/**
 * Web pairing screen — ticket #13, lot F2.
 *
 * Shown by {@link WebApp} when the client is not paired. The user types the code
 * the server printed at first launch; on submit we `POST /api/pair {code}` via
 * the {@link WebSession}. On success the server sets the HttpOnly session cookie
 * and we advance to the workspace; a wrong code shows a clear message.
 *
 * Transport-neutral at the component seam: it talks to the injected
 * {@link WebSession}, never to `@tauri-apps/api` (the CI guard `no-direct-invoke`
 * stays green). Pure web-only UI — desktop never mounts it.
 */

import { useState, type FormEvent } from "react";

import type { GatewayError } from "@/domain";
import { Button, Field, Input, Panel } from "@/shared";
import type { WebSession } from "@/adapters/http";

interface PairingScreenProps {
  /** The shared web session performing the `POST /api/pair` handshake. */
  session: WebSession;
  /** Called once pairing succeeds (cookie set) so the app can advance. */
  onPaired: () => void;
}

function describe(e: unknown): string {
  if (e && typeof e === "object" && "message" in e) {
    return String((e as GatewayError).message);
  }
  return String(e);
}

export function PairingScreen({ session, onPaired }: PairingScreenProps) {
  const [code, setCode] = useState("");
  const [error, setError] = useState<string | null>(null);
  const [busy, setBusy] = useState(false);

  async function submit(e: FormEvent): Promise<void> {
    e.preventDefault();
    const trimmed = code.trim();
    if (!trimmed || busy) return;
    setBusy(true);
    setError(null);
    try {
      await session.pair(trimmed);
      onPaired();
    } catch (err) {
      setError(describe(err));
    } finally {
      setBusy(false);
    }
  }

  return (
    <div className="flex h-full items-center justify-center overflow-y-auto bg-canvas p-4 sm:p-6">
      <Panel className="w-full max-w-sm">
        <form onSubmit={submit} className="flex flex-col gap-4">
          <div className="flex flex-col gap-1">
            <h1 className="text-lg font-semibold tracking-tight">Appairer cet appareil</h1>
            <p className="text-sm text-muted">
              Saisissez le code affiché par le serveur IdeA pour connecter ce
              navigateur.
            </p>
          </div>

          <Field label="Code d'appairage">
            {({ id, describedBy }) => (
              <Input
                id={id}
                aria-describedby={describedBy}
                value={code}
                onChange={(e) => setCode(e.target.value)}
                placeholder="p. ex. 4821-93"
                autoFocus
                autoComplete="one-time-code"
                // #69 — phones: summon the numeric-ish keypad for a pairing code
                // and keep the OS from "helpfully" capitalising/correcting it.
                inputMode="numeric"
                autoCapitalize="off"
                autoCorrect="off"
                spellCheck={false}
                disabled={busy}
                invalid={!!error}
              />
            )}
          </Field>

          {error && (
            <p role="alert" data-testid="pairing-error" className="text-sm text-danger">
              {error}
            </p>
          )}

          <Button type="submit" disabled={busy || code.trim().length === 0}>
            {busy ? "Appairage…" : "Appairer"}
          </Button>
        </form>
      </Panel>
    </div>
  );
}