// source: https://github.com/kercl/LaTeX-to-Unicode/tree/master

texparser = {
	replace_chars: function(x, table) {
		var res = "";
		for(i in x)
			if(x[i] in table)
				res = res + table[x[i]];
			else
				res = res + x[i];
		return res;
	},
	
	trim_tokens: function(tokens) {
		var beg = 0, end = tokens.length - 1;
		for(; beg < tokens.length; beg++)
			if(!this.whitespace(tokens[beg].object))
				break;
		for(; end >= 0; end--)
			if(!this.whitespace(tokens[end].object))
				break;
		return tokens.slice(beg, end);
	},

	strings_disjoint: function(x, y) {
		if(x.length != y.length)
			return false;
		
		for(var i = 0; i < x.length; i++)
			if(x[i] == y[i])
				return false;
		return true;
	},

	optimize: function(tokens) {	
		var single = "";
		var sliceat = -1;
		
		for(var i = 0; i < tokens.length; i++) {
			if((tokens[i].object.length == 1 &&
			   "_^{}$".indexOf(tokens[i].object) == -1) || this.whitespace(tokens[i].object))
				single = single + tokens[i].object;
			else {
				sliceat = i;
				break;
			}
		}
		if(sliceat == -1)
			return [{object:single}];
		return [{object:single}].concat(tokens.slice(sliceat));
	},

	tokenize: function(str) {
		var ret = [];
		
		str = str.replace(/\u200B/g, "\\");
		
		while(str != "") {
			var s = "";
			if("_^{}$".indexOf(str[0]) > -1) {
				s = str[0];
			}else if(str[0] == '\\') {
				s = str.match(/^\\([a-zA-Z]+|\$|\\|\{|\}| |\_|\^)/g);
				if(s != null)
					s = s[0];
				else
					s = str[0];
			}else {
				var s1 = str.match(/^[^_\\\$\^\{\}\s]/g),
					s2 = str.match(/^[^_\\\$\^\{\}\S]+/g);
					
				if(s1 == null) {
					s = s2[0];
				}else if(s2 == null) { // not whitespace
					s = s1[0];
				}else {
					s = s[0];
				}
			}
			
			ret.push({object:s});
			str = str.substring(Math.max(1,s.length));
		}
		var ret2 = this.optimize(ret);
		return ret2;
	},
	
	whitespace: function(str) {
		return str.match(/^\s+/g) != null;
	},
	
	tag: function(tok) {
		return (tok.object[0] == "\\" && tok.object.length > 1) || tok.object == "^" || tok.object == "_";
	},
	
	extract_block: function(tokens, begin, start_token, end_token) {
		start_token = typeof start_token !== 'undefined' ? start_token : "{";
		end_token = typeof end_token !== 'undefined' ? end_token : "}";

		if(tokens[begin] == undefined)
			return [];
		
		if((this.tag(tokens[begin]) || tokens[begin].object == "\\") && tokens[begin].caret != undefined)
			return [];
		
		if(tokens[begin].object != start_token)
			return [tokens[begin]];
		if(tokens[begin].closed != true)
			return [];
		
		var bc = 1;
		var res = [tokens[begin]];
		
		for(var i = begin+1; i < tokens.length; i++) {
			if(tokens[i].object == start_token)
				bc++;
			else if(tokens[i].object == end_token) {
				bc--;
				if(bc == 0) {
					res.push(tokens[i]);
					return res;
				}
			}
			res.push(tokens[i]);
		}
		
		return [];
	},
	
	finish: function(str) {
		return str;
	},
	
	reformat_math: function(str) {
		var res = tag_table["\\textit"].value(str.replace(/\\ /g, "\u00A0"));
		res = res.replace(/ /g, "");
		return res.replace(/[><=≌≊≆≈⋍∽≅⋞⋟⪖⪕⩵≡≧⩾≥⟵≫⪊≩⪈≳⪆⋛⪌≷⇔↔≦⩽⪅⋚⪋≲≤⪉≨⪇≴←⟵⇐↔⇔→⟶⇒↦≹∈∋∌∉≸≮≯≠≾≼≼⪹⪵⇒≿⫅⊆⫋⊊⊂≽≽⪺⪶⋩≻⫆⊇⫌⊋⊃⋑⋐]|:./g, function(x) {
			if(x.match(/:./g))
				return ": " + x[1];
			return "\u2009" + x + "\u2009";
		}).trim();
	},

