defmodule Mix.Tasks.Raxol.PreCommit do
  @moduledoc """
  Run all pre-commit checks for the Raxol project.

  ## Usage

      mix raxol.pre_commit [options]
      
  ## Options

    * `--parallel` - Run checks in parallel (default: true)
    * `--fail-fast` - Stop on first failure (default: false)
    * `--only` - Run only specific checks (comma-separated)
    * `--skip` - Skip specific checks (comma-separated)
    * `--quiet` - Minimal output
    * `--verbose` - Detailed output with timing and cache info
    * `--fix` - Auto-fix issues when possible (currently: format)
    * `--no-cache` - Disable cache, run all checks fresh
    
  ## Examples

      # Run all checks
      mix raxol.pre_commit
      
      # Run with auto-fix
      mix raxol.pre_commit --fix
      
      # Force fresh check without cache
      mix raxol.pre_commit --no-cache
      
      # Run only format and compile checks
      mix raxol.pre_commit --only format,compile
      
      # Skip docs check
      mix raxol.pre_commit --skip docs
      
      # Sequential execution with fail-fast
      mix raxol.pre_commit --no-parallel --fail-fast
      
      # Verbose output with cache statistics
      mix raxol.pre_commit --verbose
  """

  use Mix.Task
  alias Raxol.PreCommit.{Config, Progress, ErrorFormatter, Metrics}

  @shortdoc "Run all pre-commit checks"

  @check_modules %{
    format: Mix.Tasks.Raxol.Check.Format,
    compile: Mix.Tasks.Raxol.Check.Compile,
    credo: Mix.Tasks.Raxol.Check.Credo,
    tests: Mix.Tasks.Raxol.Check.Tests,
    docs: Mix.Tasks.Raxol.Check.Docs,
    dialyzer: Mix.Tasks.Raxol.Check.Dialyzer,
    security: Mix.Tasks.Raxol.Check.Security
  }

  @impl Mix.Task
  def run(args) do
    {opts, _, _} =
      OptionParser.parse(args,
        switches: [
          parallel: :boolean,
          fail_fast: :boolean,
          only: :string,
          skip: :string,
          quiet: :boolean,
          verbose: :boolean,
          fix: :boolean,
          no_cache: :boolean
        ],
        aliases: [
          p: :parallel,
          f: :fail_fast,
          q: :quiet,
          v: :verbose
        ]
      )

    # Load configuration from all sources
    config = Config.load(build_cli_config(opts))

    unless config.quiet do
      IO.puts("\n🚀 Running Raxol Pre-commit Checks\n")
    end

    start_time = System.monotonic_time(:millisecond)

    # Start progress indicator if enabled
    maybe_start_progress(config)

    checks = determine_checks(config)

    # Initialize all checks in progress display
    maybe_init_checks(checks, config)

    results = run_checks(checks, config)

    # Stop progress indicator
    maybe_stop_progress(config)

    elapsed = System.monotonic_time(:millisecond) - start_time

    # Record metrics unless disabled
    unless Map.get(config, :skip_metrics, false) do
      Metrics.record_run(results, elapsed, config)
    end

    print_summary(results, elapsed, config)

    exit_code = if all_passed?(results), do: 0, else: 1
    System.halt(exit_code)
  end

  defp build_cli_config(opts) do
    # Build config map from CLI options
    cli_config = %{}

    cli_config = maybe_put(cli_config, :parallel, Keyword.get(opts, :parallel))

    cli_config =
      maybe_put(cli_config, :fail_fast, Keyword.get(opts, :fail_fast))

    cli_config = maybe_put(cli_config, :quiet, Keyword.get(opts, :quiet))
    cli_config = maybe_put(cli_config, :verbose, Keyword.get(opts, :verbose))
    cli_config = maybe_put(cli_config, :auto_fix, Keyword.get(opts, :fix))
    cli_config = maybe_put(cli_config, :no_cache, Keyword.get(opts, :no_cache))

