use super::objbytes;
use super::objint;
use super::objstr;
use super::objtype;
use crate::obj::objtype::PyClassRef;
use crate::pyobject::{
    IntoPyObject, PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue, TypeProtocol,
};
use crate::vm::VirtualMachine;
use num_bigint::{BigInt, ToBigInt};
use num_rational::Ratio;
use num_traits::ToPrimitive;

#[pyclass(name = "float")]
#[derive(Debug, Copy, Clone, PartialEq)]
pub struct PyFloat {
    value: f64,
}

impl PyFloat {
    pub fn to_f64(&self) -> f64 {
        self.value
    }
}

impl PyValue for PyFloat {
    fn class(vm: &VirtualMachine) -> PyClassRef {
        vm.ctx.float_type()
    }
}

impl IntoPyObject for f64 {
    fn into_pyobject(self, vm: &VirtualMachine) -> PyResult {
        Ok(vm.ctx.new_float(self))
    }
}

impl From<f64> for PyFloat {
    fn from(value: f64) -> Self {
        PyFloat { value }
    }
}

fn mod_(v1: f64, v2: f64, vm: &VirtualMachine) -> PyResult {
    if v2 != 0.0 {
        Ok(vm.ctx.new_float(v1 % v2))
    } else {
        Err(vm.new_zero_division_error("float mod by zero".to_string()))
    }
}

#[pyimpl]
impl PyFloat {
    #[pymethod(name = "__eq__")]
    fn eq(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyObjectRef {
        let value = self.value;
        let result = if objtype::isinstance(&other, &vm.ctx.float_type()) {
            let other = get_value(&other);
            value == other
        } else if objtype::isinstance(&other, &vm.ctx.int_type()) {
            let other_int = objint::get_value(&other);

            if let (Some(self_int), Some(other_float)) = (value.to_bigint(), other_int.to_f64()) {
                value == other_float && self_int == *other_int
            } else {
                false
            }
        } else {
            return vm.ctx.not_implemented();
        };
        vm.ctx.new_bool(result)
    }

    #[pymethod(name = "__lt__")]
    fn lt(&self, i2: PyObjectRef, vm: &VirtualMachine) -> PyObjectRef {
        let v1 = self.value;
        if objtype::isinstance(&i2, &vm.ctx.float_type()) {
            vm.ctx.new_bool(v1 < get_value(&i2))
        } else if objtype::isinstance(&i2, &vm.ctx.int_type()) {
            vm.ctx
                .new_bool(v1 < objint::get_value(&i2).to_f64().unwrap())
        } else {
            vm.ctx.not_implemented()
        }
    }

    #[pymethod(name = "__le__")]
    fn le(&self, i2: PyObjectRef, vm: &VirtualMachine) -> PyObjectRef {
        let v1 = self.value;
        if objtype::isinstance(&i2, &vm.ctx.float_type()) {
            vm.ctx.new_bool(v1 <= get_value(&i2))
        } else if objtype::isinstance(&i2, &vm.ctx.int_type()) {
            vm.ctx
                .new_bool(v1 <= objint::get_value(&i2).to_f64().unwrap())
        } else {
            vm.ctx.not_implemented()
        }
    }

    #[pymethod(name = "__gt__")]
    fn gt(&self, i2: PyObjectRef, vm: &VirtualMachine) -> PyObjectRef {
        let v1 = self.value;
        if objtype::isinstance(&i2, &vm.ctx.float_type()) {
            vm.ctx.new_bool(v1 > get_value(&i2))
        } else if objtype::isinstance(&i2, &vm.ctx.int_type()) {
            vm.ctx
                .new_bool(v1 > objint::get_value(&i2).to_f64().unwrap())
        } else {
            vm.ctx.not_implemented()
        }
    }

    #[pymethod(name = "__ge__")]
    fn ge(&self, i2: PyObjectRef, vm: &VirtualMachine) -> PyObjectRef {
        let v1 = self.value;
        if objtype::isinstance(&i2, &vm.ctx.float_type()) {
            vm.ctx.new_bool(v1 >= get_value(&i2))
        } else if objtype::isinstance(&i2, &vm.ctx.int_type()) {
            vm.ctx
                .new_bool(v1 >= objint::get_value(&i2).to_f64().unwrap())
        } else {
            vm.ctx.not_implemented()
        }
    }

    #[pymethod(name = "__abs__")]
    fn abs(&self, _vm: &VirtualMachine) -> f64 {
        self.value.abs()
    }

    #[pymethod(name = "__add__")]
    fn add(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyObjectRef {
        let v1 = self.value;
        if objtype::isinstance(&other, &vm.ctx.float_type()) {
            vm.ctx.new_float(v1 + get_value(&other))
        } else if objtype::isinstance(&other, &vm.ctx.int_type()) {
            vm.ctx
                .new_float(v1 + objint::get_value(&other).to_f64().unwrap())
        } else {
            vm.ctx.not_implemented()
        }
    }

