defmodule Mix.Tasks.Firebird.Phoenix do
  @moduledoc """
  Compile and test Phoenix WASM components.

  ## Usage

      # Build all Phoenix WASM modules from Rust sources
      mix firebird.phoenix build

      # Run the Phoenix WASM benchmark suite
      mix firebird.phoenix bench

      # Show information about loaded Phoenix WASM modules
      mix firebird.phoenix info

  ## Build

  Compiles the Rust source files in `fixtures/phoenix_*/` to WASM modules.
  Requires Rust with the `wasm32-unknown-unknown` target installed.

  ## Bench

  Runs performance benchmarks comparing WASM-accelerated Phoenix components
  against pure Elixir implementations.

  ## Info

  Shows the available Phoenix WASM modules, their sizes, and exported functions.
  """

  use Mix.Task

  @shortdoc "Phoenix WASM tools (build, bench, info)"

  @phoenix_modules ~w(phoenix_router phoenix_template phoenix_plug phoenix_endpoint phoenix_view phoenix_controller phoenix_channel phoenix_json phoenix_session phoenix_live phoenix_validator phoenix_form phoenix_csrf phoenix_rate_limiter)

  @impl Mix.Task
  def run(args) do
    case args do
      ["build" | _] ->
        build()

      ["bench" | _] ->
        bench()

      ["info" | _] ->
        info()

      _ ->
        Mix.shell().info("""
        Usage: mix firebird.phoenix <command>

        Commands:
          build   Build Phoenix WASM modules from Rust sources
          bench   Run performance benchmarks
          info    Show module information
        """)
    end
  end

  defp build do
    Mix.shell().info("🔥 Building Phoenix WASM modules...\n")

    fixtures_dir = Path.join(File.cwd!(), "fixtures")

    results =
      Enum.map(@phoenix_modules, fn module ->
        src_dir = Path.join(fixtures_dir, module)
        wasm_output = Path.join(fixtures_dir, "#{module}.wasm")

        if File.dir?(src_dir) do
          Mix.shell().info("  📦 Building #{module}...")

          {output, code} =
            System.cmd(
              "cargo",
              [
                "build",
                "--target",
                "wasm32-unknown-unknown",
                "--release"
              ],
              cd: src_dir,
              stderr_to_stdout: true
            )

          if code == 0 do
            # Copy the built WASM to fixtures root
            built_wasm =
              Path.join([
                src_dir,
                "target",
                "wasm32-unknown-unknown",
                "release",
                "#{module}.wasm"
              ])

            if File.exists?(built_wasm) do
              File.cp!(built_wasm, wasm_output)
              size = File.stat!(wasm_output).size
              Mix.shell().info("     ✅ #{module}.wasm (#{format_bytes(size)})")
              {:ok, module}
            else
              Mix.shell().info("     ❌ WASM file not found after build")
              {:error, module}
            end
          else
            Mix.shell().info("     ❌ Build failed: #{String.slice(output, 0..200)}")
            {:error, module}
          end
        else
          Mix.shell().info("  ⏭️  #{module} - no source directory")
          {:skip, module}
        end
      end)

    ok = Enum.count(results, &(elem(&1, 0) == :ok))
    fail = Enum.count(results, &(elem(&1, 0) == :error))
    Mix.shell().info("\n📊 Built #{ok} modules, #{fail} failures")
  end

  defp bench do
    Mix.Task.run("app.start")

    Mix.shell().info("🔥 Phoenix WASM Benchmarks\n")

    components = ~w(router template plug endpoint json session channel server)a

    for comp <- components do
      try do
        Firebird.Phoenix.Benchmark.run(comp, iterations: 1_000)
      rescue
        e -> Mix.shell().info("  ⚠️  #{comp}: #{Exception.message(e)}")
      end
    end

    Mix.shell().info("\n✅ Benchmarks complete")
  end

  defp info do
    Mix.Task.run("app.start")
    fixtures_dir = Path.join(File.cwd!(), "fixtures")

    Mix.shell().info("🔥 Phoenix WASM Module Information\n")

    Enum.each(@phoenix_modules, fn module ->
      wasm_path = Path.join(fixtures_dir, "#{module}.wasm")

      if File.exists?(wasm_path) do
        size = File.stat!(wasm_path).size
        Mix.shell().info("  📦 #{module}")
        Mix.shell().info("     Path: #{wasm_path}")
        Mix.shell().info("     Size: #{format_bytes(size)}")

        # Try to load and get exports
        case Firebird.load(wasm_path) do
          {:ok, instance} ->
            exports = Firebird.exports(instance)
            Mix.shell().info("     Exports: #{inspect(exports)}")
            Firebird.stop(instance)

          {:error, reason} ->
            Mix.shell().info("     Error loading: #{inspect(reason)}")
        end

        Mix.shell().info("")
      else
        Mix.shell().info("  ❌ #{module} - not built (run `mix firebird.phoenix build`)\n")
      end
    end)
  end

  defp format_bytes(bytes) when bytes < 1024, do: "#{bytes} B"
  defp format_bytes(bytes) when bytes < 1_048_576, do: "#{Float.round(bytes / 1024, 1)} KB"
  defp format_bytes(bytes), do: "#{Float.round(bytes / 1_048_576, 1)} MB"
end