defmodule SafeZarr do
  @doc "Safely create array with validated inputs"
  def safe_create(opts) do
    with :ok <- validate_shape(opts[:shape]),
         :ok <- validate_chunks(opts[:chunks]),
         :ok <- validate_path(opts[:path]),
         :ok <- validate_dtype(opts[:dtype]) do
      ExZarr.create(opts)
    end
  end

  defp validate_shape(shape) when is_tuple(shape) do
    if Enum.all?(Tuple.to_list(shape), &is_integer/1) and
       Enum.all?(Tuple.to_list(shape), &(&1 > 0)) do
      :ok
    else
      {:error, :invalid_shape}
    end
  end
  defp validate_shape(_), do: {:error, :invalid_shape}

  defp validate_chunks(chunks) when is_tuple(chunks) do
    if Enum.all?(Tuple.to_list(chunks), &is_integer/1) and
       Enum.all?(Tuple.to_list(chunks), &(&1 > 0)) do
      :ok
    else
      {:error, :invalid_chunks}
    end
  end
  defp validate_chunks(_), do: {:error, :invalid_chunks}

  defp validate_path(path) when is_binary(path) do
    cond do
      String.contains?(path, "..") ->
        {:error, :path_traversal_attempt}
      String.starts_with?(path, "/etc") or String.starts_with?(path, "/sys") ->
        {:error, :restricted_path}
      true ->
        :ok
    end
  end
  defp validate_path(_), do: {:error, :invalid_path}

  defp validate_dtype(dtype) when dtype in [:i1, :i2, :i4, :i8, :u1, :u2, :u4, :u8, :f4, :f8] do
    :ok
  end
  defp validate_dtype(_), do: {:error, :invalid_dtype}
end

defmodule PathValidator do
  @doc "Ensure path is within allowed directory"
  def validate_path(path, base_dir) do
    absolute_path = Path.expand(path, base_dir)
    absolute_base = Path.expand(base_dir)

    if String.starts_with?(absolute_path, absolute_base) do
      {:ok, absolute_path}
    else
      {:error, :path_outside_base_directory}
    end
  end

  @doc "Sanitize user-provided path"
  def sanitize_path(path) do
    path
    |> String.replace(~r/\.\./, "")  # Remove ..
    |> String.replace(~r/\/+/, "/")   # Normalize slashes
    |> String.trim_leading("/")       # Remove leading slash
  end
end

# Usage
case PathValidator.validate_path(user_path, "/safe/base/dir") do
  {:ok, safe_path} -> ExZarr.open(storage: :filesystem, path: safe_path)
  {:error, reason} -> {:error, reason}
end

# Use IAM roles instead of hardcoded credentials
config :ex_aws,
  access_key_id: {:system, "AWS_ACCESS_KEY_ID"},
  secret_access_key: {:system, "AWS_SECRET_ACCESS_KEY"},
  region: "us-east-1"

# Enable bucket versioning for data recovery
# Use bucket policies to restrict access
# Enable server-side encryption

{:ok, array} = ExZarr.open(
  storage: :s3,
  bucket: "my-secure-bucket",
  prefix: "arrays/production",
  # S3 will use environment credentials
)

# Use service account with minimal permissions
config :goth,
  json: {:system, "GCS_CREDENTIALS_JSON"}

# Grant only necessary IAM roles:
# - roles/storage.objectViewer (read-only)
# - roles/storage.objectCreator (write-only)
# - roles/storage.objectAdmin (full control)

{:ok, array} = ExZarr.open(
  storage: :gcs,
  bucket: "my-secure-bucket",
  prefix: "arrays/production"
)

# Use managed identity or SAS tokens
config :azurex,
  account_name: {:system, "AZURE_STORAGE_ACCOUNT"},
  account_key: {:system, "AZURE_STORAGE_KEY"}

# Enable Azure Storage encryption at rest
# Use RBAC for fine-grained access control

defmodule ResourceGuard do
  @max_array_size 10 * 1024 * 1024 * 1024  # 10 GB
  @max_chunk_size 100 * 1024 * 1024        # 100 MB
  @max_dimensions 10

  def check_limits(shape, chunks, dtype) do
    element_size = dtype_size(dtype)
    total_elements = Tuple.product(shape)
    chunk_elements = Tuple.product(chunks)

    cond do
      tuple_size(shape) > @max_dimensions ->
        {:error, :too_many_dimensions}
      total_elements * element_size > @max_array_size ->
        {:error, :array_too_large}
      chunk_elements * element_size > @max_chunk_size ->
        {:error, :chunk_too_large}
      true ->
        :ok
    end
  end

  defp dtype_size(:i1), do: 1
  defp dtype_size(:i2), do: 2
  defp dtype_size(:i4), do: 4
  defp dtype_size(:i8), do: 8
  defp dtype_size(:u1), do: 1
  defp dtype_size(:u2), do: 2
  defp dtype_size(:u4), do: 4
  defp dtype_size(:u8), do: 8
  defp dtype_size(:f4), do: 4
  defp dtype_size(:f8), do: 8
end

