feat: more work on backend content and generation

lib/bds/generation.ex

@@ -0,0 +1,77 @@
+defmodule BDS.Generation do
+  @moduledoc false
+
+  import Ecto.Query
+
+  alias BDS.Generation.GeneratedFileHash
+  alias BDS.Projects
+  alias BDS.Repo
+
+  def write_generated_file(project_id, relative_path, content)
+      when is_binary(project_id) and is_binary(relative_path) and is_binary(content) do
+    project = Projects.get_project!(project_id)
+    content_hash = sha256(content)
+    now = System.system_time(:second)
+
+    case Repo.get_by(GeneratedFileHash, project_id: project_id, relative_path: relative_path) do
+      %GeneratedFileHash{content_hash: ^content_hash} ->
+        {:ok, %{relative_path: relative_path, content_hash: content_hash, written?: false}}
+
+      _existing ->
+        full_path = output_path(project, relative_path)
+        :ok = File.mkdir_p(Path.dirname(full_path))
+        :ok = File.write(full_path, content)
+
+        attrs = %{
+          project_id: project_id,
+          relative_path: relative_path,
+          content_hash: content_hash,
+          updated_at: now
+        }
+
+        %GeneratedFileHash{}
+        |> GeneratedFileHash.changeset(attrs)
+        |> Repo.insert!(
+          on_conflict: [set: [content_hash: content_hash, updated_at: now]],
+          conflict_target: [:project_id, :relative_path]
+        )
+
+        {:ok, %{relative_path: relative_path, content_hash: content_hash, written?: true}}
+    end
+  end
+
+  def list_generated_files(project_id) when is_binary(project_id) do
+    {:ok,
+     Repo.all(
+       from generated_file in GeneratedFileHash,
+         where: generated_file.project_id == ^project_id,
+         order_by: [asc: generated_file.relative_path]
+     )}
+  end
+
+  def delete_generated_file(project_id, relative_path) when is_binary(project_id) and is_binary(relative_path) do
+    project = Projects.get_project!(project_id)
+
+    case File.rm(output_path(project, relative_path)) do
+      :ok -> :ok
+      {:error, :enoent} -> :ok
+      {:error, reason} -> {:error, reason}
+    end
+
+    Repo.delete_all(
+      from generated_file in GeneratedFileHash,
+        where: generated_file.project_id == ^project_id and generated_file.relative_path == ^relative_path
+    )
+
+    :ok
+  end
+
+  defp output_path(project, relative_path) do
+    Path.join([Projects.project_data_dir(project), "html", relative_path])
+  end
+
+  defp sha256(content) do
+    :crypto.hash(:sha256, content)
+    |> Base.encode16(case: :lower)
+  end
+end