import rust from "@wasm-tool/rollup-plugin-rust";
import resolve from "@rollup/plugin-node-resolve";
import commonjs from "@rollup/plugin-commonjs";

// Flag that indicates if the build is meant for testing purposes.
const testing = process.env.MIDEN_WEB_TESTING === "true";

/**
 * Rollup configuration file for building a Cargo project and creating a WebAssembly (WASM) module.
 * The configuration sets up two build processes:
 * 1. Compiling Rust code into WASM using the @wasm-tool/rollup-plugin-rust plugin, with specific
 *    cargo arguments to enable WebAssembly features and set maximum memory limits. If the build is
 *    meant for testing, the WASM optimization level is set to 0 to improve build times, this is
 *    aimed at reducing the feedback loop during development.
 * 2. Resolving and bundling the generated WASM module along with the main JavaScript file
 *    (`index.js`) into the `dist` directory.
 *
 * The first configuration targets `wasm.js` to generate the WASM module, while the second
 * configuration targets `index.js` for the main entry point of the application.
 * Both configurations output ES module format files with source maps for easier debugging.
 */
export default [
  {
    input: {
      wasm: "./js/wasm.js",
    },
    output: {
      dir: `dist`,
      format: "es",
      sourcemap: true,
      assetFileNames: "assets/[name][extname]",
    },
    plugins: [
      rust({
        cargoArgs: [
          "--features",
          "testing",
          "--config",
          `build.rustflags=["-C", "target-feature=+atomics,+bulk-memory,+mutable-globals", "-C", "link-arg=--max-memory=4294967296"]`,
          "--no-default-features",
        ],

        experimental: {
          typescriptDeclarationDir: "dist/crates",
        },

        wasmOptArgs: testing ? ["-O0"] : null,
      }),
      resolve(),
      commonjs(),
    ],
  },
  {
    input: {
      index: "./js/index.js",
    },
    output: {
      dir: `dist`,
      format: "es",
      sourcemap: true,
    },
    plugins: [resolve(), commonjs()],
  },
];