/*
 * Copyright (c) 2011, Vicent Marti
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "buffer.h"
#include "html.h"

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>

#if defined(_WIN32)
#define snprintf _snprintf
#endif

struct smartypants_data
{
    int in_squote;
    int in_dquote;
};

static size_t smartypants_cb__ltag( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size );
static size_t smartypants_cb__dquote( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size );
static size_t smartypants_cb__amp( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size );
static size_t smartypants_cb__period( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size );
static size_t smartypants_cb__number( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size );
static size_t smartypants_cb__dash( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size );
static size_t smartypants_cb__parens( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size );
static size_t smartypants_cb__squote( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size );
static size_t smartypants_cb__backtick( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size );
static size_t smartypants_cb__escape( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size );

static size_t( *smartypants_cb_ptrs[] )
    ( struct buf*, struct smartypants_data*, uint8_t, const uint8_t*, size_t ) =
{
    NULL,                       /* 0 */
    smartypants_cb__dash,       /* 1 */
    smartypants_cb__parens,     /* 2 */
    smartypants_cb__squote,     /* 3 */
    smartypants_cb__dquote,     /* 4 */
    smartypants_cb__amp,        /* 5 */
    smartypants_cb__period,     /* 6 */
    smartypants_cb__number,     /* 7 */
    smartypants_cb__ltag,       /* 8 */
    smartypants_cb__backtick,   /* 9 */
    smartypants_cb__escape,     /* 10 */
};

static const uint8_t smartypants_cb_chars[] =
{
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 4, 0, 0, 0, 5, 3, 2, 0, 0, 0,  0, 1, 6, 0,
    0, 7, 0, 7, 0, 0, 0, 0, 0, 0, 0, 0,  8, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 0, 0, 0,
    9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0,
};

static inline int word_boundary( uint8_t c )
{
    return c == 0 || isspace( c ) || ispunct( c );
}


static int smartypants_quotes( struct buf* ob,
        uint8_t previous_char,
        uint8_t next_char,
        uint8_t quote,
        int* is_open )
{
    char ent[8];

    if( *is_open && !word_boundary( next_char ) )
        return 0;

    if( !(*is_open) && !word_boundary( previous_char ) )
        return 0;

    snprintf( ent, sizeof(ent), "&%c%cquo;", (*is_open) ? 'r' : 'l', quote );
    *is_open = !(*is_open);
    bufputs( ob, ent );
    return 1;
}


static size_t smartypants_cb__squote( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size )
{
    if( size >= 2 )
    {
        uint8_t t1 = tolower( text[1] );

        if( t1 == '\'' )
        {
            if( smartypants_quotes( ob, previous_char, size >= 3 ? text[2] : 0, 'd',
                        &smrt->in_dquote ) )
                return 1;
        }

        if( (t1 == 's' || t1 == 't' || t1 == 'm' || t1 == 'd')
            && ( size == 3 || word_boundary( text[2] ) ) )
        {
            BUFPUTSL( ob, "&rsquo;" );
            return 0;
        }

        if( size >= 3 )
        {
            uint8_t t2 = tolower( text[2] );

            if( ( (t1 == 'r' && t2 == 'e')
                  || (t1 == 'l' && t2 == 'l')
                  || (t1 == 'v' && t2 == 'e') )
                && ( size == 4 || word_boundary( text[3] ) ) )
            {
                BUFPUTSL( ob, "&rsquo;" );
                return 0;
            }
        }
    }

    if( smartypants_quotes( ob, previous_char, size > 0 ? text[1] : 0, 's', &smrt->in_squote ) )
        return 0;

    bufputc( ob, text[0] );
    return 0;
}


static size_t smartypants_cb__parens( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size )
{
    if( size >= 3 )
    {
        uint8_t t1  = tolower( text[1] );
        uint8_t t2  = tolower( text[2] );

        if( t1 == 'c' && t2 == ')' )
        {
            BUFPUTSL( ob, "&copy;" );
            return 2;
        }

        if( t1 == 'r' && t2 == ')' )
        {
            BUFPUTSL( ob, "&reg;" );
            return 2;
        }

        if( size >= 4 && t1 == 't' && t2 == 'm' && text[3] == ')' )
        {
            BUFPUTSL( ob, "&trade;" );
            return 3;
        }
    }

    bufputc( ob, text[0] );
    return 0;
}


static size_t smartypants_cb__dash( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size )
{
    if( size >= 3 && text[1] == '-' && text[2] == '-' )
    {
        BUFPUTSL( ob, "&mdash;" );
        return 2;
    }

    if( size >= 2 && text[1] == '-' )
    {
        BUFPUTSL( ob, "&ndash;" );
        return 1;
    }

    bufputc( ob, text[0] );
    return 0;
}


static size_t smartypants_cb__amp( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size )
{
    if( size >= 6 && memcmp( text, "&quot;", 6 ) == 0 )
    {
        if( smartypants_quotes( ob, previous_char, size >= 7 ? text[6] : 0, 'd',
                    &smrt->in_dquote ) )
            return 5;
    }

    if( size >= 4 && memcmp( text, "&#0;", 4 ) == 0 )
        return 3;

    bufputc( ob, '&' );
    return 0;
}


static size_t smartypants_cb__period( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size )
{
    if( size >= 3 && text[1] == '.' && text[2] == '.' )
    {
        BUFPUTSL( ob, "&hellip;" );
        return 2;
    }

