var DxfArrayScanner = require('./DxfArrayScanner.js'),
	AUTO_CAD_COLOR_INDEX = require('./AutoCadColorIndex');

var log = require('loglevel');

//log.setLevel('trace');
//log.setLevel('debug');
//log.setLevel('info');
//log.setLevel('warn');
log.setLevel('error');
//log.setLevel('silent');

function registerDefaultEntityHandlers(dxfParser) {
	// Supported entities here (some entity code is still being refactored into this flow)
	dxfParser.registerEntityHandler(require('./entities/3dface'));
	dxfParser.registerEntityHandler(require('./entities/arc'));
	dxfParser.registerEntityHandler(require('./entities/attdef'));
	dxfParser.registerEntityHandler(require('./entities/circle'));
	dxfParser.registerEntityHandler(require('./entities/dimension'));
	dxfParser.registerEntityHandler(require('./entities/ellipse'));
	dxfParser.registerEntityHandler(require('./entities/insert'));
	dxfParser.registerEntityHandler(require('./entities/line'));
	dxfParser.registerEntityHandler(require('./entities/lwpolyline'));
	dxfParser.registerEntityHandler(require('./entities/mtext'));
	dxfParser.registerEntityHandler(require('./entities/point'));
	dxfParser.registerEntityHandler(require('./entities/polyline'));
	dxfParser.registerEntityHandler(require('./entities/solid'));
	dxfParser.registerEntityHandler(require('./entities/spline'));
	dxfParser.registerEntityHandler(require('./entities/text'));
	//dxfParser.registerEntityHandler(require('./entities/vertex'));
}

function DxfParser() {
	this._entityHandlers = {};

	registerDefaultEntityHandlers(this);
}

DxfParser.prototype.parse = function(source, done) {
	throw new Error("read() not implemented. Use readSync()");
};

DxfParser.prototype.registerEntityHandler = function(handlerType) {
	var instance = new handlerType();
	this._entityHandlers[handlerType.ForEntityName] = instance;
}

DxfParser.prototype.parseSync = function(source) {
	if(typeof(source) === 'string') {
		return this._parse(source);
	}else {
		console.error('Cannot read dxf source of type `' + typeof(source));
		return null;
	}
};

DxfParser.prototype.parseStream = function(stream, done) {

	var dxfString = "";
	var self = this;

	stream.on('data', onData);
	stream.on('end', onEnd);
	stream.on('error', onError);

	function onData(chunk) {
		dxfString += chunk;
	}

	function onEnd() {
		try {
			var dxf = self._parse(dxfString);
		}catch(err) {
			return done(err);
		}
		done(null, dxf);
	}

	function onError(err) {
		done(err);
	}
};

DxfParser.prototype._parse = function(dxfString) {
	var scanner, curr, dxf = {}, lastHandle = 0;
	var dxfLinesArray = dxfString.split(/\r\n|\r|\n/g);

	scanner = new DxfArrayScanner(dxfLinesArray);
	if(!scanner.hasNext()) throw Error('Empty file');

	var self = this;

	var parseAll = function() {
		curr = scanner.next();
		while(!scanner.isEOF()) {
			if(curr.code === 0 && curr.value === 'SECTION') {
				curr = scanner.next();

				// Be sure we are reading a section code
				if (curr.code !== 2) {
					console.error('Unexpected code %s after 0:SECTION', debugCode(curr));
					curr = scanner.next();
					continue;
				}

				if (curr.value === 'HEADER') {
					log.debug('> HEADER');
					dxf.header = parseHeader();
					log.debug('<');
				} else if (curr.value === 'BLOCKS') {
					log.debug('> BLOCKS');
					dxf.blocks = parseBlocks();
					log.debug('<');
				} else if(curr.value === 'ENTITIES') {
					log.debug('> ENTITIES');
					dxf.entities = parseEntities(false);
					log.debug('<');
				} else if(curr.value === 'TABLES') {
					log.debug('> TABLES');
					dxf.tables = parseTables();
					log.debug('<');
				} else if(curr.value === 'EOF') {
					log.debug('EOF');
				} else {
					log.warn('Skipping section \'%s\'', curr.value);
				}
			} else {
				curr = scanner.next();
			}
			// If is a new section
		}
	};

	var groupIs = function(code, value) {
		return curr.code === code && curr.value === value;
	};

