/*
 * Copyright (C) 2012
 *     Wolfgang Bumiller
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include "gmqcc.h"
#include "lexer.h"

typedef struct {
	bool on;
	bool was_on;
	bool had_else;
} ppcondition;

typedef struct {
	lex_file    *lex;
	int          token;
	bool         newline;
	unsigned int errors;

	ppcondition *conditions;
} ftepp_t;

#define ftepp_tokval(f) ((f)->lex->tok.value)
#define ftepp_ctx(f)    ((f)->lex->tok.ctx)

static void ftepp_errorat(ftepp_t *ftepp, lex_ctx ctx, const char *fmt, ...)
{
	va_list ap;

	ftepp->errors++;

	va_start(ap, fmt);
    con_vprintmsg(LVL_ERROR, ctx.file, ctx.line, "error", fmt, ap);
	va_end(ap);
}

static void ftepp_error(ftepp_t *ftepp, const char *fmt, ...)
{
	va_list ap;

	ftepp->errors++;

	va_start(ap, fmt);
    con_vprintmsg(LVL_ERROR, ftepp->lex->tok.ctx.file, ftepp->lex->tok.ctx.line, "error", fmt, ap);
	va_end(ap);
}

ftepp_t* ftepp_init()
{
	ftepp_t *ftepp;

	ftepp = (ftepp_t*)mem_a(sizeof(*ftepp));
	memset(ftepp, 0, sizeof(*ftepp));

	return ftepp;
}

static inline int ftepp_next(ftepp_t *ftepp)
{
	return (ftepp->token = lex_do(ftepp->lex));
}

/* Important: this does not skip newlines! */
static bool ftepp_skipspace(ftepp_t *ftepp)
{
	while (ftepp_next(ftepp) == TOKEN_WHITE) {}
	return (ftepp->token < TOKEN_EOF);
}

static bool ftepp_if(ftepp_t *ftepp, ppcondition *cond)
{
	ftepp_error(ftepp, "TODO: #if");
	return false;
}

static bool ftepp_ifdef(ftepp_t *ftepp, ppcondition *cond)
{
	ftepp_error(ftepp, "TODO: #ifdef");
	return false;
}

static bool ftepp_define(ftepp_t *ftepp)
{
	ftepp_error(ftepp, "TODO: #define");
	return false;
}

static bool ftepp_else_allowed(ftepp_t *ftepp)
{
	if (!vec_size(ftepp->conditions)) {
		ftepp_error(ftepp, "#else without #if");
		return false;
	}
	if (vec_last(ftepp->conditions).had_else) {
		ftepp_error(ftepp, "multiple #else for a single #if");
		return false;
	}
	return true;
}

static bool ftepp_hash(ftepp_t *ftepp)
{
	ppcondition cond;
	ppcondition *pc;

	lex_ctx ctx = ftepp_ctx(ftepp);

	if (!ftepp_skipspace(ftepp))
		return false;

