defmodule Mix.Tasks.Firebird.Init do
  @moduledoc """
  Initializes Firebird WASM integration in your project.

  This task sets up everything needed to work with WASM modules:
  - Creates a `wasm/` directory for your WASM files
  - Adds sample configuration
  - Creates example usage code

  ## Usage

      mix firebird.init
      mix firebird.init --example math
      mix firebird.init --rust
      mix firebird.init --phoenix
      mix firebird.init --rust --phoenix --example math

  ## Options

  - `--example` - Generate example WASM integration (math, string)
  - `--rust` - Generate a Rust WASM scaffold in `native/`
  - `--phoenix` - Generate Phoenix helper modules
  - `--force` - Overwrite existing files
  """

  use Mix.Task

  @shortdoc "Initialize Firebird WASM integration in your project"

  @impl Mix.Task
  def run(args) do
    {opts, _, _} =
      OptionParser.parse(args,
        switches: [example: :string, force: :boolean, rust: :boolean, phoenix: :boolean],
        aliases: [e: :example, f: :force, r: :rust, p: :phoenix]
      )

    Mix.shell().info("🔥 Initializing Firebird WASM integration...")

    create_directories()
    copy_sample_wasm()
    create_config()
    create_wasm_module_template()

    if opts[:example] do
      create_example(opts[:example])
    end

    if opts[:rust] do
      create_rust_scaffold()
    end

    if opts[:phoenix] do
      create_phoenix_helpers()
    end

    create_test_template()
    print_success_message()
  end

  defp create_directories do
    Mix.Generator.create_directory("wasm")
    Mix.Generator.create_directory("lib/wasm_modules")
    Mix.shell().info("  Created wasm/ directory")
    Mix.shell().info("  Created lib/wasm_modules/ directory")
  end

  defp copy_sample_wasm do
    sample_src = Firebird.sample_wasm_path()
    sample_dest = "wasm/sample_math.wasm"

    if File.exists?(sample_src) && !File.exists?(sample_dest) do
      File.cp!(sample_src, sample_dest)
      Mix.shell().info("  Copied sample_math.wasm to wasm/ (try it now!)")
    end
  end

  defp create_config do
    config_path = "config/firebird.exs"

    if File.exists?(config_path) do
      Mix.shell().info("  #{config_path} already exists, skipping")
    else
      config_content = """
      import Config

      # Firebird WASM Configuration
      config :firebird,
        # Directory containing WASM files
        wasm_path: "wasm",

        # Default memory limit for WASM instances (64MB)
        memory_limit: 67_108_864,

        # Default execution timeout (5 seconds)
        timeout: 5_000,

        # Enable WASI support
        wasi: true
      """

      File.mkdir_p!("config")
      File.write!(config_path, config_content)
      Mix.shell().info("  Created #{config_path}")
    end
  end

  defp create_wasm_module_template do
    template_path = "lib/wasm_modules/example.ex"

    if File.exists?(template_path) do
      Mix.shell().info("  #{template_path} already exists, skipping")
    else
      template_content = ~S'''
      defmodule WasmModules.Example do
        @moduledoc """
        Example WASM module wrapper.

        Replace with your actual WASM module path and functions.
        Add to your supervision tree: `children = [WasmModules.Example]`
        Then call: `WasmModules.Example.add(5, 3)`
        """
        use Firebird, wasm: "wasm/example.wasm"

        wasm_fn :add, args: 2
        wasm_fn :multiply, args: 2
      end
      '''

      File.write!(template_path, template_content)
      Mix.shell().info("  Created #{template_path}")
    end
  end

  defp create_example("math") do
    example_path = "lib/wasm_modules/math.ex"

    example_content = ~S'''
    defmodule WasmModules.Math do
      @moduledoc """
      Math operations implemented in WASM.

      Add to your supervision tree:

          children = [WasmModules.Math]

      Then call functions:

          {:ok, [8]} = WasmModules.Math.add(5, 3)
          [55] = WasmModules.Math.fibonacci!(10)
      """
      use Firebird, wasm: "wasm/math.wasm"

      wasm_fn :add, args: 2, doc: "Add two integers"
      wasm_fn :multiply, args: 2, doc: "Multiply two integers"
      wasm_fn :fibonacci, args: 1, doc: "Calculate fibonacci number"
    end
    '''

    File.write!(example_path, example_content)
    Mix.shell().info("  Created #{example_path} (math example)")
  end

  defp create_example(_other) do
    Mix.shell().info("  Unknown example type, skipping")
  end

  defp create_rust_scaffold do
    File.mkdir_p!("native/src")

    # Cargo.toml
    cargo_toml = """
    [package]
    name = "wasm_native"
    version = "0.1.0"
    edition = "2021"

    [lib]
    crate-type = ["cdylib"]

    [profile.release]
    opt-level = "z"
    lto = true
    strip = true
    """

