WIP on Fluid model/filters

src/MyWebLog/Template.fs

@@ -1,8 +1,14 @@
 module MyWebLog.Template
 
+open System
+open System.Collections.Generic
+open System.IO
+open System.Text
 open Fluid
 open Fluid.Values
 open Giraffe.ViewEngine
+open Microsoft.AspNetCore.Antiforgery
+open Microsoft.Extensions.FileProviders
 open MyWebLog
 open MyWebLog.ViewModels
 
@@ -48,10 +54,21 @@ module private Helpers =
 
 
 /// Fluid template options customized with myWebLog filters
-let options =
+let options () =
     let sValue = StringValue >> VTask<FluidValue>
+    
     let it = TemplateOptions.Default
     it.MemberAccessStrategy.MemberNameStrategy <- MemberNameStrategies.SnakeCase
+    [ // Domain types
+      typeof<CustomFeed>; typeof<Episode>; typeof<Episode option>; typeof<MetaItem>; typeof<Page>; typeof<RssOptions>
+      typeof<TagMap>;     typeof<WebLog>
+      // View models
+      typeof<AppViewContext>; typeof<DisplayCategory>; typeof<DisplayPage>; typeof<EditPageModel>; typeof<PostDisplay>
+      typeof<PostListItem>;   typeof<UserMessage>
+      // Framework types
+      typeof<AntiforgeryTokenSet>; typeof<DateTime option>; typeof<int option>;    typeof<KeyValuePair>
+      typeof<MetaItem list>;       typeof<string list>;     typeof<string option>; typeof<TagMap list> ]
+    |> List.iter it.MemberAccessStrategy.Register
     
     // A filter to generate an absolute link
     it.Filters.AddFilter("absolute_link", fun input _ ctx -> sValue (permalink input ctx.App.WebLog.AbsoluteUrl))
@@ -132,12 +149,14 @@ let options =
     // A filter to retrieve the value of a meta item from a list
     //   (shorter than `{% assign item = list | where: "Name", [name] | first %}{{ item.value }}`)
     it.Filters.AddFilter("value",
-        fun input args _ ->
-            let items = input.ToObjectValue() :?> MetaItem list
-            let name  = args.At(0).ToStringValue()
-            match items |> List.tryFind (fun it -> it.Name = name) with
-            | Some item -> item.Value
-            | None -> $"-- {name} not found --"
+        fun input args ctx ->
+            let name = args.At(0).ToStringValue()
+            let picker (value: FluidValue) =
+                let item = value.ToObjectValue() :?> MetaItem
+                if item.Name = name then Some item.Value else None 
+            (input :?> ArrayValue).Values
+            |> Seq.tryPick picker
+            |> Option.defaultValue $"-- {name} not found --"
             |> sValue)
     
     it
@@ -234,11 +253,13 @@ let parser =
     
     it
 
+
+open MyWebLog.Data
+
 /// Cache for parsed templates
 module Cache =
     
     open System.Collections.Concurrent
-    open MyWebLog.Data
     
     /// Cache of parsed templates
     let private _cache = ConcurrentDictionary<string, IFluidTemplate> ()
@@ -277,6 +298,37 @@ module Cache =
         _cache.Clear()
 
 
+/// A file provider to retrieve files by theme 
+type ThemeFileProvider(themeId: ThemeId, data: IData) =
+    
+    interface IFileProvider with
+        
+        member _.GetDirectoryContents _ =
+            raise <| NotImplementedException "The theme file provider does not support directory listings"
+        
+        member _.GetFileInfo path =
+            match data.Theme.FindById themeId |> Async.AwaitTask |> Async.RunSynchronously with
+            | Some theme ->
+                match theme.Templates |> List.tryFind (fun t -> t.Name = path) with
+                | Some template ->
+                    { new IFileInfo with
+                        member _.Exists       = true
+                        member _.IsDirectory  = false
+                        member _.LastModified = DateTimeOffset.Now
+                        member _.Length       = int64 template.Text.Length
+                        member _.Name         = template.Name.Split '/' |> Array.last
+                        member _.PhysicalPath = null
+                        member _.CreateReadStream() =
+                            new MemoryStream(Encoding.UTF8.GetBytes template.Text) }
+                | None -> NotFoundFileInfo path
+            | None -> NotFoundFileInfo path
+        
+        member _.Watch _ =
+            raise <| NotImplementedException "The theme file provider does not support watching for changes"
+
+
 /// Render a template to a string
-let render (template: IFluidTemplate) (viewCtx: AppViewContext) =
-    template.Render(TemplateContext(viewCtx, options, true))
+let render (template: IFluidTemplate) (viewCtx: AppViewContext) data =
+    let opts = options ()
+    opts.FileProvider <- ThemeFileProvider(viewCtx.WebLog.ThemeId, data)
+    template.Render(TemplateContext(viewCtx, opts, true))