/* 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 js::jsapi::{JSContext, JSBool};
use js::jsapi::{JS_IsExceptionPending};
use js::jsapi::{JS_ReportErrorNumber, JSErrorFormatString, struct_JSErrorFormatString, JSEXN_TYPEERR};
use js::glue::{ReportError};

use libc;
use std::ptr;

#[deriving(Show)]
pub enum Error {
    IndexSize,
    FailureUnknown,
    NotFound,
    HierarchyRequest,
    InvalidCharacter,
    NotSupported,
    InvalidState,
    NamespaceError
}

pub type Fallible<T> = Result<T, Error>;

pub type ErrorResult = Fallible<()>;

pub fn throw_method_failed_with_details<T>(cx: *JSContext,
                                           result: Result<T, Error>,
                                           interface: &'static str,
                                           member: &'static str) -> JSBool {
    assert!(result.is_err());
    assert!(unsafe { JS_IsExceptionPending(cx) } == 0);
    let message = format!("Method failed: {}.{}", interface, member);
    message.with_c_str(|string| {
        unsafe { ReportError(cx, string) };
    });
    return 0;
}

pub fn throw_not_in_union(cx: *JSContext, names: &'static str) -> JSBool {
    assert!(unsafe { JS_IsExceptionPending(cx) } == 0);
    let message = format!("argument could not be converted to any of: {}", names);
    message.with_c_str(|string| {
        unsafe { ReportError(cx, string) };
    });
    return 0;
}

static ERROR_FORMAT_STRING_STRING: [libc::c_char, ..4] = [
    '{' as libc::c_char,
    '0' as libc::c_char,
    '}' as libc::c_char,
    0 as libc::c_char,
];

static ERROR_FORMAT_STRING: JSErrorFormatString = struct_JSErrorFormatString {
    format: &ERROR_FORMAT_STRING_STRING as *libc::c_char,
    argCount: 1,
    exnType: JSEXN_TYPEERR as i16,
};

extern fn get_error_message(_user_ref: *mut libc::c_void,
                            _locale: *libc::c_char,
                            error_number: libc::c_uint) -> *JSErrorFormatString
{
    assert_eq!(error_number, 0);
    &ERROR_FORMAT_STRING as *JSErrorFormatString
}

pub fn throw_type_error(cx: *JSContext, error: &str) {
    let error = error.to_c_str();
    error.with_ref(|error| unsafe {
        JS_ReportErrorNumber(cx, get_error_message, ptr::null(), 0, error);
    });
}