    File.write!("native/Cargo.toml", cargo_toml)

    # src/lib.rs
    lib_rs = ~S"""
    #[no_mangle]
    pub extern "C" fn add(a: i32, b: i32) -> i32 {
        a + b
    }

    #[no_mangle]
    pub extern "C" fn multiply(a: i32, b: i32) -> i32 {
        a * b
    }

    #[no_mangle]
    pub extern "C" fn fibonacci(n: i32) -> i32 {
        if n <= 1 {
            return n;
        }
        let mut a = 0i32;
        let mut b = 1i32;
        for _ in 2..=n {
            let tmp = b;
            b = a + b;
            a = tmp;
        }
        b
    }
    """

    File.write!("native/src/lib.rs", lib_rs)

    # build.sh
    build_sh = """
    #!/bin/bash
    # Build Rust WASM module
    set -e
    cd "$(dirname "$0")"
    cargo build --target wasm32-unknown-unknown --release
    cp target/wasm32-unknown-unknown/release/wasm_native.wasm ../wasm/
    echo "Built wasm/wasm_native.wasm"
    """

    File.write!("native/build.sh", build_sh)
    File.chmod!("native/build.sh", 0o755)

    Mix.shell().info("  Created native/ Rust scaffold")
  end

  defp create_phoenix_helpers do
    helper_path = "lib/wasm_modules/phoenix_helpers.ex"

    helper_content = ~S'''
    defmodule WasmModules.PhoenixHelpers do
      @moduledoc """
      Phoenix integration helpers for Firebird WASM modules.

      ## Setup

      Add a WASM pool to your application supervision tree:

          # application.ex
          children = [
            {Firebird.Pool, wasm: "wasm/math.wasm", size: 4, name: :wasm_math},
            MyAppWeb.Endpoint
          ]

      ## Controller Usage

          defmodule MyAppWeb.ComputeController do
            use MyAppWeb, :controller

            def compute(conn, %{"a" => a, "b" => b}) do
              [result] = Firebird.Pool.call!(:wasm_math, :add, [
                String.to_integer(a),
                String.to_integer(b)
              ])
              json(conn, %{result: result})
            end
          end

      ## LiveView Usage

          defmodule MyAppWeb.ComputeLive do
            use MyAppWeb, :live_view

            def mount(_params, _session, socket) do
              {:ok, assign(socket, :result, nil)}
            end

            def handle_event("compute", %{"n" => n}, socket) do
              [result] = Firebird.Pool.call!(:wasm_math, :fibonacci, [
                String.to_integer(n)
              ])
              {:noreply, assign(socket, :result, result)}
            end
          end

      ## One-shot Usage (no pool needed)

          # For infrequent calls, use Firebird.run!/3 directly:
          [result] = Firebird.run!("wasm/math.wasm", :add, [5, 3])
      """
    end
    '''

    File.write!(helper_path, helper_content)
    Mix.shell().info("  Created #{helper_path}")
  end

  defp create_test_template do
    test_path = "test/wasm_test.exs"

    if File.exists?(test_path) do
      Mix.shell().info("  #{test_path} already exists, skipping")
    else
      File.mkdir_p!("test")

      content = ~S'''
      defmodule WasmTest do
        use ExUnit.Case
        import Firebird.TestHelpers

        # Uses the bundled sample math.wasm
        setup_wasm "wasm/sample_math.wasm"

        test "add two numbers", %{wasm: wasm} do
          assert_wasm_call wasm, :add, [5, 3], [8]
        end

        test "multiply", %{wasm: wasm} do
          assert_wasm_call wasm, :multiply, [4, 7], [28]
        end

        test "fibonacci", %{wasm: wasm} do
          assert_wasm_call wasm, :fibonacci, [10], [55]
        end

        test "exports are available", %{wasm: wasm} do
          assert_wasm_exports wasm, [:add, :multiply, :fibonacci]
        end

        test "type signatures", %{wasm: wasm} do
          assert_wasm_type wasm, :add, {[:i32, :i32], [:i32]}
        end
      end
      '''

      File.write!(test_path, content)
      Mix.shell().info("  Created #{test_path}")
    end
  end

  defp print_success_message do
    Mix.shell().info("""

    🔥 Firebird WASM integration initialized!

    Try it NOW (zero setup):

      iex -S mix
      iex> Firebird.check!()     # Verify setup works
      iex> Firebird.demo()       # See it in action

      # Or call the sample WASM directly:
      iex> {:ok, [8]} = Firebird.run("wasm/sample_math.wasm", :add, [5, 3])

    Next steps:

    1. Add your own .wasm files to wasm/

    2. Generate a typed wrapper from any .wasm file:
       mix firebird.gen wasm/your_module.wasm --module MyApp.YourModule

    3. Run the generated tests:
       mix test test/wasm_test.exs

    See CHEATSHEET.md for a quick API reference. Happy WASM coding! 🚀
    """)
  end
end