use bindgen::MacroTypeVariation;
use std::env;
use std::path::PathBuf;

fn main() {
    if cfg!(feature = "link") {
        println!("cargo:rustc-link-lib=pam");
        println!("cargo:rustc-check-cfg=cfg(pam_impl, values(\"linux-pam\",\"openpam\"))");
        let common_builder = bindgen::Builder::default()
            .merge_extern_blocks(true)
            .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
            .blocklist_type("pam_handle")
            .blocklist_type("pam_conv")
            .allowlist_var(".*")
            .allowlist_function("pam_start")
            .allowlist_function("pam_[gs]et_item")
            .allowlist_function("pam_get_(user|authtok)")
            .allowlist_function("pam_end")
            .allowlist_function("pam_strerror")
            .allowlist_function("pam_authenticate")
            .allowlist_function("pam_chauthtok")
            .allowlist_function("pam_acct_mgmt")
            .allowlist_function("pam_(ge|pu)tenv(list)?")
            .default_macro_constant_type(MacroTypeVariation::Unsigned);

        let linux_builder = common_builder
            .clone()
            // This function is not available in OpenPAM.
            // That means if somebody tries to run a binary compiled for
            // Linux-PAM against a different impl, it will fail.
            .allowlist_function("pam_syslog")
            .header_contents(
                "linux-pam.h",
                r#"
                #include <syslog.h> // for log levels
                #include <security/_pam_types.h>
                #include <security/pam_appl.h>
                #include <security/pam_ext.h>
                #include <security/pam_modules.h>
                "#,
            );
        let openpam_builder = common_builder
            .clone()
            // This function is not available in Linux-PAM.
            // That means if somebody tries to run a binary compiled for
            // OpenPAM against a different impl, it will fail.
            .allowlist_function("openpam_log")
            .header_contents(
                "openpam.h",
                r#"
                #include <security/pam_types.h>
                #include <security/openpam.h>
                #include <security/pam_appl.h>
                #include <security/pam_constants.h>
                "#,
            );

        let (pam_impl, bindings) = {
            if let Ok(bindings) = linux_builder.generate() {
                ("linux-pam", bindings)
            } else if let Ok(bindings) = openpam_builder.generate() {
                ("openpam", bindings)
            } else {
                panic!("unrecognized PAM implementation")
            }
        };
        println!("cargo:rustc-cfg=pam_impl={pam_impl:?}");
        let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
        bindings
            .write_to_file(out_path.join("bindings.rs"))
            .unwrap();
    }
}