defmodule Firebird do
  @moduledoc """
  Run WebAssembly from Elixir — load WASM modules written in Rust, Go, C,
  or any language and call them like native functions.

  ## Quick Start (30 seconds)

      # Verify setup
      Firebird.check!()  # => :ok

      # One-liner: load → call → stop
      {:ok, 8} = Firebird.run_one("math.wasm", :add, [5, 3])

      # Load once, call many
      wasm = Firebird.load!("math.wasm")
      8 = Firebird.call_one!(wasm, :add, [5, 3])
      55 = Firebird.call_one!(wasm, :fibonacci, [10])
      Firebird.stop(wasm)

  ## `use Firebird` — Declarative Wrappers

      defmodule MyApp.Math do
        use Firebird, wasm: "priv/wasm/math.wasm"
        wasm_fn :add, args: 2
        wasm_fn :fibonacci, args: 1
      end

      # Add to supervision tree: children = [MyApp.Math]
      # Then call: {:ok, [8]} = MyApp.Math.add(5, 3)

  Or auto-discover all exports:

      defmodule MyApp.Math do
        use Firebird, wasm: "priv/wasm/math.wasm", auto: true
      end

  ## API Overview

  | Function | Returns |
  |----------|---------|
  | `run_one(path, fn, args)` | `{:ok, value}` — one-shot, single value |
  | `run_one!(path, fn, args)` | `value` — one-shot, raises |
  | `call_one(wasm, fn, args)` | `{:ok, value}` — single value |
  | `call_one!(wasm, fn, args)` | `value` — raises |
  | `call(wasm, fn, args)` | `{:ok, [results]}` — list |
  | `call!(wasm, fn, args)` | `[results]` — raises |
  | `with_instance(path, fun)` | `{:ok, result}` — auto-cleanup |
  | `functions(wasm)` | `[%{name, params, results, arity}]` |
  | `validate(source)` | `:ok` or `{:error, reason}` |
  | `sample()` | `pid` — bundled sample for quick testing |

  See `Firebird.Pool` for concurrent execution, `Firebird.Lazy` for
  on-demand loading, `Firebird.Memory` for structured memory management
  (strings, typed arrays, arena allocation), and `Firebird.Module` for
  declarative wrappers.
  """

  @doc """
  Use Firebird in a module to create a WASM wrapper.

  This is a convenient shortcut for `use Firebird.Module`.

  ## Examples

      defmodule MyApp.Math do
        use Firebird, wasm: "priv/wasm/math.wasm"

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

  All options from `Firebird.Module` are supported:

  - `:wasm` - Path to WASM file (required)
  - `:name` - Process name (default: module name)
  - `:auto` - Auto-discover exports (default: false)
  - `:opts` - Options passed to `Firebird.load/2`
  """
  defmacro __using__(opts) do
    quote do
      use Firebird.Module, unquote(opts)
    end
  end

  @doc """
  Load a WASM module from a file path or binary.

  ## Arguments

  - `wasm_source` - Path to a .wasm file (string) or raw WASM bytes (binary)
  - `opts` - Optional keyword list:
    - `:memory_limit` - Maximum memory in bytes (default: 64MB)
    - `:timeout` - Execution timeout in ms (default: 5000)
    - `:wasi` - Enable WASI support (default: false)

  ## Examples

      {:ok, instance} = Firebird.load("priv/wasm/math.wasm")
      {:ok, instance} = Firebird.load(wasm_bytes)
      {:ok, instance} = Firebird.load("app.wasm", wasi: true)
  """
  @spec load(binary() | String.t(), keyword()) :: {:ok, pid()} | {:error, term()}
  def load(wasm_source, opts \\ []) do
    Firebird.Runtime.load(wasm_source, opts)
  end

  @doc """
  Load a WASM module from the application's `priv/` directory.

  This is the idiomatic way to load WASM files that ship with your app.

  ## Examples

      # Loads from priv/wasm/math.wasm of your app
      {:ok, instance} = Firebird.load_priv(:my_app, "wasm/math.wasm")

      # Loads from priv/math.wasm of your app
      {:ok, instance} = Firebird.load_priv(:my_app, "math.wasm")
  """
  @spec load_priv(atom(), String.t(), keyword()) :: {:ok, pid()} | {:error, term()}
  def load_priv(app, relative_path, opts \\ []) do
    path = Path.join(:code.priv_dir(app) |> to_string(), relative_path)
    load(path, opts)
  end

  @doc """
  Load a WASM module from a file path explicitly.

  ## Examples

      {:ok, instance} = Firebird.load_file("fixtures/math.wasm")
  """
  @spec load_file(String.t(), keyword()) :: {:ok, pid()} | {:error, term()}
  def load_file(path, opts \\ []) do
    Firebird.Runtime.load_file(path, opts)
  end

  @doc """
  Load a WASM module using the SyncNif fast path (~2μs per-call overhead).

  Returns a reference (not a PID). Works with all `Firebird.Phoenix.*` modules.
  ~20x lower per-call overhead than `Firebird.load/2` which uses Wasmex (~40μs).

  ## Examples

      {:ok, instance} = Firebird.load_sync("fixtures/phoenix_router.wasm")
      {:ok, match} = Firebird.Phoenix.Router.match_compiled(instance, "GET", "/users/42")
  """
  @spec load_sync(String.t()) :: {:ok, reference()} | {:error, term()}
  def load_sync(path) when is_binary(path) do
    resolved = Firebird.Runtime.resolve_wasm_path(path)
    Firebird.SyncNif.load(resolved)
  end

  @doc """
  Call an exported function on a WASM instance.

