module FSharp.Data.GraphQL.Server.Ast

open System.Collections.Immutable

open FSharp.Data.GraphQL

/// A list of fields that are reserved for the GraphQL introspection system.

[<CompiledName "MetaTypeFields">]

let metaTypeFields =

seq {

"__type"

"__schema"

"__typename"

}

|> ImmutableHashSet.CreateRange

let private getOperation astDef =

match astDef with

| Ast.OperationDefinition odef -> Some odef

| _ -> None

/// Find an operation by its name.

[<CompiledName "TryFindOperationByName">]

let tryFindOperationByName operationName (astDoc: Ast.Document) =

match astDoc.Definitions |> List.choose getOperation, operationName with

| [ def ], _ -> Some def

| defs, name -> defs |> List.tryFind (fun def -> def.Name = name)

/// Determines if the operation contains fields beyond the allowed fields.

/// And executes actions based on the result.

[<CompiledName "ContainsFieldsBeyond">]

let internal containsFieldsBeyond

(allowedFields: ImmutableHashSet<_>)

(whenContains: Ast.Field -> unit)

(whenNotContains: unit -> unit)

(astOpDef: Ast.OperationDefinition)

=

astOpDef.SelectionSet

|> List.exists (fun def ->

match def with

| Ast.Field fd ->

whenContains fd

not <| allowedFields.Contains fd.Name

| _ ->

whenNotContains ()

false)