RegionsToItems_SingleTrack.lua

-- Create a table to store the region information
local regions = {}

-- Get the total number of regions
local numTotal,numMarkers,numRegions = reaper.CountProjectMarkers(0)

reaper.ShowConsoleMsg("Total markers & regions: " .. numTotal .. "\n", "Info", 0)
reaper.ShowConsoleMsg("Total regions: " .. numRegions .. "\n", "Info", 0)
reaper.ShowConsoleMsg("Total markers: " .. numMarkers .. "\n", "Info", 0)

if numRegions == 0 then
    reaper.ShowMessageBox("No regions found in the project.", "Info", 0)
  return
end

reaper.ClearConsole()

for i = 0, numTotal - 1 do
  local _, isRegion, regionStart, regionEnd, regionName, regionIdx, regionColor = reaper.EnumProjectMarkers3(0, i)
  if regionName == "" then
    regionName = "Unnamed Region"
  end
  if isRegion then
    table.insert(regions, {name = regionName, start = regionStart, endd = regionEnd, color = regionColor})
  end
end

-- Sort the regions by name and start time
table.sort(regions, function(a, b)
  return a.name < b.name or (a.name == b.name and a.start < b.start)
end)

reaper.PreventUIRefresh(1)
reaper.Undo_BeginBlock()

-- Write the regions to new tracks as items
local prevRegionName = ""
local trackCpt = 0
local itemCpt = 0
local newTrack, newItem

reaper.InsertTrackAtIndex(trackCpt, false)
newTrack = reaper.GetTrack(0, trackCpt)
reaper.GetSetMediaTrackInfo_String(newTrack, "P_NAME", "REGIONS", true)
    
for _, region in ipairs(regions) do

  -- Create track for each distinct region name
  if region.name ~= prevRegionName then
    prevRegionName = region.name
    itemCpt = 0
  end
    
  -- Create item for each region
  local newItem = reaper.AddMediaItemToTrack(newTrack)
  local newTake = reaper.AddTakeToMediaItem(newItem)
  reaper.GetSetMediaItemTakeInfo_String(newTake, "P_NAME", region.name, true)
  reaper.SetMediaItemPosition(newItem, region.start, false)
  reaper.SetMediaItemLength(newItem, region.endd - region.start, false)
  reaper.SetMediaItemInfo_Value(newItem, "I_CUSTOMCOLOR", region.color)
  reaper.SetMediaItemInfo_Value(newItem, "I_CURTAKE", 0)
  
  itemCpt = itemCpt + 1
end     

reaper.Undo_EndBlock("Regions to items", -1)
reaper.UpdateArrange()
reaper.PreventUIRefresh(-1)