/**
 * Demo mode — for filming two robots "talking".
 *
 * The screen shows ONLY the live detection (a big decoded readout + scope +
 * a running conversation) and the alphabet chart below. There is no compose
 * box and nothing reveals a message before it is heard — the magic is that the
 * robots appear to converse on their own.
 *
 * Hidden in Demo setup (the gear) are "if you hear X, answer Y" rules. When
 * this robot's mic decodes a finished message that matches a rule, it waits a
 * beat and taps out the reply on its own antennas. A self-echo guard
 * (ctx.selfEchoActive) stops a robot from replying to its own taps.
 *
 * Scripted demo: robot A is given "U OK?" (Send from setup) → robot B hears it
 * and replies "Y". Then you finger-tap "SOS" near both → both reply "WTF".
 */
import { el, clear } from "./dom.js";
import { decodeOnsets } from "../lib/wire.js";
import { matchRule } from "../lib/rules.js";
import { Scope } from "../lib/viz.js";
import { createLearn } from "./learn.js";

export function createDemo(ctx) {
    const root = el("section.view#view-demo");

    const canvas = el("canvas.scope.scope-big");
    const scope = new Scope(canvas);
    const bigText = el("div.demo-decoded", {}, "…");
    const bigMorse = el("div.decoded-morse muted");
    const statusEl = el("div.demo-status muted", {}, "Listening…");
    const transcript = el("div.transcript");
    const clearBtn = el("button.btn.ghost.small", { onclick: clearAll }, "Clear");

    let mic = null;
    let onsets = [];
    let lastOnsetMs = 0;
    let idleTimer = null;

    const timing = () => ctx.timing();

    async function start() {
        if (mic) return;
        try {
            mic = ctx.makeMic({
                onOnset: (t) => onOnset(t),
                onLevel: (lvl) => scope.pushLevel(lvl),
            });
            await mic.start();
            scope.start();
            idleTimer = setInterval(checkIdle, 250);
            statusEl.textContent = "Listening…";
        } catch {
            mic = null;
            statusEl.textContent = "Tap anywhere to enable the microphone.";
            root.addEventListener("click", start, { once: true });
        }
    }

    async function stop() {
        if (idleTimer) { clearInterval(idleTimer); idleTimer = null; }
        scope.stop();
        if (mic) { await mic.stop(); mic = null; }
    }

    function onOnset(t) {
        onsets.push(t);
        lastOnsetMs = t;
        scope.markOnset();
        render();
    }

    function render() {
        const { morse, text } = decodeOnsets(onsets, timing());
        bigText.textContent = text || "…";
        bigMorse.textContent = morse;
    }

    function checkIdle() {
        if (!mic || onsets.length === 0) return;
        if (mic.now() - lastOnsetMs > timing().wordGapMs * 2.5) finalize();
    }

    function finalize() {
        if (onsets.length === 0) return;
        const { morse, text } = decodeOnsets(onsets, timing());
        onsets = [];
        render();
        if (!text) return;
        transcript.prepend(el("div.line", {}, [
            el("span.line-text", {}, text),
            el("span.line-morse muted", {}, morse),
        ]));
        maybeReply(text);
    }

    function maybeReply(text) {
        // Don't react to our own taps / their echo tail.
        if (ctx.selfEchoActive?.()) return;
        const rule = matchRule(text, ctx.state.demo.rules);
        if (!rule) return;
        statusEl.textContent = `Heard “${text}” → replying “${rule.output}”`;
        // A short beat so it feels like an answer, not an interruption.
        setTimeout(() => {
            ctx.transmit(rule.output, { via: ctx.reachy ? "robot" : "device" })
                .then(() => { statusEl.textContent = "Listening…"; })
                .catch(() => { statusEl.textContent = "Listening…"; });
        }, 500);
    }

    function clearAll() {
        onsets = [];
        clear(transcript);
        render();
    }

    const learn = createLearn(ctx);
    render();
    root.append(
        el("h2", {}, "Demo"),
        canvas,
        bigText,
        bigMorse,
        el("div.row.between", {}, [statusEl, clearBtn]),
        el("label.field-label", {}, "Conversation"),
        transcript,
        el("hr.divider"),
        learn.node,
    );

    return {
        node: root,
        onShow: () => { start(); learn.onShow?.(); },
        onHide: stop,
    };
}