  ## Examples

      {:ok, [8]} = Firebird.call(instance, :add, [5, 3])
      {:ok, [55]} = Firebird.call(instance, "fibonacci", [10])
  """
  @spec call(pid(), atom() | String.t(), list()) :: {:ok, list()} | {:error, term()}
  def call(instance, function, args) when is_list(args) do
    Firebird.Runtime.call(instance, function, args)
  end

  def call(_instance, _function, args) when not is_list(args) do
    raise ArgumentError, """
    Firebird.call/3 expects args as a list, got: #{inspect(args)}

    Example: Firebird.call(wasm, :add, [5, 3])
             Firebird.call(wasm, :fibonacci, [10])
    """
  end

  @doc """
  Call an exported function, raising on error.

  ## Examples

      [8] = Firebird.call!(instance, :add, [5, 3])
  """
  @spec call!(pid(), atom() | String.t(), list()) :: list()
  def call!(instance, function, args) when is_list(args) do
    Firebird.Runtime.call!(instance, function, args)
  end

  def call!(_instance, _function, args) when not is_list(args) do
    raise ArgumentError, """
    Firebird.call!/3 expects args as a list, got: #{inspect(args)}

    Example: Firebird.call!(wasm, :add, [5, 3])
    """
  end

  @doc """
  Call multiple functions in sequence.

  ## Examples

      {:ok, [[3], [12]]} = Firebird.call_many(instance, [
        {:add, [1, 2]},
        {:multiply, [3, 4]}
      ])
  """
  @spec call_many(pid(), [{atom() | String.t(), list()}]) :: {:ok, [list()]} | {:error, term()}
  def call_many(instance, calls) when is_list(calls) do
    Firebird.Runtime.call_many(instance, calls)
  end

  @doc """
  Check if a function exists in the WASM module.

  ## Examples

      true = Firebird.function_exists?(instance, :add)
      false = Firebird.function_exists?(instance, :nonexistent)
  """
  @spec function_exists?(pid(), atom() | String.t()) :: boolean()
  def function_exists?(instance, function) do
    Firebird.Runtime.function_exists?(instance, function)
  end

  @doc """
  List all exported functions from a WASM instance.

  ## Examples

      exports = Firebird.exports(instance)
      # => [:add, :multiply, :fibonacci]
  """
  @spec exports(pid()) :: [atom()]
  def exports(instance) do
    Firebird.Runtime.exports(instance)
  end

  @doc """
  List all exports with their types.

  ## Examples

      all = Firebird.all_exports(instance)
      # => [{"add", :function}, {"memory", :memory}]
  """
  @spec all_exports(pid()) :: [{String.t(), atom()}]
  def all_exports(instance) do
    Firebird.Runtime.all_exports(instance)
  end

  @doc """
  List all exported functions with their type signatures.

  Returns a list of maps with `:name`, `:params`, `:results`, and `:arity` keys.
  This is a richer alternative to `exports/1` for understanding a module.

  ## Examples

      functions = Firebird.functions(instance)
      # => [
      #   %{name: :add, params: [:i32, :i32], results: [:i32], arity: 2},
      #   %{name: :fibonacci, params: [:i32], results: [:i32], arity: 1},
      #   ...
      # ]
  """
  @spec functions(pid()) :: [map()]
  def functions(instance) do
    for func <- exports(instance) do
      case function_type(instance, func) do
        {:ok, {params, results}} ->
          %{name: func, params: params, results: results, arity: length(params)}

        _ ->
          %{name: func, params: [], results: [], arity: 0}
      end
    end
  end

  @doc """
  Get the type signature of an exported function.

  ## Examples

      {:ok, {[:i32, :i32], [:i32]}} = Firebird.function_type(instance, :add)
  """
  @spec function_type(pid(), atom() | String.t()) ::
          {:ok, {list(), list()}} | {:error, :not_found}
  def function_type(instance, function) do
    Firebird.Runtime.function_type(instance, function)
  end

  @doc """
  Read bytes from WASM linear memory.

  ## Examples

      {:ok, bytes} = Firebird.read_memory(instance, 0, 10)
  """
  @spec read_memory(pid(), non_neg_integer(), non_neg_integer()) ::
          {:ok, binary()} | {:error, term()}
  def read_memory(instance, offset, length) do
    Firebird.Runtime.read_memory(instance, offset, length)
  end

  @doc """
  Write bytes to WASM linear memory.

  ## Examples

      :ok = Firebird.write_memory(instance, 0, <<1, 2, 3>>)
  """
  @spec write_memory(pid(), non_neg_integer(), binary()) :: :ok | {:error, term()}
  def write_memory(instance, offset, data) do
    Firebird.Runtime.write_memory(instance, offset, data)
  end

  @doc """
  Get the size of WASM linear memory in bytes.

  ## Examples

      {:ok, size} = Firebird.memory_size(instance)
  """
  @spec memory_size(pid()) :: {:ok, non_neg_integer()} | {:error, term()}
  def memory_size(instance) do
    Firebird.Runtime.memory_size(instance)
  end

  @doc """
  Grow WASM linear memory by pages (each page = 64KB).

  ## Examples

      {:ok, old_pages} = Firebird.grow_memory(instance, 1)
  """
  @spec grow_memory(pid(), non_neg_integer()) :: {:ok, non_neg_integer()} | {:error, term()}
  def grow_memory(instance, pages) do
    Firebird.Runtime.grow_memory(instance, pages)
  end

  @doc """
  Stop a WASM instance and free resources.

  ## Examples

      :ok = Firebird.stop(instance)
  """
  @spec stop(pid() | reference()) :: :ok
  def stop(instance) when is_reference(instance) do
    # SyncNif references are garbage collected, no explicit stop needed
    :ok
  end

  def stop(instance) do
    Firebird.Runtime.stop(instance)
  catch
    :exit, _ -> :ok
  end

  @doc """
  Check if a WASM instance is alive.

  ## Examples

      true = Firebird.alive?(instance)
  """
  @spec alive?(pid()) :: boolean()
  def alive?(instance) do
    Firebird.Runtime.alive?(instance)
  end

  @doc """
  Serialize a compiled module for caching.

