1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151

//! HTML block syntax from CommonMark
//!
//! <https://spec.commonmark.org/0.30/#html-blocks>
use once_cell::sync::Lazy;
use regex::Regex;
use crate::{MarkdownIt, Node, NodeValue, Renderer};
use crate::parser::block::{BlockRule, BlockState};
use super::utils::blocks::*;
use super::utils::regexps::*;

#[derive(Debug)]
pub struct HtmlBlock {
    pub content: String,
}

impl NodeValue for HtmlBlock {
    fn render(&self, _: &Node, fmt: &mut dyn Renderer) {
        fmt.cr();
        fmt.text_raw(&self.content);
        fmt.cr();
    }
}

pub fn add(md: &mut MarkdownIt) {
    md.block.add_rule::<HtmlBlockScanner>();
}

struct HTMLSequence {
    open: Regex,
    close: Regex,
    can_terminate_paragraph: bool,
}

impl HTMLSequence {
    pub fn new(open: Regex, close: Regex, can_terminate_paragraph: bool) -> Self {
        Self { open, close, can_terminate_paragraph }
    }
}

// An array of opening and corresponding closing sequences for html tags,
// last argument defines whether it can terminate a paragraph or not
//
static HTML_SEQUENCES : Lazy<[HTMLSequence; 7]> = Lazy::new(|| {
    let block_names = HTML_BLOCKS.join("|");
    let open_close_tag_re = HTML_OPEN_CLOSE_TAG_RE.as_str();

    [
        HTMLSequence::new(
            Regex::new(r#"(?i)^<(script|pre|style|textarea)(\s|>|$)"#).unwrap(),
            Regex::new(r#"(?i)</(script|pre|style|textarea)>"#).unwrap(),
            true
        ),

        HTMLSequence::new(
            Regex::new(r#"^<!--"#).unwrap(),
            Regex::new(r#"-->"#).unwrap(),
            true
        ),

        HTMLSequence::new(
            Regex::new(r#"^<\?"#).unwrap(),
            Regex::new(r#"\?>"#).unwrap(),
            true
        ),

        HTMLSequence::new(
            Regex::new(r#"^<![A-Z]"#).unwrap(),
            Regex::new(r#">"#).unwrap(),
            true
        ),

        HTMLSequence::new(
            Regex::new(r#"^<!\[CDATA\["#).unwrap(),
            Regex::new(r#"\]\]>"#).unwrap(),
            true
        ),

        HTMLSequence::new(
            Regex::new(&format!("(?i)^</?({block_names})(\\s|/?>|$)")).unwrap(),
            Regex::new(r#"^$"#).unwrap(),
            true
        ),

        HTMLSequence::new(
            Regex::new(&format!("{open_close_tag_re}\\s*$")).unwrap(),
            Regex::new(r#"^$"#).unwrap(),
            false
        ),
    ]
});

#[doc(hidden)]
pub struct HtmlBlockScanner;

impl HtmlBlockScanner {
    fn get_sequence(state: &mut BlockState) -> Option<&'static HTMLSequence> {
        // if it's indented more than 3 spaces, it should be a code block
        if state.line_indent(state.line) >= 4 { return None; }

        let line_text = state.get_line(state.line);

        if let Some('<') = line_text.chars().next() {} else { return None; }

        let mut sequence = None;
        for seq in HTML_SEQUENCES.iter() {
            if seq.open.is_match(line_text) {
                sequence = Some(seq);
                break;
            }
        }

        sequence
    }
}

impl BlockRule for HtmlBlockScanner {
    fn check(state: &mut BlockState) -> Option<()> {
        let sequence = Self::get_sequence(state)?;
        if !sequence.can_terminate_paragraph { return None; }
        Some(())
    }

    fn run(state: &mut BlockState) -> Option<(Node, usize)> {
        let sequence = Self::get_sequence(state)?;

        let line_text = state.get_line(state.line);
        let start_line = state.line;
        let mut next_line = state.line + 1;

        // If we are here - we detected HTML block.
        // Let's roll down till block end.
        if !sequence.close.is_match(line_text) {
            while next_line < state.line_max {
                if state.line_indent(next_line) < 0 { break; }

                let line_text = state.get_line(next_line);

                if sequence.close.is_match(line_text) {
                    if !line_text.is_empty() { next_line += 1; }
                    break;
                }

                next_line += 1;
            }
        }

        let (content, _) = state.get_lines(start_line, next_line, state.blk_indent, true);
        let node = Node::new(HtmlBlock { content });
        Some((node, next_line - state.line))
    }
}