	parse_str: function(str, cursorpos) {
		var bracketstack = [], beginstack = [];
		var tokens = this.tokenize(str);
		
		var carettrace = 0;
		var mathmodebegin = -1;
		
		for(var i = 0; i < tokens.length; i++) {
			if(tokens[i].object == "{") {
				bracketstack.push(i);
			}else if(tokens[i].object == "}" && bracketstack.length > 0) {
				tokens[bracketstack[bracketstack.length-1]].closed = true;
				tokens[i].closed = true;
				bracketstack.pop();
			}
			
			if(tokens[i].object == "\\begin") {
				beginstack.push(i);
			}else if(tokens[i].object == "\\end" && beginstack.length > 0) {
				tokens[beginstack[beginstack.length-1]].closed = true;
				tokens[i].closed = true;
				beginstack.pop();
			}

			if(tokens[i].object == "$") {
				if(mathmodebegin != -1) {
					tokens[mathmodebegin].closed = true;
					tokens[i].closed = true;
				}else {
					mathmodebegin = i;
				}
			}

			if(cursorpos > carettrace && cursorpos <= carettrace + tokens[i].object.length)
				tokens[i].caret = cursorpos - carettrace;
			carettrace = carettrace + tokens[i].object.length;
		}
		
		for(var i = 0; i < bracketstack.length; i++)
			tokens[bracketstack[i]].closed = false;
		for(var i = 0; i < beginstack.length; i++)
			tokens[beginstack[i]].closed = false;

		var res = this.parse(tokens);
		return res;
	},

	"itemize": function(tokens) {
		console.log("itemize");

		var tmp_tokens = [];
		for(var i = 0; i < tokens.length - 1; i++) {
			if(tokens[i].object == "\\item" && this.whitespace(tokens[i + 1].object)) {
				tmp_tokens.push(tokens[i]);
				i = i + 1;
			}else if(tokens[i + 1].object == "\\item" && this.whitespace(tokens[i].object)) {
			}else if(tokens[i].object.indexOf("\n") > -1) {
				tmp_tokens.push({object:"\n"});
			}else {
				tmp_tokens.push(tokens[i]);
			}
		}
		console.log(tmp_tokens);
		tag_table["\\item"] = {type:"symbol",value:"\n   • "};
		var res = this.parse(tmp_tokens);
		tag_table["\\item"] = undefined;

		res.text = res.text.replace(/\n(   • )?/g, function(x) { if(x.length == 1) return "\n     "; else return x; }) + "\n\n";

		return res;
	},

	"theorem": function(tokens) {
		var res = this.parse(this.trim_tokens(tokens));
		res.text = tag_table["\\textbf"].value("Theorem: ") + res.text + "\n";
		return res;
	},

	"proof": function(tokens) {
		var res = this.parse(this.trim_tokens(tokens));
		res.text = tag_table["\\textbf"].value("Proof: ") + res.text + "\n\u200F□\u200F\n";
		return res;
	},
	
	"align*": function(tokens) {
		var res = this.parse( [{object:"$",closed:true}].concat(this.trim_tokens(tokens)).concat([{object:"$",closed:true}]) );
		res.text = "\n    " + res.text.replace(/\n/g, "\n    ") + "\n\n";
		return res;
	},

	parse_depth:0,
	parse: function(tokens) {
		this.parse_depth++;

		var res = "", mathmode = null;
		var cursorpos = -1;

		var decorator_stack = [];

		for(var i = 0; i < tokens.length; i++) {
			if(tokens[i].caret != undefined && tokens[i].closed == undefined) {
				if(tokens[i].object != "\\\\"
				&& tokens[i].object != "\\_" 
				&& tokens[i].object != "\\}"
				&& tokens[i].object != "\\{"
				&& tokens[i].object != "\\$"
				&& tokens[i].object != "\\^"
				&& tokens[i].object != "\\$") {
					cursorpos = res.length + tokens[i].caret;
					res = res + tokens[i].object;
					continue;
				}
			}
			
