use once_cell::sync::Lazy;
use regex::{Captures, Regex};

static C_PTR_RE: Lazy<Regex> =
    Lazy::new(|| Regex::new(r"(const )?([a-zA-Z0-9_]+)\s?\*(.*)").unwrap());

static REST_C_PTR_RE: Lazy<Regex> = Lazy::new(|| Regex::new(r"(const)?\s?\*").unwrap());

pub fn c_ptr_to_rust_ptr(c_ptr: &str) -> String
{
    C_PTR_RE
        .replace(c_ptr, |captures: &Captures| {
            let const_or_mut = captures.get(1).map_or_else(|| "mut", |_| "const");

            let type_name = captures.get(2).unwrap().as_str();

            let rest = captures.get(3).unwrap();

            let rest_ptr_matches = REST_C_PTR_RE.captures_iter(rest.as_str());

            let rest_ptrs = rest_ptr_matches
                .map(|capts| {
                    let const_or_mut = capts.get(1).map_or_else(|| "mut", |_| "const");

                    format!("*{const_or_mut} ")
                })
                .collect::<Vec<_>>();

            format!("{}*{const_or_mut} {type_name}", rest_ptrs.join(" "))
        })
        .to_string()
}

#[cfg(test)]
mod tests
{
    use pretty_assertions::assert_str_eq;

    use super::*;

    #[test]
    fn c_ptr_to_rust_ptr_works()
    {
        assert_str_eq!(c_ptr_to_rust_ptr("void *"), "*mut void");
        assert_str_eq!(c_ptr_to_rust_ptr("const void*"), "*const void");
        assert_str_eq!(c_ptr_to_rust_ptr("GLint *"), "*mut GLint");
        assert_str_eq!(c_ptr_to_rust_ptr("const GLint*"), "*const GLint");
        assert_str_eq!(c_ptr_to_rust_ptr("const GLint *"), "*const GLint");
        assert_str_eq!(c_ptr_to_rust_ptr("const GLint **"), "*mut *const GLint");
        assert_str_eq!(c_ptr_to_rust_ptr("const GLint * *"), "*mut *const GLint");
        assert_str_eq!(c_ptr_to_rust_ptr("GLint **"), "*mut *mut GLint");
        assert_str_eq!(c_ptr_to_rust_ptr("GLuint * const*"), "*const *mut GLuint");

        assert_str_eq!(
            c_ptr_to_rust_ptr("const GLuint * const*"),
            "*const *const GLuint"
        );

        assert_str_eq!(c_ptr_to_rust_ptr("GLchar"), "GLchar");
    }
}