#!/usr/bin/env ruby

current_branch = `git symbolic-ref --short HEAD`.strip
target_branch = ARGV[0]

if current_branch != target_branch
    
    repository_path = Dir.getwd

    worktree_name = repository_path + "-worktree-#{target_branch.gsub('/', '_')}"
    worktree_folder = File.expand_path(worktree_name)
     
    worktree_workspace_file = Dir.glob(worktree_folder + "/*.xcworkspace").first
    worktree_workspace_file_exists = worktree_workspace_file != nil 

    xed_command = "xed #{worktree_workspace_file}"
    make_project_command = "make project"
    change_worktree_command = "cd #{worktree_folder} && #{worktree_workspace_file_exists ? xed_command : make_project_command}"

    # create worktree
    if !Dir.exist?(worktree_folder)
        `git worktree add --checkout #{worktree_name} #{target_branch} && #{change_worktree_command}`
    else 
        `#{change_worktree_command}`
    end

    # cleanup previous worktrees
    child_pid = fork {
        project_root_path = File.expand_path("..", repository_path)
        project_folder_name = repository_path.split("/").last
        all_worktree_folders = Dir.entries(project_root_path).select {|f| !File.directory? f and f.start_with?(project_folder_name) and f != project_folder_name}

        if all_worktree_folders.length > 2
            oldest_worktree_folder_name = all_worktree_folders.sort_by! {|f| File.mtime(File.join(project_root_path, f)) }.first
            if !oldest_worktree_folder_name.empty? 
                oldest_folder_path = File.join(project_root_path, oldest_worktree_folder_name)
                oldest_xcodeproj_file = File.join(oldest_folder_path, "*.xcodeproj")        
                build_dir = `xcodebuild -project #{oldest_xcodeproj_file} -showBuildSettings | grep -m 1 "BUILD_DIR" | awk '{print $3}'`
                oldest_project_derived_data_dir = build_dir.empty? ? "" : File.expand_path("../..", build_dir)
                `rm -r #{oldest_folder_path} #{oldest_project_derived_data_dir} && git worktree remove #{oldest_folder_path}`
            end
        end
        exit
    }
    Process.detach(child_pid)
end
exit 0