use super::{TryFromValue, TryIntoValue};
use crate::{ContextRef, Error, ValueRef, ValueResult};
use std::marker::PhantomData;

pub trait IntoRustFunctionResult {
    fn into_res(self, ctx: &ContextRef) -> ValueResult;
}

impl<T: TryIntoValue> IntoRustFunctionResult for T {
    fn into_res(self, ctx: &ContextRef) -> ValueResult {
        self.try_into_value(ctx)
    }
}

impl<T: TryIntoValue, E: std::fmt::Display> IntoRustFunctionResult for core::result::Result<T, E> {
    fn into_res(self, ctx: &ContextRef) -> ValueResult {
        match self {
            Ok(v) => v.try_into_value(ctx),
            Err(e) => Err(Error::RustFunctionError(e.to_string())),
        }
    }
}

pub trait RustFunction<F> {
    fn argument_count() -> usize;
    fn call(&self, context: &ContextRef, args: &[&ValueRef]) -> ValueResult;
}

impl<R, F> RustFunction<PhantomData<(&R, &F)>> for F
where
    R: IntoRustFunctionResult,
    F: Fn(&ContextRef) -> R + Sized,
{
    fn argument_count() -> usize {
        0
    }

    fn call(&self, context: &ContextRef, args: &[&ValueRef]) -> ValueResult {
        if args.len() != 0 {
            return Err(Error::ArgumentCountMismatch {
                expected: Self::argument_count(),
                received: args.len(),
            });
        }

        let res = self(context);
        res.into_res(context)
    }
}

impl<R, A, F> RustFunction<PhantomData<(&R, &A, &F)>> for F
where
    R: IntoRustFunctionResult,
    A: TryFromValue,
    F: Fn(&ContextRef, A) -> R + Sized,
{
    fn argument_count() -> usize {
        1
    }

    fn call(&self, context: &ContextRef, args: &[&ValueRef]) -> ValueResult {
        if args.len() != Self::argument_count() {
            return Err(Error::ArgumentCountMismatch {
                expected: Self::argument_count(),
                received: args.len(),
            });
        }

        let va = A::try_from_value(args[0], &context)?;
        let res = self(context, va);
        res.into_res(context)
    }
}

impl<R, A, B, F> RustFunction<PhantomData<(&R, &A, &B, &F)>> for F
where
    R: IntoRustFunctionResult,
    A: TryFromValue,
    B: TryFromValue,
    F: Fn(&ContextRef, A, B) -> R + Sized,
{
    fn argument_count() -> usize {
        2
    }

    fn call(&self, context: &ContextRef, args: &[&ValueRef]) -> ValueResult {
        if args.len() != Self::argument_count() {
            return Err(Error::ArgumentCountMismatch {
                expected: Self::argument_count(),
                received: args.len(),
            });
        }

        let va = A::try_from_value(args[0], &context)?;
        let vb = B::try_from_value(args[1], &context)?;
        let res = self(context, va, vb);
        res.into_res(context)
    }
}

impl<R, A, B, C, F> RustFunction<PhantomData<(&R, &A, &B, &C, &F)>> for F
where
    R: IntoRustFunctionResult,
    A: TryFromValue,
    B: TryFromValue,
    C: TryFromValue,
    F: Fn(&ContextRef, A, B, C) -> R + Sized,
{
    fn argument_count() -> usize {
        3
    }

    fn call(&self, context: &ContextRef, args: &[&ValueRef]) -> ValueResult {
        if args.len() != Self::argument_count() {
            return Err(Error::ArgumentCountMismatch {
                expected: Self::argument_count(),
                received: args.len(),
            });
        }

        let va = A::try_from_value(args[0], &context)?;
        let vb = B::try_from_value(args[1], &context)?;
        let vc = C::try_from_value(args[2], &context)?;
        let res = self(context, va, vb, vc);
        res.into_res(context)
    }
}

impl<R, A, B, C, D, F> RustFunction<PhantomData<(&R, &A, &B, &C, &D, &F)>> for F
where
    R: IntoRustFunctionResult,
    A: TryFromValue,
    B: TryFromValue,
    C: TryFromValue,
    D: TryFromValue,
    F: Fn(&ContextRef, A, B, C, D) -> R + Sized,
{
    fn argument_count() -> usize {
        4
    }

    fn call(&self, context: &ContextRef, args: &[&ValueRef]) -> ValueResult {
        if args.len() != Self::argument_count() {
            return Err(Error::ArgumentCountMismatch {
                expected: Self::argument_count(),
                received: args.len(),
            });
        }

        let va = A::try_from_value(args[0], &context)?;
        let vb = B::try_from_value(args[1], &context)?;
        let vc = C::try_from_value(args[2], &context)?;
        let vd = D::try_from_value(args[3], &context)?;
        let res = self(context, va, vb, vc, vd);
        res.into_res(context)
    }
}

impl<R, A, B, C, D, E, F> RustFunction<PhantomData<(&R, &A, &B, &C, &D, &E, &F)>> for F
where
    R: IntoRustFunctionResult,
    A: TryFromValue,
    B: TryFromValue,
    C: TryFromValue,
    D: TryFromValue,
    E: TryFromValue,
    F: Fn(&ContextRef, A, B, C, D, E) -> R + Sized,
{
    fn argument_count() -> usize {
        5
    }

    fn call(&self, context: &ContextRef, args: &[&ValueRef]) -> ValueResult {
        if args.len() != Self::argument_count() {
            return Err(Error::ArgumentCountMismatch {
                expected: Self::argument_count(),
                received: args.len(),
            });
        }

        let va = A::try_from_value(args[0], &context)?;
        let vb = B::try_from_value(args[1], &context)?;
        let vc = C::try_from_value(args[2], &context)?;
        let vd = D::try_from_value(args[3], &context)?;
        let ve = E::try_from_value(args[4], &context)?;
        let res = self(context, va, vb, vc, vd, ve);
        res.into_res(context)
    }
}