defmodule Mix.Tasks.Compile.FirebirdNif do
  @moduledoc """
  Compiles the Firebird sync NIF from Rust source.

  The NIF provides synchronous WASM execution via dirty CPU schedulers,
  reducing per-call overhead from ~40μs (Wasmex async) to ~6μs.

  Requires Rust toolchain (rustc + cargo). Install via:
      curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
  """

  use Mix.Task

  @impl true
  def run(_args) do
    native_dir = Path.join(File.cwd!(), "native/firebird_nif")
    priv_dir = Path.join(File.cwd!(), "priv/native")

    if File.dir?(native_dir) do
      # Check if we need to rebuild
      so_path = Path.join(priv_dir, "libfirebird_nif.so")
      src_path = Path.join(native_dir, "src/lib.rs")

      needs_build =
        !File.exists?(so_path) or
          (File.exists?(src_path) and
             File.stat!(src_path).mtime > File.stat!(so_path).mtime)

      if needs_build do
        Mix.shell().info("Compiling Firebird sync NIF...")
        File.mkdir_p!(priv_dir)

        case System.cmd("cargo", ["build", "--release"],
               cd: native_dir,
               env: [
                 {"PATH", System.get_env("PATH", "") <> ":#{System.get_env("HOME")}/.cargo/bin"}
               ],
               stderr_to_stdout: true
             ) do
          {_output, 0} ->
            # Copy the built library
            release_dir = Path.join(native_dir, "target/release")
            lib_name = "libfirebird_nif.so"

            src = Path.join(release_dir, lib_name)

            if File.exists?(src) do
              File.cp!(src, so_path)
              Mix.shell().info("  → #{so_path}")
            end

            :ok

          {output, code} ->
            Mix.shell().error("Firebird NIF compilation failed (exit #{code}):")
            Mix.shell().error(output)
            # Don't fail the build - SyncNif is optional
            :ok
        end
      else
        :ok
      end
    else
      :ok
    end
  end
end