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

/*
 * mCaptcha - A proof of work based DoS protection system
 * Copyright © 2021 Aravinth Manivannan <realravinth@batsense.net>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

use serde::{Deserialize, Serialize};

use crate::defense::Defense;
use crate::errors::*;

/// Builder for [MCaptcha]
#[derive(Clone, Serialize, Deserialize, Debug)]
pub struct MCaptchaBuilder {
    visitor_threshold: u32,
    defense: Option<Defense>,
    duration: Option<u64>,
}

impl Default for MCaptchaBuilder {
    fn default() -> Self {
        MCaptchaBuilder {
            visitor_threshold: 0,
            defense: None,
            duration: None,
        }
    }
}

impl MCaptchaBuilder {
    /// set defense
    pub fn defense(&mut self, d: Defense) -> &mut Self {
        self.defense = Some(d);
        self
    }

    /// set duration
    pub fn duration(&mut self, d: u64) -> &mut Self {
        self.duration = Some(d);
        self
    }

    /// Builds new [MCaptcha]
    pub fn build(self: &mut MCaptchaBuilder) -> CaptchaResult<MCaptcha> {
        if self.duration.is_none() {
            Err(CaptchaError::PleaseSetValue("duration".into()))
        } else if self.defense.is_none() {
            Err(CaptchaError::PleaseSetValue("defense".into()))
        } else if self.duration <= Some(0) {
            Err(CaptchaError::CaptchaDurationZero)
        } else {
            let m = MCaptcha {
                duration: self.duration.unwrap(),
                defense: self.defense.clone().unwrap(),
                visitor_threshold: self.visitor_threshold,
            };
            Ok(m)
        }
    }
}

#[derive(Clone, Serialize, Deserialize, Debug)]
pub struct MCaptcha {
    visitor_threshold: u32,
    defense: Defense,
    duration: u64,
}

impl From<MCaptcha> for crate::master::CreateMCaptcha {
    fn from(m: MCaptcha) -> Self {
        Self {
            levels: m.defense.into(),
            duration: m.duration,
        }
    }
}

impl MCaptcha {
    /// increments the visitor count by one
    #[inline]
    pub fn add_visitor(&mut self) {
        self.visitor_threshold += 1;
        let current_level = self.defense.current_level();
        if self.visitor_threshold > current_level.visitor_threshold {
            self.defense.tighten_up();
        } else {
            self.defense.loosen_up();
        }
    }

    /// decrements the visitor count by specified count
    #[inline]
    pub fn decrement_visitor_by(&mut self, count: u32) {
        if self.visitor_threshold > 0 {
            if self.visitor_threshold >= count {
                self.visitor_threshold -= count;
            } else {
                self.visitor_threshold = 0;
            }
        }
    }

    /// get current difficulty factor
    #[inline]
    pub fn get_difficulty(&self) -> u32 {
        self.defense.get_difficulty()
    }

    /// get [Counter]'s lifetime
    #[inline]
    pub fn get_duration(&self) -> u64 {
        self.duration
    }

    /// get [Counter]'s current visitor_threshold
    #[inline]
    pub fn get_visitors(&self) -> u32 {
        self.visitor_threshold
    }

    /// get mCaptcha's defense configuration
    #[inline]
    pub fn get_defense(&self) -> Defense {
        self.defense.clone()
    }
}