// PairDevice — the pairing surface, opened from the Settings → Sync card.
//
// Settings owns the sync "hub" (paired-device list, revoke, sync-now); this
// view is purely the pairing flow, returning to Settings (`onBack`) when done
// or cancelled: the user types the pairing code their phone displays, the
// browser dials out to the address inside it, and the NK handshake + SAS run
// from there (enter code → connecting → SAS → paired).
//
// There is one path because there can only be one: the browser cannot listen,
// so it is always the side that dials.
//
// The pairing itself runs in the background (code-pairing.ts) and reaches
// this view via the PAIR_WITH_CODE / CODE_PAIR_* messages.

import {
  Component,
  Show,
  createEffect,
  createSignal,
  onCleanup,
  onMount,
} from "solid-js";
import { sendMessage } from "../../shared/bridge";
import type { PairedDevice } from "../../shared/sync-types";
import { DesktopBird, MobileBird } from "../components/PairingBirds";
import { formatPairingCode, parsePairingCode } from "../../shared/pairing-code";

export interface PairDeviceViewProps {
  isPro: boolean;
  onBack(): void;
  onLearnPro(): void;
  /**
   * Set when the user taps the pairing option on the Settings sync card. With
   * no method there is nothing to do here, so the view returns to Settings.
   * Read once on mount.
   */
  initialPair?: "code" | null;
  /** Called after a peer's Pro license is activated, so the app re-reads Pro status. */
  onProChanged?: () => void;
}

// Code-pairing phases. Mirrors the background CodePairingError union.
type PairPhase = "enter" | "connecting" | "sas" | "paired" | "error";
type CodePairingError =
  | "invalid_code"
  | "no_host_found"
  | "handshake_failed"
  | "sas_mismatch"
  | "vault_locked";

const PAIRED_DISMISS_MS = 2_000;

function errorCopy(error: CodePairingError | "unknown"): { headline: string; sub: string } {
  switch (error) {
    case "invalid_code":
      // Ground truth §0.3: wrong vs expired is indistinguishable on the wire —
      // the listener closes the socket either way, with no error frame.
      return {
        headline: "Code not found or expired",
        sub: "Check the code on your phone and try again. Codes expire, so grab a fresh one if it's been a while.",
      };
    case "no_host_found":
      return {
        headline: "Couldn't reach your phone",
        sub: "Make sure both devices are on the same Wi-Fi and the pairing screen is still open on your phone.",
      };
    case "sas_mismatch":
      return {
        headline: "Codes don't match",
        sub: "For your safety, pairing was stopped. Start over and compare the two codes carefully.",
      };
    case "vault_locked":
      return {
        headline: "Unlock Peach first",
        sub: "Your vault needs to be unlocked before you can pair a device.",
      };
    case "handshake_failed":
    default:
      return {
        headline: "Pairing failed",
        sub: "Something went wrong while connecting. Please try again.",
      };
  }
}

export const PairDeviceView: Component<PairDeviceViewProps> = (props) => {
  // The whole NK pairing runs in the background; this view drives the UI and
  // the out-of-band SAS confirmation round-trip via the PAIR_WITH_CODE /
  // CODE_PAIR_* messages. The SAS gate is what authenticates the peer
  // (audit HIGH — pairing initiator authentication), not the pairing token.
  const [phase, setPhase] = createSignal<PairPhase>("enter");
  const [code, setCode] = createSignal("");
  const [sas, setSas] = createSignal<string | null>(null);
  const [errorKind, setErrorKind] = createSignal<CodePairingError | "unknown">("unknown");
  const [pairedDevice, setPairedDevice] = createSignal<PairedDevice | undefined>(undefined);
  const [busy, setBusy] = createSignal(false);

  // Two accepted forms: the pairing code a phone displays, and the legacy
  // 6-digit desktop-helper code. `parsePairingCode` returning null just means
  // "not that form", so the check falls through to the digit shape.
  const codeReady = () =>
    parsePairingCode(code()) !== null || /^\d{6}$/.test(code());

  function startFlow(): void {
    setCode("");
    setSas(null);
    setErrorKind("unknown");
    setPairedDevice(undefined);
    setBusy(false);
    setPhase("enter");
  }

  function onCodeInput(value: string): void {
    const cleaned = value.toUpperCase().replace(/[^0-9A-Z]/g, "").slice(0, 32);
    // Group once the input outgrows a 6-digit helper code, so a pairing code
    // regains its dashes as it is typed without mangling the short form. Length
    // rather than character class, so an all-digit pairing code still groups.
    setCode(cleaned.length > 6 ? formatPairingCode(cleaned) : cleaned);
  }