  ## Examples

      {:ok, bytes} = Firebird.serialize(instance)
  """
  @spec serialize(pid()) :: {:ok, binary()} | {:error, term()}
  def serialize(instance) do
    Firebird.Runtime.serialize(instance)
  end

  @doc """
  Get a summary of a WASM instance: exports, memory size, alive status.

  ## Examples

      info = Firebird.info(instance)
      # => %{alive: true, exports: [:add, :multiply], memory_bytes: 65536}
  """
  @spec info(pid()) :: map()
  def info(instance) do
    is_alive = alive?(instance)

    if is_alive do
      %{
        alive: true,
        exports: exports(instance),
        memory_bytes:
          case memory_size(instance) do
            {:ok, size} -> size
            _ -> nil
          end
      }
    else
      %{alive: false, exports: [], memory_bytes: nil}
    end
  end

  # ---------------------------------------------------------------------------
  # Convenience APIs
  # ---------------------------------------------------------------------------

  @doc """
  Load a WASM module, raising on error.

  ## Examples

      instance = Firebird.load!("priv/wasm/math.wasm")
  """
  @spec load!(binary() | String.t(), keyword()) :: pid()
  def load!(wasm_source, opts \\ []) do
    case load(wasm_source, opts) do
      {:ok, pid} ->
        pid

      error ->
        raise_wasm_error!(nil, [], error)
    end
  end

  @doc """
  Load a WASM module, call a function, and stop the instance — all in one step.

  Perfect for one-off computations where you don't need to keep the instance alive.

  ## Examples

      iex> Firebird.run("fixtures/math.wasm", :add, [5, 3])
      {:ok, [8]}

      iex> Firebird.run("fixtures/math.wasm", :fibonacci, [10])
      {:ok, [55]}
  """
  @spec run(binary() | String.t(), atom() | String.t(), list(), keyword()) ::
          {:ok, list()} | {:error, term()}
  def run(wasm_source, function, args, opts \\ []) do
    with {:ok, pid} <- load(wasm_source, opts) do
      try do
        call(pid, function, args)
      after
        stop(pid)
      end
    end
  end

  @doc """
  Load, call, and stop — raising on error.

  ## Examples

      iex> Firebird.run!("fixtures/math.wasm", :add, [5, 3])
      [8]

      iex> Firebird.run!("fixtures/math.wasm", :fibonacci, [10])
      [55]
  """
  @spec run!(binary() | String.t(), atom() | String.t(), list(), keyword()) :: list()
  def run!(wasm_source, function, args, opts \\ []) do
    case run(wasm_source, function, args, opts) do
      {:ok, results} ->
        results

      error ->
        raise_wasm_error!(function, args, error)
    end
  end

  @doc """
  Execute a block with a WASM instance, automatically cleaning up afterward.

  ## Examples

      iex> Firebird.with_instance("fixtures/math.wasm", fn instance ->
      ...>   {:ok, [a]} = Firebird.call(instance, :add, [5, 3])
      ...>   {:ok, [b]} = Firebird.call(instance, :multiply, [a, 2])
      ...>   b
      ...> end)
      {:ok, 16}
  """
  @spec with_instance(binary() | String.t(), (pid() -> term()), keyword()) ::
          {:ok, term()} | {:error, term()}
  def with_instance(wasm_source, fun, opts \\ []) when is_function(fun, 1) do
    case load(wasm_source, opts) do
      {:ok, pid} ->
        try do
          {:ok, fun.(pid)}
        after
          stop(pid)
        end

      {:error, _} = error ->
        error
    end
  end

  @doc """
  Returns the Firebird library version.

  ## Examples

      iex> Firebird.version()
      "1.0.0"
  """
  @spec version() :: String.t()
  def version do
    "1.0.0"
  end

  @doc """
  Load a WASM module from bytes (binary data).

  Explicit API for loading from in-memory WASM bytes rather than file paths.
  Useful when you generate or fetch WASM dynamically.

  ## Examples

      bytes = File.read!("math.wasm")
      {:ok, instance} = Firebird.load_bytes(bytes)
  """
  @spec load_bytes(binary(), keyword()) :: {:ok, pid()} | {:error, term()}
  def load_bytes(bytes, opts \\ []) when is_binary(bytes) do
    load(bytes, opts)
  end

  # ---------------------------------------------------------------------------
  # Pipe-friendly API
  # ---------------------------------------------------------------------------

  @doc """
  Pipe-friendly call that threads the instance through.

  Returns `{:ok, results, instance}` so you can pipe further calls.

  ## Examples

      {:ok, instance} = Firebird.load("math.wasm")
      {:ok, [sum], instance} = Firebird.pipe(instance, :add, [5, 3])
      {:ok, [product], instance} = Firebird.pipe(instance, :multiply, [sum, 2])
      Firebird.stop(instance)

      # Or use the pipeline operator:
      {:ok, wasm} = Firebird.load("math.wasm")
      {:ok, [8], wasm} = Firebird.pipe(wasm, :add, [5, 3])
  """
  @spec pipe(pid(), atom() | String.t(), list()) :: {:ok, list(), pid()} | {:error, term()}
  def pipe(instance, function, args) when is_list(args) do
    case call(instance, function, args) do
      {:ok, results} -> {:ok, results, instance}
      error -> error
    end
  end

  @doc """
  Pipe-friendly call that raises on error and returns `{results, instance}`.

