/*
  Copyright (c) 2015, 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 "output.hpp"

#include <cerrno>
#include <cstring>
#include <system_error>


namespace solar {

output_t::output_t(const generator_t *generator0, const char *header, const char *source)
	: prefix_str("parse_"),
	  token_prefix_str("TOK_"),
	  stack_size(100),
	  generator(generator0),
	  header_filename(header) {
	header_file = std::fopen(header, "w");
	if (!header_file)
		throw std::system_error(errno, std::generic_category(), "unable to open header output file for writing");

	source_file = std::fopen(source, "w");
	if (!source_file)
		throw std::system_error(errno, std::generic_category(), "unable to open source output file for writing");

	for (const std::string &nonterm : generator->get_nonterminals())
		symbol_values.emplace(symbol_t::make_nonterm(nonterm.c_str()), "symbol_" + nonterm);

	for (const symbol_t &term : generator->get_terminals()) {
		if (term.get_type() == SYMBOL_TYPE_TERM)
			tokens.emplace(term.get_value(), tokens.size());

		symbol_values.emplace(term, "token." + generator->get_term_type(term).second);
	}
}

void output_t::emit_tokens() {
	if (tokens.empty())
		return;

	std::fprintf(header_file, "enum %stoken_t {\n", prefix());

	for (const auto &token : tokens)
		std::fprintf(header_file, "\t%s%s = %u,\n", token_prefix(), token.first.c_str(), token.second + 256);

	std::fprintf(header_file, "};\n\n");
}

void output_t::emit_token_value() {
	std::fprintf(header_file, "typedef struct %stoken_value {\n", prefix());

	std::map<std::string, std::string> token_values;

	for (const auto &term : generator->get_terminals()) {
		const auto &type = generator->get_term_type(term);
		if (!type.first.empty())
			token_values.emplace(type.second, type.first);
	}

	for (const auto &value : token_values)
		std::fprintf(header_file, "\t%s %s;\n", value.second.c_str(), value.first.c_str());

	std::fprintf(header_file, "} %stoken_value_t;\n\n", prefix());
}

void output_t::emit_header() {
	emit_tokens();
	emit_token_value();

	std::fprintf(header_file, "typedef struct %scontext %scontext_t;\n", prefix(), prefix());
}

void output_t::emit_reduction(unsigned rule_id) {
	const auto &rule = generator->get_rules()[rule_id];

	std::fprintf(source_file, "static inline ");

	const item_t &item = std::get<0>(rule);
	const std::string &type = generator->get_nonterm_type(item.get_lhs());
	if (type.empty())
		std::fprintf(source_file, "void");
	else
		std::fprintf(source_file, "%s", type.c_str());

	std::fprintf(source_file, " %sreduce_%u(", prefix(), rule_id);

	bool empty = true;
	for (unsigned i = 0; i < std::get<1>(rule).size(); i++) {
		const std::string &var = std::get<1>(rule)[i];

		if (var.empty())
			continue;

		if (!empty)
			std::fprintf(source_file, ", ");

		std::fprintf(source_file, "%s %s", generator->get_type(item.get_rhs()[i]).c_str(), var.c_str());

		empty = false;
	}

	if (empty)
		std::fprintf(source_file, "void");

	std::fprintf(source_file, ") {");
	std::fprintf(source_file, "%s", std::get<2>(rule).c_str());
	std::fprintf(source_file, "}\n\n");

}

void output_t::emit_reductions() {
	const auto &rules = generator->get_rules();

	for (size_t i = 0; i < rules.size(); i++) {
		if (!std::get<2>(rules[i]).empty())
			emit_reduction(i);
	}
}

void output_t::emit_state_shift(unsigned i) {
	std::fprintf(source_file, "\t\t\tswitch (token) {\n");

	if (generator->get_shifts().find(std::make_pair(i, symbol_t::make_nonterm(""))) != generator->get_shifts().end()) {
		std::fprintf(source_file, "\t\t\tcase 0:\n");
		std::fprintf(source_file, "\t\t\t\treturn 0;\n\n");
	}

	for (const auto &token : generator->get_terminals()) {
		auto it = generator->get_shifts().find(std::make_pair(i, token));
		if (it == generator->get_shifts().end())
			continue;

		if (token.get_type() == SYMBOL_TYPE_CHAR)
			std::fprintf(source_file, "\t\t\tcase '%c':\n", token.get_value()[0]);
		else
			std::fprintf(source_file, "\t\t\tcase %s%s:\n", token_prefix(), token.get_value().c_str());

		std::fprintf(source_file, "\t\t\t\tparser->stack[++parser->top].state = %u;\n", unsigned(it->second));
		std::fprintf(source_file, "\t\t\t\tparser->stack[parser->top].value.token = *value;\n");
		std::fprintf(source_file, "\t\t\t\treturn 1;\n\n");
	}

	std::fprintf(source_file, "\t\t\tdefault:\n");
	std::fprintf(source_file, "\t\t\t\treturn -1;\n");

