using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Razor.TagHelpers;

namespace Library;

public class ViewScriptTagHelper : TagHelper
{
	private readonly IWebHostEnvironment environment;
	private readonly IFileVersionProvider fileVersionProvider;
	private const string AppendVersionAttributeName = "append-version";

	public ViewScriptTagHelper( IWebHostEnvironment environment , IFileVersionProvider fileVersionProvider )
	{
		this.environment = environment;
		this.fileVersionProvider = fileVersionProvider;
	}

	[ViewContext]
	public ViewContext? ViewContext { get; set; }

	/// <summary>
	/// Value indicating if file version should be appended to src urls.
	/// </summary>
	/// <remarks>
	/// A query string "v" with the encoded content of the file is added.
	/// </remarks>
	[HtmlAttributeName( AppendVersionAttributeName )]
	public bool? AppendVersion { get; set; }

	public override void Process( TagHelperContext context , TagHelperOutput output )
	{
		// remove the `page-script` tag if script doesn't exist
		output.TagName = null;
		output.TagMode = TagMode.StartTagAndEndTag;

		var viewPath = ViewContext?.View.Path;
		var src = $"{viewPath}.js";

		/* When the app is published, the framework automatically moves the script to the web root.
           So we should check both places, with the content root first for development */
		var fileInfo = environment.ContentRootFileProvider.GetFileInfo(src) ??
					   environment.WebRootFileProvider.GetFileInfo(src);

		if ( fileInfo is { Exists: true } )
		{
			// switch it to script now
			output.TagName = "script";
			output.Content = new DefaultTagHelperContent( );

			if ( AppendVersion == true )
			{
				// people love their cache busting versions
				src = fileVersionProvider.AddFileVersionToPath( src , src );
			}

			output.Attributes.Add( "src" , src );
		}
	}
}