  ## Examples

      wasm = Firebird.load!("math.wasm")
      {[sum], wasm} = Firebird.pipe!(wasm, :add, [5, 3])
      {[product], wasm} = Firebird.pipe!(wasm, :multiply, [sum, 2])
      Firebird.stop(wasm)
  """
  @spec pipe!(pid(), atom() | String.t(), list()) :: {list(), pid()}
  def pipe!(instance, function, args) when is_list(args) do
    {call!(instance, function, args), instance}
  end

  # ---------------------------------------------------------------------------
  # Inspection convenience
  # ---------------------------------------------------------------------------

  @doc """
  Inspect a WASM file and return information about its exports.

  Convenience wrapper around `Firebird.Inspector.inspect_file/2`.

  ## Examples

      {:ok, info} = Firebird.inspect_file("math.wasm")
      info.functions
      # => [%{name: "add", params: [:i32, :i32], results: [:i32], arity: 2}, ...]
  """
  @spec inspect_file(String.t(), keyword()) :: {:ok, map()} | {:error, term()}
  defdelegate inspect_file(path, opts \\ []), to: Firebird.Inspector

  # ---------------------------------------------------------------------------
  # Pool convenience wrappers
  # ---------------------------------------------------------------------------

  @doc """
  Start a pool of WASM instances for concurrent execution.

  ## Options

  - `:wasm` or `:wasm_path` - Path to WASM file
  - `:wasm_bytes` - Raw WASM bytes
  - `:size` or `:pool_size` - Number of instances (default: schedulers_online)
  - `:name` - Optional GenServer name

  ## Examples

      {:ok, pool} = Firebird.start_pool(wasm: "math.wasm", size: 4)
      {:ok, [8]} = Firebird.pool_call(pool, :add, [5, 3])
      Firebird.stop_pool(pool)
  """
  @spec start_pool(keyword()) :: {:ok, pid()} | {:error, term()}
  def start_pool(opts) do
    Firebird.Pool.start_link(opts)
  end

  @doc """
  Call a WASM function using a pooled instance.

  ## Examples

      {:ok, [8]} = Firebird.pool_call(pool, :add, [5, 3])
  """
  @spec pool_call(GenServer.server(), atom() | String.t(), list()) ::
          {:ok, list()} | {:error, term()}
  def pool_call(pool, function, args) do
    Firebird.Pool.call(pool, function, args)
  end

  @doc """
  Call a WASM function using a pooled instance, raising on error.

  ## Examples

      [8] = Firebird.pool_call!(pool, :add, [5, 3])
  """
  @spec pool_call!(GenServer.server(), atom() | String.t(), list()) :: list()
  def pool_call!(pool, function, args) do
    Firebird.Pool.call!(pool, function, args)
  end

  @doc """
  Call a WASM function using a pooled instance, returning unwrapped single value.

  ## Examples

      {:ok, 8} = Firebird.pool_call_one(pool, :add, [5, 3])
  """
  @spec pool_call_one(GenServer.server(), atom() | String.t(), list()) ::
          {:ok, term()} | {:error, term()}
  def pool_call_one(pool, function, args) do
    Firebird.Pool.call_one(pool, function, args)
  end

  @doc """
  Call a WASM function using a pooled instance, returning unwrapped single value, raising on error.

  ## Examples

      8 = Firebird.pool_call_one!(pool, :add, [5, 3])
  """
  @spec pool_call_one!(GenServer.server(), atom() | String.t(), list()) :: term()
  def pool_call_one!(pool, function, args) do
    Firebird.Pool.call_one!(pool, function, args)
  end

  @doc """
  Stop a pool and all its instances.
  """
  @spec stop_pool(GenServer.server()) :: :ok
  def stop_pool(pool) do
    Firebird.Pool.stop(pool)
  catch
    :exit, _ -> :ok
  end

  # ---------------------------------------------------------------------------
  # WAT (WebAssembly Text) support
  # ---------------------------------------------------------------------------

  @doc """
  Load a WASM module from WAT (WebAssembly Text Format) source code.

  This is great for prototyping and learning — write WASM in human-readable
  text format and load it directly. Requires `wat2wasm` to be installed.

  ## Examples

      {:ok, wasm} = Firebird.from_wat(\"""
      (module
        (func (export "add") (param i32 i32) (result i32)
          local.get 0
          local.get 1
          i32.add)
      )
      \""")
      {:ok, [8]} = Firebird.call(wasm, :add, [5, 3])
      Firebird.stop(wasm)
  """
  @spec from_wat(String.t(), keyword()) :: {:ok, pid()} | {:error, term()}
  def from_wat(wat_source, opts \\ []) do
    with {:ok, wasm_bytes} <- compile_wat(wat_source) do
      load(wasm_bytes, opts)
    end
  end

  @doc """
  Load a WASM module from WAT source, raising on error.

  ## Examples

      wasm = Firebird.from_wat!(\"""
      (module
        (func (export "double") (param i32) (result i32)
          local.get 0
          i32.const 2
          i32.mul)
      )
      \""")
      [10] = Firebird.call!(wasm, :double, [5])
  """
  @spec from_wat!(String.t(), keyword()) :: pid()
  def from_wat!(wat_source, opts \\ []) do
    case from_wat(wat_source, opts) do
      {:ok, pid} ->
        pid

      {:error, {:wat_compile_error, msg}} ->
        raise Firebird.WasmError.load_failed({:wat_compile_error, msg})

      {:error, {:wat2wasm_not_found, _}} ->
        raise %Firebird.WasmError{
          message: """
          wat2wasm not found. Install it:
            • macOS: brew install wabt
            • Ubuntu: apt install wabt
            • Or download from: https://github.com/WebAssembly/wabt/releases
          """,
          reason: :wat2wasm_not_found
        }

      {:error, reason} ->
        raise Firebird.WasmError.load_failed(reason)
    end
  end

  @doc """
  Compile WAT source to WASM binary bytes.

