MIDI Program Change Support (#7171)

Addresses #576

I might even go as so far as to say we are done with #576 with this
commit but I'm sure there will be comments and changes still. So here's
how it works

1. We add a new directory %USER%/Patches/MIDI Programs
2. We add a new data structure `patchIdToMidiBankAndProgram[128][128]` which
   for a bank and program is used for a patch id
3. We populate it as follows

   a. If `MIDI Programs` has top level patches those become bank 0
   b. If `MIDI Programs` has directories, those fill in order. So a
      just-directories MIDI programs has bank 0 as the first directory
      and a mix and match has bank 0 as the raw top level and bank 1
      as the first directory
   c. If there's still banks to be filled we fill them one at a time
      from factor. So if you have 6 directories in MIDI Programs,
      bank 7 will become 'Basses' (the first factory)

By 'fill' we mean traverse the category in alphabetical order and
set the patches as programs, up to 128

Banks with < 128 patches don't respond to PCH for the empty slots
Categories with > 128 patches only map the first 128

src/common/SurgeStorage.cpp

@@ -299,6 +299,7 @@ SurgeStorage::SurgeStorage(const SurgeStorage::SurgeStorageConfig &config) : oth
 
     // append separator if not present
     userPatchesPath = userDataPath / "Patches";
+    userPatchesMidiProgramChangePath = userPatchesPath / midiProgramChangePatchesSubdir;
     userWavetablesPath = userDataPath / "Wavetables";
     userWavetablesExportPath = userWavetablesPath / "Exported";
     userFXPath = userDataPath / "FX Presets";
@@ -557,6 +558,19 @@ void SurgeStorage::createUserDirectory()
             reportError(e.what(), "Unable to set up User Directory");
         }
     }
+
+    // Special case - MIDI Program Changes came later
+    if (!fs::exists(userPatchesMidiProgramChangePath))
+    {
+        try
+        {
+            fs::create_directories(userPatchesMidiProgramChangePath);
+        }
+        catch (const fs::filesystem_error &e)
+        {
+            reportError(e.what(), "Unable to set up User Directory");
+        }
+    }
 }
 
 void SurgeStorage::initializePatchDb(bool force)
@@ -729,6 +743,64 @@ void SurgeStorage::refresh_patchlist()
         else
             p.isFavorite = false;
     }
+
+    /*
+     * Update midi program change here
+     */
+    int loadFactoryBanksInAt{0};
+
+    auto loadCategoryIntoBank = [this](int catid, int bk) {
+        int currProg = 0;
+        for (const auto &pd : patchOrdering)
+        {
+            auto &p = patch_list[pd];
+            if (p.category == catid)
+            {
+                patchIdToMidiBankAndProgram[bk][currProg] = pd;
+                currProg++;
+                if (currProg >= 128)
+                    break;
+            }
+        }
+    };
+    int currBank = 0;
+    // TODO: Initialize the data structure with init patch everywhere
+    for (auto &a : patchIdToMidiBankAndProgram)
+        for (auto &p : a)
+            p = -1;
+
+    for (const auto &c : patch_category)
+    {
+        if (c.name == midiProgramChangePatchesSubdir)
+        {
+            if (c.numberOfPatchesInCatgory > 0)
+            {
+                loadCategoryIntoBank(c.internalid, currBank);
+                currBank++;
+            }
+
+            // And luckily .children are sorted
+            for (const auto &k : c.children)
+            {
+                loadCategoryIntoBank(k.internalid, currBank);
+                currBank++;
+                if (currBank >= 128)
+                    break;
+            }
+        }
+    }
+
+    if (currBank < 128)
+    {
+        for (auto c : patchCategoryOrdering)
+        {
+            loadCategoryIntoBank(c, currBank);
+
+            currBank++;
+            if (currBank >= 128)
+                break;
+        }
+    }
 }
 
 void SurgeStorage::refreshPatchlistAddDir(bool userDir, string subdir)

src/common/SurgeStorage.h

@@ -1355,6 +1355,7 @@ class alignas(16) SurgeStorage
     int firstUserCategory;
     std::vector<int> patchOrdering;
     std::vector<int> patchCategoryOrdering;
+    std::array<std::array<int, 128>, 128> patchIdToMidiBankAndProgram;
 
     // The in-memory wavetable database
     std::vector<Patch> wt_list;
@@ -1372,6 +1373,7 @@ class alignas(16) SurgeStorage
     fs::path userDefaultFilePath;
     fs::path userDataPath;
     fs::path userPatchesPath;
+    fs::path userPatchesMidiProgramChangePath;
     fs::path userWavetablesPath;
     fs::path userModulatorSettingsPath;
     fs::path userFXPath;
@@ -1380,6 +1382,8 @@ class alignas(16) SurgeStorage
     fs::path userMidiMappingsPath;
     fs::path extraThirdPartyWavetablesPath; // used by rack
 
+    std::string midiProgramChangePatchesSubdir{"MIDI Programs"};
+
     std::map<std::string, TiXmlDocument> userMidiMappingsXMLByName;
     void rescanUserMidiMappings();
     void loadMidiMappingByName(std::string name);

src/common/SurgeSynthesizer.cpp

@@ -1929,8 +1929,10 @@ void SurgeSynthesizer::programChange(char channel, int value)
         return;
 
     PCH = value;
-    // load_patch((CC0<<7) + PCH);
-    patchid_queue = (CC0 << 7) + PCH;
+
+    auto pid = storage.patchIdToMidiBankAndProgram[CC0][PCH];
+    if (pid >= 0)
+        patchid_queue = pid;
 }
 
 void SurgeSynthesizer::updateDisplay()