  async function handleConnect(): Promise<void> {
    if (!codeReady() || busy()) return;
    setBusy(true);
    setPhase("connecting");
    try {
      const res = (await sendMessage({
        type: "PAIR_WITH_CODE",
        payload: { code: code() },
      })) as { ok: boolean; error?: string };
      // A synchronous start failure (e.g. vault_locked) returns here; the SAS
      // and the terminal result arrive later as pushes.
      if (!res.ok) {
        setErrorKind((res.error as CodePairingError) ?? "unknown");
        setPhase("error");
      }
    } catch {
      setErrorKind("unknown");
      setPhase("error");
    } finally {
      setBusy(false);
    }
  }

  async function respondConfirm(confirmed: boolean): Promise<void> {
    if (busy()) return;
    setBusy(true);
    // Optimistically move on; the terminal CODE_PAIR_RESULT push decides the
    // final phase (paired vs sas_mismatch error).
    if (confirmed) setPhase("connecting");
    else { setErrorKind("sas_mismatch"); setPhase("error"); }
    try {
      await sendMessage({ type: "CODE_PAIR_CONFIRM", payload: { confirmed } });
    } finally {
      setBusy(false);
    }
  }

  // Auto-dismiss after the paired state settles — back to the Settings hub,
  // which reloads the paired-device list on mount.
  createEffect(() => {
    if (phase() !== "paired") return;
    const t = setTimeout(() => props.onBack(), PAIRED_DISMISS_MS);
    onCleanup(() => clearTimeout(t));
  });

  onMount(() => {
    // Opened straight into a pairing path from the Settings sync card. With no
    // method there's nothing to do here — return to Settings (the hub).
    if (props.initialPair === "code") startFlow();
    else props.onBack();

    // Pairing pushes from the background (bg → popup). The whole NK
    // pairing runs in the service worker; the SAS to confirm and the terminal
    // result arrive here as runtime messages.
    if (typeof chrome !== "undefined" && chrome.runtime?.onMessage) {
      const handler = (msg: { type?: string; payload?: unknown }) => {
        if (msg?.type === "CODE_PAIR_SAS") {
          const p = msg.payload as { sas?: string } | undefined;
          if (typeof p?.sas === "string") { setSas(p.sas); setPhase("sas"); }
        } else if (msg?.type === "CODE_PAIR_RESULT") {
          const p = msg.payload as
            | { status: "complete"; device: PairedDevice }
            | { status: "error"; error: CodePairingError }
            | undefined;
          if (p?.status === "complete") { setPairedDevice(p.device); setPhase("paired"); }
          else if (p?.status === "error") { setErrorKind(p.error); setPhase("error"); }
        }
      };
      chrome.runtime.onMessage.addListener(handler);
      onCleanup(() => chrome.runtime.onMessage.removeListener(handler));
    }
    // If the popup closes while the user is on the SAS screen, resolve the
    // pending background confirm as false so the service worker clears
    // inFlight and future pairing attempts aren't stuck with "pairing_in_progress".
    onCleanup(() => {
      if (phase() === "sas") {
        void sendMessage({ type: "CODE_PAIR_CONFIRM", payload: { confirmed: false } });
      }
    });
  });

  // --- Sub-views --------------------------------------------------

  const backArrow = (
    <svg viewBox="0 0 16 16" width="14" height="14" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round">
      <path d="M10 3 L5 8 L10 13" />
    </svg>
  );

  // The bird stage — always animating — shared by every pairing screen.
  const birdStage = (active: boolean) => (
    <div class={`peach-pair-stage ${active ? "act-handshake" : "act-listening"}`} aria-hidden="true">
      <div class="peach-pair-bird-slot peach-pair-bird-slot-desktop">
        <DesktopBird pose="chirping" />
      </div>
      <div class="peach-pair-bird-slot peach-pair-bird-slot-mobile">
        <MobileBird pose="attentive" />
      </div>
    </div>
  );

  function liveText(): string {
    switch (phase()) {
      case "enter": return "Enter the pairing code from your phone";
      case "connecting": return "Connecting to your phone";
      case "sas": return "Confirm the code matches on your phone";
      case "paired": return "Paired";
      case "error": return errorCopy(errorKind()).headline;
    }
  }

