/*
 * HTML Source mode for QEmacs.
 *
 * Copyright (c) 2000-2024 Charlie Gordon.
 *
 * 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 "qe.h"

static int get_html_entity(const char32_t *p) {
    const char32_t *p_start;
    char32_t c;

    p_start = p;
    c = *p;

    if (c != '&')
        return 0;

    c = *++p;
    if (c == '#') {
        c = *++p;
        if (c == 'x') {
            do {
                c = *++p;
            } while (qe_isxdigit(c));
        } else {
            while (qe_isdigit(c))
                c = *++p;
        }
    } else
    if (qe_isalpha(c)) {
        do {
            c = *++p;
        } while (qe_isalnum(c));
    } else {
        /* not an entity */
        return 0;
    }
    if (c == ';') {
        p++;
    }
    return p - p_start;
}

/* colorization states */
enum {
    IN_HTML_COMMENT    = 0x0001,      /* <!-- ... --> */
    IN_HTML_COMMENT1   = 0x0002,      /* <! ... > */
    IN_HTML_ENTITY     = 0x0004,      /* &name[;] / &#123[;] */
    IN_HTML_EMBEDDED   = 0x00ff,      /* flags for embedded php, js, css, c# */
    IN_HTML_TAG        = 0x0100,      /* <tag ... > */
    IN_HTML_STRING     = 0x0200,      /* <tag " ... " > */
    IN_HTML_STRING1    = 0x0400,      /* <tag ' ... ' > */
    IN_HTML_SCRIPT     = 0x1000,      /* <script> [...] </script> */
    IN_HTML_STYLE      = 0x2000,      /* <style> [...] </style> */
    IN_HTML_PHP        = 0x4000,      /* <?php ... ?> */
    IN_HTML_ASP        = 0x8000,      /* <% ... %> */
};

enum {
    HTML_STYLE_PREPROCESS = QE_STYLE_PREPROCESS,
    HTML_STYLE_COMMENT    = QE_STYLE_HTML_COMMENT,
    HTML_STYLE_COMMENT1   = QE_STYLE_HTML_COMMENT,
    HTML_STYLE_ENTITY     = QE_STYLE_HTML_ENTITY,
    HTML_STYLE_STRING     = QE_STYLE_HTML_STRING,
    HTML_STYLE_TAG        = QE_STYLE_HTML_TAG,
    HTML_STYLE_CSS        = QE_STYLE_CSS,
};

static int htmlsrc_tag_match(const char32_t *buf, int i, const char *str,
                             int *iend)
{
    int len;

    if (ustristart(buf + i, str, &len)
    &&  buf[i + len] != '-' && !qe_isalnum_(buf[i + len])) {
        if (iend)
            *iend = i + len;
        return 1;
    } else {
        return 0;
    }
}

static void htmlsrc_colorize_line(QEColorizeContext *cp,
                                  const char32_t *str, int n,
                                  QETermStyle *sbuf, ModeDef *syn)
{
    int i = 0, start, len;
    char32_t c;
    int state = cp->colorize_state;

    while (i < n) {
        start = i;

