import {Express, Router} from "express";
import path from "path";
import config from "config";
import ApplicationComponent from "../ApplicationComponent";
import {logger} from "../Logger";
import "svelte/register";
import ViewEngine from "../frontend/ViewEngine";
import {readdirRecursively} from "../Utils";
import FileCache from "../utils/FileCache";

export default class FrontendToolsComponent extends ApplicationComponent {
    private readonly publicAssetsCache: FileCache = new FileCache();

    public constructor(
        private readonly viewEngine: ViewEngine,
    ) {
        super();
    }

    public async start(app: Express): Promise<void> {
        // Cache public assets
        if (config.get<boolean>('view.enable_asset_cache')) {
            logger.info('Caching assets from', this.viewEngine.getPublicDir(), '...');
            await readdirRecursively(
                this.viewEngine.getPublicDir(),
                async file => await this.publicAssetsCache.load(file),
            );
        } else {
            logger.info('Asset cache disabled.');
        }

        // Pre-compile and watch in dev mode
        if (config.get<boolean>('view.dev')) {
            await this.viewEngine.preCompileAll();
            await this.viewEngine.watch();
        }

        // Setup express view engine
        app.engine(this.viewEngine.getExtension(), (path, options, callback) => {
            this.viewEngine.render(path, options as Record<string, unknown>, callback)
                .catch(err => callback(err));
        });
        app.set('views', this.viewEngine.getViewPaths());
        app.set('view engine', 'svelte');
    }

    public async stop(): Promise<void> {
        await this.viewEngine.end?.();
    }

    public async handle(router: Router): Promise<void> {
        router.use((req, res, next) => {
            res.locals.inlineAsset = (urlPath: string) => {
                return this.publicAssetsCache.getOrFail(path.join(this.viewEngine.getPublicDir(), urlPath));
            };

            next();
        });
    }
}