#!/usr/bin/env node

/**
 * External dependencies
 */
const gettextParser = require( 'gettext-parser' );
const fs = require( 'fs' );

const TAB = '\t';
const NEWLINE = '\n';

const fileHeader =
	[
		'<?php',
		'/* THIS IS A GENERATED FILE. DO NOT EDIT DIRECTLY. */',
		'$generated_i18n_strings = array(',
	].join( NEWLINE ) + NEWLINE;

const fileFooter =
	NEWLINE +
	[ ');', '/* THIS IS THE END OF THE GENERATED FILE */' ].join( NEWLINE ) +
	NEWLINE;

/**
 * Escapes single quotes.
 *
 * @param {string} input The string to be escaped.
 * @return {string} The escaped string.
 */
function escapeSingleQuotes( input ) {
	return input.replace( /'/g, "\\'" );
}

/**
 * Converts a translation parsed from the POT file to lines of WP PHP.
 *
 * @param {Object} translation The translation to convert.
 * @param {string} textdomain  The text domain to use in the WordPress translation function call.
 * @param {string} context     The context for the translation.
 * @return {string} Lines of PHP that match the translation.
 */
function convertTranslationToPHP( translation, textdomain, context = '' ) {
	let php = '';

	// The format of gettext-js matches the terminology in gettext itself.
	let original = translation.msgid;
	const comments = translation.comments ?? {};

	if ( Object.values( comments ).length ) {
		if ( comments.reference ) {
			// All references are split by newlines, add a // Reference prefix to make them tidy.
			php +=
				TAB +
				'// Reference: ' +
				comments.reference
					.split( NEWLINE )
					.join( NEWLINE + TAB + '// Reference: ' ) +
				NEWLINE;
		}

		if ( comments.translator ) {
			// All extracted comments are split by newlines, add a tab to line them up nicely.
			const translator = comments.translator
				.split( NEWLINE )
				.join( NEWLINE + TAB + '   ' );

			php += TAB + `/* ${ translator } */${ NEWLINE }`;
		}

		if ( comments.extracted ) {
			php +=
				TAB + `/* translators: ${ comments.extracted } */${ NEWLINE }`;
		}
	}

	if ( '' !== original ) {
		original = escapeSingleQuotes( original );

		if ( ! translation.msgid_plural ) {
			if ( ! context ) {
				php += TAB + `__( '${ original }', '${ textdomain }' )`;
			} else {
				php +=
					TAB +
					`_x( '${ original }', '${ translation.msgctxt }', '${ textdomain }' )`;
			}
		} else {
			const plural = escapeSingleQuotes( translation.msgid_plural );

			if ( ! context ) {
				php +=
					TAB +
					`_n_noop( '${ original }', '${ plural }', '${ textdomain }' )`;
			} else {
				php +=
					TAB +
					`_nx_noop( '${ original }',  '${ plural }', '${ translation.msgctxt }', '${ textdomain }' )`;
			}
		}
	}

	return php;
}

function convertPOTToPHP( potFile, phpFile, options ) {
	const poContents = fs.readFileSync( potFile );
	const parsedPO = gettextParser.po.parse( poContents );

	let output = [];

	for ( const context of Object.keys( parsedPO.translations ) ) {
		const translations = parsedPO.translations[ context ];

		const newOutput = Object.values( translations )
			.map( ( translation ) =>
				convertTranslationToPHP(
					translation,
					options.textdomain,
					context
				)
			)
			.filter( ( php ) => php !== '' );

		output = [ ...output, ...newOutput ];
	}

	const fileOutput =
		fileHeader + output.join( ',' + NEWLINE + NEWLINE ) + fileFooter;

	fs.writeFileSync( phpFile, fileOutput );
}

const args = process.argv.slice( 2 );

convertPOTToPHP( args[ 0 ], args[ 1 ], {
	textdomain: args[ 2 ],
} );