//! Helper for defining sub-builders that map a serializable type (typically String)

//! to a configuration type.

/// Define a map type, and an associated builder struct, suitable for use in a configuration object.

///

/// We use this macro when we want a configuration structure to contain a key-to-value map,

/// and therefore we want its associated builder structure to contain

/// a map from the same key type to a value-builder type.

///

/// The key of the map type must implement `Serialize`, `Clone`, and `Debug`.

/// The value of the map type must have an associated "Builder"

/// type formed by appending `Builder` to its name.

/// This Builder type must implement `Serialize`, `Deserialize`, `Clone`, and `Debug`,

/// and it must have a `build(&self)` method returning `Result<value, ConfigBuildError>`.

///

/// # Syntax and behavior

///

/// ```ignore

/// define_map_builder! {

///     BuilderAttributes

///     pub struct BuilderName =>

///

///     MapAttributes

///     pub type MapName = ContainerType<KeyType, ValueType>;

///

///     defaults: defaults_func(); // <--- this line is optional

/// }

/// ```

///

/// In the example above,

///

/// * BuilderName, MapName, and ContainerType may be replaced with any identifier;

/// * BuilderAttributes and MapAttributes can be replaced with any set of attributes

///   (such sa doc comments, `#derive`, and so on);

/// * The `pub`s may be replaced with any visibility;

/// * and `KeyType` and `ValueType` may be replaced with any appropriate types.

///    * `ValueType` must have a corresponding `ValueTypeBuilder`.

///    * `ValueTypeBuilder` must implement

///      [`ExtendBuilder`](crate::extend_builder::ExtendBuilder).

///

/// Given this syntax, this macro will define "MapType" as an alias for

/// `Container<KeyType,ValueType>`,

/// and "BuilderName" as a builder type for that container.

///

/// "BuilderName" will implement:

///  * `Deref` and `DerefMut` with a target type of `Container<KeyType, ValueTypeBuilder>`

///  * `Default`, `Clone`, and `Debug`.

///  * `Serialize` and `Deserialize`

///  * A `build()` function that invokes `build()` on every value in its contained map.

///

/// (Note that in order to work as a sub-builder within our configuration system,

/// "BuilderName" should be the same as "MapName" concatenated with "Builder.")

///

/// The `defaults_func()`, if provided, must be

/// a function returning `ContainerType<KeyType, ValueType>`.

/// The values returned by `default_func()` map are used to implement

/// `Default` and `Deserialize` for `BuilderName`,

/// extending from the defaults with `ExtendStrategy::ReplaceLists`.

/// If no `defaults_func` is given, `ContainerType::default()` is used.

///

/// # Example

///

/// ```

/// # use derive_builder::Builder;

/// # use derive_deftly::Deftly;

/// # use std::collections::BTreeMap;

/// # use tor_config::{ConfigBuildError, define_map_builder, derive_deftly_template_ExtendBuilder};

/// # use serde::{Serialize, Deserialize};

/// # use tor_config::extend_builder::{ExtendBuilder,ExtendStrategy};

/// #[derive(Clone, Debug, Builder, Deftly, Eq, PartialEq)]

/// #[derive_deftly(ExtendBuilder)]

/// #[builder(build_fn(error = "ConfigBuildError"))]

/// #[builder(derive(Debug, Serialize, Deserialize))]

/// pub struct ConnectionsConfig {

///     #[builder(sub_builder)]

///     #[deftly(extend_builder(sub_builder))]

///     conns: ConnectionMap

/// }

///

/// define_map_builder! {

///     pub struct ConnectionMapBuilder =>

///     pub type ConnectionMap = BTreeMap<String, ConnConfig>;

/// }

///

/// #[derive(Clone, Debug, Builder, Deftly, Eq, PartialEq)]

/// #[derive_deftly(ExtendBuilder)]

/// #[builder(build_fn(error = "ConfigBuildError"))]

/// #[builder(derive(Debug, Serialize, Deserialize))]

/// pub struct ConnConfig {

///     #[builder(default="true")]

///     enabled: bool,

///     port: u16,

/// }

///

/// let defaults: ConnectionsConfigBuilder = toml::from_str(r#"

/// [conns."socks"]

/// enabled = true

/// port = 9150

///

/// [conns."http"]

/// enabled = false

/// port = 1234

///

/// [conns."wombat"]

/// port = 5050

/// "#).unwrap();

/// let user_settings: ConnectionsConfigBuilder = toml::from_str(r#"

/// [conns."http"]

/// enabled = false

/// [conns."quokka"]

/// enabled = true

/// port = 9999

/// "#).unwrap();

///

/// let mut cfg = defaults.clone();

/// cfg.extend_from(user_settings, ExtendStrategy::ReplaceLists);

