import fs from 'fs';
import path from 'path';

const LOCALES_DIR = path.join( __dirname, '..', 'locale-data', 'en' );
const GENERATED_DIR = path.join( __dirname, '..', 'locales', 'generated' );

function toPascalCase( name: string ): string
{
  return name
    .split( /[-_]/ )
    .map( part => part.charAt( 0 ).toUpperCase() + part.slice( 1 ) )
    .join( '' );
}

function toMemberName( fileName: string ): string
{
  const withUnderscores = fileName.replace( /\./g, '_' );
  return withUnderscores.replace( /-([a-zA-Z])/g, ( _, c: string ) => c.toUpperCase() );
}

function generateDir( absLocaleDir: string, enRoot: string, absOutDir: string, className: string ): void
{
  const files: { memberName: string; relativePath: string }[] = [];
  const dirs: { dirName: string; childClassName: string }[] = [];

  for ( const entry of fs.readdirSync( absLocaleDir ) )
  {
    if ( entry.endsWith( '.md' ) ) continue;

    const abs = path.join( absLocaleDir, entry );

    if ( fs.statSync( abs ).isDirectory() )
    {
      const childClassName = toPascalCase( entry );
      dirs.push( { dirName: entry, childClassName } );
      generateDir( abs, enRoot, path.join( absOutDir, entry ), childClassName );
    }
    else
    {
      const rel = path.relative( enRoot, abs ).replace( /\\/g, '/' );
      files.push( { memberName: toMemberName( entry ), relativePath: rel } );
    }
  }

  const lines: string[] = [];
  lines.push( '// Auto-generated by localeGenerator — do not edit manually.' );

  if ( dirs.length > 0 )
  {
    lines.push( '' );

    for ( const { dirName, childClassName } of dirs )
    {
      lines.push( `import { ${childClassName} } from './${dirName}/${childClassName}.js';` );
    }
  }

  lines.push( '' );
  lines.push( `export class ${className}` );
  lines.push( '{' );

  for ( const { memberName, relativePath } of files )
  {
    lines.push( `  static readonly ${memberName} = '${relativePath}';` );
  }

  for ( const { childClassName } of dirs )
  {
    lines.push( `  static readonly ${childClassName} = ${childClassName};` );
  }

  lines.push( '}' );

  fs.mkdirSync( absOutDir, { recursive: true } );
  fs.writeFileSync( path.join( absOutDir, `${className}.ts` ), lines.join( '\n' ) + '\n', 'utf8' );
}

export function generateLocales(): void
{
  if ( !fs.existsSync( LOCALES_DIR ) ) return;
  generateDir( LOCALES_DIR, LOCALES_DIR, GENERATED_DIR, 'Locales' );
}