    # Handle special cases
    cli_config =
      case Keyword.get(opts, :only) do
        nil -> cli_config
        only_str -> Map.put(cli_config, :checks, parse_check_list(only_str))
      end

    cli_config =
      case Keyword.get(opts, :skip) do
        nil -> cli_config
        skip_str -> Map.put(cli_config, :skip, parse_check_list(skip_str))
      end

    cli_config
  end

  defp maybe_put(map, _key, nil), do: map
  defp maybe_put(map, key, value), do: Map.put(map, key, value)

  defp parse_check_list(nil), do: []

  defp parse_check_list(str) do
    str
    |> String.split(",")
    |> Enum.map(&String.trim/1)
    |> Enum.map(&String.to_atom/1)
  end

  defp determine_checks(config) do
    # Get checks from config (defaults, file config, or CLI override)
    base_checks =
      Map.get(config, :checks, [:format, :compile, :credo, :tests, :docs])

    # Apply skip filter if present
    skip_list = Map.get(config, :skip, [])

    checks =
      case skip_list do
        [] -> base_checks
        skips -> Enum.reject(base_checks, &(&1 in skips))
      end

    checks
    |> Enum.map(&{&1, Map.get(@check_modules, &1)})
    |> Enum.filter(fn {_, module} -> module != nil end)
  end

  defp run_checks(checks, %{parallel: true, fail_fast: false} = config) do
    # Smart parallel execution with CPU core detection
    max_concurrency = determine_concurrency(checks)

    checks
    |> Task.async_stream(
      fn {name, module} ->
        maybe_start_check(name, config)
        check_config = Config.get_check_config(config, name)
        result = run_single_check(module, check_config)
        maybe_update_check_status(name, result, config)
        {name, result}
      end,
      ordered: true,
      timeout: 30_000,
      max_concurrency: max_concurrency
    )
    |> Enum.map(fn {:ok, result} -> result end)
  end

  defp run_checks(checks, %{parallel: false} = config) do
    Enum.reduce_while(checks, [], fn {name, module}, acc ->
      maybe_start_check(name, config)
      check_config = Config.get_check_config(config, name)
      result = run_single_check(module, check_config)
      maybe_update_check_status(name, result, config)
      new_acc = [{name, result} | acc]

      if config.fail_fast and result.status == :error do
        {:halt, Enum.reverse(new_acc)}
      else
        {:cont, new_acc}
      end
    end)
    |> Enum.reverse()
  end

  defp run_checks(checks, config) do
    # Parallel with fail-fast (more complex, simplified for now)
    run_checks(checks, %{config | parallel: false})
  end

  defp determine_concurrency(checks) do
    # Get CPU cores available
    cpu_cores = System.schedulers_online()

    # Determine check dependencies
    # compile must run before tests (tests might need compiled code)
    has_compile = Enum.any?(checks, fn {name, _} -> name == :compile end)
    has_tests = Enum.any?(checks, fn {name, _} -> name == :tests end)

    if has_compile and has_tests do
      # If we have dependent checks, limit concurrency
      min(2, cpu_cores)
    else
      # Otherwise use available cores, but cap at check count
      min(length(checks), cpu_cores)
    end
  end

  defp run_single_check(module, config) do
    start_time = System.monotonic_time(:millisecond)

    result =
      try do
        # Ensure module is compiled and loaded
        case Code.ensure_compiled(module) do
          {:module, _} ->
            if function_exported?(module, :run, 1) do
              module.run(config)
            else
              {:error, "Check module #{inspect(module)} not implemented"}
            end

          {:error, _} ->
            # Try loading all Mix tasks
            Mix.Task.load_all()
            # Retry
            case Code.ensure_compiled(module) do
              {:module, _} ->
                if function_exported?(module, :run, 1) do
                  module.run(config)
                else
                  {:error, "Check module #{inspect(module)} not implemented"}
                end