	/**
	 *
	 * @return {object} header
	 */
	var parseHeader = function() {
		// interesting variables:
		//  $ACADVER, $VIEWDIR, $VIEWSIZE, $VIEWCTR, $TDCREATE, $TDUPDATE
		// http://www.autodesk.com/techpubs/autocad/acadr14/dxf/header_section_al_u05_c.htm
		// Also see VPORT table entries
		var currVarName = null, currVarValue = null;
		var header = {};
		// loop through header variables
		curr = scanner.next();

		while(true) {
			if(groupIs(0, 'ENDSEC')) {
				if(currVarName) header[currVarName] = currVarValue;
				break;
			} else if(curr.code === 9) {
				if(currVarName) header[currVarName] = currVarValue;
				currVarName = curr.value;
				// Filter here for particular variables we are interested in
			} else {
				if(curr.code === 10) {
					currVarValue = { x: curr.value };
				} else if(curr.code === 20) {
					currVarValue.y = curr.value;
				} else if(curr.code === 30) {
					currVarValue.z = curr.value;
				} else {
					currVarValue = curr.value;
				}
			}
			curr = scanner.next();
		}
		// console.log(util.inspect(header, { colors: true, depth: null }));
		curr = scanner.next(); // swallow up ENDSEC
		return header;
	};


	/**
	 *
	 */
	var parseBlocks = function() {
		var blocks = {}, block;

        curr = scanner.next();

		while(curr.value !== 'EOF') {
			if(groupIs(0, 'ENDSEC')) {
				break;
			}

			if(groupIs(0, 'BLOCK')) {
				log.debug('block {');
				block = parseBlock();
				log.debug('}');
				ensureHandle(block);
                if(!block.name)
                    log.error('block with handle "' + block.handle + '" is missing a name.');
				else
                    blocks[block.name] = block;
			} else {
				logUnhandledGroup(curr);
				curr = scanner.next();
			}
		}
		return blocks;
	};

	var parseBlock = function() {
		var block = {};
		curr = scanner.next();

		while(curr.value !== 'EOF') {
			switch(curr.code) {
				case 1:
					block.xrefPath = curr.value;
					curr = scanner.next();
					break;
				case 2:
					block.name = curr.value;
					curr = scanner.next();
					break;
				case 3:
					block.name2 = curr.value;
					curr = scanner.next();
					break;
				case 5:
					block.handle = curr.value;
					curr = scanner.next();
					break;
				case 8:
					block.layer = curr.value;
					curr = scanner.next();
					break;
				case 10:
					block.position = parsePoint();
					curr = scanner.next();
					break;
				case 67:
					block.paperSpace = (curr.value && curr.value == 1) ? true : false;
					curr = scanner.next();
					break;
				case 70:
					if (curr.value != 0) {
						//if(curr.value & BLOCK_ANONYMOUS_FLAG) console.log('  Anonymous block');
						//if(curr.value & BLOCK_NON_CONSTANT_FLAG) console.log('  Non-constant attributes');
						//if(curr.value & BLOCK_XREF_FLAG) console.log('  Is xref');
						//if(curr.value & BLOCK_XREF_OVERLAY_FLAG) console.log('  Is xref overlay');
						//if(curr.value & BLOCK_EXTERNALLY_DEPENDENT_FLAG) console.log('  Is externally dependent');
						//if(curr.value & BLOCK_RESOLVED_OR_DEPENDENT_FLAG) console.log('  Is resolved xref or dependent of an xref');
						//if(curr.value & BLOCK_REFERENCED_XREF) console.log('  This definition is a referenced xref');
						block.type = curr.value;
					}
					curr = scanner.next();
					break;
				case 100:
					// ignore class markers
					curr = scanner.next();
					break;
				case 330:
					block.ownerHandle = curr.value;
					curr = scanner.next();
					break;
				case 0:
					if(curr.value == 'ENDBLK')
						break;
					block.entities = parseEntities(true);
					break;
				default:
					logUnhandledGroup(curr);
					curr = scanner.next();
			}

			if(groupIs(0, 'ENDBLK')) {
				curr = scanner.next();
				break;
			}
		}
		return block;
	};