  ## Examples

      {:ok, bytes} = Firebird.compile_wat("(module)")
  """
  @spec compile_wat(String.t()) :: {:ok, binary()} | {:error, term()}
  def compile_wat(wat_source) do
    case System.find_executable("wat2wasm") do
      nil ->
        {:error,
         {:wat2wasm_not_found,
          "Install wabt: brew install wabt (macOS) or apt install wabt (Ubuntu)"}}

      wat2wasm ->
        tmp_wat =
          Path.join(System.tmp_dir!(), "firebird_#{:erlang.unique_integer([:positive])}.wat")

        tmp_wasm = Path.rootname(tmp_wat) <> ".wasm"

        try do
          File.write!(tmp_wat, wat_source)

          case System.cmd(wat2wasm, [tmp_wat, "-o", tmp_wasm], stderr_to_stdout: true) do
            {_, 0} ->
              wasm_bytes = File.read!(tmp_wasm)
              {:ok, wasm_bytes}

            {error_output, _} ->
              {:error, {:wat_compile_error, error_output}}
          end
        after
          File.rm(tmp_wat)
          File.rm(tmp_wasm)
        end
    end
  end

  # ---------------------------------------------------------------------------
  # Quick describe
  # ---------------------------------------------------------------------------

  @doc """
  Print a human-readable summary of a WASM file or instance.

  Works with file paths or running instances.

  ## Examples

      Firebird.describe("path/to/math.wasm")
      Firebird.describe(instance)
  """
  @spec describe(pid() | String.t()) :: :ok
  def describe(instance) when is_pid(instance) do
    info = info(instance)
    IO.puts("🔥 WASM Instance (#{if info.alive, do: "alive", else: "stopped"})")
    IO.puts("   Memory: #{format_bytes(info.memory_bytes || 0)}")
    IO.puts("   Exports (#{length(info.exports)}):")

    for func <- info.exports do
      case function_type(instance, func) do
        {:ok, {params, results}} ->
          IO.puts(
            "     #{func}(#{Enum.join(Enum.map(params, &inspect/1), ", ")}) → #{inspect(results)}"
          )

        _ ->
          IO.puts("     #{func}")
      end
    end

    :ok
  end

  def describe(path) when is_binary(path) do
    # Use smart path resolution for bare filenames
    resolved = Firebird.Runtime.resolve_wasm_path(path)

    case inspect_file(resolved) do
      {:ok, info} ->
        IO.puts("🔥 #{Path.basename(resolved)} (#{format_bytes(info.size_bytes)})")
        IO.puts("   Functions (#{length(info.functions)}):")

        for f <- info.functions do
          IO.puts(
            "     #{f.name}(#{Enum.join(Enum.map(f.params, &inspect/1), ", ")}) → #{inspect(f.results)}"
          )
        end

        :ok

      {:error, reason} ->
        IO.puts("❌ Cannot inspect #{path}: #{inspect(reason)}")
        :ok
    end
  end

  defp format_bytes(0), do: "0 B"
  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"

  # ---------------------------------------------------------------------------
  # Setup verification & bundled sample
  # ---------------------------------------------------------------------------

  @doc """
  Returns the path to the bundled sample math.wasm file.

  This WASM module exports `add/2`, `multiply/2`, and `fibonacci/1` functions
  and is included with Firebird for testing and getting started quickly.

  ## Examples

      iex> path = Firebird.sample_wasm_path()
      iex> File.exists?(path)
      true
      iex> String.ends_with?(path, "sample_math.wasm")
      true
  """
  @spec sample_wasm_path() :: String.t()
  def sample_wasm_path do
    Path.join(:code.priv_dir(:firebird), "wasm/sample_math.wasm")
  end

  @doc """
  Load a pre-loaded sample WASM instance for quick experimentation.

  Shortcut for `Firebird.load!(Firebird.sample_wasm_path())`.
  Perfect for `iex` sessions:

      iex> wasm = Firebird.sample()
      iex> is_pid(wasm) and Process.alive?(wasm)
      true
      iex> Firebird.call_one!(wasm, :add, [5, 3])
      8
      iex> Firebird.stop(wasm)
      :ok
  """
  @spec sample() :: pid()
  def sample do
    load!(sample_wasm_path())
  end

  @doc """
  Validate that a WASM file or binary can be loaded without keeping the instance.

  Returns `:ok` if the WASM is valid and loadable, or `{:error, reason}` otherwise.
  Useful for build-time validation or CI checks.

  ## Examples

      iex> Firebird.validate("fixtures/math.wasm")
      :ok

      iex> match?({:error, _}, Firebird.validate("nonexistent_file.wasm"))
      true
  """
  @spec validate(binary() | String.t()) :: :ok | {:error, term()}
  def validate(wasm_source) do
    case load(wasm_source) do
      {:ok, pid} ->
        stop(pid)
        :ok

      {:error, _} = error ->
        error
    end
  end

  @doc """
  Verify that Firebird is correctly installed and working.

  Loads the bundled sample WASM module, calls `add(2, 3)`, and verifies
  the result is `[5]`. Returns `:ok` on success, raises on failure.

  Use this to quickly confirm your setup is working:

      iex> Firebird.check!()
      :ok

  ## What it checks

  1. Wasmex NIF is loaded and working
  2. WASM module loading works
  3. Function calls work correctly
  4. Results are returned properly
  """
  @spec check!() :: :ok
  def check! do
    path = sample_wasm_path()

    unless File.exists?(path) do
      raise """
      Firebird sample WASM file not found at: #{path}

      This usually means the :firebird dependency wasn't compiled properly.
      Try: mix deps.compile firebird --force
      """
    end

    case run(path, :add, [2, 3]) do
      {:ok, [5]} ->
        :ok

      {:ok, other} ->
        raise "Firebird check failed: expected [5], got #{inspect(other)}"

      {:error, reason} ->
        raise """
        Firebird check failed: #{inspect(reason)}

        Common fixes:
          • mix deps.get
          • mix deps.compile wasmex --force
          • Ensure your system has a compatible Rust toolchain for wasmex
        """
    end
  end

  @doc """
  Start a playground with a pre-loaded sample WASM instance.

