/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use dom::bindings::js::JS;
use dom::bindings::utils::Reflectable;
use dom::bindings::utils::jsstring_to_str;
use servo_util::str::DOMString;

use js::jsapi::{JSBool, JSContext};
use js::jsapi::{JS_ValueToUint64, JS_ValueToInt64};
use js::jsapi::{JS_ValueToECMAUint32, JS_ValueToECMAInt32};
use js::jsapi::{JS_ValueToUint16, JS_ValueToNumber, JS_ValueToBoolean};
use js::jsapi::{JS_NewUCStringCopyN, JS_ValueToString};
use js::jsapi::{JS_WrapValue};
use js::jsval::JSVal;
use js::jsval::{NullValue, BooleanValue, Int32Value, UInt32Value, StringValue};
use js::jsval::ObjectValue;
use js::glue::RUST_JS_NumberValue;
use std::libc;

pub trait ToJSValConvertible {
    fn to_jsval(&self, cx: *JSContext) -> JSVal;
}

pub trait FromJSValConvertible<T> {
    fn from_jsval(cx: *JSContext, val: JSVal, option: T) -> Result<Self, ()>;
}


unsafe fn convert_from_jsval<T: Default>(
    cx: *JSContext, value: JSVal,
    convert_fn: extern "C" unsafe fn(*JSContext, JSVal, *T) -> JSBool) -> Result<T, ()> {
    let mut ret = Default::default();
    if convert_fn(cx, value, &mut ret as *mut T as *T) == 0 {
        Err(())
    } else {
        Ok(ret)
    }
}


impl ToJSValConvertible for bool {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        BooleanValue(*self)
    }
}

impl FromJSValConvertible<()> for bool {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<bool, ()> {
        let result = unsafe { convert_from_jsval(cx, val, JS_ValueToBoolean) };
        result.map(|b| b != 0)
    }
}

impl ToJSValConvertible for i8 {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        Int32Value(*self as i32)
    }
}

impl FromJSValConvertible<()> for i8 {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<i8, ()> {
        let result = unsafe { convert_from_jsval(cx, val, JS_ValueToECMAInt32) };
        result.map(|v| v as i8)
    }
}

impl ToJSValConvertible for u8 {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        Int32Value(*self as i32)
    }
}

impl FromJSValConvertible<()> for u8 {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<u8, ()> {
        let result = unsafe { convert_from_jsval(cx, val, JS_ValueToECMAInt32) };
        result.map(|v| v as u8)
    }
}

impl ToJSValConvertible for i16 {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        Int32Value(*self as i32)
    }
}

impl FromJSValConvertible<()> for i16 {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<i16, ()> {
        let result = unsafe { convert_from_jsval(cx, val, JS_ValueToECMAInt32) };
        result.map(|v| v as i16)
    }
}

impl ToJSValConvertible for u16 {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        Int32Value(*self as i32)
    }
}

impl FromJSValConvertible<()> for u16 {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<u16, ()> {
        unsafe { convert_from_jsval(cx, val, JS_ValueToUint16) }
    }
}

impl ToJSValConvertible for i32 {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        Int32Value(*self)
    }
}

impl FromJSValConvertible<()> for i32 {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<i32, ()> {
        unsafe { convert_from_jsval(cx, val, JS_ValueToECMAInt32) }
    }
}

impl ToJSValConvertible for u32 {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        UInt32Value(*self)
    }
}

impl FromJSValConvertible<()> for u32 {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<u32, ()> {
        unsafe { convert_from_jsval(cx, val, JS_ValueToECMAUint32) }
    }
}

impl ToJSValConvertible for i64 {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        unsafe {
            RUST_JS_NumberValue(*self as f64)
        }
    }
}

impl FromJSValConvertible<()> for i64 {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<i64, ()> {
        unsafe { convert_from_jsval(cx, val, JS_ValueToInt64) }
    }
}

impl ToJSValConvertible for u64 {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        unsafe {
            RUST_JS_NumberValue(*self as f64)
        }
    }
}

impl FromJSValConvertible<()> for u64 {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<u64, ()> {
        unsafe { convert_from_jsval(cx, val, JS_ValueToUint64) }
    }
}

impl ToJSValConvertible for f32 {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        unsafe {
            RUST_JS_NumberValue(*self as f64)
        }
    }
}

impl FromJSValConvertible<()> for f32 {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<f32, ()> {
        let result = unsafe { convert_from_jsval(cx, val, JS_ValueToNumber) };
        result.map(|f| f as f32)
    }
}

impl ToJSValConvertible for f64 {
    fn to_jsval(&self, _cx: *JSContext) -> JSVal {
        unsafe {
            RUST_JS_NumberValue(*self)
        }
    }
}

impl FromJSValConvertible<()> for f64 {
    fn from_jsval(cx: *JSContext, val: JSVal, _option: ()) -> Result<f64, ()> {
        unsafe { convert_from_jsval(cx, val, JS_ValueToNumber) }
    }
}

impl ToJSValConvertible for DOMString {
    fn to_jsval(&self, cx: *JSContext) -> JSVal {
        unsafe {
            let string_utf16 = self.to_utf16();
            let jsstr = JS_NewUCStringCopyN(cx, string_utf16.as_ptr(), string_utf16.len() as libc::size_t);
            if jsstr.is_null() {
                fail!("JS_NewUCStringCopyN failed");
            }
            StringValue(&*jsstr)
        }
    }
}

#[deriving(Eq)]
pub enum StringificationBehavior {
    Default,
    Empty,
}

impl Default for StringificationBehavior {
    fn default() -> StringificationBehavior {
        Default
    }
}

impl FromJSValConvertible<StringificationBehavior> for DOMString {
    fn from_jsval(cx: *JSContext, value: JSVal, nullBehavior: StringificationBehavior) -> Result<DOMString, ()> {
        if nullBehavior == Empty && value.is_null() {
            Ok(~"")
        } else {
            let jsstr = unsafe { JS_ValueToString(cx, value) };
            if jsstr.is_null() {
                debug!("JS_ValueToString failed");
                Err(())
            } else {
                Ok(jsstring_to_str(cx, jsstr))
            }
        }
    }
}

impl<T: Reflectable> ToJSValConvertible for JS<T> {
    fn to_jsval(&self, cx: *JSContext) -> JSVal {
        let obj = self.reflector().get_jsobject();
        assert!(obj.is_not_null());
        let mut value = ObjectValue(unsafe { &*obj });
        if unsafe { JS_WrapValue(cx, &mut value as *mut JSVal as *JSVal) } == 0 {
            fail!("JS_WrapValue failed.");
        }
        value
    }
}

impl<T: ToJSValConvertible> ToJSValConvertible for Option<T> {
    fn to_jsval(&self, cx: *JSContext) -> JSVal {
        match self {
            &Some(ref value) => value.to_jsval(cx),
            &None => NullValue(),
        }
    }
}

impl<X: Default, T: FromJSValConvertible<X>> FromJSValConvertible<()> for Option<T> {
    fn from_jsval(cx: *JSContext, value: JSVal, _: ()) -> Result<Option<T>, ()> {
        if value.is_null_or_undefined() {
            Ok(None)
        } else {
            let option: X = Default::default();
            let result: Result<T, ()> = FromJSValConvertible::from_jsval(cx, value, option);
            result.map(Some)
        }
    }
}