	switch (ftepp->token) {
		case TOKEN_IDENT:
			if (!strcmp(ftepp_tokval(ftepp), "define")) {
				return ftepp_define(ftepp);
			}
			else if (!strcmp(ftepp_tokval(ftepp), "ifdef")) {
				if (!ftepp_ifdef(ftepp, &cond))
					return false;
				vec_push(ftepp->conditions, cond);
				return true;
			}
			else if (!strcmp(ftepp_tokval(ftepp), "ifndef")) {
				if (!ftepp_ifdef(ftepp, &cond))
					return false;
				cond.on = !cond.on;
				vec_push(ftepp->conditions, cond);
				return true;
			}
			else if (!strcmp(ftepp_tokval(ftepp), "elifdef")) {
				if (!ftepp_else_allowed(ftepp))
					return false;
				if (!ftepp_ifdef(ftepp, &cond))
					return false;
				pc = &vec_last(ftepp->conditions);
				pc->on     = !pc->was_on && cond.on;
				pc->was_on = pc->was_on || pc->on;
				return true;
			}
			else if (!strcmp(ftepp_tokval(ftepp), "elifndef")) {
				if (!ftepp_else_allowed(ftepp))
					return false;
				if (!ftepp_ifdef(ftepp, &cond))
					return false;
				cond.on = !cond.on;
				pc = &vec_last(ftepp->conditions);
				pc->on     = !pc->was_on && cond.on;
				pc->was_on = pc->was_on || pc->on;
				return true;
			}
			else if (!strcmp(ftepp_tokval(ftepp), "elif")) {
				if (!ftepp_else_allowed(ftepp))
					return false;
				if (!ftepp_if(ftepp, &cond))
					return false;
				pc = &vec_last(ftepp->conditions);
				pc->on     = !pc->was_on && cond.on;
				pc->was_on = pc->was_on  || pc->on;
				return true;
			}
			else if (!strcmp(ftepp_tokval(ftepp), "if")) {
				if (!ftepp_if(ftepp, &cond))
					return false;
				vec_push(ftepp->conditions, cond);
				return true;
			}
			else if (!strcmp(ftepp_tokval(ftepp), "else")) {
				if (!ftepp_else_allowed(ftepp))
					return false;
				pc = &vec_last(ftepp->conditions);
				pc->on = !pc->was_on;
				pc->had_else = true;
				return true;
			}
			else if (!strcmp(ftepp_tokval(ftepp), "endif")) {
				if (!vec_size(ftepp->conditions)) {
					ftepp_error(ftepp, "#endif without #if");
					return false;
				}
				vec_pop(ftepp->conditions);
				break;
			}
			else {
				ftepp_error(ftepp, "unrecognized preprocessor directive: `%s`", ftepp_tokval(ftepp));
				return false;
			}
			break;
		case TOKEN_KEYWORD:
			if (!strcmp(ftepp_tokval(ftepp), "if")) {
				if (!ftepp_if(ftepp, &cond))
					return false;
				vec_push(ftepp->conditions, cond);
				return true;
			}
		/* fall through */
		default:
			ftepp_error(ftepp, "unexpected preprocessor token: `%s`", ftepp_tokval(ftepp));
			return false;
		case TOKEN_EOL:
			ftepp_errorat(ftepp, ctx, "empty preprocessor directive");
			return false;
		case TOKEN_EOF:
			ftepp_error(ftepp, "missing newline at end of file", ftepp_tokval(ftepp));
			return false;
	}
	return true;
}

static bool ftepp_preprocess(ftepp_t *ftepp)
{
	bool newline = true;

	ftepp->lex->flags.preprocessing = true;

	do
	{
		ftepp_next(ftepp);

		if (ftepp->token >= TOKEN_EOF)
			break;

		ftepp->newline = newline;
		newline = false;

		switch (ftepp->token) {
			case '#':
				if (!ftepp->newline) {
					printf("%s", ftepp_tokval(ftepp));
					break;
				}
				if (!ftepp_hash(ftepp))
					return false;
				break;
			case TOKEN_EOL:
				newline = true;
				printf("\n");
				break;
			default:
				printf("%s", ftepp_tokval(ftepp));
				break;
		}
	} while (!ftepp->errors && ftepp->token < TOKEN_EOF);

	return (ftepp->token == TOKEN_EOF);
}

bool ftepp_preprocess_file(const char *filename)
{
	ftepp_t *ftepp = ftepp_init();
    ftepp->lex = lex_open(filename);
    if (!ftepp->lex) {
        con_out("failed to open file \"%s\"\n", filename);
        return false;
    }
    return ftepp_preprocess(ftepp);
}

bool ftepp_preprocess_string(const char *name, const char *str)
{
	ftepp_t *ftepp = ftepp_init();
    ftepp->lex = lex_open_string(str, strlen(str), name);
    if (!ftepp->lex) {
        con_out("failed to create lexer for string \"%s\"\n", name);
        return false;
    }
    return ftepp_preprocess(ftepp);
}