              {:error, reason} ->
                {:error,
                 "Module #{inspect(module)} not found: #{inspect(reason)}"}
            end
        end
      rescue
        e -> {:error, Exception.format(:error, e, __STACKTRACE__)}
      catch
        :exit, reason -> {:error, "Check exited: #{inspect(reason)}"}
      end

    elapsed = System.monotonic_time(:millisecond) - start_time

    case result do
      {:ok, details} ->
        %{status: :ok, details: details, elapsed: elapsed}

      {:error, reason} ->
        %{status: :error, reason: reason, elapsed: elapsed}

      {:warning, reason} ->
        %{status: :warning, reason: reason, elapsed: elapsed}
    end
  end

  defp all_passed?(results) do
    Enum.all?(results, fn {_, result} ->
      result.status in [:ok, :warning]
    end)
  end

  defp print_summary(results, total_elapsed, config) do
    unless config.quiet do
      IO.puts("\n" <> String.duplicate("─", 50))
      IO.puts("📊 Pre-commit Check Summary\n")

      Enum.each(results, fn {name, result} ->
        icon =
          case result.status do
            :ok -> "✅"
            :warning -> "⚠️ "
            :error -> "❌"
          end

        time_str =
          if config.verbose do
            " (#{result.elapsed}ms)"
          else
            ""
          end

        check_name = name |> to_string() |> String.capitalize()
        IO.puts("  #{icon} #{check_name}#{time_str}")

        # Show detailed error information for failures
        case {result.status, result[:reason], config.verbose} do
          {:error, reason, true} when is_map(reason) ->
            ErrorFormatter.print_error(name, reason, verbose: true, color: true)

          {:error, reason, _} when is_binary(reason) ->
            IO.puts("     #{reason}")

          {:warning, reason, _} when is_binary(reason) ->
            IO.puts("     #{reason}")

          _ ->
            :ok
        end
      end)

      IO.puts("\n" <> String.duplicate("─", 50))

      passed = Enum.count(results, fn {_, r} -> r.status == :ok end)
      warnings = Enum.count(results, fn {_, r} -> r.status == :warning end)
      failed = Enum.count(results, fn {_, r} -> r.status == :error end)
      total = length(results)

      IO.puts(
        "Total: #{total} checks, #{passed} passed, #{warnings} warnings, #{failed} failed"
      )

      IO.puts("Time: #{format_time(total_elapsed)}\n")

      case all_passed?(results) do
        true ->
          IO.puts("✨ All checks passed! Ready to commit.")

        false ->
          IO.puts("❌ Pre-commit checks failed. Please fix the issues above.")
          # Show error summary if not verbose (verbose shows full errors inline)
          unless config.verbose do
            ErrorFormatter.print_summary(results, color: true)
          end
      end
    end
  end

  defp format_time(ms) when ms < 1000, do: "#{ms}ms"
  defp format_time(ms), do: "#{Float.round(ms / 1000, 1)}s"

  # Progress indicator helpers

  defp maybe_start_progress(config) do
    case Progress.enabled?(config) do
      true ->
        {:ok, _} =
          Progress.start_link(
            verbose: Map.get(config, :verbose, false),
            parallel: Map.get(config, :parallel, true)
          )

      false ->
        :ok
    end
  end

  defp maybe_stop_progress(config) do
    case Progress.enabled?(config) do
      true -> Progress.stop()
      false -> :ok
    end
  catch
    :exit, _ -> :ok
  end

  defp maybe_init_checks(checks, config) do
    case Progress.enabled?(config) do
      true ->
        Enum.each(checks, fn {name, _module} ->
          Progress.init_check(name)
        end)

      false ->
        :ok
    end
  end

  defp maybe_start_check(name, config) do
    case Progress.enabled?(config) do
      true -> Progress.start_check(name)
      false -> :ok
    end
  catch
    :exit, _ -> :ok
  end

  defp maybe_update_check_status(name, result, config) do
    case Progress.enabled?(config) do
      true ->
        case result.status do
          :ok -> Progress.complete_check(name, result[:elapsed])
          :warning -> Progress.warn_check(name, result[:reason])
          :error -> Progress.fail_check(name, result[:reason])
        end

      false ->
        :ok
    end
  catch
    :exit, _ -> :ok
  end
end