  Returns a WASM instance loaded with the bundled sample math module.
  Perfect for exploring in `iex`:

      iex> wasm = Firebird.playground()
      iex> Firebird.call!(wasm, :add, [5, 3])
      [8]
      iex> Firebird.call!(wasm, :fibonacci, [10])
      [55]
      iex> Firebird.stop(wasm)
      :ok
  """
  @spec playground() :: pid()
  def playground do
    wasm = load!(sample_wasm_path())
    IO.puts("🔥 Firebird playground ready! Instance: #{inspect(wasm)}")
    IO.puts("   Try: Firebird.call!(wasm, :add, [5, 3])")
    IO.puts("   Try: Firebird.call!(wasm, :fibonacci, [10])")
    IO.puts("   Try: Firebird.describe(wasm)")
    IO.puts("   Done: Firebird.stop(wasm)")
    wasm
  end

  @doc """
  Non-raising version of `check!/0`. Returns `:ok` or `{:error, reason}`.

  ## Examples

      iex> Firebird.check()
      :ok
  """
  @spec check() :: :ok | {:error, term()}
  def check do
    check!()
  rescue
    e -> {:error, Exception.message(e)}
  end

  @doc """
  Run a quick demo showing Firebird in action.

  Loads the bundled sample WASM, runs a few operations, and prints the results.
  Great for verifying setup in `iex`.

      Firebird.demo()
      # 🔥 Firebird Demo
      #    Loading sample_math.wasm...
      #    add(5, 3) = 8
      #    ...
  """
  @spec demo() :: :ok
  def demo do
    path = sample_wasm_path()
    IO.puts("🔥 Firebird Demo")
    IO.puts("   Loading #{Path.basename(path)}...")

    {:ok, wasm} = load(path)
    exports = exports(wasm)
    IO.puts("   Exports: #{inspect(exports)}")

    {:ok, [sum]} = call(wasm, :add, [5, 3])
    IO.puts("   add(5, 3) = #{sum}")

    {:ok, [product]} = call(wasm, :multiply, [4, 7])
    IO.puts("   multiply(4, 7) = #{product}")

    {:ok, [fib]} = call(wasm, :fibonacci, [10])
    IO.puts("   fibonacci(10) = #{fib}")

    stop(wasm)
    IO.puts("   ✅ Everything works!")
    :ok
  end

  # ---------------------------------------------------------------------------
  # Map convenience
  # ---------------------------------------------------------------------------

  @doc """
  Map a WASM function over a list of argument lists.

  Returns a list of unwrapped single values. Perfect for batch processing.

  ## Examples

      wasm = Firebird.load!("math.wasm")
      results = Firebird.map(wasm, :fibonacci, [[1], [2], [3], [4], [5]])
      # => [1, 1, 2, 3, 5]

      results = Firebird.map(wasm, :add, [[1, 2], [3, 4], [5, 6]])
      # => [3, 7, 11]

      Firebird.stop(wasm)
  """
  @spec map(pid(), atom() | String.t(), [list()]) :: [term()]
  def map(instance, function, args_list) when is_list(args_list) do
    Enum.map(args_list, fn args ->
      call_one!(instance, function, args)
    end)
  end

  # ---------------------------------------------------------------------------
  # Single-value convenience APIs
  # ---------------------------------------------------------------------------

  @doc """
  Call a WASM function and return a single unwrapped value.

  Most WASM functions return exactly one value. This avoids the `[value]`
  list wrapping that `call/3` uses. For multi-value returns, use `call/3`.

  ## Examples

      {:ok, 8} = Firebird.call_one(instance, :add, [5, 3])
      {:ok, 55} = Firebird.call_one(instance, :fibonacci, [10])
  """
  @spec call_one(pid(), atom() | String.t(), list()) :: {:ok, term()} | {:error, term()}
  def call_one(instance, function, args) do
    case call(instance, function, args) do
      {:ok, [single]} -> {:ok, single}
      {:ok, multi} -> {:ok, multi}
      error -> error
    end
  end

  @doc """
  Call a WASM function and return a single unwrapped value, raising on error.

  ## Examples

      8 = Firebird.call_one!(instance, :add, [5, 3])
      55 = Firebird.call_one!(instance, :fibonacci, [10])
  """
  @spec call_one!(pid(), atom() | String.t(), list()) :: term()
  def call_one!(instance, function, args) do
    case call_one(instance, function, args) do
      {:ok, result} ->
        result

      {:error, {:call_error, func_name, :instance_stopped}} ->
        raise Firebird.WasmError.instance_stopped(func_name)

      {:error, {:call_error, func_name, reason}} ->
        if Process.alive?(instance) do
          available = exports(instance)

          if to_string(func_name) not in Enum.map(available, &to_string/1) do
            raise Firebird.WasmError.function_not_found(func_name, available)
          else
            raise Firebird.WasmError.call_failed(func_name, reason, args)
          end
        else
          raise Firebird.WasmError.instance_stopped(func_name)
        end

      {:error, reason} ->
        raise Firebird.WasmError.call_failed(function, reason, args)
    end
  end

  @doc """
  One-shot: load, call (single-value), and stop — all in one step.

  Like `run/4` but unwraps single-value results automatically.

  ## Examples

      iex> Firebird.run_one("fixtures/math.wasm", :add, [5, 3])
      {:ok, 8}

      iex> Firebird.run_one("fixtures/math.wasm", :fibonacci, [10])
      {:ok, 55}
  """
  @spec run_one(binary() | String.t(), atom() | String.t(), list(), keyword()) ::
          {:ok, term()} | {:error, term()}
  def run_one(wasm_source, function, args, opts \\ []) do
    case run(wasm_source, function, args, opts) do
      {:ok, [single]} -> {:ok, single}
      {:ok, multi} -> {:ok, multi}
      error -> error
    end
  end

  @doc """
  One-shot: load, call (single-value), and stop — raising on error.

