import { plugin, $, type BunPlugin } from "bun";
import path from 'path';

interface WasmLoaderConfig {
    production?: boolean;
    portable?: boolean;
}

const wasmPlugin = ({ production, portable }: WasmLoaderConfig = {}): BunPlugin => {
    const p: BunPlugin = {
        name: "WASM loader",
        async setup(build) {
            build.onLoad({ filter: /\.(c(pp)?|wasm)$/ }, async (args) => {
                let wasmPath = path.resolve(import.meta.dir, '..', 'dist', 'tmp.wasm');
                let jsContent: string = `
                    async function instantiate(url) {
                        const memory = new WebAssembly.Memory({
                            initial: 32,
                        });
                        let data = new DataView(memory.buffer);
                        const decoder = new TextDecoder();
                        const getString = (ptr) => {
                            const view = new Uint8Array(memory.buffer, ptr);
                            const start = ptr;
                            const end = ptr + view.indexOf(0);

                            return decoder.decode(memory.buffer.slice(start, end));
                        };
                        let buf = '';
                        const { instance } = await WebAssembly.instantiateStreaming(fetch(url), {
                            env: {
                                memory,
                                log(format, argsPtr) {
                                    format = getString(format);
                                    let isFormat = false;
                                    let w = 4;
                                    const align = (a) => argsPtr += (argsPtr % a);
                                    for (const c of format) {
                                        if (!isFormat) {
                                            if (c === '%') {
                                                isFormat = true;
                                            } else if (c === '\\n') {
                                                console.log('[wasm]', buf);
                                                buf = '';
                                            } else {
                                                buf += c;
                                            }
                                        } else switch(c) {
                                            case '%': buf += '%'; isFormat = false; break;
                                            case 's': align(4); buf += getString(data.getInt32(argsPtr, true)); argsPtr += 4; isFormat = false; break;
                                            case 'd': align(w); buf += data[w === 4 ? 'getInt32': 'getBigInt64'](argsPtr, true); argsPtr += w; isFormat = false; break;
                                            case 'x': align(w); buf += data[w === 4 ? 'getUint32': 'getBigUint64'](argsPtr, true).toString(16); argsPtr += w; isFormat = false; break;
                                            case 'o': align(w); buf += data[w === 4 ? 'getUint32': 'getBigUint64'](argsPtr, true).toString(8); argsPtr += w; isFormat = false; break;
                                            case 'u': align(w); buf += data[w === 4 ? 'getUint32': 'getBigUint64'](argsPtr, true); argsPtr += w; isFormat = false; break;
                                            case 'f': align(8); buf += data.getFloat64(argsPtr, true); argsPtr += 8; isFormat = false; break;
                                            case 'c': align(4); buf += String.fromCharCode(data.getInt32(argsPtr, true)); argsPtr += 4; isFormat = false; break;
                                            case 'l': w = 8; break;
                                            default: buf += '%' + c; isFormat = false; break;
                                        }
                                    }
                                },
                                grow(blocks) {
                                    if (blocks > 0) {
                                        memory.grow(blocks);
                                        data = new DataView(memory.buffer);
                                    }
                                }
                            }
                        });

                        return {
                            ...instance.exports,
                            memory,
                            get data() { return data; },
                        };
                    }
                    const module = await instantiate(new URL($WASM$));
                    if (typeof module.__srand === 'function') module.__srand(BigInt(Date.now()));

                    export default module;
                `;
                if (args.path.endsWith('.wasm')) {
                    wasmPath = args.path;
                } else {
                    const buildAssets = path.resolve(import.meta.dir, 'assets');
                    const stdlib = `${buildAssets}/stdlib.c`;
                    const opt = production ? '-O3' : '-O0';
                    const result = await $`clang --target=wasm32 ${opt} -flto -fno-builtin --no-standard-libraries -I ${buildAssets} -Wall -Wextra -Wpedantic -Werror -Wl,--lto-O3 -Wl,--no-entry -Wl,--import-memory -o ${wasmPath} ${args.path} ${stdlib}`;

                    if (result.exitCode !== 0) {
                        throw new Error('Compile failed, check output');
                    }
                }

                const wasmContent = await Bun.file(wasmPath).arrayBuffer();
                const wasmBuffer = Buffer.from(wasmContent).toString('base64');
                const wasmURL = `data:application/wasm;base64,${wasmBuffer}`;

                return {
                    loader: 'js',
                    contents: jsContent.replace(/new URL\([^)]*\)/, `new URL(${JSON.stringify(wasmURL)})`),
                };
            });
        }
    };
    plugin(p);
    return p;
};

export default wasmPlugin;