defmodule Mix.Tasks.Firebird.Target.Inspect do
  @moduledoc """
  Inspect the compilation pipeline for a specific source file.

  Shows the output of each pipeline stage, useful for debugging
  compilation issues.

  ## Usage

      # Inspect all stages for a file
      mix firebird.target.inspect lib/math.ex

      # Inspect a specific stage
      mix firebird.target.inspect lib/math.ex --stage ir
      mix firebird.target.inspect lib/math.ex --stage wat
      mix firebird.target.inspect lib/math.ex --stage type_infer

      # Run with optimizations
      mix firebird.target.inspect lib/math.ex --optimize --tco

  ## Stages

  - `parse` - Elixir AST
  - `ir` - Firebird IR
  - `optimize` - Optimized IR
  - `type_infer` - Typed IR
  - `validate` - Validation result
  - `wat` - WebAssembly Text Format
  - `wasm` - WASM binary info
  """

  use Mix.Task

  @shortdoc "Inspect WASM compilation pipeline stages"

  @switches [
    stage: :string,
    optimize: :boolean,
    tco: :boolean,
    inline: :boolean
  ]

  @aliases [
    s: :stage
  ]

  @impl Mix.Task
  def run(args) do
    {opts, paths, _} = OptionParser.parse(args, switches: @switches, aliases: @aliases)

    if Enum.empty?(paths) do
      Mix.raise("Usage: mix firebird.target.inspect <file.ex> [--stage <stage>]")
    end

    file = hd(paths)

    unless File.regular?(file) do
      Mix.raise("File not found: #{file}")
    end

    source = File.read!(file)
    stage = Keyword.get(opts, :stage)
    pipeline_opts = Keyword.take(opts, [:optimize, :tco, :inline])

    Mix.shell().info("🔍 Firebird Pipeline Inspector")
    Mix.shell().info("   File: #{file}")
    Mix.shell().info("")

    if stage do
      stage_atom = String.to_atom(stage)
      output = Firebird.Target.Pipeline.inspect_stage(stage_atom, source, pipeline_opts)
      Mix.shell().info(output)
    else
      # Show all stages
      case Firebird.Target.Pipeline.run_all(source, pipeline_opts) do
        {:ok, results} ->
          Mix.shell().info("  ✅ Parse: AST generated")

          Mix.shell().info(
            "  ✅ IR: #{results.ir.name} (#{length(results.ir.functions)} functions)"
          )

          Mix.shell().info("  ✅ Validated")

          Enum.each(results.typed_ir.functions, fn f ->
            params =
              if f.type, do: Enum.map(f.type.params, &to_string/1) |> Enum.join(", "), else: "?"

            ret = if f.type, do: to_string(f.type.return), else: "?"
            Mix.shell().info("     #{f.name}(#{params}) -> #{ret}")
          end)

          Mix.shell().info("  ✅ WAT: #{byte_size(results.wat)} bytes")
          Mix.shell().info("  ✅ WASM: #{byte_size(results.wasm)} bytes")

        {:error, reason} ->
          Mix.shell().error("  ❌ Pipeline failed: #{inspect(reason)}")
      end
    end

    :ok
  end
end