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

use serde::Serialize;
use std::collections::VecDeque;
use toml::value::Table;

#[derive(Serialize, Debug, Default)]
#[must_use]
pub struct BuildPlan {
    #[serde(skip_serializing_if = "Vec::is_empty")]
    pub provides: Vec<Provide>,
    #[serde(skip_serializing_if = "Vec::is_empty")]
    pub requires: Vec<Require>,
    #[serde(skip_serializing_if = "Vec::is_empty")]
    pub or: Vec<Or>,
}

impl BuildPlan {
    pub fn new() -> Self {
        Self::default()
    }
}

#[derive(Default)]
#[must_use]
pub struct BuildPlanBuilder {
    acc: VecDeque<(Vec<Provide>, Vec<Require>)>,
    current_provides: Vec<Provide>,
    current_requires: Vec<Require>,
}

impl BuildPlanBuilder {
    pub fn new() -> Self {
        Self::default()
    }

    pub fn provides(mut self, name: impl AsRef<str>) -> Self {
        self.current_provides.push(Provide::new(name.as_ref()));
        self
    }

    pub fn requires(mut self, require: impl Into<Require>) -> Self {
        self.current_requires.push(require.into());
        self
    }

    pub fn or(mut self) -> Self {
        self.acc
            .push_back((self.current_provides, self.current_requires));
        self.current_provides = vec![];
        self.current_requires = vec![];

        self
    }

    pub fn build(self) -> BuildPlan {
        let mut xyz = self.or();

        if let Some(head) = xyz.acc.pop_front() {
            let mut build_plan = BuildPlan::new();
            build_plan.provides = head.0;
            build_plan.requires = head.1;

            for alternative in xyz.acc {
                build_plan.or.push(Or {
                    provides: alternative.0,
                    requires: alternative.1,
                });
            }

            build_plan
        } else {
            BuildPlan::new()
        }
    }
}

#[derive(Serialize, Debug)]
pub struct Or {
    #[serde(skip_serializing_if = "Vec::is_empty")]
    provides: Vec<Provide>,
    #[serde(skip_serializing_if = "Vec::is_empty")]
    requires: Vec<Require>,
}

#[derive(Serialize, Debug)]
pub struct Provide {
    name: String,
}

impl Provide {
    pub fn new(name: impl Into<String>) -> Self {
        Self { name: name.into() }
    }
}

#[derive(Serialize, Debug)]
pub struct Require {
    pub name: String,
    pub metadata: Table,
}

impl Require {
    pub fn new(name: impl Into<String>) -> Self {
        Self {
            name: name.into(),
            metadata: Table::new(),
        }
    }

    /// Convert a Serializable struct and store it as a toml Table for metadata
    ///
    /// # Errors
    /// This will return error for any normal TOML serialization error as well if it's not
    /// possible to serialize as a TOML Table.
    pub fn metadata<T: Serialize>(&mut self, metadata: T) -> Result<(), toml::ser::Error> {
        if let toml::Value::Table(table) = toml::Value::try_from(metadata)? {
            self.metadata = table;

            Ok(())
        } else {
            Err(toml::ser::Error::Custom(String::from(
                "Could not be serialized as a TOML Table.",
            )))
        }
    }
}

impl<S: Into<String>> From<S> for Require {
    fn from(s: S) -> Self {
        Self::new(s)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn it_writes_simple_build_plan() {
        let mut build_plan = BuildPlan::new();
        build_plan.provides.push(Provide::new("rust"));
        build_plan.requires.push(Require::new("rust"));

        assert!(toml::to_string(&build_plan).is_ok());
    }

    #[test]
    fn it_serializes_metadata() {
        #[derive(Serialize)]
        struct Metadata {
            foo: String,
        }

        let mut require = Require::new("foo");
        let metadata = Metadata {
            foo: String::from("bar"),
        };
        let result = require.metadata(metadata);
        assert!(result.is_ok());
        assert_eq!(
            require.metadata.get("foo"),
            Some(&toml::Value::String(String::from("bar")))
        );
    }
}