feat: datasheet upload and auto-retrieve

- store datasheet PDFs on the server
- download PDF automatically when given a link

lib/components_elixir/datasheet_downloader.ex

@@ -0,0 +1,137 @@
+defmodule ComponentsElixir.DatasheetDownloader do
+  @moduledoc """
+  Module for downloading datasheet PDFs from URLs.
+  """
+
+  require Logger
+
+  @doc """
+  Downloads a PDF from the given URL and saves it to the datasheets folder.
+  Returns {:ok, filename} on success or {:error, reason} on failure.
+  """
+  def download_pdf_from_url(url) when is_binary(url) do
+    with {:ok, %URI{scheme: scheme}} when scheme in ["http", "https"] <- validate_url(url),
+         {:ok, filename} <- generate_filename(url),
+         {:ok, response} <- fetch_pdf(url),
+         :ok <- validate_pdf_content(response.body),
+         :ok <- save_file(filename, response.body) do
+      {:ok, filename}
+    else
+      {:error, reason} -> {:error, reason}
+      error -> {:error, "Unexpected error: #{inspect(error)}"}
+    end
+  end
+
+  def download_pdf_from_url(_), do: {:error, "Invalid URL"}
+
+  defp validate_url(url) do
+    case URI.parse(url) do
+      %URI{scheme: scheme} when scheme in ["http", "https"] ->
+        {:ok, URI.parse(url)}
+      _ ->
+        {:error, "Invalid URL scheme. Only HTTP and HTTPS are supported."}
+    end
+  end
+
+  defp generate_filename(url) do
+    # Try to extract a meaningful filename from the URL
+    uri = URI.parse(url)
+    original_filename =
+      case Path.basename(uri.path || "") do
+        "" -> "datasheet"
+        basename ->
+          # Remove extension and sanitize
+          basename
+          |> Path.rootname()
+          |> sanitize_filename()
+      end
+
+    # Create a unique filename with timestamp
+    timestamp = System.unique_integer([:positive])
+    filename = "#{timestamp}_#{original_filename}.pdf"
+    {:ok, filename}
+  end
+
+  defp sanitize_filename(filename) do
+    filename
+    |> String.replace(~r/[^\w\-_]/, "_")  # Replace non-word chars with underscores
+    |> String.replace(~r/_+/, "_")        # Replace multiple underscores with single
+    |> String.trim("_")                   # Remove leading/trailing underscores
+    |> String.slice(0, 50)                # Limit length
+    |> case do
+      "" -> "datasheet"
+      name -> name
+    end
+  end
+
+  defp fetch_pdf(url) do
+    case Req.get(url,
+      redirect: true,
+      max_redirects: 5,
+      receive_timeout: 30_000,
+      headers: [
+        {"User-Agent", "ComponentSystem/1.0 DatasheetDownloader"}
+      ]
+    ) do
+      {:ok, %Req.Response{status: 200} = response} ->
+        {:ok, response}
+      {:ok, %Req.Response{status: status}} ->
+        {:error, "HTTP error: #{status}"}
+      {:error, reason} ->
+        Logger.error("Failed to download PDF from #{url}: #{inspect(reason)}")
+        {:error, "Download failed: #{inspect(reason)}"}
+    end
+  end
+
+  defp validate_pdf_content(body) do
+    # Check if the response body looks like a PDF (starts with %PDF)
+    case body do
+      <<"%PDF", _rest::binary>> ->
+        :ok
+      _ ->
+        {:error, "Downloaded content is not a valid PDF file"}
+    end
+  end
+
+  defp save_file(filename, content) do
+    uploads_dir = Application.get_env(:components_elixir, :uploads_dir)
+    datasheets_dir = Path.join([uploads_dir, "datasheets"])
+    file_path = Path.join(datasheets_dir, filename)
+
+    # Ensure the datasheets directory exists
+    case File.mkdir_p(datasheets_dir) do
+      :ok ->
+        case File.write(file_path, content) do
+          :ok ->
+            Logger.info("Successfully saved datasheet: #{filename}")
+            :ok
+          {:error, reason} ->
+            Logger.error("Failed to save datasheet file: #{inspect(reason)}")
+            {:error, "Failed to save file: #{inspect(reason)}"}
+        end
+      {:error, reason} ->
+        Logger.error("Failed to create datasheets directory: #{inspect(reason)}")
+        {:error, "Failed to create directory: #{inspect(reason)}"}
+    end
+  end
+
+  @doc """
+  Deletes a datasheet file from the filesystem.
+  """
+  def delete_datasheet_file(nil), do: :ok
+  def delete_datasheet_file(""), do: :ok
+
+  def delete_datasheet_file(filename) do
+    uploads_dir = Application.get_env(:components_elixir, :uploads_dir)
+    file_path = Path.join([uploads_dir, "datasheets", filename])
+
+    case File.rm(file_path) do
+      :ok ->
+        Logger.info("Deleted datasheet file: #{filename}")
+        :ok
+      {:error, reason} ->
+        Logger.warning("Failed to delete datasheet file #{filename}: #{inspect(reason)}")
+        {:error, reason}
+    end
+  end
+end