use std::mem::transmute;

use signature::Primitive;

use errors::*;
use sys::*;

use objects::JObject;

/// Rusty version of the JNI C `jvalue` enum. Used in Java method call arguments
/// and returns.
#[allow(missing_docs)]
#[derive(Clone, Copy, Debug)]
pub enum JValue<'a> {
    Object(JObject<'a>),
    Byte(jbyte),
    Char(jchar),
    Short(jshort),
    Int(jint),
    Long(jlong),
    Bool(jboolean),
    Float(jfloat),
    Double(jdouble),
    Void,
}

impl<'a> From<JValue<'a>> for jvalue {
    fn from(other: JValue) -> jvalue {
        other.to_jni()
    }
}

impl<'a> JValue<'a> {
    /// Convert the enum to its jni-compatible equivalent.
    pub fn to_jni(self) -> jvalue {
        let val: jvalue = unsafe {
            match self {
                JValue::Object(obj) => transmute(obj.into_inner() as i64),
                JValue::Byte(byte) => transmute(byte as i64),
                JValue::Char(char) => transmute(char as u64),
                JValue::Short(short) => transmute(short as i64),
                JValue::Int(int) => transmute(int as i64),
                JValue::Long(long) => transmute(long),
                JValue::Bool(boolean) => transmute(boolean as u64),
                JValue::Float(float) => transmute(float as f64),
                JValue::Double(double) => transmute(double),
                JValue::Void => Default::default(),
            }
        };
        trace!("converted {:?} to jvalue {:?}", self, val._data);
        val
    }

    /// Get the type name for the enum variant.
    pub fn type_name(&self) -> &'static str {
        match *self {
            JValue::Void => "void",
            JValue::Object(_) => "object",
            JValue::Byte(_) => "byte",
            JValue::Char(_) => "char",
            JValue::Short(_) => "short",
            JValue::Int(_) => "int",
            JValue::Long(_) => "long",
            JValue::Bool(_) => "bool",
            JValue::Float(_) => "float",
            JValue::Double(_) => "double",
        }
    }

    /// Get the primitive type for the enum variant. If it's not a primitive
    /// (i.e. an Object), returns None.
    pub fn primitive_type(&self) -> Option<Primitive> {
        Some(match *self {
            JValue::Object(_) => return None,
            JValue::Void => Primitive::Void,
            JValue::Byte(_) => Primitive::Byte,
            JValue::Char(_) => Primitive::Char,
            JValue::Short(_) => Primitive::Short,
            JValue::Int(_) => Primitive::Int,
            JValue::Long(_) => Primitive::Long,
            JValue::Bool(_) => Primitive::Boolean,
            JValue::Float(_) => Primitive::Float,
            JValue::Double(_) => Primitive::Double,
        })
    }

    /// Try to unwrap to an Object.
    pub fn l(self) -> Result<JObject<'a>> {
        match self {
            JValue::Object(obj) => Ok(obj),
            _ => {
                Err(ErrorKind::WrongJValueType("object", self.type_name())
                    .into())
            }
        }
    }

    /// Try to unwrap to a boolean.
    pub fn z(self) -> Result<bool> {
        match self {
            JValue::Bool(b) => Ok(b != 0),
            _ => {
                Err(ErrorKind::WrongJValueType("bool", self.type_name()).into())
            }
        }
    }

    /// Try to unwrap to a byte.
    pub fn b(self) -> Result<jbyte> {
        match self {
            JValue::Byte(b) => Ok(b),
            _ => {
                Err(ErrorKind::WrongJValueType("jbyte", self.type_name())
                    .into())
            }
        }
    }

    /// Try to unwrap to a char.
    pub fn c(self) -> Result<jchar> {
        match self {
            JValue::Char(b) => Ok(b),
            _ => {
                Err(ErrorKind::WrongJValueType("jchar", self.type_name())
                    .into())
            }
        }
    }

    /// Try to unwrap to a double.
    pub fn d(self) -> Result<jdouble> {
        match self {
            JValue::Double(b) => Ok(b),
            _ => {
                Err(ErrorKind::WrongJValueType("jdouble", self.type_name())
                    .into())
            }
        }
    }

    /// Try to unwrap to a float.
    pub fn f(self) -> Result<jfloat> {
        match self {
            JValue::Float(b) => Ok(b),
            _ => {
                Err(ErrorKind::WrongJValueType("jfloat", self.type_name())
                    .into())
            }
        }
    }

    /// Try to unwrap to an int.
    pub fn i(self) -> Result<jint> {
        match self {
            JValue::Int(b) => Ok(b),
            _ => {
                Err(ErrorKind::WrongJValueType("jint", self.type_name()).into())
            }
        }
    }

    /// Try to unwrap to a long.
    pub fn j(self) -> Result<jlong> {
        match self {
            JValue::Long(b) => Ok(b),
            _ => {
                Err(ErrorKind::WrongJValueType("jlong", self.type_name())
                    .into())
            }
        }
    }

    /// Try to unwrap to a short.
    pub fn s(self) -> Result<jshort> {
        match self {
            JValue::Short(b) => Ok(b),
            _ => {
                Err(ErrorKind::WrongJValueType("jshort", self.type_name())
                    .into())
            }
        }
    }

    /// Try to unwrap to a void.
    pub fn v(self) -> Result<()> {
        match self {
            JValue::Void => Ok(()),
            _ => {
                Err(ErrorKind::WrongJValueType("void", self.type_name()).into())
            }
        }
    }
}

impl<'a> From<JObject<'a>> for JValue<'a> {
    fn from(other: JObject<'a>) -> Self {
        JValue::Object(other)
    }
}

// jbool
impl<'a> From<bool> for JValue<'a> {
    fn from(other: bool) -> Self {
        JValue::Bool(other as jboolean)
    }
}

// jchar
impl<'a> From<jchar> for JValue<'a> {
    fn from(other: jchar) -> Self {
        JValue::Char(other)
    }
}

// jshort
impl<'a> From<jshort> for JValue<'a> {
    fn from(other: jshort) -> Self {
        JValue::Short(other)
    }
}

// jfloat
impl<'a> From<jfloat> for JValue<'a> {
    fn from(other: jfloat) -> Self {
        JValue::Float(other)
    }
}

// jdouble
impl<'a> From<jdouble> for JValue<'a> {
    fn from(other: jdouble) -> Self {
        JValue::Double(other)
    }
}

// jint
impl<'a> From<jint> for JValue<'a> {
    fn from(other: jint) -> Self {
        JValue::Int(other)
    }
}

// jlong
impl<'a> From<jlong> for JValue<'a> {
    fn from(other: jlong) -> Self {
        JValue::Long(other)
    }
}

// jbyte
impl<'a> From<jbyte> for JValue<'a> {
    fn from(other: jbyte) -> Self {
        JValue::Byte(other)
    }
}

// jvoid
impl<'a> From<()> for JValue<'a> {
    fn from(_: ()) -> Self {
        JValue::Void
    }
}