/*
  Copyright (c) 2013-2014, Matthias Schiffer <mschiffer@universe-factory.net>
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice,
       this list of conditions and the following disclaimer in the documentation
       and/or other materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/


#include "lex.hpp"

#include <cstdlib>


#define array_size(array) (sizeof(array)/sizeof((array)[0]))


namespace solar {


struct keyword_t {
	const char *keyword;
	int token;
};

/* the keyword list must be sorted */
static const keyword_t keywords[] = {
};

static int compare_keywords(const void *v1, const void *v2) {
	const keyword_t *k1 = static_cast<const keyword_t*>(v1), *k2 = static_cast<const keyword_t*>(v2);
	return std::strcmp(k1->keyword, k2->keyword);
}


bool lex_t::advance() {
	if (start > 0) {
		std::memmove(buffer, buffer+start, end - start);
		end -= start;
		start = 0;
	}

	if (end == sizeof(buffer))
		return false;

	size_t l = std::fread(buffer+end, 1, sizeof(buffer) - end, file);

	end += l;
	return l;
}

bool lex_t::next(bool move) {
	if (start + tok_len >= end)
		return false;

	if (current() == '\n') {
		loc.last_column = 0;
		loc.last_line++;
	}
	else {
		loc.last_column++;
	}

	if (move)
		start++;
	else
		tok_len++;


	if (start + tok_len >= end)
		return advance();

	return true;
}

void lex_t::consume(bool consume_needspace) {
	start += tok_len;
	tok_len = 0;

	needspace = consume_needspace;
}

int lex_t::io_error(value_t *value) {
	value->error = "I/O error";
	return -1;
}

int lex_t::syntax_error(value_t *value) {
	if (std::ferror(file))
		return io_error(value);

	value->error = "syntax error";
	return -1;
}

int lex_t::consume_comment(value_t *value) {
	char prev = 0;

	while (next(true)) {
		if (prev == '*' && current() == '/') {
			next(true);
			consume(false);
			return 0;
		}

		prev = current();
	}

	if (std::ferror(file))
		return io_error(value);

	value->error = "unterminated block comment";
	return -1;
}

int lex_t::unterminated_string(value_t *value) {
	if (ferror(file))
		return io_error(value);

	value->error = "unterminated string";
	return -1;
}

int lex_t::lex_string(value_t *value) {
	char *buf = NULL;
	size_t len = 1024;
	size_t pos = 0;

	if (needspace)
		return syntax_error(value);

	buf = static_cast<char*>(std::malloc(len));

	while (true) {
		if (!next(true)) {
			std::free(buf);
			return unterminated_string(value);
		}

		char cur = current();

		if (cur == '"')
			break;

		if (cur == '\\') {
			if (!next(true)) {
				free(buf);
				return unterminated_string(value);
			}

			cur = current();

			if (cur == '\n')
				continue;
		}

		if (pos >= len) {
			len *= 2;
			buf = static_cast<char*>(std::realloc(buf, len));
		}

		buf[pos++] = cur;
	}

	value->str = strndup(buf, pos);
	std::free(buf);

	next(true);
	consume(true);

	return TOK_STRING;
}

int lex_t::lex_number(value_t *value) {
	if (needspace)
		return syntax_error(value);

	while (next(false)) {
		char cur = current();

		if (cur >= '0' && cur <= '9')
			continue;

		if (cur == 'x' || (cur >= 'a' && cur <= 'f') || (cur >= 'A' && cur <= 'F'))
			continue;

		break;
	}

	char *endptr, *token = get_token();
	value->number = std::strtoull(token, &endptr, 0);

	bool ok = !*endptr;
	free(token);

	if (!ok)
		return syntax_error(value);

	consume(true);

	return TOK_UINT;
}

int lex_t::lex_keyword(value_t *value) {
	if (needspace)
		return syntax_error(value);

	while (next(false)) {
		char cur = current();

		if (!((cur >= 'a' && cur <= 'z') || (cur >= '0' && cur <= '9') || cur == '-'))
			break;
	}

	char *token = get_token();
	const keyword_t key = { .keyword = token };
	const keyword_t *ret = static_cast<const keyword_t*>(bsearch(&key, keywords, array_size(keywords), sizeof(keyword_t), compare_keywords));
	free(token);

	if (!ret)
		return syntax_error(value);

	consume(true);

	return ret->token;
}

int lex_t::lex_symbol(value_t *value, bool terminal) {
	if (needspace)
		return syntax_error(value);

	while (next(false)) {
		char cur = current();

		switch (cur) {
		case 'A' ... 'Z':
			if (!terminal)
				break;

			continue;

		case 'a' ... 'z':
			if (terminal)
				break;

			continue;

		case '0' ... '9':
		case '_':
			continue;
		}

		break;
	}

	value->str = get_token();
	return terminal ? TOK_TERM : TOK_NONTERM;
}

lex_t::lex_t(FILE *file0) : file(file0), needspace(false), start(0), end(0), tok_len(0) {
	advance();
}

int lex_t::lex(value_t *value) {
	int token;

	while (end > start) {
		loc.first_line = loc.last_line;
		loc.first_column = loc.last_column+1;

		switch (current()) {
		case ' ':
		case '\n':
		case '\t':
		case '\r':
			next(true);
			consume(false);
			continue;

		case ';':
		case ':':
		case '{':
		case '}':
		case '|':
		case '=':
			token = current();
			next(true);
			consume(false);
			return token;

		case '/':
			if (!next(true))
				return syntax_error(value);

			if (current() == '*') {
				token = consume_comment(value);
				if (token)
					return token;

				continue;
			}

			if (current() != '/')
				return syntax_error(value);

			/* fall-through */
		case '#':
			while (next(true)) {
				if (current() == '\n')
					break;
			}

			next(true);
			consume(false);
			continue;

		case '\'':
			if (!next(true))
				return syntax_error(value);

			value->number = current();

			if (!next(true) || current() != '\'')
				return syntax_error(value);

			next(true);

			consume(false);

			return TOK_CHAR;

		case '"':
			return lex_string(value);

		case '0' ... '9':
			return lex_number(value);

		case 'a' ... 'z':
			return lex_symbol(value, false);

		case 'A' ... 'Z':
			return lex_symbol(value, true);

		default:
			return syntax_error(value);
		}
	}

	if (ferror(file))
		return io_error(value);

	return 0;
}

}