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use vortex_error::{VortexExpect, VortexResult};
use vortex_scalar::{ExtScalar, Scalar};

use crate::array::extension::ExtensionArray;
use crate::array::ConstantArray;
use crate::compute::unary::{scalar_at, scalar_at_unchecked, CastFn, ScalarAtFn};
use crate::compute::{
    compare, slice, take, ArrayCompute, MaybeCompareFn, Operator, SliceFn, TakeFn,
};
use crate::variants::ExtensionArrayTrait;
use crate::{Array, ArrayDType, IntoArray};

impl ArrayCompute for ExtensionArray {
    fn cast(&self) -> Option<&dyn CastFn> {
        // It's not possible to cast an extension array to another type.
        // TODO(ngates): we should allow some extension arrays to implement a callback
        //  to support this
        None
    }

    fn compare(&self, other: &Array, operator: Operator) -> Option<VortexResult<Array>> {
        MaybeCompareFn::maybe_compare(self, other, operator)
    }

    fn scalar_at(&self) -> Option<&dyn ScalarAtFn> {
        Some(self)
    }

    fn slice(&self) -> Option<&dyn SliceFn> {
        Some(self)
    }

    fn take(&self) -> Option<&dyn TakeFn> {
        Some(self)
    }
}

impl MaybeCompareFn for ExtensionArray {
    fn maybe_compare(&self, array: &Array, operator: Operator) -> Option<VortexResult<Array>> {
        if let Ok(const_ext) = ConstantArray::try_from(array) {
            return Some({
                let scalar_ext =
                    ExtScalar::try_from(const_ext.scalar()).vortex_expect("Expected ExtScalar");
                let const_storage = ConstantArray::new(
                    Scalar::new(self.storage().dtype().clone(), scalar_ext.value().clone()),
                    const_ext.len(),
                );
                compare(self.storage(), const_storage, operator)
            });
        }

        if let Ok(rhs_ext) = ExtensionArray::try_from(array) {
            return Some(compare(self.storage(), rhs_ext.storage(), operator));
        }

        None
    }
}

impl ScalarAtFn for ExtensionArray {
    fn scalar_at(&self, index: usize) -> VortexResult<Scalar> {
        Ok(Scalar::extension(
            self.ext_dtype().clone(),
            scalar_at(&self.storage(), index)?,
        ))
    }

    fn scalar_at_unchecked(&self, index: usize) -> Scalar {
        Scalar::extension(
            self.ext_dtype().clone(),
            scalar_at_unchecked(&self.storage(), index),
        )
    }
}

impl SliceFn for ExtensionArray {
    fn slice(&self, start: usize, stop: usize) -> VortexResult<Array> {
        Ok(Self::new(
            self.ext_dtype().clone(),
            slice(self.storage(), start, stop)?,
        )
        .into_array())
    }
}

impl TakeFn for ExtensionArray {
    fn take(&self, indices: &Array) -> VortexResult<Array> {
        Ok(Self::new(self.ext_dtype().clone(), take(self.storage(), indices)?).into_array())
    }
}