path: root/src/html/html.c

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

#include "config.h"
#include "cmark.h"
#include "node.h"
#include "buffer.h"
#include "debug.h"
#include "html/houdini.h"

typedef struct RenderStack {
    struct RenderStack *previous;
    const char* literal;
    cmark_node* next_sibling;
    bool tight;
    bool trim;
} render_stack;

static void free_render_stack(render_stack * rstack)
{
    render_stack * tempstack;
    while (rstack) {
        tempstack = rstack;
        rstack = rstack->previous;
        free(tempstack);
    }
}

static render_stack* push_render_stack(render_stack* rstack,
                       cmark_node* node,
                       const char* literal)
{
    render_stack* newstack;
    newstack = (render_stack*)malloc(sizeof(render_stack));
    if (newstack == NULL) {
        return NULL;
    }
    newstack->previous = rstack;
    newstack->next_sibling = node;
    newstack->literal = literal;
    newstack->tight = false;
    newstack->trim = false;
    return newstack;
}

static render_stack* pop_render_stack(render_stack* rstack)
{
    render_stack* top = rstack;

    if (rstack == NULL) {
        return NULL;
    }
    rstack = rstack->previous;
    top->previous = NULL;
    free_render_stack(top);
    return rstack;
}

// Functions to convert cmark_node and inline lists to HTML strings.

static void escape_html(strbuf *dest, const unsigned char *source, int length)
{
    if (length < 0)
        length = strlen((char *)source);

    houdini_escape_html0(dest, source, (size_t)length, 0);
}

static void escape_href(strbuf *dest, const unsigned char *source, int length)
{
    if (length < 0)
        length = strlen((char *)source);

    houdini_escape_href(dest, source, (size_t)length);
}

static inline void cr(strbuf *html)
{
    if (html->size && html->ptr[html->size - 1] != '\n')
        strbuf_putc(html, '\n');
}

// Convert an inline list to HTML.  Returns 0 on success, and sets result.
static void inlines_to_plain_html(strbuf *html, cmark_node* ils)
{
    cmark_node* children;
    bool visit_children;
    render_stack* rstack = NULL;

    while(ils != NULL) {
        visit_children = false;
        switch(ils->type) {
        case NODE_STRING:
        case NODE_INLINE_CODE:
        case NODE_INLINE_HTML:
            escape_html(html, ils->as.literal.data, ils->as.literal.len);
            break;

        case NODE_LINEBREAK:
        case NODE_SOFTBREAK:
            strbuf_putc(html, '\n');
            break;

        case NODE_LINK:
        case NODE_IMAGE:
        case NODE_STRONG:
        case NODE_EMPH:
            children = ils->first_child;
            visit_children = true;
            rstack = push_render_stack(rstack, ils->next, "");
            break;
        default:
            break;
        }
        if (visit_children) {
            ils = children;
        } else {
            ils = ils->next;
        }
        while (ils == NULL && rstack != NULL) {
            strbuf_puts(html, rstack->literal);
            ils = rstack->next_sibling;
            rstack = pop_render_stack(rstack);
        }
    }

    free_render_stack(rstack);
}


// Convert an inline list to HTML.  Returns 0 on success, and sets result.
static void inlines_to_html(strbuf *html, cmark_node* ils)
{
    bool visit_children;
    render_stack* rstack = NULL;

    while(ils != NULL) {
            visit_children = false;
        switch(ils->type) {
        case NODE_STRING:
            escape_html(html, ils->as.literal.data, ils->as.literal.len);
            break;

        case NODE_LINEBREAK:
            strbuf_puts(html, "<br />\n");
            break;

        case NODE_SOFTBREAK:
            strbuf_putc(html, '\n');
            break;

        case NODE_INLINE_CODE:
            strbuf_puts(html, "<code>");
            escape_html(html, ils->as.literal.data, ils->as.literal.len);
            strbuf_puts(html, "</code>");
            break;

        case NODE_INLINE_HTML:
            strbuf_put(html,
                   ils->as.literal.data,
                   ils->as.literal.len);
            break;

        case NODE_LINK:
            strbuf_puts(html, "<a href=\"");
            if (ils->as.link.url)
                escape_href(html, ils->as.link.url, -1);

            if (ils->as.link.title) {
                strbuf_puts(html, "\" title=\"");
                escape_html(html, ils->as.link.title, -1);
            }

            strbuf_puts(html, "\">");
            visit_children = true;
            rstack = push_render_stack(rstack, ils->next, "</a>");
            break;

        case NODE_IMAGE:
            strbuf_puts(html, "<img src=\"");
            if (ils->as.link.url)
                escape_href(html, ils->as.link.url, -1);

            strbuf_puts(html, "\" alt=\"");
            inlines_to_plain_html(html, ils->first_child);

            if (ils->as.link.title) {
                strbuf_puts(html, "\" title=\"");
                escape_html(html, ils->as.link.title, -1);
            }