# Usage
case ResourceGuard.check_limits(shape, chunks, dtype) do
  :ok -> ExZarr.create(shape: shape, chunks: chunks, dtype: dtype)
  {:error, reason} -> {:error, reason}
end

# config/runtime.exs - DO NOT hardcode secrets
import Config

config :ex_zarr,
  max_cache_size: System.get_env("EXZARR_CACHE_SIZE", "1000") |> String.to_integer(),
  enable_telemetry: true

config :ex_aws,
  access_key_id: System.fetch_env!("AWS_ACCESS_KEY_ID"),
  secret_access_key: System.fetch_env!("AWS_SECRET_ACCESS_KEY"),
  region: System.get_env("AWS_REGION", "us-east-1")

# Use tools like:
# - HashiCorp Vault for secret management
# - AWS Secrets Manager
# - Google Secret Manager
# - Azure Key Vault

# BAD - Leaks internal paths
{:error, "Failed to read /internal/secret/path/data.zarr"}

# GOOD - Generic message
{:error, :read_failed}

# For debugging, log detailed errors securely
Logger.debug("Failed to read array", path: path, reason: reason)

# Monitor decompression ratios
defmodule CompressionMonitor do
  def safe_decompress(compressed_data, expected_size) do
    case decompress(compressed_data) do
      {:ok, decompressed} ->
        ratio = byte_size(decompressed) / byte_size(compressed_data)

        if ratio > 1000 do
          Logger.warn("Suspicious compression ratio: #{ratio}")
          {:error, :compression_bomb_suspected}
        else
          {:ok, decompressed}
        end

      error ->
        error
    end
  end
end

# Validate that paths don't escape via symlinks
defp check_symlink_safety(path, base_dir) do
  real_path = File.realpath!(path)
  real_base = File.realpath!(base_dir)

  if String.starts_with?(real_path, real_base) do
    :ok
  else
    {:error, :symlink_escape_attempt}
  end
rescue
  _ -> {:error, :invalid_path}
end

# Enable server for concurrent write protection
{:ok, array} = ExZarr.create(
  shape: {1000, 1000},
  enable_server: true  # Prevents concurrent write corruption
)

# For distributed systems, use external coordination:
# - Redis locks (Redlock)
# - etcd
# - Consul
# - Database row-level locks

defmodule RateLimiter do
  use GenServer

  def check_rate(user_id) do
    GenServer.call(__MODULE__, {:check, user_id})
  end

  # Implementation using ETS for rate tracking
  # Limit: 100 requests per minute per user
end

# Use timeouts for all operations
{:ok, array} = ExZarr.open(storage: :s3, bucket: "data", timeout: 30_000)

# Read with timeout
case Task.await(
  Task.async(fn -> ExZarr.Array.read(array, {0, 0}, {100, 100}) end),
  30_000
) do
  {:ok, data} -> process(data)
  _ -> {:error, :timeout}
end

# ✓ SAFE: User controls their own filesystem
{:ok, array} = ExZarr.create(
  shape: {1000},
  storage: :filesystem,
  path: "/home/user/data/my_array"
)

# ✗ UNSAFE: Accepting untrusted path from web request
def create_array(conn, %{"path" => user_path}) do
  # DANGER: user_path could be "../../../etc/passwd"
  ExZarr.create(shape: {100}, storage: :filesystem, path: user_path)
end

# ✓ SAFE: Validate and constrain paths from external sources
def create_array(conn, %{"array_name" => name}) do
  if valid_array_name?(name) do
    safe_path = Path.join(["/var/data/arrays", sanitize_name(name)])
    ExZarr.create(shape: {100}, storage: :filesystem, path: safe_path)
  end
end

# ✓ SAFE: Configuration from application config
config :ex_zarr,
  storage: [
    s3: [
      bucket: "my-data-bucket",
      region: "us-west-2"
    ]
  ]

# ✗ UNSAFE: Dynamic configuration from user input
def init_storage(user_config) do
  # Don't do this with untrusted input
  ExZarr.Storage.init(storage_type: :s3, bucket: user_config["bucket"])
end