        if (state & IN_HTML_PHP) {
            for (; i < n; i++) {
                if (str[i] == '?' && str[i + 1] == '>')
                    break;
            }
            cp->colorize_state = state & IN_HTML_EMBEDDED;
            cp_colorize_line(cp, str, start, i, sbuf, &php_mode);
            state &= ~IN_HTML_EMBEDDED;
            state |= cp->colorize_state & IN_HTML_EMBEDDED;
            if (str[i]) {
                /* found ?> end tag */
                state &= ~(IN_HTML_EMBEDDED | IN_HTML_PHP);
                start = i;
                i += 2;
                SET_STYLE(sbuf, start, i, HTML_STYLE_PREPROCESS);
            }
            continue;
        }
        if (state & IN_HTML_ASP) {
            for (; i < n; i++) {
                if (str[i] == '%' && str[i + 1] == '>')
                    break;
            }
            cp->colorize_state = state & IN_HTML_EMBEDDED;
            cp_colorize_line(cp, str, start, i, sbuf, &csharp_mode);
            state &= ~IN_HTML_EMBEDDED;
            state |= cp->colorize_state & IN_HTML_EMBEDDED;
            if (str[i]) {
                /* found %> end tag */
                state &= ~(IN_HTML_EMBEDDED | IN_HTML_ASP);
                start = i;
                i += 2;
                SET_STYLE(sbuf, start, i, HTML_STYLE_PREPROCESS);
            }
            continue;
        }
        if ((state & (IN_HTML_SCRIPT | IN_HTML_TAG)) == IN_HTML_SCRIPT) {
            for (; i < n; i++) {
                if (str[i] == '<'
                &&  htmlsrc_tag_match(str, i + 1, "/script", NULL)) {
                    break;
                }
            }
            cp->colorize_state = state & IN_HTML_EMBEDDED;
            cp_colorize_line(cp, str, start, i, sbuf, &js_mode);
            state &= ~IN_HTML_EMBEDDED;
            state |= cp->colorize_state & IN_HTML_EMBEDDED;
            if (str[i]) {
                /* found </script> tag */
                state &= ~(IN_HTML_EMBEDDED | IN_HTML_SCRIPT);
            }
            continue;
        }
        if ((state & (IN_HTML_STYLE | IN_HTML_TAG)) == IN_HTML_STYLE) {
            for (; i < n; i++) {
                if (str[i] == '<'
                &&  htmlsrc_tag_match(str, i + 1, "/style", NULL)) {
                    break;
                }
            }
            cp->colorize_state = state & IN_HTML_EMBEDDED;
            cp_colorize_line(cp, str, start, i, sbuf, &css_mode);
            state &= ~IN_HTML_EMBEDDED;
            state |= cp->colorize_state & IN_HTML_EMBEDDED;
            if (str[i]) {
                /* found </style> tag */
                state &= ~(IN_HTML_EMBEDDED | IN_HTML_STYLE);
            }
            continue;
        }
        if (state & IN_HTML_COMMENT) {
            for (; i < n; i++) {
                if (str[i] == '-' && str[i + 1] == '-' && str[i + 2] == '>') {
                    i += 3;
                    state &= ~(IN_HTML_COMMENT | IN_HTML_COMMENT1);
                    break;
                }
            }
            SET_STYLE(sbuf, start, i, HTML_STYLE_COMMENT);
            continue;
        }
        if (state & IN_HTML_COMMENT1) {
            for (; i < n; i++) {
                if (str[i] == '>') {
                    i++;
                    state &= ~IN_HTML_COMMENT1;
                    break;
                }
            }
            SET_STYLE(sbuf, start, i, HTML_STYLE_COMMENT1);
            continue;
        }
        if (state & IN_HTML_ENTITY) {
            if ((len = get_html_entity(str + i)) == 0)
                i++;
            else
                i += len;
            state &= ~IN_HTML_ENTITY;
            SET_STYLE(sbuf, start, i, HTML_STYLE_ENTITY);
            continue;
        }
        if (state & (IN_HTML_STRING | IN_HTML_STRING1)) {
            char32_t delim = (state & IN_HTML_STRING1) ? '\'' : '\"';

            for (; i < n; i++) {
                if (str[i] == '&' && get_html_entity(str + i)) {
                    state |= IN_HTML_ENTITY;
                    break;
                }
                if (str[i] == delim) {
                    i++;
                    state &= ~(IN_HTML_STRING | IN_HTML_STRING1);
                    break;
                }
                if (str[i] == '<'
                &&  htmlsrc_tag_match(str, i, "<?php", NULL)) {
                    SET_STYLE(sbuf, start, i, HTML_STYLE_STRING);
                    SET_STYLE(sbuf, i, i + 5, HTML_STYLE_PREPROCESS);
                    i += 5;
                    start = i;
                    state |= IN_HTML_PHP;
                    break;
                } else
                if (str[i] == '<' && str[i + 1] == '%') {
                    SET_STYLE(sbuf, start, i, HTML_STYLE_STRING);
                    SET_STYLE(sbuf, i, i + 2, HTML_STYLE_PREPROCESS);
                    i += 2;
                    start = i;
                    state |= IN_HTML_ASP;
                    break;
                } else
                if (str[i] == '?' && str[i + 1] == '>') {
                    /* special case embedded php script tags */
                    i += 1;
                } else
                if (str[i] == '%' && str[i + 1] == '>') {
                    /* special case embedded asp script tags */
                    i += 1;
                } else
                if (str[i] == '>') {
                    /* Premature end of string */
                    state &= ~(IN_HTML_STRING | IN_HTML_STRING1);
                    break;
                }
            }
            SET_STYLE(sbuf, start, i, HTML_STYLE_STRING);
            continue;
        }
        if (state & IN_HTML_TAG) {
            for (; i < n; i++) {
                c = str[i];
                if (c == '&' && get_html_entity(str + i)) {
                    state |= IN_HTML_ENTITY;
                    break;
                }
                if (c == '\"') {
                    state |= IN_HTML_STRING;
                    break;
                }
                if (c == '\'') {
                    state |= IN_HTML_STRING1;
                    break;
                }
                if (c == '/' && str[i + 1] == '>') {
                    i += 2;
                    state = 0;
                    break;
                }
                if (c == '>') {
                    i++;
                    state &= ~IN_HTML_TAG;
                    break;
                }
            }
            SET_STYLE(sbuf, start, i, HTML_STYLE_TAG);
            if (state & (IN_HTML_STRING | IN_HTML_STRING1)) {
                SET_STYLE1(sbuf, i, HTML_STYLE_STRING);
                i++;
            }
            continue;
        }
        /* Plain text stream */
        for (; i < n; i++) {
            start = i;
            c = str[i];