	std::fprintf(source_file, "\t\t\t}\n");
}

void output_t::emit_state_reduce(const item_t &item, int rule_id) {
	const auto &rhs = item.get_rhs();
	if (rhs.size())
		std::fprintf(source_file, "\t\t\tparser->top -= %u;\n", unsigned(rhs.size()));

	if (rule_id >= 0) {
		const std::string &type = generator->get_nonterm_type(item.get_lhs());

		std::fprintf(source_file, "\t\t\t");
		if (!type.empty())
			std::fprintf(source_file, "parser->stack[parser->top].value.symbol_%s = ", item.get_lhs().c_str());
		std::fprintf(source_file, "%sreduce_%i(", prefix(), rule_id);

		bool empty = true;
		const auto &vars = std::get<1>(generator->get_rules()[rule_id]);
		for (unsigned i = 0; i < vars.size(); i++) {
			const std::string &var = vars[i];
			if (var.empty())
				continue;

			if (!empty)
				std::fprintf(source_file, ", ");

			std::fprintf(source_file, "parser->stack[parser->top + %u].value.%s", i, symbol_values[rhs[i]].c_str());
			empty = false;
		}

		std::fprintf(source_file, ");\n");
	}

	std::vector<std::pair<unsigned, unsigned>> gotos;

	for (size_t i = 0; i < generator->get_state_count(); i++) {
		auto it = generator->get_gotos().find(std::make_pair(i, item.get_lhs()));
		if (it == generator->get_gotos().end())
			continue;

		gotos.emplace_back(i, it->second);
	}

	if (gotos.size() == 1) {
		std::fprintf(source_file, "\t\t\tparser->stack[++parser->top].state = %u;\n", gotos[0].second);
	}
	else {
		std::fprintf(source_file, "\t\t\tswitch (parser->stack[parser->top].state) {\n");

		for (size_t i = 0; i < generator->get_state_count(); i++) {
			auto it = generator->get_gotos().find(std::make_pair(i, item.get_lhs()));
			if (it == generator->get_gotos().end())
				continue;

			std::fprintf(source_file, "\t\t\tcase %u:\n", unsigned(i));
			std::fprintf(source_file, "\t\t\t\tparser->stack[++parser->top].state = %u;\n", unsigned(it->second));
			std::fprintf(source_file, "\t\t\t\tbreak;\n");
		}


		std::fprintf(source_file, "\t\t\t}\n");
	}
}

void output_t::emit_state(unsigned i) {
	std::fprintf(source_file, "\t\tcase %u:\n", i);

	auto it = generator->get_reductions().find(i);
	if (it == generator->get_reductions().end()) {
		emit_state_shift(i);
	}
	else {
		const auto &rule = generator->get_rules()[it->second];
		emit_state_reduce(std::get<0>(rule), std::get<2>(rule).empty() ? -1 : it->second);
	}

	std::fprintf(source_file, "\t\t\tbreak;\n\n");
}

void output_t::emit_states() {
	for (size_t i = 0; i < generator->get_state_count(); i++)
		emit_state(i);
}

void output_t::emit_header_include() {
#ifdef _WIN32
	const char sep = '\\';
#else
	const char sep = '/';
#endif

	const char *slash = std::strrchr(header_filename.c_str(), sep);
	const char *basename = slash ? slash+1 : header_filename.c_str();

	std::fprintf(source_file, "#include \"%s\"\n\n\n", basename);
}

void output_t::emit_source() {
	emit_header_include();

	std::fprintf(source_file, "typedef union %ssymbol_value {\n", prefix());
	std::fprintf(source_file, "\t%stoken_value_t token;\n", prefix());

	for (const auto &nonterm : generator->get_nonterminals()) {
		const std::string &type = generator->get_nonterm_type(nonterm);

		if (!type.empty())
			std::fprintf(source_file, "\t%s symbol_%s;\n", type.c_str(), nonterm.c_str());
	}

	std::fprintf(source_file, "} %ssymbol_value_t;\n\n", prefix());

	std::fprintf(source_file, "typedef struct %scontext_state {\n", prefix());
	std::fprintf(source_file, "\tunsigned state;\n");
	std::fprintf(source_file, "\t%ssymbol_value_t value;\n", prefix());
	std::fprintf(source_file, "} %scontext_state_t;\n\n", prefix());

	std::fprintf(source_file, "struct %scontext {\n", prefix());
	std::fprintf(source_file, "\tunsigned top;\n");
	std::fprintf(source_file, "\t%scontext_state_t stack[%u];\n", prefix(), stack_size);
	std::fprintf(source_file, "};\n\n");

	emit_reductions();

	std::fprintf(source_file, "int %spush(%scontext_t *parser, int token, const %stoken_value_t *value) {\n", prefix(), prefix(), prefix());
	std::fprintf(source_file, "\twhile (1) {\n");
	std::fprintf(source_file, "\t\tswitch (parser->stack[parser->top].state) {\n");

	emit_states();

	std::fprintf(source_file, "\t\t}\n");
	std::fprintf(source_file, "\t}\n");
	std::fprintf(source_file, "}\n");
}

void output_t::write() {
	emit_header();
	emit_source();
}

}