  // Code pairing — birds animate on every screen below.
  const pairingScreen = () => (
    <div class="peach-pair-pair peach-desktop-pair" data-phase={phase()} role="dialog" aria-label="Pair a device with a code">
      <header class="peach-pair-head">
        <button class="peach-pair-back" aria-label="Back" onClick={() => props.onBack()}>{backArrow}</button>
        <div class="peach-pair-title">Enter a code</div>
        <div class="peach-pair-head-spacer" />
      </header>

      {birdStage(phase() !== "enter")}

      <Show when={phase() === "enter"}>
        <div class="peach-desktop-enter">
          <div class="peach-pair-headline">Enter the code from your phone</div>
          <div class="peach-pair-sub">
            Open Peach on your phone, tap “Pair a device”, and type the code it shows.
            Both devices need to be on the same Wi-Fi.
          </div>
          <label class="peach-label" for="pair-code">pairing code</label>
          <input
            id="pair-code"
            class="peach-underline-input peach-unlock-input peach-code-input"
            type="text"
            autocapitalize="characters"
            autocomplete="one-time-code"
            spellcheck={false}
            maxlength={32}
            placeholder="A74H-48J3-KI32-OEP4"
            aria-label="Pairing code"
            value={code()}
            ref={(el) => setTimeout(() => el.focus(), 80)}
            onInput={(e) => onCodeInput((e.target as HTMLInputElement).value)}
            onKeyDown={(e) => { if (e.key === "Enter") void handleConnect(); }}
          />
          <div class="peach-pair-action">
            <button class="peach-btn peach-btn-ghost" onClick={() => props.onBack()}>Cancel</button>
            <button
              class="peach-btn peach-btn-primary peach-desktop-connect"
              disabled={!codeReady() || busy()}
              onClick={() => void handleConnect()}
            >
              Connect
            </button>
          </div>
        </div>
      </Show>

      <Show when={phase() === "connecting"}>
        <div class="peach-desktop-searching">
          <div class="peach-pair-headline">Connecting…</div>
          <div class="peach-pair-sub">Reaching your phone over the local network.</div>
        </div>
      </Show>

      <Show when={phase() === "sas"}>
        <div class="peach-desktop-confirm" style="display:flex;flex-direction:column;align-items:center;gap:12px;padding:8px 18px 16px;text-align:center;">
          <div class="peach-pair-headline">Confirm this code matches on your phone:</div>
          <div
            class="peach-desktop-sas"
            style="font-size:30px;font-weight:700;letter-spacing:0.32em;font-family:'IBM Plex Mono',monospace;color:var(--peach-accent);padding:6px 0 2px;"
          >
            {sas()}
          </div>
          <div class="peach-pair-sub" style="max-width:240px;">
            Only continue if this 6-digit code is identical on both screens. This is
            what proves you're talking to your own device.
          </div>
          <div style="display:flex;flex-direction:column;gap:8px;width:100%;max-width:240px;">
            <button class="peach-btn peach-btn-primary" disabled={busy()} onClick={() => void respondConfirm(true)}>
              Confirm
            </button>
            <button class="peach-btn peach-btn-ghost" disabled={busy()} onClick={() => void respondConfirm(false)}>
              Cancel
            </button>
          </div>
        </div>
      </Show>

      <Show when={phase() === "paired"}>
        <div class="peach-desktop-paired">
          <div class="peach-pair-headline">Paired!</div>
          <div class="peach-pair-sub">
            {pairedDevice()?.deviceName ? `Connected to ${pairedDevice()!.deviceName}` : "Connected to your phone"}
          </div>
          <div class="peach-pair-action">
            <button class="peach-btn peach-btn-primary" onClick={() => props.onBack()}>Done</button>
          </div>
        </div>
      </Show>

      <Show when={phase() === "error"}>
        <div class="peach-desktop-error">
          <div class="peach-pair-headline">{errorCopy(errorKind()).headline}</div>
          <div class="peach-pair-sub">{errorCopy(errorKind()).sub}</div>
          <div class="peach-pair-action">
            <button class="peach-btn peach-btn-ghost" onClick={() => props.onBack()}>Cancel</button>
            <button class="peach-btn peach-btn-primary" onClick={() => startFlow()}>Try again</button>
          </div>
        </div>
      </Show>

      <div class="peach-sr-only" aria-live="polite">{liveText()}</div>
    </div>
  );

  // Sync is no longer Pro-gated: anyone may attempt to pair so a free device can
  // receive Pro from an already-Pro peer. The upsell lives on the Settings card.
  return pairingScreen();
};