    #[pymethod(name = "__radd__")]
    fn radd(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyObjectRef {
        self.add(other, vm)
    }

    #[pymethod(name = "__bool__")]
    fn bool(&self, _vm: &VirtualMachine) -> bool {
        self.value != 0.0
    }

    #[pymethod(name = "__divmod__")]
    fn divmod(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult {
        if objtype::isinstance(&other, &vm.ctx.float_type())
            || objtype::isinstance(&other, &vm.ctx.int_type())
        {
            let r1 = self.floordiv(other.clone(), vm)?;
            let r2 = self.mod_(other, vm)?;
            Ok(vm.ctx.new_tuple(vec![r1, r2]))
        } else {
            Ok(vm.ctx.not_implemented())
        }
    }

    #[pymethod(name = "__floordiv__")]
    fn floordiv(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult {
        let v1 = self.value;
        let v2 = if objtype::isinstance(&other, &vm.ctx.float_type) {
            get_value(&other)
        } else if objtype::isinstance(&other, &vm.ctx.int_type) {
            objint::get_float_value(&other, vm)?
        } else {
            return Ok(vm.ctx.not_implemented());
        };

        if v2 != 0.0 {
            Ok(vm.ctx.new_float((v1 / v2).floor()))
        } else {
            Err(vm.new_zero_division_error("float floordiv by zero".to_string()))
        }
    }

    fn new_float(cls: PyClassRef, arg: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyFloatRef> {
        let value = if objtype::isinstance(&arg, &vm.ctx.float_type()) {
            get_value(&arg)
        } else if objtype::isinstance(&arg, &vm.ctx.int_type()) {
            match objint::get_float_value(&arg, vm) {
                Ok(f) => f,
                Err(e) => {
                    return Err(e);
                }
            }
        } else if objtype::isinstance(&arg, &vm.ctx.str_type()) {
            match lexical::try_parse(objstr::get_value(&arg)) {
                Ok(f) => f,
                Err(_) => {
                    let arg_repr = vm.to_pystr(&arg)?;
                    return Err(vm.new_value_error(format!(
                        "could not convert string to float: {}",
                        arg_repr
                    )));
                }
            }
        } else if objtype::isinstance(&arg, &vm.ctx.bytes_type()) {
            match lexical::try_parse(objbytes::get_value(&arg).as_slice()) {
                Ok(f) => f,
                Err(_) => {
                    let arg_repr = vm.to_pystr(&arg)?;
                    return Err(vm.new_value_error(format!(
                        "could not convert string to float: {}",
                        arg_repr
                    )));
                }
            }
        } else {
            return Err(vm.new_type_error(format!("can't convert {} to float", arg.class().name)));
        };
        PyFloat { value }.into_ref_with_type(vm, cls)
    }

    #[pymethod(name = "__mod__")]
    fn mod_(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult {
        let v1 = self.value;
        let v2 = if objtype::isinstance(&other, &vm.ctx.float_type) {
            get_value(&other)
        } else if objtype::isinstance(&other, &vm.ctx.int_type) {
            objint::get_float_value(&other, vm)?
        } else {
            return Ok(vm.ctx.not_implemented());
        };

        mod_(v1, v2, vm)
    }

    #[pymethod(name = "__rmod__")]
    fn rmod(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult {
        let v2 = self.value;
        let v1 = if objtype::isinstance(&other, &vm.ctx.int_type) {
            objint::get_float_value(&other, vm)?
        } else {
            return Ok(vm.ctx.not_implemented());
        };

        mod_(v1, v2, vm)
    }

    #[pymethod(name = "__neg__")]
    fn neg(&self, _vm: &VirtualMachine) -> f64 {
        -self.value
    }

    #[pymethod(name = "__pow__")]
    fn pow(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyObjectRef {
        let v1 = self.value;
        if objtype::isinstance(&other, &vm.ctx.float_type()) {
            vm.ctx.new_float(v1.powf(get_value(&other)))
        } else if objtype::isinstance(&other, &vm.ctx.int_type()) {
            let result = v1.powf(objint::get_value(&other).to_f64().unwrap());
            vm.ctx.new_float(result)
        } else {
            vm.ctx.not_implemented()
        }
    }

    #[pymethod(name = "__sub__")]
    fn sub(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult {
        let v1 = self.value;
        if objtype::isinstance(&other, &vm.ctx.float_type()) {
            Ok(vm.ctx.new_float(v1 - get_value(&other)))
        } else if objtype::isinstance(&other, &vm.ctx.int_type()) {
            Ok(vm
                .ctx
                .new_float(v1 - objint::get_value(&other).to_f64().unwrap()))
        } else {
            Ok(vm.ctx.not_implemented())
        }
    }