			if(tokens[i].object == "{" || tokens[i].object == "}") {
				if(tokens[i].closed != true)
					res = res + tokens[i].object;
				if(tokens[i].caret != undefined && tokens[i].object == "}") {
					cursorpos = cursorpos + res.length + 1;
				}
			}else if(tokens[i].object == "$" && tokens[i].closed == true) {
				if(mathmode == null) {
					mathmode = res;
					res = "";
				}else {
					res = mathmode + this.reformat_math(res);
					mathmode = null;
				}
			}else {
				if(this.tag(tokens[i])) {
					if(tag_table[tokens[i].object] != undefined) {
						if(tag_table[tokens[i].object].type == "symbol") {
							var val = tag_table[tokens[i].object].value;
							res = res + val;
							if(tokens[i].caret != undefined && cursorpos == -1)
								cursorpos = res.length + val.length - 1;
						}else if(tag_table[tokens[i].object].type == "decorator" && i < tokens.length - 1) {
							var subblock = this.extract_block(tokens, i+1);
							if(subblock.length > 0) {
								sret = this.parse(subblock);
								var subs = tag_table[tokens[i].object].value(sret.text);
								res = res + subs;
								if(sret.caret != -1 && cursorpos == -1) {
									cursorpos = res.length;
								}
								i = i + subblock.length;
							}else {
								res = res + tokens[i].object;
							}
						}else if(tag_table[tokens[i].object].type == "decorator2" && i < tokens.length - 1) {
							var subblock = this.extract_block(tokens, i+1);
							var init_i = i;
							if(subblock.length > 0) {
								i = i + subblock.length;
								var subblock2 = this.extract_block(tokens, i+1);
								if(subblock2.length > 0) {
									var sret1 = this.parse(subblock);
									var sret2 = this.parse(subblock2);
									if(cursorpos == -1)
										cursorpos = sret1.caret + res.length;
									if(cursorpos == -1)
										cursorpos = sret2.caret + res.length;
									var subs = tag_table[tokens[init_i].object].value(sret1.text, sret2.text);
									res = res + subs;
									
									i = i + subblock2.length;
									
									if((sret1.caret != -1 || sret2.caret != -1) && cursorpos == -1) {
										cursorpos = res.length + subs.length + 2;
									}else if(tokens[i].caret != undefined) {
										cursorpos = res.length + subs.length + 1;
										
									}
								}else {
									res = res + tokens[init_i].object;
									i = init_i;
									if(tokens[i + 1].object == "{") {
										tokens[i + 1].closed = undefined;
										console.log(tokens[i + subblock.length]);
										tokens[i + subblock.length].closed = undefined;
									}
									console.log("frac not finished:");
									console.log(tokens);
								}
							}else {
								res = res + tokens[i].object;
							}
						}else
							res = res + tokens[i].object;
					}else if(tokens[i].object == "\\begin" && i+1 < tokens.length) {
						if(tokens[i+1].object == "{") {
							var subblock = this.extract_block(tokens, i, "\\begin", "\\end");
							var argument = this.extract_block(tokens, i+1);
							if(argument.length > 0) {
								tokens[i+1].closed = false;
								tokens[i+argument.length].closed = false;

								if(subblock.length > 0) {
									var argument_parsed = this.parse(argument.slice(1,argument.length-1));
									if(argument_parsed.text != this.parse(this.extract_block(tokens, i + subblock.length)).text) {
										res = res + tokens[i].object;
										continue;
									}
									if(argument_parsed.text in this) {
										i = i + subblock.length + argument.length;
										var parsed_block = this[argument_parsed.text](subblock.slice(argument.length + 1, subblock.length));
										res = res + parsed_block.text;

									}else {
										res = res + tokens[i].object;
									}
								}else
									res = res + tokens[i].object;
							}else {
								res = res + tokens[i].object;
							}
						}else
							res = res + tokens[i].object;
					}else if(tokens[i].object == "\\end" && i+1 < tokens.length) {
						if(tokens[i+1].object == "{") {
							var argument = this.extract_block(tokens, i+1);
							if(argument.length > 0) {
								tokens[i+1].closed = false;
								tokens[i+argument.length].closed = false;
								res = res + tokens[i].object;
							}else {
								res = res + tokens[i].object;
							}
						}else
							res = res + tokens[i].object;
					}else {
						res = res + tokens[i].object;
					}
				}else {
					res = res + tokens[i].object;
				}
			}
		}
		this.parse_depth--;
		return {text:res, caret:cursorpos};
	}
}