use std::process::Command;

fn pg_config(arg: &str) -> String {
    let exe = std::env::var("PG_CONFIG").unwrap_or_else(|_| "pg_config".to_string());
    let out = Command::new(&exe)
        .arg(arg)
        .output()
        .unwrap_or_else(|_| panic!("Failed to run `{exe} {arg}`. Set PG_CONFIG env var."));
    String::from_utf8(out.stdout)
        .expect("pg_config output is not valid UTF-8")
        .trim()
        .to_string()
}

fn main() {
    let includedir_server = pg_config("--includedir-server");
    let includedir = pg_config("--includedir");

    println!("cargo:rerun-if-changed=src/shim.c");
    println!("cargo:rerun-if-changed=build.rs");
    println!("cargo:rerun-if-env-changed=PG_CONFIG");

    let mut build = cc::Build::new();
    build
        .file("src/shim.c")
        .include(&includedir_server)
        .include(&includedir)
        .flag("-Wno-unused-parameter")
        .flag("-Wno-declaration-after-statement")
        .flag("-Wno-missing-field-initializers");

    // On macOS, PostgreSQL headers require libintl.h from Homebrew gettext.
    // Add its include path when brew is available.
    #[cfg(target_os = "macos")]
    if let Ok(out) = Command::new("brew").args(["--prefix", "gettext"]).output() {
        if out.status.success() {
            let prefix = String::from_utf8_lossy(&out.stdout).trim().to_string();
            build.include(format!("{prefix}/include"));
        }
    }

    build.compile("kham_pg_shim");

    // On macOS the linker requires explicit permission to leave PG server
    // symbols (palloc, ereport, etc.) unresolved at link time.  They are
    // resolved by the PostgreSQL backend at dlopen time.
    // On Linux these symbols are left UNDEF by default — no flag needed.
    #[cfg(target_os = "macos")]
    {
        println!("cargo:rustc-cdylib-link-arg=-undefined");
        println!("cargo:rustc-cdylib-link-arg=dynamic_lookup");
    }
}