  ## Examples

      iex> Firebird.run_one!("fixtures/math.wasm", :add, [5, 3])
      8

      iex> Firebird.run_one!("fixtures/math.wasm", :fibonacci, [10])
      55
  """
  @spec run_one!(binary() | String.t(), atom() | String.t(), list(), keyword()) :: term()
  def run_one!(wasm_source, function, args, opts \\ []) do
    case run_one(wasm_source, function, args, opts) do
      {:ok, result} ->
        result

      error ->
        raise_wasm_error!(function, args, error)
    end
  end

  # ---------------------------------------------------------------------------
  # Result unwrapping
  # ---------------------------------------------------------------------------

  @doc """
  Unwrap a single-value WASM result.

  WASM functions return results as lists. This pipes nicely to extract
  single values:

      {:ok, 8} = Firebird.call(wasm, :add, [5, 3]) |> Firebird.unwrap()
      {:ok, 8} = Firebird.run("math.wasm", :add, [5, 3]) |> Firebird.unwrap()
  """
  @spec unwrap({:ok, list()} | {:error, term()}) :: {:ok, term()} | {:error, term()}
  defdelegate unwrap(result), to: Firebird.Unwrap

  @doc """
  Unwrap a single-value WASM result from a bang call.

      8 = Firebird.call!(wasm, :add, [5, 3]) |> Firebird.unwrap!()
      8 = Firebird.run!("math.wasm", :add, [5, 3]) |> Firebird.unwrap!()
  """
  @spec unwrap!(list()) :: term()
  defdelegate unwrap!(result), to: Firebird.Unwrap

  # ---------------------------------------------------------------------------
  # Builder API
  # ---------------------------------------------------------------------------

  @doc """
  Build a WASM module from a source directory (Go or Rust).

  Auto-detects the project type and compiles using the appropriate toolchain.

  ## Examples

      {:ok, wasm_path} = Firebird.build("src/go_math")
      {:ok, wasm_path} = Firebird.build("src/rust_math", output: "priv/wasm/math.wasm")
  """
  @spec build(String.t(), keyword()) :: {:ok, String.t()} | {:error, term()}
  defdelegate build(source_dir, opts \\ []), to: Firebird.Builder

  @doc """
  Build a WASM module and immediately load it.

  Auto-detects WASI requirements for Go projects.

  ## Examples

      {:ok, instance} = Firebird.build_and_load("fixtures/go_math")
      {:ok, [8]} = Firebird.call(instance, :add, [5, 3])
  """
  @spec build_and_load(String.t(), keyword()) :: {:ok, pid()} | {:error, term()}
  defdelegate build_and_load(source_dir, opts \\ []), to: Firebird.Builder

  # ---------------------------------------------------------------------------
  # Cache API
  # ---------------------------------------------------------------------------

  @doc """
  Load a WASM module with caching for fast subsequent loads.

  On first load, compiles the module and caches the serialized form.
  On subsequent loads, deserializes from cache (significantly faster).

  ## Examples

      {:ok, instance} = Firebird.load_cached("math.wasm")
      {:ok, instance} = Firebird.load_cached("math.wasm", cache_dir: "/tmp/cache")
  """
  @spec load_cached(String.t(), keyword()) :: {:ok, pid()} | {:error, term()}
  defdelegate load_cached(wasm_path, opts \\ []), to: Firebird.Cache

  # ---------------------------------------------------------------------------
  # Preloader API
  # ---------------------------------------------------------------------------

  @doc """
  Precompile a WASM module for fast multi-instance creation.

  Compiles the WASM bytes once, then allows creating instances
  without recompilation. Essential for pools and concurrent execution.

  ## Examples

      {:ok, compiled} = Firebird.precompile("math.wasm")
      {:ok, inst1} = Firebird.instantiate(compiled)
      {:ok, inst2} = Firebird.instantiate(compiled)
  """
  @spec precompile(binary() | String.t(), keyword()) ::
          {:ok, Firebird.Preloader.compiled()} | {:error, term()}
  defdelegate precompile(wasm_source, opts \\ []), to: Firebird.Preloader, as: :compile

  @doc """
  Create a new instance from a precompiled WASM module.

  Much faster than `load/2` because it skips compilation.

  ## Examples

      {:ok, compiled} = Firebird.precompile("math.wasm")
      {:ok, instance} = Firebird.instantiate(compiled)
  """
  @spec instantiate(Firebird.Preloader.compiled()) :: {:ok, pid()} | {:error, term()}
  defdelegate instantiate(compiled), to: Firebird.Preloader

  # ---------------------------------------------------------------------------
  # Memory Management API
  # ---------------------------------------------------------------------------

  @doc """
  Create a structured memory allocator for a WASM instance.

  Returns a `Firebird.Memory` struct with typed read/write helpers,
  bump allocation, and arena-style deallocation. Essential for passing
  strings, arrays, and complex data to/from Go/Rust WASM modules.

  ## Options

  - `:alignment` — byte alignment for allocations (default: 8)
  - `:base_offset` — starting offset in linear memory (default: 1024)

  ## Examples

      wasm = Firebird.load!("string_utils.wasm")
      alloc = Firebird.memory_allocator(wasm)

      # Write string, call WASM, read result
      {alloc, ptr, len} = Firebird.Memory.write_string(alloc, "hello")
      {:ok, [hash]} = Firebird.call(wasm, :hash, [ptr, len])

      # Arena-style cleanup
      alloc = Firebird.Memory.free_all(alloc)

  See `Firebird.Memory` for the full API including typed arrays,
  scalar helpers, secure free, and scoped arenas.
  """
  @spec memory_allocator(pid(), keyword()) :: Firebird.Memory.t()
  def memory_allocator(instance, opts \\ []) do
    Firebird.Memory.new(instance, opts)
  end

  # ---------------------------------------------------------------------------
  # Pipeline API
  # ---------------------------------------------------------------------------

  @doc """
  Create a new WASM function pipeline for chaining calls.

