const multiline = require( './multiline' );

function uniqueMatchId( match ) {
	return ' msgid=' + match.single + ' ctxt=' + ( match.context || '' );
}

// Reference for the PO format: http://www.gnu.org/software/gettext/manual/gettext.html#PO-Files
// More details: http://pology.nedohodnik.net/doc/user/en_US/ch-poformat.html
module.exports = function pot( matches, options ) {
	const uniqueMatchesMap = {};
	let output;

	// default match for the header
	uniqueMatchesMap[ uniqueMatchId( { single: '' } ) ] = true;

	output = '# THIS IS A GENERATED FILE. DO NOT EDIT DIRECTLY.\n';

	if ( options.copyrightNotice ) {
		if ( Array.isArray( options.copyrightNotice ) ) {
			output += '# ' + options.copyrightNotice.join( '\n#' );
		} else {
			output += '# ' + options.copyrightNotice;
		}
		output += '\n';
	}

	output += '\n';

	output +=
		options.potHeader ||
		[
			'msgid ""',
			'msgstr ""',
			'"Project-Id-Version: _s ' + ( options.projectName || '' ) + '\\n"',
			'"Report-Msgid-Bugs-To: ' + ( options.projectBugsUrl || '' ) + '\\n"',
			'"POT-Creation-Date: ' + new Date().toISOString() + '\\n"',
			'"MIME-Version: 1.0\\n"',
			'"Content-Type: text/plain; charset=UTF-8\\n"',
			'"Content-Transfer-Encoding: 8bit\\n"',
			'"PO-Revision-Date: 2014-MO-DA HO:MI+ZONE\\n"',
			'"Last-Translator: FULL NAME <EMAIL@ADDRESS>\\n"',
			'"Language-Team: LANGUAGE <LL@li.org>\\n"',
			'',
		].join( '\n' );

	output += '\n';

	matches = matches
		.map( function ( match ) {
			const matchId = uniqueMatchId( match );
			const firstMatch = uniqueMatchesMap[ matchId ];

			if ( ! firstMatch ) {
				match.lines = {};
				match.comments = {};
				uniqueMatchesMap[ matchId ] = match;
			}

			// Aggregate lines and comments for output later.
			if ( match.line ) {
				uniqueMatchesMap[ matchId ].lines[ match.line ] = true;
			}
			if ( match.comment ) {
				uniqueMatchesMap[ matchId ].comments[ match.comment ] = true;
			}

			if ( ! uniqueMatchesMap[ matchId ].plural && match.plural ) {
				// We group singular only-s and version with plurals, so make sure that we keep the plural
				uniqueMatchesMap[ matchId ].plural = match.plural;
			}

			// ignore this match now that we have updated the first match
			if ( firstMatch ) {
				return undefined;
			}

			return match;
		} )
		.filter( function ( match ) {
			// removes undefined
			return match;
		} );

	output += matches
		.map( function ( match ) {
			let matchPotStr = '';

			matchPotStr += Object.keys( match.lines )
				.map( function ( line ) {
					return '#: ' + line + '\n';
				} )
				.join( '' );

			matchPotStr += Object.keys( match.comments )
				.map( function ( commentLine ) {
					return '#. ' + commentLine + '\n';
				} )
				.join( '' );

			if ( match.context ) {
				matchPotStr += 'msgctxt ' + multiline( match.context, 'msgctxt ' ) + '\n';
			}

			matchPotStr += 'msgid ' + multiline( match.single, 'msgid ' ) + '\n';

			if ( match.plural ) {
				matchPotStr += 'msgid_plural ' + multiline( match.plural, 'msgid_plural ' ) + '\n';
				matchPotStr += 'msgstr[0] ""\n';
				matchPotStr += 'msgstr[1] ""\n';
			} else {
				matchPotStr += 'msgstr ""\n';
			}

			return matchPotStr;
		} )
		.join( '\n' );

	output += '\n# THIS IS THE END OF THE GENERATED FILE.\n';

	return output;
};