manabrew-engine 0.6.0

Magic: The Gathering rules engine — a Rust port of Forge
Documentation 
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
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167

use crate::ability::api_type::ApiType;
use crate::card::Card;
use crate::keyword::keyword_instance::Keyword;
use crate::spellability::SpellAbility;

pub fn matches_valid_sa(
    filter: &str,
    sa: &SpellAbility,
    source: &Card,
    ability_host: Option<&Card>,
) -> bool {
    let filter = filter.trim();
    if filter.is_empty() {
        return true;
    }

    filter
        .split(',')
        .map(str::trim)
        .filter(|restriction| !restriction.is_empty())
        .any(|restriction| matches_restriction(restriction, sa, source, ability_host))
}

fn matches_restriction(
    restriction: &str,
    sa: &SpellAbility,
    source: &Card,
    ability_host: Option<&Card>,
) -> bool {
    let mut parts = restriction.splitn(2, '.');
    let base = parts.next().unwrap_or("").trim();
    let properties = parts.next();

    let base_matches = matches_base_token(base, sa, ability_host);
    if !base_matches {
        return false;
    }

    if let Some(properties) = properties {
        for property in properties
            .split('+')
            .map(str::trim)
            .filter(|property| !property.is_empty())
        {
            if !matches_property_token(property, sa, source, ability_host) {
                return false;
            }
        }
    }

    true
}

fn matches_base_token(token: &str, sa: &SpellAbility, ability_host: Option<&Card>) -> bool {
    let token = token.trim();
    let (negated, token) = match token.strip_prefix('!') {
        Some(stripped) => (true, stripped),
        None => (false, token),
    };

    let matched = match token.to_ascii_lowercase().as_str() {
        "spell" => sa.is_spell,
        "ability" => !sa.is_spell,
        "activated" => sa.is_activated,
        "trigger" | "triggered" => sa.is_trigger,
        "spellability" => true,
        "instant" => ability_host.is_some_and(|card| card.type_line.is_instant()),
        "sorcery" => ability_host.is_some_and(|card| card.type_line.is_sorcery()),
        _ => false,
    };

    matched != negated
}

fn matches_property_token(
    token: &str,
    sa: &SpellAbility,
    source: &Card,
    ability_host: Option<&Card>,
) -> bool {
    let token = token.trim();
    let (negated, token) = match token.strip_prefix('!') {
        Some(stripped) => (true, stripped),
        None => (false, token),
    };

    let matched = matches_property_token_positive(token, sa, source, ability_host);
    matched != negated
}

fn matches_property_token_positive(
    token: &str,
    sa: &SpellAbility,
    source: &Card,
    ability_host: Option<&Card>,
) -> bool {
    match token.to_ascii_lowercase().as_str() {
        "self" => ability_host.is_some_and(|host| host.id == source.id),
        "youctrl" => sa.activating_player == source.controller,
        "oppctrl" => sa.activating_player != source.controller,
        "manaability" => sa.is_mana_ability || sa.api == Some(ApiType::Mana),
        "nonmanaability" => !(sa.is_mana_ability || sa.api == Some(ApiType::Mana)),
        "istargeting" => sa.target_restrictions.is_some(),
        "xcost" => sa.cost_has_x(),
        "singletarget" => sa.targets_single_target(),
        "crew" => is_crew(sa, ability_host),
        "saddle" => is_keyword_ability(sa, ability_host, Keyword::Saddle, "saddle"),
        "station" => is_keyword_ability(sa, ability_host, Keyword::Station, "station"),
        "vehicle" | "mount" | "spacecraft" | "planet" => {
            ability_host.is_some_and(|host| host.type_line.has_subtype(token))
        }
        _ => {
            if sa.has_property(token) {
                return true;
            }
            if sa
                .api
                .is_some_and(|api| api.name().eq_ignore_ascii_case(token))
            {
                return true;
            }
            ability_host.is_some_and(|host| host.has_property(token))
        }
    }
}

fn is_crew(sa: &SpellAbility, ability_host: Option<&Card>) -> bool {
    if ability_text_has_keyword(sa, "crew") {
        return true;
    }

    ability_host.is_some_and(|host| {
        host.has_keyword_enum(Keyword::Crew)
            && sa.api == Some(ApiType::Animate)
            && sa.description.trim_start().starts_with("Crew")
    })
}

fn is_keyword_ability(
    sa: &SpellAbility,
    ability_host: Option<&Card>,
    keyword: Keyword,
    text: &str,
) -> bool {
    if ability_text_has_keyword(sa, text) {
        return true;
    }

    ability_host.is_some_and(|host| {
        host.has_keyword_enum(keyword)
            && sa
                .description
                .trim_start()
                .to_ascii_lowercase()
                .starts_with(text)
    })
}

fn ability_text_has_keyword(sa: &SpellAbility, keyword: &str) -> bool {
    let keyword = keyword.to_ascii_lowercase();
    let description = sa.description.trim_start().to_ascii_lowercase();
    let ability_text = sa.ability_text.to_ascii_lowercase();

    description.starts_with(&keyword)
        || ability_text.contains(&format!("precostdesc$ {keyword}"))
        || ability_text.contains(&format!("spelldescription$ {keyword}"))
}