const fs = require('fs');
const path = require('path');
const { exec }= require("child_process");

const directoryPath = path.resolve(__dirname, 'build');

function postProcess() {
  fs.readdir(directoryPath, (err, files) => {
    if (err) {
      console.error("Error reading directory: ", err);
      return;
    }
    processHtmlFiles(files);

    // 
    // wanted to take it out of the readdir callback but it messes up print orders
    // 
    appendToCxcore();

    console.log("---Finished post-processing---");
  });
}

function processHtmlFiles(files) {
  console.log();
  console.log(`---Starting post-processing---`);
  console.log();
  const htmlFiles = files.filter(file => file.endsWith('html'));
  htmlFiles.forEach(htmlFile => {
    console.log( '-' + htmlFile);
    const filePath = path.join(directoryPath, htmlFile);
    const fileContent = fs.readFileSync(filePath, 'utf-8');

    const scriptContent = extractScript(fileContent);
    if (scriptContent === '') {
      if (htmlFile === 'login.html')  {
        console.log(`\tAll good! No expected script for ${filePath}, skipped`);
        return;
      }
      console.warn(`\tWarning: no script content for ${filePath}`);
      return;
    }
    const scriptName = createJsFile(htmlFile, scriptContent);
    if (scriptName === '') {
      console.warn(`\tWarning: no scriptName for ${filePath}`);
      return;
    }
    replaceScript(fileContent, filePath, scriptName);
    console.log(`\tSuccessfully extracted scripts from [${htmlFile}] into separate [${scriptName}].`);
  });


  console.log();
  console.log("---Finished post-processing HTML files---");
  
}

function appendToCxcore() {
  const cxcoreFile = path.resolve(directoryPath, 'cxcore.js');
  const content = 'cxCoreInit.promise.then(function(){cxCoreInit();}).catch(function(e){postMessage({type:", m, ",value:e.toString()});})';

  try {
    fs.appendFileSync(cxcoreFile, content);
    console.log(`\nappended cxCoreInit() to build/cxcore.js`);
  } catch (err) {
    console.error("Failed to append: ", err);
  }
}

function extractScript(fileContent) {
  const scriptStart = fileContent.indexOf('__sveltekit_');
  if (scriptStart === -1)  {
    console.log('\tCould not find __sveltekit_ script start');
    return '';
  }
  var scriptEnd = fileContent.lastIndexOf('</script>');
  scriptEnd -= 6; // getting rid of extra } closing bracket. Will find a better solution than this.
  if (scriptEnd === -1) {
    console.log('\tCould not match the closing <script> tag');
    return '';
  }
  const scriptContent = fileContent.substring(scriptStart, scriptEnd);
  const containsPromiseAll = scriptContent.indexOf('Promise.all');
  if (containsPromiseAll !== -1) {
    return scriptContent;
  } else {
    console.log('\tCould not find Promise.all call in generated __sveltekit_ script');
    return '';
  }
}

function createJsFile(ogFileName, fileContent) {
  const name = path.parse(ogFileName).name;
  const filename = name + '_extracted_script.js'
  fs.writeFileSync(directoryPath + '/' + filename, fileContent, (err) => {
    if (err) {
      console.log("Error writing extracted script into .js file: ", err);
      return '';
    }
  });

  return filename;
}

function replaceScript(fileContent, filePath, scriptName) {
  const updatedContent = fileContent.replace(/<script>[\s\S]*?<\/script>/, `<script src="${scriptName}" defer></script>`);
  fs.writeFileSync(filePath, updatedContent, 'utf-8', (err) =>{
    if (err) {
      console.log("Failed to write replacedContent instead of inlined script: ", err);
    }
  });
}

postProcess();