking.appointmentDate);
        const html = await renderBookingCancelledHTML({ name: booking.customerName, date: booking.appointmentDate, time: booking.appointmentTime });
        await sendEmail({
          to: booking.customerEmail,
          subject: "Dein Termin wurde abgesagt",
          text: `Hallo ${booking.customerName},\n\nleider wurde dein Termin am ${formattedDate} um ${booking.appointmentTime} abgesagt. Bitte buche einen neuen Termin.\n\nLiebe Grüße\nStargirlnails Kiel`,
          html,
          cc: process.env.ADMIN_EMAIL ? [process.env.ADMIN_EMAIL] : undefined,
        });
      }
    } catch (e) {
      console.error("Email send failed:", e);
    }
    return updatedBooking;
  });

const remove = os.input(z.string()).handler(async ({ input }) => {
  await kv.removeItem(input);
});

const list = os.handler(async () => {
  return kv.getAllItems();
});

const get = os.input(z.string()).handler(async ({ input }) => {
  return kv.getItem(input);
});

const getByDate = os
  .input(z.string()) // YYYY-MM-DD format
  .handler(async ({ input }) => {
    const allBookings = await kv.getAllItems();
    return allBookings.filter(booking => booking.appointmentDate === input);
  });

const live = {
  list: os.handler(async function* ({ signal }) {
    yield call(list, {}, { signal });
    for await (const _ of kv.subscribe()) {
      yield call(list, {}, { signal });
    }
  }),
  
  byDate: os
    .input(z.string())
    .handler(async function* ({ input, signal }) {
      yield call(getByDate, input, { signal });
      for await (const _ of kv.subscribe()) {
        yield call(getByDate, input, { signal });
      }
    }),
};

export const router = {
  create,
  updateStatus,
  remove,
  list,
  get,
  getByDate,
  live,
};