	/**
	 * parseTables
	 * @return {Object} Object representing tables
	 */
	var parseTables = function() {
		var tables = {};
		curr = scanner.next();
		while(curr.value !== 'EOF') {
			if(groupIs(0, 'ENDSEC'))
				break;

			if(groupIs(0, 'TABLE')) {
				curr = scanner.next();

				var tableDefinition = tableDefinitions[curr.value];
				if(tableDefinition) {
					log.debug(curr.value + ' Table {');
					tables[tableDefinitions[curr.value].tableName] = parseTable();
					log.debug('}');
				} else {
					log.debug('Unhandled Table ' + curr.value);
				}
			} else {
				// else ignored
				curr = scanner.next();
			}
		}

		curr = scanner.next();
		return tables;
	};

	const END_OF_TABLE_VALUE = 'ENDTAB';

	var parseTable = function() {
		var tableDefinition = tableDefinitions[curr.value],
			table = {},
			expectedCount = 0,
			actualCount;

		curr = scanner.next();
		while(!groupIs(0, END_OF_TABLE_VALUE)) {

			switch(curr.code) {
				case 5:
					table.handle = curr.value;
					curr = scanner.next();
					break;
				case 330:
					table.ownerHandle = curr.value;
					curr = scanner.next();
					break;
				case 100:
					if(curr.value === 'AcDbSymbolTable') {
						// ignore
						curr = scanner.next();
					}else{
						logUnhandledGroup(curr);
						curr = scanner.next();
					}
					break;
				case 70:
					expectedCount = curr.value;
					curr = scanner.next();
					break;
				case 0:
					if(curr.value === tableDefinition.dxfSymbolName) {
						table[tableDefinition.tableRecordsProperty] = tableDefinition.parseTableRecords();
					} else {
						logUnhandledGroup(curr);
						curr = scanner.next();
					}
					break;
				default:
					logUnhandledGroup(curr);
					curr = scanner.next();
			}
		}
		var tableRecords = table[tableDefinition.tableRecordsProperty];
		if(tableRecords) {
			if(tableRecords.constructor === Array){
				actualCount = tableRecords.length;
			} else if(typeof(tableRecords) === 'object') {
				actualCount = Object.keys(tableRecords).length;
			}
			if(expectedCount !== actualCount) log.warn('Parsed ' + actualCount + ' ' + tableDefinition.dxfSymbolName + '\'s but expected ' + expectedCount);
		}
		curr = scanner.next();
		return table;
	};

	var parseViewPortRecords = function() {
		var viewPorts = [], // Multiple table entries may have the same name indicating a multiple viewport configuration
			viewPort = {};

		log.debug('ViewPort {');
		curr = scanner.next();
		while(!groupIs(0, END_OF_TABLE_VALUE)) {

