From bc36ddea65fda2088f7e8fa98390e3feac07df84 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Wed, 11 Mar 2020 20:23:11 +0000
Subject: [PATCH] Give a better error when opening a DCP with File -> Open by
 mistake (#1723).

---
 src/lib/exceptions.cc  |  7 +++++++
 src/lib/exceptions.h   | 16 ++++++++++++++++
 src/lib/film.cc        |  4 ++++
 src/tools/dcpomatic.cc | 19 +++++++++++++++----
 4 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/src/lib/exceptions.cc b/src/lib/exceptions.cc
index 99d4c3979..ba3d4a05c 100644
--- a/src/lib/exceptions.cc
+++ b/src/lib/exceptions.cc
@@ -40,6 +40,13 @@ OpenFileError::OpenFileError (boost::filesystem::path f, int error, Mode mode)
 
 }
 
+FileNotFoundError::FileNotFoundError (boost::filesystem::path f)
+	: runtime_error(String::compose("File %1 not found", f.string()))
+	, _file (f)
+{
+
+}
+
 ReadFileError::ReadFileError (boost::filesystem::path f, int e)
 	: FileError (String::compose (_("could not read from file %1 (%2)"), f.string(), strerror (e)), f)
 {
diff --git a/src/lib/exceptions.h b/src/lib/exceptions.h
index 391258bd5..73b8cc85a 100644
--- a/src/lib/exceptions.h
+++ b/src/lib/exceptions.h
@@ -117,6 +117,22 @@ public:
 	OpenFileError (boost::filesystem::path f, int error, Mode mode);
 };
 
+class FileNotFoundError : public std::runtime_error
+{
+public:
+	FileNotFoundError (boost::filesystem::path f);
+	virtual ~FileNotFoundError () throw () {}
+
+	/** @return name of the file that this exception concerns */
+	boost::filesystem::path file () const {
+		return _file;
+	}
+
+private:
+	/** name of the file that this exception concerns */
+	boost::filesystem::path _file;
+};
+
 /** @class ReadFileError.
  *  @brief Indicates that some error occurred when trying to read from a file
  */
diff --git a/src/lib/film.cc b/src/lib/film.cc
index 90b18ea70..691ef58da 100644
--- a/src/lib/film.cc
+++ b/src/lib/film.cc
@@ -475,6 +475,10 @@ Film::read_metadata (optional<boost::filesystem::path> path)
 		path = file (metadata_file);
 	}
 
+	if (!boost::filesystem::exists(*path)) {
+		throw FileNotFoundError(*path);
+	}
+
 	cxml::Document f ("Metadata");
 	f.read_file (path.get ());
 
diff --git a/src/tools/dcpomatic.cc b/src/tools/dcpomatic.cc
index ea3cfbe32..aea058d80 100644
--- a/src/tools/dcpomatic.cc
+++ b/src/tools/dcpomatic.cc
@@ -447,10 +447,21 @@ public:
 
 		JobManager::instance()->add(shared_ptr<Job>(new CheckContentChangeJob(film)));
 	}
-	catch (std::exception& e) {
-		wxString p = std_to_wx (file.string ());
-		wxCharBuffer b = p.ToUTF8 ();
-		error_dialog (this, wxString::Format (_("Could not open film at %s"), p.data()), std_to_wx (e.what()));
+	catch (FileNotFoundError& e) {
+		boost::filesystem::path const dir = e.file().parent_path();
+		if (boost::filesystem::exists(dir / "ASSETMAP") || boost::filesystem::exists(dir / "ASSETMAP.xml")) {
+			error_dialog (
+				this, _("Could not open this folder as a DCP-o-matic project."),
+				_("It looks like you are trying to open a DCP.  File -> Open is for loading DCP-o-matic projects, not DCPs.  To import a DCP, create a new project with File -> New and then click the \"Add DCP...\" button.")
+				);
+		} else {
+			wxString const p = std_to_wx(file.string ());
+			error_dialog (this, wxString::Format(_("Could not open film at %s"), p.data()), std_to_wx(e.what()));
+		}
+
+	} catch (std::exception& e) {
+		wxString const p = std_to_wx (file.string());
+		error_dialog (this, wxString::Format(_("Could not open film at %s"), p.data()), std_to_wx(e.what()));
 	}
 
 	void set_film (shared_ptr<Film> film)
-- 
2.30.2