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use crate::blueprint::constructor::CloningStrategy;
use crate::blueprint::conversions::{cloning2cloning, lint2lint, raw_callable2registered_callable};
use crate::blueprint::linter::Lint;
use crate::blueprint::reflection::RawCallable;
use pavex_bp_schema::{Blueprint as BlueprintSchema, LintSetting};
use pavex_bp_schema::{Component, Constructor};

/// The type returned by [`Blueprint::constructor`].
///
/// It allows you to further configure the behaviour of the registered constructor.
///
/// [`Blueprint::constructor`]: crate::blueprint::Blueprint::constructor
pub struct RegisteredConstructor<'a> {
    pub(crate) blueprint: &'a mut BlueprintSchema,
    /// The index of the registered middleware in the blueprint's `constructors` vector.
    pub(crate) component_id: usize,
}

impl<'a> RegisteredConstructor<'a> {
    #[track_caller]
    /// Register an error handler.
    ///
    /// If an error handler has already been registered for this constructor, it will be
    /// overwritten.
    ///
    /// # Guide
    ///
    /// Check out the ["Error handlers"](https://pavex.dev/docs/guide/errors/error_handlers)
    /// section of Pavex's guide for a thorough introduction to error handlers
    /// in Pavex applications.
    ///
    /// # Example
    ///
    /// ```rust
    /// use pavex::f;
    /// use pavex::blueprint::{Blueprint, constructor::Lifecycle};
    /// use pavex::response::Response;
    /// # struct LogLevel;
    /// # struct Logger;
    /// # struct ConfigurationError;
    ///
    /// // 👇 a fallible constructor
    /// fn logger() -> Result<Logger, ConfigurationError> {
    ///     // [...]
    ///     # todo!()
    /// }
    ///
    /// fn error_to_response(error: &ConfigurationError, log_level: LogLevel) -> Response {
    ///     // [...]
    ///     # todo!()
    /// }
    ///
    /// # fn main() {
    /// let mut bp = Blueprint::new();
    /// bp.constructor(f!(crate::logger), Lifecycle::Transient)
    ///     .error_handler(f!(crate::error_to_response));
    /// # }
    /// ```
    pub fn error_handler(mut self, error_handler: RawCallable) -> Self {
        let callable = raw_callable2registered_callable(error_handler);
        self.constructor().error_handler = Some(callable);
        self
    }

    /// Set the cloning strategy for the output type returned by this constructor.
    ///
    /// By default,
    /// Pavex will **never** try to clone the output type returned by a constructor.  
    /// If the output type implements [`Clone`], you change the default by setting the cloning strategy
    /// to [`CloningStrategy::CloneIfNecessary`]: Pavex will clone the output type if
    /// it's necessary to generate code that satisfies Rust's borrow checker.
    pub fn cloning(mut self, strategy: CloningStrategy) -> Self {
        self.constructor().cloning_strategy = Some(cloning2cloning(strategy));
        self
    }

    /// Tell Pavex to ignore a specific [`Lint`] when analysing
    /// this constructor and the way it's used.
    pub fn ignore(mut self, lint: Lint) -> Self {
        self.constructor()
            .lints
            .insert(lint2lint(lint), LintSetting::Ignore);
        self
    }

    /// Tell Pavex to enforce a specific [`Lint`] when analysing
    /// this constructor and the way it's used.
    pub fn enforce(mut self, lint: Lint) -> Self {
        self.constructor()
            .lints
            .insert(lint2lint(lint), LintSetting::Enforce);
        self
    }

    fn constructor(&mut self) -> &mut Constructor {
        let component = &mut self.blueprint.components[self.component_id];
        let Component::Constructor(c) = component else {
            unreachable!("The component should be a constructor")
        };
        c
    }
}