			switch(curr.code) {
				case 2: // layer name
					viewPort.name = curr.value;
					curr = scanner.next();
					break;
				case 10:
					viewPort.lowerLeftCorner = parsePoint();
					curr = scanner.next();
					break;
				case 11:
					viewPort.upperRightCorner = parsePoint();
					curr = scanner.next();
					break;
				case 12:
					viewPort.center = parsePoint();
					curr = scanner.next();
					break;
				case 13:
					viewPort.snapBasePoint = parsePoint();
					curr = scanner.next();
					break;
				case 14:
					viewPort.snapSpacing = parsePoint();
					curr = scanner.next();
					break;
				case 15:
					viewPort.gridSpacing = parsePoint();
					curr = scanner.next();
					break;
				case 16:
					viewPort.viewDirectionFromTarget = parsePoint();
					curr = scanner.next();
					break;
				case 17:
					viewPort.viewTarget = parsePoint();
					curr = scanner.next();
					break;
				case 42:
					viewPort.lensLength = curr.value;
					curr = scanner.next();
					break;
				case 43:
					viewPort.frontClippingPlane = curr.value;
					curr = scanner.next();
					break;
				case 44:
					viewPort.backClippingPlane = curr.value;
					curr = scanner.next();
					break;
				case 45:
					viewPort.viewHeight = curr.value;
					curr = scanner.next();
					break;
				case 50:
					viewPort.snapRotationAngle = curr.value;
					curr = scanner.next();
					break;
				case 51:
					viewPort.viewTwistAngle = curr.value;
					curr = scanner.next();
					break;
                case 79:
                    viewPort.orthographicType = curr.value;
                    curr = scanner.next();
                    break;
				case 110:
					viewPort.ucsOrigin = parsePoint();
					curr = scanner.next();
					break;
				case 111:
					viewPort.ucsXAxis = parsePoint();
					curr = scanner.next();
					break;
				case 112:
					viewPort.ucsYAxis = parsePoint();
					curr = scanner.next();
					break;
				case 110:
					viewPort.ucsOrigin = parsePoint();
					curr = scanner.next();
					break;
				case 281:
					viewPort.renderMode = curr.value;
					curr = scanner.next();
					break;
				case 281:
					// 0 is one distant light, 1 is two distant lights
					viewPort.defaultLightingType = curr.value;
					curr = scanner.next();
					break;
				case 292:
					viewPort.defaultLightingOn = curr.value;
					curr = scanner.next();
					break;
				case 330:
					viewPort.ownerHandle = curr.value;
					curr = scanner.next();
					break;
				case 63:
				case 421:
				case 431:
					viewPort.ambientColor = curr.value;
					curr = scanner.next();
					break;
				case 0:
					// New ViewPort
					if(curr.value === 'VPORT') {
						log.debug('}');
						viewPorts.push(viewPort);
						log.debug('ViewPort {');
						viewPort = {};
						curr = scanner.next();
					}
					break;
				default:
					logUnhandledGroup(curr);
					curr = scanner.next();
					break;
			}
		}
		// Note: do not call scanner.next() here,
		//  parseTable() needs the current group
		log.debug('}');
		viewPorts.push(viewPort);

		return viewPorts;
	};

	var parseLineTypes = function() {
		var ltypes = {},
			ltypeName,
			ltype = {},
			length;

		log.debug('LType {');
		curr = scanner.next();
		while(!groupIs(0, 'ENDTAB')) {

			switch(curr.code) {
				case 2:
					ltype.name = curr.value;
					ltypeName = curr.value;
					curr = scanner.next();
					break;
				case 3:
					ltype.description = curr.value;
					curr = scanner.next();
					break;
				case 73: // Number of elements for this line type (dots, dashes, spaces);
					length = curr.value;
					if(length > 0) ltype.pattern = [];
					curr = scanner.next();
					break;
				case 40: // total pattern length
					ltype.patternLength = curr.value;
					curr = scanner.next();
					break;
				case 49:
					ltype.pattern.push(curr.value);
					curr = scanner.next();
					break;
				case 0:
					log.debug('}');
					if(length > 0 && length !== ltype.pattern.length) log.warn('lengths do not match on LTYPE pattern');
					ltypes[ltypeName] = ltype;
					ltype = {};
					log.debug('LType {');
					curr = scanner.next();
					break;
				default:
					curr = scanner.next();
			}
		}

		log.debug('}');
		ltypes[ltypeName] = ltype;
		return ltypes;
	};

	var parseLayers = function() {
		var layers = {},
			layerName,
			layer = {};

		log.debug('Layer {');
		curr = scanner.next();
		while(!groupIs(0, 'ENDTAB')) {

			switch(curr.code) {
				case 2: // layer name
					layer.name = curr.value;
					layerName = curr.value;
					curr = scanner.next();
					break;
				case 62: // color, visibility
					layer.visible = curr.value >= 0;
					// TODO 0 and 256 are BYBLOCK and BYLAYER respectively. Need to handle these values for layers?.
					layer.colorIndex = Math.abs(curr.value);
					layer.color = getAcadColor(layer.colorIndex);
					curr = scanner.next();
					break;
				case 70: // frozen layer
					layer.frozen = ((curr.value & 1) != 0 || (curr.value & 2) != 0);
					curr = scanner.next();
					break;
				case 0:
					// New Layer
					if(curr.value === 'LAYER') {
						log.debug('}');
						layers[layerName] = layer;
						log.debug('Layer {');
						layer = {};
						layerName = undefined;
						curr = scanner.next();
					}
					break;
				default:
					logUnhandledGroup(curr);
					curr = scanner.next();
					break;
			}
		}
		// Note: do not call scanner.next() here,
		//  parseLayerTable() needs the current group
		log.debug('}');
		layers[layerName] = layer;

