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use super::*;

/// An error code value returned by most COM functions.
#[repr(transparent)]
#[derive(Copy, Clone, Default, Eq, PartialEq)]
#[must_use]
#[allow(non_camel_case_types)]
pub struct HRESULT(pub i32);

impl HRESULT {
    /// Returns [`true`] if `self` is a success code.
    #[inline]
    pub const fn is_ok(self) -> bool {
        self.0 >= 0
    }

    /// Returns [`true`] if `self` is a failure code.
    #[inline]
    pub const fn is_err(self) -> bool {
        !self.is_ok()
    }

    /// Asserts that `self` is a success code.
    ///
    /// This will invoke the [`panic!`] macro if `self` is a failure code and display
    /// the [`HRESULT`] value for diagnostics.
    #[inline]
    #[track_caller]
    pub fn unwrap(self) {
        assert!(self.is_ok(), "HRESULT 0x{:X}", self.0);
    }

    /// Converts the [`HRESULT`] to [`Result<()>`][Result<_>].
    #[inline]
    pub fn ok(self) -> Result<()> {
        if self.is_ok() {
            Ok(())
        } else {
            Err(self.into())
        }
    }

    /// Calls `op` if `self` is a success code, otherwise returns [`HRESULT`]
    /// converted to [`Result<T>`].
    #[inline]
    pub fn map<F, T>(self, op: F) -> Result<T>
    where
        F: FnOnce() -> T,
    {
        self.ok()?;
        Ok(op())
    }

    /// Calls `op` if `self` is a success code, otherwise returns [`HRESULT`]
    /// converted to [`Result<T>`].
    #[inline]
    pub fn and_then<F, T>(self, op: F) -> Result<T>
    where
        F: FnOnce() -> Result<T>,
    {
        self.ok()?;
        op()
    }

    /// The error message describing the error.
    pub fn message(&self) -> String {
        let mut message = HeapString::default();
        let mut code = self.0;
        let mut module = 0;

        let mut flags = FORMAT_MESSAGE_ALLOCATE_BUFFER
            | FORMAT_MESSAGE_FROM_SYSTEM
            | FORMAT_MESSAGE_IGNORE_INSERTS;

        unsafe {
            if self.0 & 0x1000_0000 == 0x1000_0000 {
                code ^= 0x1000_0000;
                flags |= FORMAT_MESSAGE_FROM_HMODULE;

                module =
                    LoadLibraryExA(b"ntdll.dll\0".as_ptr(), 0, LOAD_LIBRARY_SEARCH_DEFAULT_DIRS);
            }

            let size = FormatMessageW(
                flags,
                module as _,
                code as _,
                0,
                &mut message.0 as *mut _ as *mut _,
                0,
                std::ptr::null(),
            );

            if !message.0.is_null() && size > 0 {
                String::from_utf16_lossy(wide_trim_end(std::slice::from_raw_parts(
                    message.0,
                    size as usize,
                )))
            } else {
                String::default()
            }
        }
    }

    /// Maps a Win32 error code to an HRESULT value.
    pub const fn from_win32(error: u32) -> Self {
        Self(if error as i32 <= 0 {
            error
        } else {
            (error & 0x0000_FFFF) | (7 << 16) | 0x8000_0000
        } as i32)
    }

    /// Maps an NT error code to an HRESULT value.
    pub const fn from_nt(error: i32) -> Self {
        Self(if error >= 0 {
            error
        } else {
            error | 0x1000_0000
        })
    }
}

impl<T> From<Result<T>> for HRESULT {
    fn from(result: Result<T>) -> Self {
        if let Err(error) = result {
            return error.into();
        }
        HRESULT(0)
    }
}

impl std::fmt::Display for HRESULT {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("{:#010X}", self.0))
    }
}

impl std::fmt::Debug for HRESULT {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!("HRESULT({})", self))
    }
}