  ## Examples

      {:ok, [result]} =
        Firebird.pipeline(instance)
        |> Firebird.Pipeline.call(:add, [5, 3])
        |> Firebird.Pipeline.call(:multiply, [:_, 2])
        |> Firebird.Pipeline.run()
  """
  @spec pipeline(pid()) :: Firebird.Pipeline.t()
  def pipeline(instance), do: Firebird.Pipeline.new(instance)

  # ---------------------------------------------------------------------------
  # Quick / Inline Execution
  # ---------------------------------------------------------------------------

  @doc """
  Execute a WASM function with the absolute minimum ceremony.

  Accepts a `.wasm` file path (auto-resolved) or inline WAT source.
  Returns the single unwrapped value.

  ## Examples

      # With a file — auto-resolves from priv/wasm, wasm/, fixtures/
      8 = Firebird.quick("math.wasm", :add, [5, 3])

      # With inline WAT
      42 = Firebird.quick(~s|(module (func (export "answer") (result i32) i32.const 42))|, :answer, [])

      # With the bundled sample
      55 = Firebird.quick(:sample, :fibonacci, [10])
  """
  @spec quick(String.t() | :sample, atom() | String.t(), list()) :: term()
  def quick(:sample, function, args) do
    run_one!(sample_wasm_path(), function, args)
  end

  def quick(source, function, args) when is_binary(source) do
    # Check if it looks like WAT (starts with parenthesis)
    trimmed = String.trim(source)

    if String.starts_with?(trimmed, "(") do
      {:ok, instance} = from_wat(source)

      try do
        call_one!(instance, function, args)
      after
        stop(instance)
      end
    else
      run_one!(source, function, args)
    end
  end

  # ---------------------------------------------------------------------------
  # Introspection helpers
  # ---------------------------------------------------------------------------

  @doc """
  List the function signatures of all exports in a WASM file.

  Loads the file, inspects it, and stops the instance. Useful for
  exploring unfamiliar WASM modules.

  ## Examples

      Firebird.list_functions("math.wasm")
      # => [
      #   %{name: :add, params: [:i32, :i32], results: [:i32], arity: 2},
      #   %{name: :multiply, params: [:i32, :i32], results: [:i32], arity: 2},
      #   %{name: :fibonacci, params: [:i32], results: [:i32], arity: 1}
      # ]
  """
  @spec list_functions(String.t(), keyword()) :: [map()] | {:error, term()}
  def list_functions(path, opts \\ []) do
    case load(path, opts) do
      {:ok, instance} ->
        fns = functions(instance)
        stop(instance)
        fns

      {:error, _} = error ->
        error
    end
  end

  @doc """
  Print a status overview of Firebird.

  Shows version, runtime status, and available WASM files.
  Useful for debugging and verifying your setup.

      Firebird.status()
      # 🔥 Firebird 1.0.0
      # ✅ Runtime: operational
      # ...
  """
  @spec status() :: :ok
  def status do
    IO.puts("🔥 Firebird #{version()}")
    IO.puts("")

    # Check runtime
    case check() do
      :ok -> IO.puts("  ✅ Runtime: working")
      {:error, reason} -> IO.puts("  ❌ Runtime: #{reason}")
    end

    # Check tools
    tools = Firebird.Builder.check_tools()
    IO.puts("  🔧 Tools:")

    for {name, version} <- tools do
      status = if version, do: "✅ #{version}", else: "❌ not found"
      IO.puts("     #{name}: #{status}")
    end

    # Check WASM directories
    IO.puts("  📁 WASM files:")

    for dir <- ["priv/wasm", "wasm", "fixtures"] do
      if File.dir?(dir) do
        wasm_files = Path.wildcard(Path.join(dir, "*.wasm"))

        if length(wasm_files) > 0 do
          IO.puts("     #{dir}/: #{length(wasm_files)} file(s)")
        end
      end
    end

    # Sample
    IO.puts("")
    IO.puts("  Try: Firebird.quick(:sample, :add, [5, 3])")
    :ok
  end

  # ---------------------------------------------------------------------------
  # Shared error raising for bang functions
  # ---------------------------------------------------------------------------

  # Raises the appropriate WasmError for a given error tuple.
  # Centralizes error dispatch so all bang functions (run!, run_one!, etc.)
  # produce the same helpful, structured error messages as call!/3.
  @doc false
  defp raise_wasm_error!(function, args, error) do
    case error do
      {:error, {:file_error, :enoent, path}} ->
        raise Firebird.WasmError.file_not_found(path)

      {:error, {:file_error, reason, path}} ->
        raise Firebird.WasmError.load_failed(reason, path)

      {:error, {:wasm_error, reason}} ->
        raise Firebird.WasmError.load_failed(reason)

      {:error, {:arity_mismatch, func_name, expected: expected, got: got}} ->
        raise Firebird.WasmError.arity_mismatch(func_name, expected, got)

      {:error, {:type_mismatch, func_name, arg_index, expected: expected_type, got: actual_value}} ->
        raise Firebird.WasmError.type_mismatch(func_name, arg_index, expected_type, actual_value)

      {:error, {:call_error, func_name, :instance_stopped}} ->
        raise Firebird.WasmError.instance_stopped(func_name)

      {:error, {:call_error, func_name, reason}} ->
        raise Firebird.WasmError.call_failed(func_name, reason, args)

      {:error, reason} ->
        raise Firebird.WasmError.call_failed(function, reason, args)
    end
  end
end