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

use proc_macro::TokenStream;
use quote::quote;
use syn::{self};

#[proc_macro_derive(CosmicConfigEntry, attributes(version, id))]
pub fn cosmic_config_entry_derive(input: TokenStream) -> TokenStream {
    // Construct a representation of Rust code as a syntax tree
    // that we can manipulate
    let ast = syn::parse(input).unwrap();

    // Build the trait implementation
    impl_cosmic_config_entry_macro(&ast)
}

fn impl_cosmic_config_entry_macro(ast: &syn::DeriveInput) -> TokenStream {
    let attributes = &ast.attrs;
    let version = attributes
        .iter()
        .find_map(|attr| {
            if attr.path.is_ident("version") {
                match attr.parse_meta() {
                    Ok(syn::Meta::NameValue(syn::MetaNameValue {
                        lit: syn::Lit::Int(lit_int),
                        ..
                    })) => Some(lit_int.base10_parse::<u64>().unwrap()),
                    _ => None,
                }
            } else {
                None
            }
        })
        .unwrap_or(0);

    let name = &ast.ident;

    // Get the fields of the struct
    let fields = match ast.data {
        syn::Data::Struct(ref data_struct) => match data_struct.fields {
            syn::Fields::Named(ref fields) => &fields.named,
            _ => unimplemented!("Only named fields are supported"),
        },
        _ => unimplemented!("Only structs are supported"),
    };

    let write_each_config_field = fields.iter().map(|field| {
        let field_name = &field.ident;
        quote! {
            cosmic_config::ConfigSet::set(&tx, stringify!(#field_name), &self.#field_name)?;
        }
    });

    let get_each_config_field = fields.iter().map(|field| {
        let field_name = &field.ident;
        let field_type = &field.ty;
        quote! {
            match cosmic_config::ConfigGet::get::<#field_type>(config, stringify!(#field_name)) {
                Ok(#field_name) => default.#field_name = #field_name,
                Err(why) if matches!(why, cosmic_config::Error::NoConfigDirectory) => (),
                Err(e) => errors.push(e),
            }
        }
    });

    let update_each_config_field = fields.iter().map(|field| {
        let field_name = &field.ident;
        let field_type = &field.ty;
        quote! {
            stringify!(#field_name) => {
                match cosmic_config::ConfigGet::get::<#field_type>(config, stringify!(#field_name)) {
                    Ok(value) => {
                        if self.#field_name != value {
                            keys.push(stringify!(#field_name));
                        }
                        self.#field_name = value;
                    },
                    Err(e) => {
                        errors.push(e);
                    }
                }
            }
        }
    });

    let setters = fields.iter().filter_map(|field| {
        let field_name = &field.ident.as_ref()?;
        let field_type = &field.ty;
        let setter_name = quote::format_ident!("set_{}", field_name);
        let doc = format!("Sets [`{name}::{field_name}`] and writes to [`cosmic_config::Config`] if changed");
        Some(quote! {
            #[doc = #doc]
            ///
            /// Returns `Ok(true)` when the field's value has changed and was written to disk
            pub fn #setter_name(&mut self, config: &cosmic_config::Config, value: #field_type) -> Result<bool, cosmic_config::Error> {
                if self.#field_name != value {
                    self.#field_name = value;
                    cosmic_config::ConfigSet::set(config, stringify!(#field_name), &self.#field_name)?;
                    Ok(true)
                } else {
                    Ok(false)
                }
            }
        })
    });

    let gen = quote! {
        impl CosmicConfigEntry for #name {
            const VERSION: u64 = #version;

            fn write_entry(&self, config: &cosmic_config::Config) -> Result<(), cosmic_config::Error> {
                let tx = config.transaction();
                #(#write_each_config_field)*
                tx.commit()
            }

            fn get_entry(config: &cosmic_config::Config) -> Result<Self, (Vec<cosmic_config::Error>, Self)> {
                let mut default = Self::default();
                let mut errors = Vec::new();

                #(#get_each_config_field)*

                if errors.is_empty() {
                    Ok(default)
                } else {
                    Err((errors, default))
                }
            }

            fn update_keys<T: AsRef<str>>(&mut self, config: &cosmic_config::Config, changed_keys: &[T]) -> (Vec<cosmic_config::Error>, Vec<&'static str>){
                let mut keys = Vec::with_capacity(changed_keys.len());
                let mut errors = Vec::new();
                for key in changed_keys.iter() {
                    match key.as_ref() {
                        #(#update_each_config_field)*
                        _ => (),
                    }
                }
                (errors, keys)
            }
        }

        impl #name {
            #(#setters)*
        }
    };

    gen.into()
}