#
# blogc: A blog compiler.
# Copyright (C) 2015 Rafael G. Martins <rafael@rafaelmartins.eng.br>
#
# This program can be distributed under the terms of the BSD License.
# See the file COPYING.
#

%{

#include <stdio.h>
#include "utils/utils.h"
#include "template-grammar.h"

#define YY_INPUT(buf, result, max_size)                          \
{                                                                \
    int yyc = (charbuf && *charbuf != '\0') ? *charbuf++ : EOF;  \
    result = (EOF == yyc) ? 0 : (*buf = yyc, 1);                 \
}


static b_slist_t *stmts = NULL;
static int if_count = 0;
static int block_count = 0;
static const char *charbuf = NULL;


static void
blogc_template_if_stmt(const char *value)
{
    if (block_count <= 0) {
        fprintf(stderr, "Syntax error: {" "%% if ... %%" "} statement before "
            "any {" "%% block ... %%" "} statement\n");
        exit(1);
    }
    blogc_template_stmt_t *stmt = malloc(sizeof(blogc_template_stmt_t));
    stmt->value = b_strdup(value);
    stmt->type = BLOGC_TEMPLATE_IF_STMT;
    stmts = b_slist_append(stmts, stmt);
    if_count++;
}


static void
blogc_template_else_stmt(void)
{
    if (if_count <= 0) {
        fprintf(stderr, "Syntax error: {" "%% else %%" "} statement without "
            "any open {" "%% if ... %%" "} statement\n");
        exit(1);
    }
    blogc_template_stmt_t *stmt = malloc(sizeof(blogc_template_stmt_t));
    stmt->value = NULL;
    stmt->type = BLOGC_TEMPLATE_ELSE_STMT;
    stmts = b_slist_append(stmts, stmt);
}


static void
blogc_template_endif_stmt(void)
{
    if (if_count-- <= 0) {
        fprintf(stderr, "Syntax error: {" "%% endif %%" "} statement before "
            "any {" "%% if ... %%" "} statement\n");
        exit(1);
    }
    blogc_template_stmt_t *stmt = malloc(sizeof(blogc_template_stmt_t));
    stmt->value = NULL;
    stmt->type = BLOGC_TEMPLATE_ENDIF_STMT;
    stmts = b_slist_append(stmts, stmt);
}


static void
blogc_template_block_stmt(const char *value)
{
    if (block_count > 0) {
        fprintf(stderr, "Syntax error: {" "%% block %%" "} statements "
            "can't be nested\n");
        exit(1);
    }
    blogc_template_stmt_t *stmt = malloc(sizeof(blogc_template_stmt_t));
    stmt->value = b_strdup(value);
    stmt->type = BLOGC_TEMPLATE_BLOCK_STMT;
    stmts = b_slist_append(stmts, stmt);
    block_count++;
}


static void
blogc_template_endblock_stmt(void)
{
    if (block_count-- <= 0) {
        fprintf(stderr, "Syntax error: {" "%% endblock %%" "} statement before "
            "any {" "%% block ... %%" "} statement\n");
        exit(1);
    }
    blogc_template_stmt_t *stmt = malloc(sizeof(blogc_template_stmt_t));
    stmt->value = NULL;
    stmt->type = BLOGC_TEMPLATE_ENDBLOCK_STMT;
    stmts = b_slist_append(stmts, stmt);
}


static void
blogc_template_variable_stmt(const char *value)
{
    if (block_count <= 0) {
        fprintf(stderr, "Syntax error: {{ ... }} statement before "
            "any {" "%% block ... %%" "} statement\n");
        exit(1);
    }
    blogc_template_stmt_t *stmt = malloc(sizeof(blogc_template_stmt_t));
    stmt->value = b_strdup(value);
    stmt->type = BLOGC_TEMPLATE_VARIABLE_STMT;
    stmts = b_slist_append(stmts, stmt);
}


static void
blogc_template_content_stmt(const char *value)
{
    blogc_template_stmt_t *stmt = malloc(sizeof(blogc_template_stmt_t));
    stmt->value = b_strdup(value);
    stmt->type = BLOGC_TEMPLATE_CONTENT_STMT;
    stmts = b_slist_append(stmts, stmt);
}

%}

page = if | else | endif | block | endblock | print | content | anything
    { fprintf(stderr, "Syntax error near: %s\n", yytext); exit(1); }


# Useful rules
eol = '\n' | '\r\n' | '\r'
eof = !.
- = [\t ]*
id = [A-Z][A-Z0-9_]*
anything = < ( !eol . )* > eol

# Conditionals
if_open = '{%' -
if_close = - '%}'
if = if_open 'if' ' '+ < id > if_close  { blogc_template_if_stmt(yytext); }
else = if_open 'else' if_close          { blogc_template_else_stmt(); }
endif = if_open 'endif' if_close        { blogc_template_endif_stmt(); }

# Blocks
block_open = '{%' -
block_close = - '%}'
block_name = ( 'single_source' | 'multiple_sources_once' | 'multiple_sources' )
block = block_open 'block' ' '+ < block_name > block_close  { blogc_template_block_stmt(yytext); }
endblock = block_open 'endblock' block_close                { blogc_template_endblock_stmt(); }

# Print calls
print_open = '{{' -
print_close = - '}}'
print_var = < id >                      { blogc_template_variable_stmt(yytext); }
print = print_open print_var print_close

# Generic content
content = < ( !eof !if_open !if_close !block_open !block_close !print_open !print_close . )+ >
    { blogc_template_content_stmt(yytext); }

%%


void
blogc_template_free_stmts(b_slist_t *stmts)
{
    for (b_slist_t *tmp = stmts; tmp != NULL; tmp = tmp->next) {
        blogc_template_stmt_t *data = tmp->data;
        free(data->value);
        free(data);
    }
    b_slist_free(stmts);
}


b_slist_t*
blogc_template_parse(const char *tmpl)
{
    if_count = 0;
    block_count = 0;
    charbuf = tmpl;
    while(yyparse());
    if (if_count != 0) {
        fprintf(stderr, "Syntax error: You left %d open {" "%% if ... %%" "} statements.\n", if_count);
        exit(1);
    }
    if (block_count != 0) {
        fprintf(stderr, "Syntax error: You left %d open {" "%% block ... %%" "} statements.\n", block_count);
        exit(1);
    }
    b_slist_t *rv = stmts;
    charbuf = NULL;
    stmts = NULL;
    return rv;
}