import { dirname, resolve } from "node:path";
import { fileURLToPath } from "node:url";
import { defineConfig, type Plugin } from "vite";

const __dirname = dirname(fileURLToPath(import.meta.url));

/**
 * Vite plugin that inlines extracted CSS into the JS entry chunk.
 * Injects a <style> tag at runtime so the module is a single .js file.
 */
function inlineCssPlugin(): Plugin {
    return {
        name: "inline-css",
        apply: "build",
        enforce: "post",
        generateBundle(_, bundle) {
            let cssContent = "";
            const cssKeys: string[] = [];

            for (const [key, chunk] of Object.entries(bundle)) {
                if (key.endsWith(".css") && chunk.type === "asset" && typeof chunk.source === "string") {
                    cssContent += chunk.source;
                    cssKeys.push(key);
                }
            }

            // Remove CSS files from the bundle
            for (const key of cssKeys) {
                delete bundle[key];
            }

            // Inject CSS into the entry JS chunk
            if (cssContent) {
                for (const chunk of Object.values(bundle)) {
                    if (chunk.type === "chunk" && chunk.isEntry) {
                        const injection =
                            `(function(){` +
                            `var s=document.createElement("style");` +
                            `s.textContent=${JSON.stringify(cssContent)};` +
                            `document.head.appendChild(s)` +
                            `})();\n`;
                        chunk.code = injection + chunk.code;
                    }
                }
            }
        },
    };
}

export default defineConfig({
    build: {
        lib: {
            entry: resolve(__dirname, "src/index.ts"),
            formats: ["es"],
            fileName: "user-directory-module",
        },
        outDir: "dist",
        rollupOptions: {
            /* @element-hq/element-web-module-api is type-only at runtime;
               the module API object is passed via constructor, not imported. */
            external: ["@element-hq/element-web-module-api"],
        },
        cssCodeSplit: false,
    },
    resolve: {
        alias: {
            /* React is provided globally by Element Web (window.React).
               Alias to a shim so the bundle uses the host app's React. */
            "react": resolve(__dirname, "src/shims/react.ts"),
        },
    },
    plugins: [inlineCssPlugin()],
});