    if( size >= 5 && text[1] == ' ' && text[2] == '.' && text[3] == ' ' && text[4] == '.' )
    {
        BUFPUTSL( ob, "&hellip;" );
        return 4;
    }

    bufputc( ob, text[0] );
    return 0;
}


static size_t smartypants_cb__backtick( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size )
{
    if( size >= 2 && text[1] == '`' )
    {
        if( smartypants_quotes( ob, previous_char, size >= 3 ? text[2] : 0, 'd',
                    &smrt->in_dquote ) )
            return 1;
    }

    return 0;
}


static size_t smartypants_cb__number( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size )
{
    if( word_boundary( previous_char ) && size >= 3 )
    {
        if( text[0] == '1' && text[1] == '/' && text[2] == '2' )
        {
            if( size == 3 || word_boundary( text[3] ) )
            {
                BUFPUTSL( ob, "&frac12;" );
                return 2;
            }
        }

        if( text[0] == '1' && text[1] == '/' && text[2] == '4' )
        {
            if( size == 3 || word_boundary( text[3] )
                || (size >= 5 && tolower( text[3] ) == 't' && tolower( text[4] ) == 'h') )
            {
                BUFPUTSL( ob, "&frac14;" );
                return 2;
            }
        }

        if( text[0] == '3' && text[1] == '/' && text[2] == '4' )
        {
            if( size == 3 || word_boundary( text[3] )
                || (size >= 6 && tolower( text[3] ) == 't' && tolower( text[4] ) == 'h'
                    && tolower( text[5] ) == 's') )
            {
                BUFPUTSL( ob, "&frac34;" );
                return 2;
            }
        }
    }

    bufputc( ob, text[0] );
    return 0;
}


static size_t smartypants_cb__dquote( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size )
{
    if( !smartypants_quotes( ob, previous_char, size > 0 ? text[1] : 0, 'd', &smrt->in_dquote ) )
        BUFPUTSL( ob, "&quot;" );

    return 0;
}


static size_t smartypants_cb__ltag( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size )
{
    static const char* skip_tags[] =
    {
        "pre", "code", "var", "samp", "kbd", "math", "script", "style"
    };
    static const size_t skip_tags_count = 8;

    size_t tag, i = 0;

    while( i < size && text[i] != '>' )
        i++;

    for( tag = 0; tag < skip_tags_count; ++tag )
    {
        if( sdhtml_is_tag( text, size, skip_tags[tag] ) == HTML_TAG_OPEN )
            break;
    }

    if( tag < skip_tags_count )
    {
        for( ; ; )
        {
            while( i < size && text[i] != '<' )
                i++;

            if( i == size )
                break;

            if( sdhtml_is_tag( text + i, size - i, skip_tags[tag] ) == HTML_TAG_CLOSE )
                break;

            i++;
        }

        while( i < size && text[i] != '>' )
            i++;
    }

    bufput( ob, text, i + 1 );
    return i;
}


static size_t smartypants_cb__escape( struct buf* ob,
        struct smartypants_data* smrt,
        uint8_t previous_char,
        const uint8_t* text,
        size_t size )
{
    if( size < 2 )
        return 0;

    switch( text[1] )
    {
    case '\\':
    case '"':
    case '\'':
    case '.':
    case '-':
    case '`':
        bufputc( ob, text[1] );
        return 1;

    default:
        bufputc( ob, '\\' );
        return 0;
    }
}


#if 0
static struct
{
    uint8_t c0;
    const uint8_t* pattern;
    const uint8_t* entity;
    int skip;
}
smartypants_subs[] =
{
    { '\'', "'s>",       "&rsquo;",          0 },
    { '\'', "'t>",       "&rsquo;",          0 },
    { '\'', "'re>",      "&rsquo;",          0 },
    { '\'', "'ll>",      "&rsquo;",          0 },
    { '\'', "'ve>",      "&rsquo;",          0 },
    { '\'', "'m>",       "&rsquo;",          0 },
    { '\'', "'d>",       "&rsquo;",          0 },
    { '-',  "--",        "&mdash;",          1 },
    { '-',  "<->",       "&ndash;",          0 },
    { '.',  "...",       "&hellip;",         2 },
    { '.',  ". . .",     "&hellip;",         4 },
    { '(',  "(c)",       "&copy;",           2 },
    { '(',  "(r)",       "&reg;",            2 },
    { '(',  "(tm)",      "&trade;",          3 },
    { '3',  "<3/4>",     "&frac34;",         2 },
    { '3',  "<3/4ths>",  "&frac34;",         2 },
    { '1',  "<1/2>",     "&frac12;",         2 },
    { '1',  "<1/4>",     "&frac14;",         2 },
    { '1',  "<1/4th>",   "&frac14;",         2 },
    { '&',  "&#0;",                    0,    3 },
};
#endif

void sdhtml_smartypants( struct buf* ob, const uint8_t* text, size_t size )
{
    size_t i;
    struct smartypants_data smrt = { 0, 0 };

    if( !text )
        return;

    bufgrow( ob, size );

    for( i = 0; i < size; ++i )
    {
        size_t org;
        uint8_t action = 0;

        org = i;

        while( i < size && (action = smartypants_cb_chars[text[i]]) == 0 )
            i++;

        if( i > org )
            bufput( ob, text + org, i - org );

        if( i < size )
        {
            i += smartypants_cb_ptrs[(int) action]
                     ( ob, &smrt, i ? text[i - 1] : 0, text + i, size - i );
        }
    }
}