#pragma once

#include <unordered_map>
#include <vector>
#include <string>
#include <iostream>
#include <exception>

#include "bufio.h"

struct BXParseError: std::exception {
	BXParseError(std::string msg): message(msg) {}
	std::string message;

	const char *what() const noexcept override {
		return message.c_str();
	}
};

using BXVariables = std::unordered_map<std::string, std::vector<std::string>>;

class BXParser {
public:
	enum class TokenKind {
		E_O_F,
		INDENTATION,
		NEWLINE,
		COMMA,
		COLON_EQUALS,
		PLUS_EQUALS,
		EQUALS_PLUS,
		BAR_EQUALS,
		EXPANSION,
		STRING,
		NONE,
	};

	struct Token {
		TokenKind kind;
		std::string str;
		int line;
		int ch;
	};

	BXParser(bufio::IStream &stream, int line = 1, int ch = 1):
		line_(line), ch_(ch), buf_(stream) {}

	int get();
	int peek(size_t count = 1) { return buf_.peek(count); }
	void skip(char expected);
	void skip() { get(); }

	int line() const { return line_; }
	int ch() const { return ch_; }

	Token readToken(const BXVariables &vars);
	Token &peekToken() { return tok_; }

	void parse(BXVariables &vars, bool oneLine = false);
	void parseLine(BXVariables &vars) { parse(vars, true); }
	void parseList(BXVariables &vars, std::vector<std::string> &list);

private:
	[[noreturn]] void error(std::string);
	[[noreturn]] void error(std::string, TokenKind);

	std::string readIdent(const BXVariables &vars);
	void skipWhitespace();
	Token getToken(const BXVariables &vars);
	std::string readString(const BXVariables &vars);
	std::string readQuotedString(const BXVariables &vars);
	std::string readStringExpansion(const BXVariables &vars);
	char readEscape();
	void parseList(
			BXVariables &vars, std::vector<std::string> &var,
			void (*addVal)(std::vector<std::string> &var, std::string val),
			bool oneLine);

	int line_;
	int ch_;
	Token tok_;

	bufio::IBuf<> buf_;
};

class BXWriter {
public:
	BXWriter(bufio::OStream &stream): buf_(stream) {}

	void write(const BXVariables &vars);

private:
	void newline();
	void escape(const std::string &str);

	bufio::OBuf<> buf_;
};