From c1e582e85cac4557156cb8cc99b8c9e7c30681f3 Mon Sep 17 00:00:00 2001
From: William Sanches <william.sanches@plataformatec.com.br>
Date: Mon, 17 Dec 2018 17:19:32 -0200
Subject: [PATCH] Add better error messages

---
 .../features/pages/contract_verify_page.ex               | 5 +----
 apps/explorer/lib/explorer/chain/smart_contract.ex       | 9 +++++++--
 apps/explorer/lib/explorer/smart_contract/publisher.ex   | 9 +++++----
 .../explorer/smart_contract/solidity/code_compiler.ex    | 2 +-
 .../smart_contract/solidity/code_compiler_test.exs       | 4 ++--
 5 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/apps/block_scout_web/test/block_scout_web/features/pages/contract_verify_page.ex b/apps/block_scout_web/test/block_scout_web/features/pages/contract_verify_page.ex
index 38af90be22..995b95d481 100644
--- a/apps/block_scout_web/test/block_scout_web/features/pages/contract_verify_page.ex
+++ b/apps/block_scout_web/test/block_scout_web/features/pages/contract_verify_page.ex
@@ -39,10 +39,7 @@ defmodule BlockScoutWeb.ContractVerifyPage do
   end
 
   def validation_error do
-    css(
-      "[data-test='contract-source-code-error']",
-      text: "there was an error validating your contract, please try again."
-    )
+    css("[data-test='contract-source-code-error']")
   end
 
   def verify_and_publish(session) do
diff --git a/apps/explorer/lib/explorer/chain/smart_contract.ex b/apps/explorer/lib/explorer/chain/smart_contract.ex
index dcc089dc27..07d51b2216 100644
--- a/apps/explorer/lib/explorer/chain/smart_contract.ex
+++ b/apps/explorer/lib/explorer/chain/smart_contract.ex
@@ -45,10 +45,15 @@ defmodule Explorer.Chain.SmartContract do
     |> unique_constraint(:address_hash)
   end
 
-  def invalid_contract_changeset(%__MODULE__{} = smart_contract, attrs) do
+  def invalid_contract_changeset(%__MODULE__{} = smart_contract, attrs, error) do
     smart_contract
     |> cast(attrs, [:name, :compiler_version, :optimization, :contract_source_code, :address_hash])
     |> validate_required([:name, :compiler_version, :optimization, :address_hash])
-    |> add_error(:contract_source_code, "there was an error validating your contract, please try again.")
+    |> add_error(:contract_source_code, error_message(error))
   end
+
+  defp error_message(:compilation), do: "There was an error compiling your contract."
+  defp error_message(:generated_bytecode), do: "Bytecode does not match, please try again."
+  defp error_message(:name), do: "Wrong contract name, please try again."
+  defp error_message(_), do: "There was an error validating your contract, please try again."
 end
diff --git a/apps/explorer/lib/explorer/smart_contract/publisher.ex b/apps/explorer/lib/explorer/smart_contract/publisher.ex
index f66d567c17..8a9b31e2b9 100644
--- a/apps/explorer/lib/explorer/smart_contract/publisher.ex
+++ b/apps/explorer/lib/explorer/smart_contract/publisher.ex
@@ -28,8 +28,8 @@ defmodule Explorer.SmartContract.Publisher do
       {:ok, %{abi: abi}} ->
         publish_smart_contract(address_hash, params, abi)
 
-      {:error, _} ->
-        {:error, unverified_smart_contract(address_hash, params)}
+      {:error, error} ->
+        {:error, unverified_smart_contract(address_hash, params, error)}
     end
   end
 
@@ -39,13 +39,14 @@ defmodule Explorer.SmartContract.Publisher do
     |> Chain.create_smart_contract()
   end
 
-  defp unverified_smart_contract(address_hash, params) do
+  defp unverified_smart_contract(address_hash, params, error) do
     attrs = attributes(address_hash, params)
 
     changeset =
       SmartContract.invalid_contract_changeset(
         %SmartContract{address_hash: address_hash},
-        attrs
+        attrs,
+        error
       )
 
     %{changeset | action: :insert}
diff --git a/apps/explorer/lib/explorer/smart_contract/solidity/code_compiler.ex b/apps/explorer/lib/explorer/smart_contract/solidity/code_compiler.ex
index b21cd81864..115c3a1033 100644
--- a/apps/explorer/lib/explorer/smart_contract/solidity/code_compiler.ex
+++ b/apps/explorer/lib/explorer/smart_contract/solidity/code_compiler.ex
@@ -81,7 +81,7 @@ defmodule Explorer.SmartContract.Solidity.CodeCompiler do
     end
   end
 
-  def get_contract_info(contracts, _) when contracts == %{}, do: %{"errors" => []}
+  def get_contract_info(contracts, _) when contracts == %{}, do: {:error, :compilation}
 
   def get_contract_info(contracts, name) do
     new_versions_name = ":" <> name
diff --git a/apps/explorer/test/explorer/smart_contract/solidity/code_compiler_test.exs b/apps/explorer/test/explorer/smart_contract/solidity/code_compiler_test.exs
index 98a83bdd6d..a6235967f0 100644
--- a/apps/explorer/test/explorer/smart_contract/solidity/code_compiler_test.exs
+++ b/apps/explorer/test/explorer/smart_contract/solidity/code_compiler_test.exs
@@ -108,12 +108,12 @@ defmodule Explorer.SmartContract.Solidity.CodeCompilerTest do
       assert {:error, :name} == response
     end
 
-    test "returns an empty list of errors for empty info" do
+    test "returns compilation error for empty info" do
       name = "Name"
 
       response = CodeCompiler.get_contract_info(%{}, name)
 
-      assert %{"errors" => []} == response
+      assert {:error, :compilation} == response
     end
 
     test "the contract info is returned when the name matches" do