/* jslint node: true */
'use strict';

//	ENiGMA½
const ANSIEscapeParser	= require('./ansi_escape_parser.js').ANSIEscapeParser;
const ANSI				= require('./ansi_term.js');
const { 
	splitTextAtTerms,
	renderStringLength
}						= require('./string_util.js');

//	deps
const _					= require('lodash');

module.exports = function ansiPrep(input, options, cb) {
	if(!input) {
		return cb(null, '');
	}

	options.termWidth			= options.termWidth 	|| 80;
	options.termHeight			= options.termHeight	|| 25;
	options.cols				= options.cols || options.termWidth		|| 80;
	options.rows				= options.rows || options.termHeight	|| 'auto';
	options.startCol			= options.startCol || 1;
	options.exportMode			= options.exportMode || false;

	//	in auto we start out at 25 rows, but can always expand for more
	const canvas = Array.from( { length : 'auto' === options.rows ? 25 : options.rows }, () => Array.from( { length : options.cols}, () => new Object() ) );
	const parser = new ANSIEscapeParser( { termHeight : options.termHeight, termWidth : options.termWidth } );

	const state = {
		row	: 0,
		col	: 0,
	};

	let lastRow = 0;

	function ensureRow(row) {
		if(canvas[row]) {
			return;
		}
		
		canvas[row] = Array.from( { length : options.cols}, () => new Object() );
	}

	parser.on('position update', (row, col) => {
		state.row	= row - 1;
		state.col	= col - 1;

		if(0 === state.col) {
			state.initialSgr = state.lastSgr;
		}

		lastRow		= Math.max(state.row, lastRow);
	});

	parser.on('literal', literal => {
		//
		//	CR/LF are handled for 'position update'; we don't need the chars themselves
		//
		literal = literal.replace(/\r?\n|[\r\u2028\u2029]/g, '');

		for(let c of literal) {
			if(state.col < options.cols && ('auto' === options.rows || state.row < options.rows)) {
				ensureRow(state.row);

				if(0 === state.col) {
					canvas[state.row][state.col].initialSgr = state.initialSgr;
				}

				canvas[state.row][state.col].char = c;

				if(state.sgr) {
					canvas[state.row][state.col].sgr	= _.clone(state.sgr);
					state.lastSgr						= canvas[state.row][state.col].sgr;
					state.sgr							= null;
				}
			}

			state.col += 1;
		}
	});

	parser.on('sgr update', sgr => {
		ensureRow(state.row);

		if(state.col < options.cols) {
			canvas[state.row][state.col].sgr	= _.clone(sgr);
			state.lastSgr						= canvas[state.row][state.col].sgr;
		} else {
			state.sgr = sgr;
		}
	});

	function getLastPopulatedColumn(row) {
		let col = row.length;
		while(--col > 0) {
			if(row[col].char || row[col].sgr) {
				break;
			}
		}
		return col;
	}

	parser.on('complete', () => {
		let output = '';
		let line;
		let sgr;

		canvas.slice(0, lastRow + 1).forEach(row => {
			const lastCol = getLastPopulatedColumn(row) + 1;

			let i;
			line = '';
			for(i = 0; i < lastCol; ++i) {
				const col = row[i];

				sgr = 0 === i ? 
					col.initialSgr ? ANSI.getSGRFromGraphicRendition(col.initialSgr) : '' :
					'';
				
				if(col.sgr) {
					sgr += ANSI.getSGRFromGraphicRendition(col.sgr);
				}

				line += `${sgr}${col.char || ' '}`;
			}

			output += line;

			if(i < row.length) {
				output += `${ANSI.blackBG()}${row.slice(i).map( () => ' ').join('')}`;//${lastSgr}`;
			}

			if(options.startCol + i < options.termWidth || options.forceLineTerm) {
				output += '\r\n';
			}
		});

		if(options.exportMode) {
			//
			//	If we're in export mode, we do some additional hackery:
			//	
			//	* Hard wrap ALL lines at <= 79 *characters* (not visible columns)
			//	  if a line must wrap early, we'll place a ESC[A ESC[<N>C where <N>
			//	  represents chars to get back to the position we were previously at
			//
			//	* Replace contig spaces with ESC[<N>C as well to save... space.
			//
			//	:TODO: this would be better to do as part of the processing above, but this will do for now
			const MAX_CHARS	= 79 - 8;	//	79 max, - 8 for max ESC seq's we may prefix a line with
			let exportOutput = '';			
			
			let m;
			let afterSeq;
			let wantMore;
			let renderStart;

			splitTextAtTerms(output).forEach(fullLine => {
				renderStart = 0;

				while(fullLine.length > 0) {
					let splitAt;
					const ANSI_REGEXP = ANSI.getFullMatchRegExp();
					wantMore = true;

					while((m = ANSI_REGEXP.exec(fullLine))) {
						afterSeq = m.index + m[0].length;

						if(afterSeq < MAX_CHARS) {
							//	after current seq
							splitAt = afterSeq;
						} else {
							if(m.index < MAX_CHARS) {
								//	before last found seq
								splitAt = m.index;
								wantMore = false;	//	can't eat up any more
							}
							
							break;	//	seq's beyond this point are >= MAX_CHARS
						}
					}

					if(splitAt) {
						if(wantMore) {
							splitAt = Math.min(fullLine.length, MAX_CHARS - 1);
						}
					} else {
						splitAt = Math.min(fullLine.length, MAX_CHARS - 1);
					}

					const part = fullLine.slice(0, splitAt);
					fullLine = fullLine.slice(splitAt);
					renderStart += renderStringLength(part);
					exportOutput += `${part}\r\n`;

					if(fullLine.length > 0) {	//	more to go for this line?
						exportOutput += `${ANSI.up()}${ANSI.right(renderStart)}`;	
					} else {
						exportOutput += ANSI.up();
					}
				}
			});

			return cb(null, exportOutput);
		}

		return cb(null, output);
	});

	parser.parse(input);
};