// Copyright 2022 the Gigamono authors. All rights reserved. GPL-3.0 License.

use std::ffi::CString;
use anyhow::Result;

use llvm_sys::{core::LLVMAddFunction, prelude::LLVMValueRef};

use super::{module::LLModule, types::LLFunctionType};

/// This is a wrapper for LLVM Function.
pub(crate) struct LLFunction {
    function_ref: LLVMValueRef,
}

impl LLFunction {
    /// Creates a new LLVM function.
    ///
    /// # Safety
    /// I'm unsure of the safety using a temporary `CString` here.
    /// From the doc, it appears it may use a reference or copy the value depending on context.
    ///
    /// - https://llvm.org/doxygen/Twine_8h_source.html#l00477
    /// - https://llvm.org/doxygen/Value_8cpp_source.html#l00315
    pub(crate) fn new(name: &str, module: &LLModule, signature: &LLFunctionType) -> Result<Self> {
        // TODO(appcypher): Investigate safety properly.
        Ok(Self {
            function_ref: unsafe {
                LLVMAddFunction(
                    module.as_ptr(),
                    CString::new(name)?.as_ptr(),
                    signature.as_ptr(),
                )
            },
        })
    }
}