            /* Kludge for preprocessed html */
            if (c == '#' && i == 0) {
                i = n;
                SET_STYLE(sbuf, start, i, HTML_STYLE_PREPROCESS);
                break;
            }
            if (c == '<'
            &&  htmlsrc_tag_match(str, i, "<?php", &i)) {
                SET_STYLE(sbuf, start, i, HTML_STYLE_PREPROCESS);
                state |= IN_HTML_PHP;
                break;
            }
            if (c == '<' && str[i + 1] == '%') {
                i += 2;
                SET_STYLE(sbuf, start, i, HTML_STYLE_PREPROCESS);
                state |= IN_HTML_ASP;
                break;
            }
            if (c == '<'
            &&  (qe_isalpha(str[i + 1]) || str[i + 1] == '!'
            ||   str[i + 1] == '/' || str[i + 1] == '?')) {
                state |= IN_HTML_TAG;
                if (htmlsrc_tag_match(str, i, "<script", NULL)) {
                    state |= IN_HTML_SCRIPT;
                    break;
                }
                if (htmlsrc_tag_match(str, i, "<style", NULL)) {
                    state |= IN_HTML_STYLE;
                    break;
                }
                if (str[i + 1] == '!') {
                    state ^= IN_HTML_TAG ^ IN_HTML_COMMENT1;
                    i += 2;
                    if (str[i] == '-' && str[i + 1] == '-') {
                        i += 2;
                        state ^= IN_HTML_COMMENT ^ IN_HTML_COMMENT1;
                    }
                    SET_STYLE(sbuf, start, i, HTML_STYLE_COMMENT);
                }
                break;
            }
            if (str[i] == '&' && get_html_entity(str + i)) {
                state |= IN_HTML_ENTITY;
                break;
            }
        }
    }
    cp->colorize_state = state;
}

static int html_tagcmp(const char *s1, const char *s2) {
    while (*s2) {
        u8 uc1 = *s1++;
        u8 uc2 = *s2++;
        int d = uc2 - qe_toupper(uc1);
        if (d)
            return d;
    }
    if (qe_isalnum_(*s1))
        return -1;
    return 0;
}

static int htmlsrc_mode_probe(ModeDef *mode, ModeProbeData *p)
{
    const char *buf = cs8(p->buf);
    static const unsigned char scores[3] = { 1, 80, 85 };
    const unsigned char *pscore = scores;

    /* first check file extension */
    if (match_extension(p->filename, mode->extensions))
        pscore++;

    /* then try buffer contents */
    if (buf[0] == '<'
    &&  (!html_tagcmp(buf, "<HTML") ||
         !html_tagcmp(buf, "<SCRIPT") ||
         !html_tagcmp(buf, "<?XML") ||
         !html_tagcmp(buf, "<PLIST") ||
         !html_tagcmp(buf, "<!DOCTYPE"))) {
         pscore++;
    }

    return *pscore;
}

/* specific htmlsrc commands */
/* CG: need move / kill by tag level */
#if 0
static const CmdDef htmlsrc_commands[] = {
};
#endif

ModeDef htmlsrc_mode = {
    .name = "html-src",
    .extensions = "html|htm|asp|aspx|shtml|hta|htp|phtml|"
                  "php|php3|php4|xml|eex|plist",
    .mode_probe = htmlsrc_mode_probe,
    .colorize_func = htmlsrc_colorize_line,
};

static int htmlsrc_init(QEmacsState *qs)
{
    qe_register_mode(qs, &htmlsrc_mode, MODEF_SYNTAX);
    //qe_register_commands(qs, &htmlsrc_mode, htmlsrc_commands, countof(htmlsrc_commands));
    return 0;
}

qe_module_init(htmlsrc_init);