		return layers;
	};

	var tableDefinitions = {
		VPORT: {
			tableRecordsProperty: 'viewPorts',
			tableName: 'viewPort',
			dxfSymbolName: 'VPORT',
			parseTableRecords: parseViewPortRecords
		},
		LTYPE: {
			tableRecordsProperty: 'lineTypes',
			tableName: 'lineType',
			dxfSymbolName: 'LTYPE',
			parseTableRecords: parseLineTypes
		},
		LAYER: {
			tableRecordsProperty: 'layers',
			tableName: 'layer',
			dxfSymbolName: 'LAYER',
			parseTableRecords: parseLayers
		}
	};

	/**
	 * Is called after the parser first reads the 0:ENTITIES group. The scanner
	 * should be on the start of the first entity already.
	 * @return {Array} the resulting entities
	 */
	var parseEntities = function(forBlock) {
		var entities = [];

		var endingOnValue = forBlock ? 'ENDBLK' : 'ENDSEC';

		if (!forBlock) {
			curr = scanner.next();
		}
		while(true) {

			if(curr.code === 0) {
				if(curr.value === endingOnValue) {
					break;
				}

				var entity;
				var handler = self._entityHandlers[curr.value];
				if(handler != null) {
					log.debug(curr.value + ' {');
					entity = handler.parseEntity(scanner, curr);
					curr = scanner.lastReadGroup;
					log.debug('}');
				} else {
					log.warn('Unhandled entity ' + curr.value);
					curr = scanner.next();
					continue;
				}
				ensureHandle(entity);
				entities.push(entity);
			} else {
				// ignored lines from unsupported entity
				curr = scanner.next();
			}
		}
		if(endingOnValue == 'ENDSEC') curr = scanner.next(); // swallow up ENDSEC, but not ENDBLK
		return entities;
	};

	/**
	 * Parses a 2D or 3D point, returning it as an object with x, y, and
	 * (sometimes) z property if it is 3D. It is assumed the current group
	 * is x of the point being read in, and scanner.next() will return the
	 * y. The parser will determine if there is a z point automatically.
	 * @return {Object} The 2D or 3D point as an object with x, y[, z]
	 */
	var parsePoint = function() {
		var point = {},
			code = curr.code;

		point.x = curr.value;

		code += 10;
		curr = scanner.next();
		if(curr.code != code)
			throw new Error('Expected code for point value to be ' + code +
			' but got ' + curr.code + '.');
		point.y = curr.value;

		code += 10;
		curr = scanner.next();
		if(curr.code != code)
		{
			scanner.rewind();
			return point;
		}
		point.z = curr.value;
		
		return point;
	};

	var ensureHandle = function(entity) {
		if(!entity) throw new TypeError('entity cannot be undefined or null');

		if(!entity.handle) entity.handle = lastHandle++;
	};

	parseAll();
	return dxf;
};

function logUnhandledGroup(curr) {
	log.debug('unhandled group ' + debugCode(curr));
}


function debugCode(curr) {
	return curr.code + ':' + curr.value;
}

/**
 * Returns the truecolor value of the given AutoCad color index value
 * @return {Number} truecolor value as a number
 */
function getAcadColor(index) {
	return AUTO_CAD_COLOR_INDEX[index];
}

const BLOCK_ANONYMOUS_FLAG = 1;
const BLOCK_NON_CONSTANT_FLAG = 2;
const BLOCK_XREF_FLAG = 4;
const BLOCK_XREF_OVERLAY_FLAG = 8;
const BLOCK_EXTERNALLY_DEPENDENT_FLAG = 16;
const BLOCK_RESOLVED_OR_DEPENDENT_FLAG = 32;
const BLOCK_REFERENCED_XREF = 64;



module.exports = DxfParser;


/* Notes */
// Code 6 of an entity indicates inheritance of properties (eg. color).
//   BYBLOCK means inherits from block
//   BYLAYER (default) mean inherits from layer