/// let cfg = cfg.build().unwrap();

/// assert_eq!(cfg, ConnectionsConfig {

///     conns: vec![

///         ("http".into(), ConnConfig { enabled: false, port: 1234}),

///         ("quokka".into(), ConnConfig { enabled: true, port: 9999}),

///         ("socks".into(), ConnConfig { enabled: true, port: 9150}),

///         ("wombat".into(), ConnConfig { enabled: true, port: 5050}),

///     ].into_iter().collect(),

/// });

/// ```

///

/// In the example above, the `derive_map_builder` macro expands to something like:

///

/// ```ignore

/// pub type ConnectionMap = BTreeMap<String, ConnConfig>;

///

/// #[derive(Clone,Debug,Serialize,Educe)]

/// #[educe(Deref,DerefMut)]

/// pub struct ConnectionMapBuilder(BTreeMap<String, ConnConfigBuilder);

///

/// impl ConnectionMapBuilder {

///     fn build(&self) -> Result<ConnectionMap, ConfigBuildError> {

///         ...

///     }

/// }

/// impl Default for ConnectionMapBuilder { ... }

/// impl Deserialize for ConnectionMapBuilder { ... }

/// impl ExtendBuilder for ConnectionMapBuilder { ... }

/// ```

///

/// # Notes and rationale

///

/// We use this macro, instead of using a Map directly in our configuration object,

/// so that we can have a separate Builder type with a reasonable build() implementation.

///

/// We don't support complicated keys; instead we require that the keys implement Deserialize.

/// If we ever need to support keys with their own builders,

/// we'll have to define a new macro.

///

/// We use `ExtendBuilder` to implement Deserialize with defaults,

/// so that the provided configuration options can override

/// only those parts of the default configuration tree

/// that they actually replace.

#[macro_export]

macro_rules! define_map_builder {

    {

        $(#[ $b_m:meta ])*

        $b_v:vis struct $btype:ident =>

        $(#[ $m:meta ])*

        $v:vis type $maptype:ident = $coltype:ident < $keytype:ty , $valtype: ty >;

        $( defaults: $defaults:expr; )?

    } => {

        $crate::deps::paste!{$crate::define_map_builder! {

            $(#[$b_m])*

            $b_v struct $btype =>

            $(#[$m])*

            $v type $maptype = {

                map: $coltype < $keytype , $valtype >,

                builder_map: $coltype < $keytype, [<$valtype Builder>] > ,

            }

            $( defaults: $defaults; )?

        }}

    };

    // This _undocumented_ internal syntax allows us to take the map types explicitly,

    // so that we can accept derive-deftly outputs.

    //

    // Syntax:

    // ```

    //   «#[builder_attrs]»

    //   «vis» struct «FooMapBuilder» =>

    //   «#[maptype_attrs]»

    //   «vis» type «FooMap» = {

    //       map: «maptype»,

    //       builder_map: «builder_map_type»,

    //   }

    //   ⟦ defaults: «default_expr» ; ⟧

    // ```

    //

    // The defaults line and the attributes are optional.

    // This (undocumented) syntax is identical to the documented variant above,

    // except in the braced section after the `=` and before the optional `defaults`.

    // In that section,

    // the `maptype` is the type of the map which we are trying to build,

    // (for example, `HashMap<String, WombatCfg>`),

    // and the `builder_map` is the type of the map which instantiates the builder

    // (for example, `HashMap<String, WombatCfgBuilder>`).

    {

        $(#[ $b_m:meta ])*

        $b_v:vis struct $btype:ident =>

        $(#[ $m:meta ])*

        $v:vis type $maptype:ident = {

            map: $mtype:ty,

            builder_map: $bmtype:ty $(,)?

        }

        $( defaults: $defaults:expr; )?

    } =>

    {$crate::deps::paste!{

        $(#[ $m ])*

        $v type $maptype = $mtype ;

        $(#[ $b_m ])*

        #[derive(Clone,Debug,$crate::deps::serde::Serialize, $crate::deps::educe::Educe)]

        #[educe(Deref, DerefMut)]

        #[serde(transparent)]

        $b_v struct $btype( $bmtype );

        impl $btype {

            /// Construct the final map.

        }

        $(

            // This section is expanded when we have a defaults_fn().

            impl ::std::default::Default for $btype {

            }

            impl<'de> $crate::deps::serde::Deserialize<'de> for $btype {

                        use $crate::deps::serde::Deserialize;

                        // To deserialize into this type, we create a builder holding the defaults,

                        // and we create a builder holding the values from the deserializer.

                        // We then use ExtendBuilder to extend the defaults with the deserialized values.

            }

        )?

