From 926b21676ae80c5ed1abfda11a8ebb727cd3cec3 Mon Sep 17 00:00:00 2001
From: Sasan Hezarkhani <sasan.hezarkhani@vungle.com>
Date: Tue, 16 May 2017 23:13:47 +0100
Subject: [PATCH] Uses tdiff

---
 apps/edeet/priv/static/edeet.js   |  1 -
 apps/edeet/src/edeet_diff.erl     | 66 +++++++++++++++++++++++++++++++
 apps/edeet/src/edeet_document.erl |  3 ++
 rebar.config                      |  1 +
 rebar.lock                        |  6 ++-
 5 files changed, 75 insertions(+), 2 deletions(-)
 create mode 100644 apps/edeet/src/edeet_diff.erl

diff --git a/apps/edeet/priv/static/edeet.js b/apps/edeet/priv/static/edeet.js
index 736e8ca..76d96a4 100644
--- a/apps/edeet/priv/static/edeet.js
+++ b/apps/edeet/priv/static/edeet.js
@@ -64,7 +64,6 @@ function handle_message(event) {
         $('#people data[connection-id="' + message.lost + '"]').fadeOut()
     }
 
-
     if (message.init) {
         window.location.hash = message.doc_id;
     }
diff --git a/apps/edeet/src/edeet_diff.erl b/apps/edeet/src/edeet_diff.erl
new file mode 100644
index 0000000..5d35133
--- /dev/null
+++ b/apps/edeet/src/edeet_diff.erl
@@ -0,0 +1,66 @@
+%%%-------------------------------------------------------------------
+%%% @doc For more info look at https://neil.fraser.name/writing/diff/
+%%%
+%%% @end
+%%%-------------------------------------------------------------------
+-module(edeet_diff).
+
+%% API
+-export([
+    diff/2
+]).
+
+-type diff_step() :: {add | del, binary()}.
+
+
+-define(TERNARY(Cond, TrueVal, FalseVal), (case (Cond) of true -> (TrueVal); false -> (FalseVal) end)).
+
+-spec diff(binary(), binary()) -> list(diff_step()).
+diff(Bin, Bin) ->
+    [];
+
+diff(<<>>, Bin) ->
+    [{ins, Bin}];
+
+diff(Bin, <<>>) ->
+    [{del, Bin}];
+
+diff(BinA, BinB) ->
+    tdiff:diff_binaries(BinA, BinB).
+
+%%diff(BinA, BinB) ->
+%%    Prefix = binary:longest_common_prefix([BinA, BinB]),
+%%    Suffix = binary:longest_common_suffix([BinA, BinB]),
+%%
+%%    BinA2 = binary:part(BinA, {0, Prefix}),
+%%    BinA3 = binary:part(BinA2, {Suffix, bit_size(BinA)}),
+%%
+%%    BinB2 = binary:part(BinB, {0, Prefix}),
+%%    BinB3 = binary:part(BinB2, {Suffix, bit_size(BinB)}),
+%%
+%%    case {BinA3, BinB3} of
+%%        {<<>>, BinB3} ->
+%%            [{add, BinB3, Prefix}];
+%%        {BinA3, <<>>} ->
+%%            [{del, BinA3, Prefix}];
+%%        _ ->
+%%            {Long, Short} = ?TERNARY(bit_size(BinA3) > bit_size(BinB3), {BinA3, BinB3}, {BinB3, BinA3}),
+%%            case binary:match(Long, Short) of
+%%                nomatch ->
+%%                    [];
+%%                {Start, Len} ->
+%%                    Insert = binary:part(Long, {0, Start}),
+%%                    Delete = binary:part(Long, {Len, bit_size(Long)}),
+%%
+%%                    [{add, Insert, Start},
+%%                     {del, Delete, Len}]
+%%
+%%            end
+%%    end.
+
+
+
+
+
+
+
diff --git a/apps/edeet/src/edeet_document.erl b/apps/edeet/src/edeet_document.erl
index d02bb70..cdce296 100644
--- a/apps/edeet/src/edeet_document.erl
+++ b/apps/edeet/src/edeet_document.erl
@@ -42,6 +42,9 @@ get_document(DocId) ->
     end.
 
 edit_document(DocId, Bin) ->
+    [{DocId, _, DocBin}] = ets:lookup(edeet_documents, DocId),
+    io:format("Diffing: ~p~n", [edeet_diff:diff(DocBin, Bin)]),
+
     ets:update_element(edeet_documents, DocId, {3, Bin}).
 
 -spec generate_doc_id(binary()) -> binary().
diff --git a/rebar.config b/rebar.config
index 03b365b..b8ec0ce 100644
--- a/rebar.config
+++ b/rebar.config
@@ -5,6 +5,7 @@
 
 {deps, [
     {cowboy, ".*", {git, "https://github.com/ninenines/cowboy.git", {tag, "2.0.0-pre.8"}}},
+    {tdiff, ".*", {git, "https://github.com/tomas-abrahamsson/tdiff.git", {tag, "0.1"}}},
     {jsone, "1.4.3"},
     {lager, "3.4.2"}
 ]}.
diff --git a/rebar.lock b/rebar.lock
index 6258894..5bacb06 100644
--- a/rebar.lock
+++ b/rebar.lock
@@ -13,7 +13,11 @@
  {<<"ranch">>,
   {git,"https://github.com/ninenines/ranch",
        {ref,"40809cd2b257a8a53bcb5588ecaa88cc5381ff5c"}},
-  1}]}.
+  1},
+ {<<"tdiff">>,
+  {git,"https://github.com/tomas-abrahamsson/tdiff.git",
+       {ref,"bbb54ce20df388f2c7d01e8df30ef471ca98d0fb"}},
+  0}]}.
 [
 {pkg_hash,[
  {<<"goldrush">>, <<"F06E5D5F1277DA5C413E84D5A2924174182FB108DABB39D5EC548B27424CD106">>},