/*
 * XML text mode for QEmacs.
 *
 * Copyright (c) 2002 Fabrice Bellard.
 * Copyright (c) 2014-2017 Charlie Gordon.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "qe.h"

/* colorization states */
enum {
    IN_XML_TAG = 1,
    IN_XML_COMMENT,
    IN_XML_TAG_SCRIPT,
    IN_XML_TAG_STYLE,
    IN_XML_SCRIPT = 0x80, /* Inside a script tag, ored with c-mode state */
    IN_XML_STYLE = 0x100, /* Inside a style tag, ored with c-mode state */
};

enum {
    XML_STYLE_COMMENT = QE_STYLE_COMMENT,
    XML_STYLE_TAG     = QE_STYLE_TAG,
    XML_STYLE_CSS     = QE_STYLE_CSS,
};

static int xml_tag_match(const unsigned int *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 xml_colorize_line(QEColorizeContext *cp,
                              unsigned int *str, int n, ModeDef *syn)
{
    int i = 0, start = i, c;
    int state = cp->colorize_state;

    /* XXX: should recognize and colorize entities, attribute strings */

    /* if already in a state, go directly in the code parsing it */
    if (state & IN_XML_SCRIPT)
        goto parse_script;
    if (state & IN_XML_STYLE)
        goto parse_style;

    switch (state) {
    case IN_XML_COMMENT:
        goto parse_comment;
    case IN_XML_TAG:
    case IN_XML_TAG_SCRIPT:
    case IN_XML_TAG_STYLE:
        goto parse_tag;
    default:
        break;
    }

    for (;;) {
        start = i;
        c = str[i++];

        if (c == '\0')
            break;

        if (c == '<' && state == 0) {
            if (str[i] == '!' && str[i + 1] == '-' && str[i + 2] == '-') {
                i += 3;
                state = IN_XML_COMMENT;
            parse_comment:
                /* scan for end of comment */
                for (; str[i] != '\0'; i++) {
                    if (str[i] == '-' && str[i + 1] == '-'
                    &&  str[i + 2] == '>') {
                        i += 3;
                        state = 0;
                        break;
                    }
                }
                SET_COLOR(str, start, i, XML_STYLE_COMMENT);
            } else {
                /* we are in a tag */
                if (xml_tag_match(str, i, "script", &i)) {
                    state = IN_XML_TAG_SCRIPT;
                } else
                if (xml_tag_match(str, i, "style", &i)) {
                    state = IN_XML_TAG_STYLE;
                }
            parse_tag:
                while (str[i] != '\0') {
                    c = str[i++];
                    if (c == '/' && str[i] == '>') {
                        i++;
                        state = 0;
                        break;
                    }
                    if (c == '>') {
                        if (state == IN_XML_TAG_SCRIPT)
                            state = IN_XML_SCRIPT;
                        else
                        if (state == IN_XML_TAG_STYLE)
                            state = IN_XML_STYLE;
                        else
                            state = 0;
                        break;
                    }
                }
                SET_COLOR(str, start, i, XML_STYLE_TAG);
                start = i;
                if (state & IN_XML_SCRIPT) {
                    /* javascript coloring */
                    /* XXX: should support actual scripting language if supported */
                parse_script:
                    for (; str[i] != '\0'; i++) {
                        if (str[i] == '<'
                        &&  xml_tag_match(str, i + 1, "/script", NULL)) {
                            break;
                        }
                    }
                    c = str[i];     /* save char to set '\0' delimiter */
                    str[i] = '\0';
                    state &= ~IN_XML_SCRIPT;
                    cp->colorize_state = state;
                    js_mode.colorize_func(cp, str + start, i - start, &js_mode);
                    state = cp->colorize_state;
                    state |= IN_XML_SCRIPT;
                    str[i] = c;
                    if (c) {
                        state = 0;
                    }
                    continue;
                } else
                if (state & IN_XML_STYLE) {
                    /* stylesheet coloring */
                parse_style:
                    for (; str[i] != '\0'; i++) {
                        if (str[i] == '<'
                        &&  xml_tag_match(str, i + 1, "/style", NULL)) {
                            break;
                        }
                    }
                    c = str[i];
                    str[i] = '\0';
                    state &= ~IN_XML_STYLE;
                    cp->colorize_state = state;
                    css_mode.colorize_func(cp, str + start, i - start, &css_mode);
                    state = cp->colorize_state;
                    state |= IN_XML_STYLE;
                    str[i] = c;
                    if (c) {
                        state = 0;
                    }
                }
            }
        }
    }
    cp->colorize_state = state;
}

static int xml_mode_probe(ModeDef *mode, ModeProbeData *p1)
{
    const u8 *p;

    p = p1->buf;
    while (qe_isspace(*p))
        p++;
    if (*p != '<')
        return 0;
    p++;
    if (*p != '!' && *p != '?' && !qe_isalpha(*p))
        return 0;

    return 60; /* leave some room for more specific XML parser */
}

ModeDef xml_mode = {
    .name = "xml",
    .mode_probe = xml_mode_probe,
    .colorize_func = xml_colorize_line,
};

static int xml_init(void)
{
    qe_register_mode(&xml_mode, MODEF_SYNTAX);

    return 0;
}

qe_module_init(xml_init);