const fs = require('fs');
const path = require('path');
const process = require('process');
const { spawnSync, execSync } = require('child_process');
const rimraf = require('rimraf');

const DIR_BUILD = path.resolve('build');
const DIR_GENERATED = path.resolve(DIR_BUILD, 'generated');
const DIR_OBJ = path.resolve(DIR_BUILD, 'obj');
const DIR_SRC = path.resolve('src');
const DIR_GBDK = path.resolve(process.env['GBDKDIR']);
const FILE_OUT = path.resolve(DIR_BUILD, 'Penny.gb');
const FILE_LINKFILE = path.join(DIR_BUILD, `linkflile.lk`);

const LCC = path.join(DIR_GBDK, 'bin', 'lcc');
const LCCFLAGS = '';

// Create build dirs
[
  DIR_BUILD, DIR_GENERATED, DIR_OBJ
].forEach(d => {
  if(fs.existsSync(d)) return;
  fs.mkdirSync(d);
});

// Scandir
const buildSourceFiles = directory => {
  const sources = [];

  fs.readdirSync(directory).forEach(file => {
    const fullPath = path.join(directory, file);
    const stats = fs.statSync(fullPath);
    if(stats.isDirectory()) {
      sources.push(...buildSourceFiles(fullPath));
      return;
    }

    if(file.endsWith('.c')) {
      sources.push(file.split(DIR_SRC).join(''));
    }
  });

  return sources;
}

const logOut = (out, buffer) => {
  const str = [
    out.stderr, out.stdout
  ].filter(n => n)
    .map(n => n.toString())
    .filter(n => n)
    .join('')
  ;
  if(!str || !str.length) return;
  buffer(str);
}


// Get a list of sources and build each of them prior to linking.
const allSources = buildSourceFiles(DIR_SRC);
const compiledSources = [];
for(let i = 0; i < allSources.length; i++) {
  const source = allSources[i];
  const fileIn = path.join(DIR_SRC, source);
  const fileNameOut = path.basename(fileIn, '.c') + '.o';
  const sourceRelativePath = path.dirname(source).split(DIR_SRC).join('');
  const fileOut = path.join(DIR_OBJ, sourceRelativePath, fileNameOut);

  compiledSources.push(path.join(sourceRelativePath, fileNameOut));

  if(fs.existsSync(fileOut)) continue;

  let result;
  try {
    result = execSync(`${LCC} ${LCCFLAGS} -c -o ${fileOut} ${fileIn}`);
    logOut(result, console.log);
  } catch(e) {
    logOut(e, console.error);
    process.exit(1);
  }
}

// Generate a linkfile.
fs.writeFileSync(FILE_LINKFILE, compiledSources.map(cs=>{
  return path.join(DIR_OBJ, cs);
}).join('\n'));

// Compile BIN
let result;
try {
  result = execSync(`${LCC} ${LCCFLAGS} -o ${FILE_OUT} -Wl-f${FILE_LINKFILE}`);
  logOut(result, console.log);
} catch(e) {
  logOut(e, console.error);
  process.exit(1);
}