// file: kb_app_demo/frontend/ts/splash.ts
// version: 4

//! Splash-screen event handling for the Tauri startup window.

import { listen } from "@tauri-apps/api/event";
import type { SplashOrder } from "./bindings/kb_app_demo/splash/SplashOrder";
import { frontendError, frontendDebug, installFrontendConsoleBridge } from "./frontend_log";


const splashTarget = "kb_app_demo.frontend.splash";
const defaultFadeDurationMs = 3000;
let activeOpacityFrame: number | null = null;

function normalizeDurationMs(value: number | null | undefined): number {
    if (typeof value !== "number") {
        return defaultFadeDurationMs;
    }
    if (!Number.isFinite(value) || value <= 0) {
        return defaultFadeDurationMs;
    }
    return value;
}

function easeInOut(progress: number): number {
    if (progress < 0.5) {
        return 2 * progress * progress;
    }
    return 1 - Math.pow(-2 * progress + 2, 2) / 2;
}

async function animateOpacity(element: HTMLElement, fromOpacity: number, toOpacity: number, durationMs: number): Promise<void> {
    frontendDebug(splashTarget, `Animating from ${fromOpacity} to ${toOpacity} over ${durationMs}ms`);
    if (activeOpacityFrame !== null) {
        cancelAnimationFrame(activeOpacityFrame);
        activeOpacityFrame = null;
    }
    element.style.opacity = fromOpacity.toString();
    element.style.willChange = "opacity";
    await new Promise<void>(resolve => requestAnimationFrame(() => resolve()));
    await new Promise<void>(resolve => {
        const startedAt = performance.now();
        const opacityDelta = toOpacity - fromOpacity;
        const updateOpacity = (currentTime: number): void => {
            const elapsedMs = currentTime - startedAt;
            const rawProgress = Math.min(elapsedMs / durationMs, 1);
            const easedProgress = easeInOut(rawProgress);
            const nextOpacity = fromOpacity + opacityDelta * easedProgress;
            element.style.opacity = nextOpacity.toString();
            if (rawProgress >= 1) {
                element.style.opacity = toOpacity.toString();
                element.style.willChange = "auto";
                activeOpacityFrame = null;
                resolve();
                return;
            }
            activeOpacityFrame = requestAnimationFrame(updateOpacity);
        };
        activeOpacityFrame = requestAnimationFrame(updateOpacity);
    });
}

function addLogMessage(message: string): void {
    const debugInfo = document.getElementById("debug-info");
    if (!debugInfo) {
        return;
    }
    const time = new Date().toLocaleTimeString();
    debugInfo.innerHTML += `${time}: ${message}<br>`;
    frontendDebug(splashTarget, `addLogMessage: ${message}`);
}

function addMessage(message: string, status: string): void {
    const messagesContainer = document.getElementById("messages-container");
    if (!messagesContainer) {
        return;
    }
    const messageElement = document.createElement("div");
    messageElement.className = `splash-message ${status}`;
    messageElement.textContent = message;
    messagesContainer.appendChild(messageElement);
    messagesContainer.scrollTop = messagesContainer.scrollHeight;
    frontendDebug(splashTarget, `addMessage: ${message} - ${status}`);
}

async function handleSplashOrder(order: SplashOrder): Promise<void> {
    const durationMs = normalizeDurationMs(order.duration_ms);
    const container = document.getElementById("splash-container");
    if (order.order === "fadein" && container) {
        frontendDebug(splashTarget, `fadein`);
        await animateOpacity(container, 0, 1, durationMs);
        return;
    }
    if (order.order === "fadeout" && container) {
        frontendDebug(splashTarget, `fadeout`);
        await animateOpacity(container, 1, 0, durationMs);
        return;
    }
    if (order.order === "add_msg" && order.msg && order.status) {
        addMessage(order.msg, order.status);
        return;
    }
    if (order.order === "add_log" && order.msg) {
        addLogMessage(order.msg);
        return;
    }
    frontendError(splashTarget, `unknown splash order: ${order.order}`);
}

function initializeSplashDom(): void {
    const container = document.getElementById("splash-container");
    if (container) {
        container.style.opacity = "0";
        container.style.willChange = "opacity";
    }
    installFrontendConsoleBridge(splashTarget);
}

async function initializeSplashListeners(): Promise<void> {
    await listen<SplashOrder>("splash", event => {
        void handleSplashOrder(event.payload);
    });
}

document.addEventListener("DOMContentLoaded", () => {
    initializeSplashDom();
    void initializeSplashListeners();
    frontendDebug(splashTarget, "splash window loaded");
});