        $crate::define_map_builder!{@if_empty { $($defaults)? } {

            // This section is expanded when we don't have a defaults_fn().

            impl ::std::default::Default for $btype {

            }

            // We can't conditionally derive() here, since Rust doesn't like macros that expand to

            // attributes.

            impl<'de> $crate::deps::serde::Deserialize<'de> for $btype {

                    use $crate::deps::serde::Deserialize;

            }

        }}

        impl $crate::extend_builder::ExtendBuilder for $btype

        {

        }

    }};

    {@if_empty {} {$($x:tt)*}} => {$($x)*};

    {@if_empty {$($y:tt)*} {$($x:tt)*}} => {};

}

#[cfg(test)]

mod test {

    // @@ begin test lint list maintained by maint/add_warning @@

    #![allow(clippy::bool_assert_comparison)]

    #![allow(clippy::clone_on_copy)]

    #![allow(clippy::dbg_macro)]

    #![allow(clippy::mixed_attributes_style)]

    #![allow(clippy::print_stderr)]

    #![allow(clippy::print_stdout)]

    #![allow(clippy::single_char_pattern)]

    #![allow(clippy::unwrap_used)]

    #![allow(clippy::unchecked_time_subtraction)]

    #![allow(clippy::useless_vec)]

    #![allow(clippy::needless_pass_by_value)]

    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->

    use crate::ConfigBuildError;

    use derive_builder::Builder;

    use derive_deftly::Deftly;

    use serde::{Deserialize, Serialize};

    use std::collections::BTreeMap;

    #[derive(Clone, Debug, Eq, PartialEq, Builder)]

    #[builder(derive(Deserialize, Serialize, Debug))]

    #[builder(build_fn(error = "ConfigBuildError"))]

    struct Outer {

        #[builder(sub_builder(fn_name = "build"))]

        #[builder_field_attr(serde(default))]

        things: ThingMap,

    }

    #[derive(Clone, Debug, Eq, PartialEq, Builder, Deftly)]

    #[derive_deftly(ExtendBuilder)]

    #[builder(derive(Deserialize, Serialize, Debug))]

    #[builder(build_fn(error = "ConfigBuildError"))]

    struct Inner {

        #[builder(default)]

        fun: bool,

        #[builder(default)]

        explosive: bool,

    }

    define_map_builder! {

        struct ThingMapBuilder =>

        type ThingMap = BTreeMap<String, Inner>;

    }

    #[test]

    fn parse_and_build() {

        let builder: OuterBuilder = toml::from_str(

            r#"

[things.x]

fun = true

explosive = false

[things.yy]

explosive = true

fun = true

"#,

        )

        .unwrap();

        let built = builder.build().unwrap();

        assert_eq!(

            built.things.get("x").unwrap(),

            &Inner {

                fun: true,

                explosive: false

            }

        );

        assert_eq!(

            built.things.get("yy").unwrap(),

            &Inner {

                fun: true,

                explosive: true

            }

        );

    }

    #[test]

    fn build_directly() {

        let mut builder = OuterBuilder::default();

        let mut bld = InnerBuilder::default();

        bld.fun(true);

        builder.things().insert("x".into(), bld);

        let built = builder.build().unwrap();

        assert_eq!(

            built.things.get("x").unwrap(),

            &Inner {

                fun: true,

                explosive: false

            }

        );

    }

    define_map_builder! {

        struct ThingMap2Builder =>

        type ThingMap2 = BTreeMap<String, Inner>;

        defaults: thingmap2_default();

    }

    fn thingmap2_default() -> BTreeMap<String, InnerBuilder> {

        let mut map = BTreeMap::new();

        {

            let mut bld = InnerBuilder::default();

            bld.fun(true);

            map.insert("x".to_string(), bld);

        }

        {

            let mut bld = InnerBuilder::default();

            bld.explosive(true);

            map.insert("y".to_string(), bld);

        }

        map

    }

    #[test]

    fn with_defaults() {

        let mut tm2 = ThingMap2Builder::default();

        tm2.get_mut("x").unwrap().explosive(true);

        let mut bld = InnerBuilder::default();

        bld.fun(true);

        tm2.insert("zz".into(), bld);

        let built = tm2.build().unwrap();

        assert_eq!(

            built.get("x").unwrap(),

            &Inner {

                fun: true,

                explosive: true

            }

        );

        assert_eq!(

            built.get("y").unwrap(),

            &Inner {

                fun: false,

                explosive: true

            }

        );

        assert_eq!(

            built.get("zz").unwrap(),

            &Inner {

                fun: true,

                explosive: false

            }

        );

        let tm2: ThingMap2Builder = toml::from_str(

            r#"

            [x]

            explosive = true

            [zz]

            fun = true

            "#,

        )

        .unwrap();

        let built2 = tm2.build().unwrap();

        assert_eq!(built, built2);

    }

}