    #[pymethod(name = "__rsub__")]
    fn rsub(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult {
        let v1 = self.value;
        if objtype::isinstance(&other, &vm.ctx.float_type()) {
            Ok(vm.ctx.new_float(get_value(&other) - v1))
        } else if objtype::isinstance(&other, &vm.ctx.int_type()) {
            Ok(vm
                .ctx
                .new_float(objint::get_value(&other).to_f64().unwrap() - v1))
        } else {
            Ok(vm.ctx.not_implemented())
        }
    }

    #[pymethod(name = "__repr__")]
    fn repr(&self, _vm: &VirtualMachine) -> String {
        self.value.to_string()
    }

    #[pymethod(name = "__truediv__")]
    fn truediv(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult {
        let v1 = self.value;
        let v2 = if objtype::isinstance(&other, &vm.ctx.float_type) {
            get_value(&other)
        } else if objtype::isinstance(&other, &vm.ctx.int_type) {
            objint::get_float_value(&other, vm)?
        } else {
            return Ok(vm.ctx.not_implemented());
        };

        if v2 != 0.0 {
            Ok(vm.ctx.new_float(v1 / v2))
        } else {
            Err(vm.new_zero_division_error("float division by zero".to_string()))
        }
    }

    #[pymethod(name = "__rtruediv__")]
    fn rtruediv(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult {
        let v1 = self.value;
        let v2 = if objtype::isinstance(&other, &vm.ctx.float_type) {
            get_value(&other)
        } else if objtype::isinstance(&other, &vm.ctx.int_type) {
            objint::get_float_value(&other, vm)?
        } else {
            return Ok(vm.ctx.not_implemented());
        };

        if v1 != 0.0 {
            Ok(vm.ctx.new_float(v2 / v1))
        } else {
            Err(vm.new_zero_division_error("float division by zero".to_string()))
        }
    }

    #[pymethod(name = "__mul__")]
    fn mul(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult {
        let v1 = self.value;
        if objtype::isinstance(&other, &vm.ctx.float_type) {
            Ok(vm.ctx.new_float(v1 * get_value(&other)))
        } else if objtype::isinstance(&other, &vm.ctx.int_type) {
            Ok(vm
                .ctx
                .new_float(v1 * objint::get_value(&other).to_f64().unwrap()))
        } else {
            Ok(vm.ctx.not_implemented())
        }
    }

    #[pymethod(name = "__rmul__")]
    fn rmul(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult {
        self.mul(other, vm)
    }

    #[pymethod(name = "__trunc__")]
    fn trunc(&self, _vm: &VirtualMachine) -> BigInt {
        self.value.to_bigint().unwrap()
    }

    #[pymethod(name = "__int__")]
    fn int(&self, vm: &VirtualMachine) -> BigInt {
        self.trunc(vm)
    }

    #[pymethod(name = "__float__")]
    fn float(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyFloatRef {
        zelf
    }

    #[pyproperty(name = "real")]
    fn real(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyFloatRef {
        zelf
    }

    #[pymethod(name = "is_integer")]
    fn is_integer(&self, _vm: &VirtualMachine) -> bool {
        let v = self.value;
        (v - v.round()).abs() < std::f64::EPSILON
    }

    #[pymethod(name = "as_integer_ratio")]
    fn as_integer_ratio(&self, vm: &VirtualMachine) -> PyResult {
        let value = self.value;
        if value.is_infinite() {
            return Err(
                vm.new_overflow_error("cannot convert Infinity to integer ratio".to_string())
            );
        }
        if value.is_nan() {
            return Err(vm.new_value_error("cannot convert NaN to integer ratio".to_string()));
        }

        let ratio = Ratio::from_float(value).unwrap();
        let numer = vm.ctx.new_int(ratio.numer().clone());
        let denom = vm.ctx.new_int(ratio.denom().clone());
        Ok(vm.ctx.new_tuple(vec![numer, denom]))
    }
}

pub type PyFloatRef = PyRef<PyFloat>;

// Retrieve inner float value:
pub fn get_value(obj: &PyObjectRef) -> f64 {
    obj.payload::<PyFloat>().unwrap().value
}

pub fn make_float(vm: &VirtualMachine, obj: &PyObjectRef) -> PyResult<f64> {
    if objtype::isinstance(obj, &vm.ctx.float_type()) {
        Ok(get_value(obj))
    } else if let Ok(method) = vm.get_method(obj.clone(), "__float__") {
        let res = vm.invoke(method, vec![])?;
        Ok(get_value(&res))
    } else {
        Err(vm.new_type_error(format!("Cannot cast {} to float", obj)))
    }
}

#[rustfmt::skip] // to avoid line splitting
pub fn init(context: &PyContext) {
    PyFloat::extend_class(context, &context.float_type);
    let float_doc = "Convert a string or number to a floating point number, if possible.";
    extend_class!(context, &context.float_type, {
        "__new__" => context.new_rustfunc(PyFloat::new_float),
        "__doc__" => context.new_str(float_doc.to_string()),
    });
}