"use client";

import { FormEvent, useState } from "react";
import {
  Branch,
  Service,
  Tenant,
  Ticket,
  createTicket,
  getBranchServices,
  getBranches,
  getTenant,
} from "@/lib/api";
import { getDeviceToken } from "@/lib/device";

type Step = "tenant" | "branch" | "service" | "ticket";

export default function CustomerTicketFlow() {
  const [step, setStep] = useState<Step>("tenant");
  const [tenantCode, setTenantCode] = useState("DFLT");
  const [tenant, setTenant] = useState<Tenant | null>(null);
  const [branches, setBranches] = useState<Branch[]>([]);
  const [services, setServices] = useState<Service[]>([]);
  const [selectedBranch, setSelectedBranch] = useState<Branch | null>(null);
  const [ticket, setTicket] = useState<Ticket | null>(null);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);

  async function handleTenantSubmit(event: FormEvent<HTMLFormElement>) {
    event.preventDefault();
    const code = tenantCode.trim().toUpperCase();
    if (!code) {
      setError("Enter a company code.");
      return;
    }

    setLoading(true);
    setError(null);

    try {
      const [tenantData, branchData] = await Promise.all([
        getTenant(code),
        getBranches(code),
      ]);
      setTenant(tenantData);
      setBranches(branchData);
      setTenantCode(code);
      setStep("branch");
    } catch {
      setError("Could not find that company. Check the code and try again.");
    } finally {
      setLoading(false);
    }
  }

  async function handleSelectBranch(branch: Branch) {
    if (!tenant) return;

    setLoading(true);
    setError(null);
    setSelectedBranch(branch);

    try {
      const branchServices = await getBranchServices(tenant.code, branch.id);
      setServices(branchServices);
      setStep("service");
    } catch {
      setError("Could not load services for this branch.");
    } finally {
      setLoading(false);
    }
  }

  async function handleSelectService(service: Service) {
    if (!selectedBranch) return;

    setLoading(true);
    setError(null);

    try {
      const response = await createTicket({
        branchId: selectedBranch.id,
        serviceId: service.id,
        deviceToken: getDeviceToken(),
      });
      setTicket(response.ticket);
      setStep("ticket");
    } catch {
      setError(
        "Could not get a ticket number. Make sure this branch has services assigned."
      );
    } finally {
      setLoading(false);
    }
  }

  function resetFlow() {
    setStep(tenant ? "branch" : "tenant");
    setSelectedBranch(null);
    setServices([]);
    setTicket(null);
    setError(null);
  }

  function startOver() {
    setStep("tenant");
    setTenant(null);
    setBranches([]);
    setSelectedBranch(null);
    setServices([]);
    setTicket(null);
    setError(null);
  }

  return (
    <main className="mx-auto flex min-h-full w-full max-w-xl flex-col gap-8 px-6 py-12">
      <header className="space-y-2">
        <p className="text-sm tracking-wide text-zinc-500 uppercase">
          Queue Management
        </p>
        <h1 className="text-3xl font-semibold tracking-tight text-zinc-900">
          {tenant?.name ?? "Get a ticket"}
        </h1>
        <p className="text-base text-zinc-600">
          {tenant?.welcomeMessage ??
            "Enter your company code, pick a branch and service, then take a number."}
        </p>
      </header>

      {error ? (
        <p className="rounded-md border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-700">
          {error}
        </p>
      ) : null}

      {step === "tenant" ? (
        <form onSubmit={handleTenantSubmit} className="space-y-4">
          <label className="block space-y-2">
            <span className="text-sm font-medium text-zinc-700">
              Company code
            </span>
            <input
              value={tenantCode}
              onChange={(event) => setTenantCode(event.target.value)}
              className="w-full rounded-md border border-zinc-300 bg-white px-3 py-2 text-zinc-900 outline-none focus:border-zinc-900"
              placeholder="e.g. DFLT"
              autoComplete="off"
              disabled={loading}
            />
          </label>
          <button
            type="submit"
            disabled={loading}
            className="w-full rounded-md bg-zinc-900 px-4 py-3 text-sm font-medium text-white disabled:opacity-60"
          >
            {loading ? "Loading…" : "Continue"}
          </button>
        </form>
      ) : null}

      {step === "branch" ? (
        <section className="space-y-4">
          <div className="flex items-center justify-between gap-3">
            <h2 className="text-lg font-medium text-zinc-900">Choose a branch</h2>
            <button
              type="button"
              onClick={startOver}
              className="text-sm text-zinc-500 underline-offset-2 hover:underline"
            >
              Change company
            </button>
          </div>
          {branches.length === 0 ? (
            <p className="text-sm text-zinc-600">No branches available.</p>
          ) : (
            <ul className="space-y-2">
              {branches.map((branch) => (
                <li key={branch.id}>
                  <button
                    type="button"
                    disabled={loading}
                    onClick={() => handleSelectBranch(branch)}
                    className="flex w-full items-center justify-between rounded-md border border-zinc-200 bg-white px-4 py-3 text-left text-zinc-900 transition hover:border-zinc-400 disabled:opacity-60"
                  >
                    <span>{branch.name}</span>
                    <span className="text-zinc-400">→</span>
                  </button>
                </li>
              ))}
            </ul>
          )}
        </section>
      ) : null}

      {step === "service" && selectedBranch ? (
        <section className="space-y-4">
          <div className="flex items-center justify-between gap-3">
            <h2 className="text-lg font-medium text-zinc-900">
              Service at {selectedBranch.name}
            </h2>
            <button
              type="button"
              onClick={() => {
                setStep("branch");
                setSelectedBranch(null);
                setServices([]);
                setError(null);
              }}
              className="text-sm text-zinc-500 underline-offset-2 hover:underline"
            >
              Back
            </button>
          </div>
          {services.length === 0 ? (
            <p className="text-sm text-zinc-600">
              No services are assigned to this branch yet. Link services via a
              branch group in the admin app, then try again.
            </p>
          ) : (
            <ul className="space-y-2">
              {services.map((service) => (
                <li key={service.id}>
                  <button
                    type="button"
                    disabled={loading}
                    onClick={() => handleSelectService(service)}
                    className="flex w-full items-center justify-between rounded-md border border-zinc-200 bg-white px-4 py-3 text-left text-zinc-900 transition hover:border-zinc-400 disabled:opacity-60"
                  >
                    <span>{service.name}</span>
                    <span className="text-sm text-zinc-500">
                      {loading ? "…" : "Get number"}
                    </span>
                  </button>
                </li>
              ))}
            </ul>
          )}
        </section>
      ) : null}

      {step === "ticket" && ticket ? (
        <section className="space-y-6 rounded-md border border-zinc-200 bg-white px-6 py-8 text-center">
          <p className="text-sm tracking-wide text-zinc-500 uppercase">
            Your ticket number
          </p>
          <p className="text-6xl font-semibold tracking-tight text-zinc-900">
            {ticket.number}
          </p>
          <div className="space-y-1 text-sm text-zinc-600">
            <p>{ticket.service.name}</p>
            <p>{ticket.branch.name}</p>
          </div>
          <button
            type="button"
            onClick={resetFlow}
            className="w-full rounded-md bg-zinc-900 px-4 py-3 text-sm font-medium text-white"
          >
            Get another ticket
          </button>
        </section>
      ) : null}
    </main>
  );
}