            strbuf_puts(html, "\" />");
            break;

        case NODE_STRONG:
            strbuf_puts(html, "<strong>");
            visit_children = true;
            rstack = push_render_stack(rstack, ils->next, "</strong>");
            break;

        case NODE_EMPH:
            strbuf_puts(html, "<em>");
            visit_children = true;
            rstack = push_render_stack(rstack, ils->next, "</em>");
            break;
        default:
            break;
        }
        if (visit_children) {
            ils = ils->first_child;
        } else {
            ils = ils->next;
        }
        while (ils == NULL && rstack != NULL) {
            strbuf_puts(html, rstack->literal);
            ils = rstack->next_sibling;
            rstack = pop_render_stack(rstack);
        }
    }

    free_render_stack(rstack);
}

// Convert a cmark_node list to HTML.  Returns 0 on success, and sets result.
static void blocks_to_html(strbuf *html, cmark_node *b)
{
    cmark_list *data;
    render_stack* rstack = NULL;
    bool visit_children = false;
    bool tight = false;

    while(b != NULL) {
        visit_children = false;
        switch(b->type) {
        case NODE_DOCUMENT:
            rstack = push_render_stack(rstack, b->next, "");
            rstack->tight = false;
            rstack->trim = false;
            visit_children = true;
            break;

        case NODE_PARAGRAPH:
            if (tight) {
                inlines_to_html(html, b->first_child);
            } else {
                cr(html);
                strbuf_puts(html, "<p>");
                inlines_to_html(html, b->first_child);
                strbuf_puts(html, "</p>\n");
            }
            break;

        case NODE_BQUOTE:
            cr(html);
            strbuf_puts(html, "<blockquote>\n");
            rstack = push_render_stack(rstack, b->next, "</blockquote>\n");
            rstack->tight = tight;
            rstack->trim = false;
            tight = false;
            visit_children = true;
            break;

        case NODE_LIST_ITEM:
            cr(html);
            strbuf_puts(html, "<li>");
            rstack = push_render_stack(rstack, b->next, "</li>\n");
            rstack->tight = tight;
            rstack->trim = true;
            visit_children = true;
            break;

        case NODE_LIST:
            // make sure a list starts at the beginning of the line:
            cr(html);
            data = &(b->as.list);

            if (data->start > 1) {
                strbuf_printf(html, "<%s start=\"%d\">\n",
                          data->list_type == CMARK_BULLET_LIST ? "ul" : "ol",
                          data->start);
            } else {
                strbuf_puts(html, data->list_type == CMARK_BULLET_LIST ? "<ul>\n" : "<ol>\n");
            }

            rstack = push_render_stack(rstack, b->next,
                           data->list_type == CMARK_BULLET_LIST ?
                           "\n</ul>\n" : "\n</ol>\n");
            rstack->tight = tight;
            rstack->trim = false;
            tight = data->tight;
            visit_children = true;
            break;

        case NODE_ATX_HEADER:
        case NODE_SETEXT_HEADER:
            cr(html);
            strbuf_printf(html, "<h%d>", b->as.header.level);
            inlines_to_html(html, b->first_child);
            strbuf_printf(html, "</h%d>\n", b->as.header.level);
            break;

        case NODE_INDENTED_CODE:
        case NODE_FENCED_CODE:
            cr(html);

            strbuf_puts(html, "<pre><code");

            if (b->type == NODE_FENCED_CODE) {
                strbuf *info = &b->as.code.info;

                if (strbuf_len(info) > 0) {
                    int first_tag = strbuf_strchr(info, ' ', 0);
                    if (first_tag < 0)
                        first_tag = strbuf_len(info);

                    strbuf_puts(html, " class=\"language-");
                    escape_html(html, info->ptr, first_tag);
                    strbuf_putc(html, '"');
                }
            }

            strbuf_putc(html, '>');
            escape_html(html, b->string_content.ptr, b->string_content.size);
            strbuf_puts(html, "</code></pre>\n");
            break;

        case NODE_HTML:
            strbuf_put(html, b->string_content.ptr, b->string_content.size);
            break;

        case NODE_HRULE:
            strbuf_puts(html, "<hr />\n");
            break;

        case NODE_REFERENCE_DEF:
            break;

        default:
            assert(false);
        }
        if (visit_children) {
            b = b->first_child;
        } else {
            b = b->next;
        }
        while (b == NULL && rstack != NULL) {
            strbuf_puts(html, rstack->literal);
            if (rstack->trim) {
                strbuf_rtrim(html);
            }
            tight = rstack->tight;
            b = rstack->next_sibling;
            rstack = pop_render_stack(rstack);
        }
    }

    free_render_stack(rstack);
}

unsigned char *cmark_render_html(cmark_node *root)
{
    unsigned char *result;
    strbuf html = GH_BUF_INIT;
    blocks_to_html(&html, root);
    result = strbuf_detach(&html);
    strbuf_free(&html);
    return result;
}