WIP for file upload (Merkle tree for signatures)

1 files changed, 114 insertions, 0 deletions

diff --git a/shard/lib/app/file.ex b/shard/lib/app/file.ex
new file mode 100644
index 0000000..a874222
--- /dev/null
+++ b/shard/lib/app/file.ex
@@ -0,0 +1,114 @@
+defmodule SApp.File do
+  @moduledoc"""
+  Shard application for a file identified by its infohash. The file cannot be modified.
+
+  The infohash is the hash of an info struct containing:
+
+      %Info{
+        merkle_root: hash
+        file_hash: hash
+        size: int
+        mime_type: string
+    }
+
+  The file is cut in blocks of 4kb that are collected in a 64-ary Merkle tree.
+  """
+
+  use GenServer
+
+  require Logger
+
+  alias SData.MerkleTree, as: MT
+
+  defmodule Manifest do
+    @moduledoc"""
+    Manifest for a file.
+    The file is identified by the root hash of its Merkle tree and by its mime type.
+    """
+    defstruct [:infohash]
+
+    defimpl Shard.Manifest do
+      def module(_m), do: SApp.File
+      def is_valid?(m) do
+        byte_size(m.infohash) == 32
+      end
+    end
+  end
+
+  defmodule Info do
+    @moduledoc"""
+    A file info struct.
+    """
+    defstruct [:merkle_root, :file_hash, :size, :mime_type]
+  end
+
+  defmodule State do
+    defstruct [:infohash, :id, :manifest, :netgroup, :info, :infobin, :store, :missing, :path]
+  end
+
+  def start_link(manifest) do
+    GenServer.start_link(__MODULE__, manifest)
+  end  
+
+  def init(manifest) do
+    %Manifest{infohash: infohash} = manifest
+    id = SData.term_hash manifest
+
+    Shard.Manager.dispatch_to(id, nil, self())
+    {infobin, info} = case Shard.Manager.load_state(id) do
+      nil -> {nil, nil}
+      infobin -> {infobin, SData.term_unbin infobin}
+    end
+    netgroup = %SNet.PubShardGroup{id: id}
+    SNet.Group.init_lookup(netgroup, self())
+
+    path = [Application.get_env(:shard, :data_path), "#{id|>Base.encode16}"] |> Path.join
+
+    {:ok, store} = SApp.PageStore.start_link(id, :meta, netgroup)
+
+    {:ok, %State{
+      id: id, infohash: infohash, manifest: manifest, netgroup: netgroup,
+      infobin: infobin, info: info, store: store, missing: nil, path: path
+    }}
+  end
+
+  def handle_cast({:init_with, file_path, infobin, mt}, state) do
+    info = SData.term_unbin(infobin)
+    for {k, v} <- mt.store do
+      {^k, _} = SData.PageStore.put(state.store, v)
+    end
+    File.copy!(file_path, state.path)
+    new_state = %{state |
+      infobin: infobin,
+      info: info,
+    }
+    {:noreply, new_state}
+  end
+
+  # TODO networking etc
+
+  # =========
+  # INTERFACE
+  # =========
+  
+  @doc"""
+  Create a File shard from a file path
+  """
+  def create(path, mime_type) do
+    %File.Stat{size: size} = File.stat!(path)
+    mt = MT.create(path)
+    hash = SData.file_hash(path)
+
+    info = %Info{
+      merkle_root: mt.root,
+      file_hash: hash,
+      size: size,
+      mime_type: mime_type,
+    }
+    infobin = SData.term_bin(info)
+    infohash = SData.bin_hash(infobin)
+    manifest = %Manifest{infohash: infohash}
+    pid = Shard.Manager.find_or_start(manifest)
+    GenServer.cast(pid, {:init_with, path, infobin, mt})
+  end
+end