/// Generates curryable functional wrappers for .Net types.
namespace CurryUp

open System
open System.Reflection
open System.Text


[<AutoOpen>] 
module Configuration =

    type NamespaceTypeOrLibrary = string
    type Sourcefile             = string
    type Config = 
        { From             : NamespaceTypeOrLibrary 
          To               : Sourcefile
          NameOverload     : string -> string
          CurriedNamespace : string -> string }


[<AutoOpen>] 
module Shared =

    let instance (m:MethodBase) = not m.IsStatic
    let isVoid (m:MethodBase) = (m :?> MethodInfo).ReturnType = typeof<Void>
    let iff b v = if b(v) then Some v else None 
    let (|SourceFile|_|)     = iff (fun (f:string) -> IO.Path.GetExtension(f).ToLower() = ".fs")
    let (|ScriptFile|_|)     = iff (fun (f:string) -> IO.Path.GetExtension(f).ToLower() = ".fsx")
    let (|Library|_|)        = iff (fun (f:string) -> IO.Path.GetExtension(f).ToLower() = ".dll")
    let (|IsRefParam|_|)     = iff (fun (p:ParameterInfo) -> p.ParameterType.IsByRef)
    let (|IsGenericParam|_|) = iff (fun (p:ParameterInfo) -> p.ParameterType.IsGenericType)
    let (|IsStaticProp|_|)   = iff (fun (p:PropertyInfo) -> p.GetGetMethod().IsStatic )
    let (|IsConstructor|_|)  = iff (fun (m:MethodBase) -> m.MemberType = MemberTypes.Constructor)
    let (|IsStatic|_|)       = iff (fun (m:MethodBase) -> m.IsStatic)
    let (|HasParams|_|)      = iff (fun (m:MethodBase) -> m.GetParameters().Length <> 0)
    let (|IsInstanceVoid|_|) = iff (fun (m:MethodBase) -> m |> instance && m |> isVoid)
    let (|IsGeneric|_|)      = iff (fun (t:Type) -> t.IsGenericType || t.Name.Contains("`"))
    let (|HasGenericName|_|) = function
            | IsGeneric t -> Some t
            | t when t.FullName |> isNull -> Some t
            | t when t.FullName = "T[]" -> Some t
            | _ -> None
    let fmt format = sprintf format
    let trimTo (char:string) (input:string) = if input.Contains(char) then input.Substring(0, input.IndexOf(char)) else input
    let kill (char:string) (input:string) = input.Replace(char, "")
    let replace (char:string) (replaceWith:string) (input:string) = input.Replace(char, replaceWith)
    let trimGeneric = trimTo "`"
    let tickEscape s = "'" + s
    let tick s = s + "'"
    let safeName = (kill "&" >> kill "*") >> replace "+" "."
    let lcaseFirstLetter = function | "" -> "" | s -> s.Substring(0,1).ToLower() + s.Substring(1)
    let name t = (t:Type).Name
    let safeTypeName t = sprintf "%s.%s" (t:Type).Namespace t.Name
    let nonGenericName type' = (type':Type).Name |> trimGeneric
    let fullName type' = (type':Type).FullName
    let methName = function | IsConstructor _ -> "new" | m -> m.Name |> lcaseFirstLetter
    let naughtyNames = [| "val"; "yield"; "use"; "type"; "to"; "then"; "select"; "rec"; 
                        "open"; "namespace"; "module"; "match"; "inline"; "inherit";
                        "function"; "func"; "params"; "end"; "done"; "begin"; "assert"; 
                        "and"; "or"; "not"; "with" |]
    let isNaughty name = naughtyNames |> Array.contains name
    let cleanName name = if name |> isNaughty then tick name else name
    let overloadName escapeName (prevOrig,prevName) name = 
        if name = prevOrig then prevName |> escapeName  else name |> cleanName
    let nameOverloads (escape:string -> string) (getName:'a -> string) (prev,acc) (element:'a) =
        let origName = element |> getName
        let finalName = overloadName escape prev origName
        ((origName, finalName), acc @ [(finalName, element)])
    let overloadAcc = (("",""), [])


module private Type' =  

    [<AutoOpen>] 
    module private shh =
        let complianceAttributes m = (m:MethodInfo).GetCustomAttributes<System.CLSCompliantAttribute>() |> Seq.toList
        let isClsCompliant m =
            match m |> complianceAttributes with
            | []   -> true
            | atts -> atts |> List.fold (fun acc a -> acc && a.IsCompliant) true
        let getMethods t = (t:Type).GetMethods() |> Array.filter isClsCompliant
        let isGetterOrSetter m = (m:MethodBase).Name.StartsWith("get_") || m.Name.StartsWith("set_")
        let isMethod = not << isGetterOrSetter
        let noProps = List.filter isMethod
        let toMethodBase = Seq.cast<MethodBase>
        let typeMethods = getMethods >> toMethodBase
        let sortByName = Seq.sortBy methName >> Seq.toList
        let allMethods = typeMethods >> sortByName
        let methods = allMethods >> noProps
        let customEscape escape methods =
            let overload = nameOverloads escape methName
            methods |> List.fold overload overloadAcc |> snd
        let escapeNames (config:Config) = customEscape config.NameOverload

    let methods (config:Config) t = t |> (methods >> escapeNames config)
    let constructors (t:Type) = t.GetConstructors()


module private Namespace =
    
    [<AutoOpen>] 
    module private shh =
        let assemblies () = AppDomain.CurrentDomain.GetAssemblies()
        let isIn namespace' type' = (type':Type).IsClass && type'.IsPublic && not (type'.IsAbstract) && type'.Namespace = namespace'
        let isTypeName namespace' type' = (type':Type).FullName = namespace'
        let matches namespace' type' = type' |> isIn namespace' || type' |> isTypeName namespace'
        let forNamespace namespace' = Seq.filter (namespace' |> matches)
        let types' ass = (ass:Assembly).GetTypes()
        let typesIn namespace' = types' >> forNamespace namespace'
        let findTypesIn namespace' = Seq.collect <| typesIn namespace'
        let findNames = Seq.map fullName >> Seq.toList
        let genericArgs (type':Type) : (string * int) =
            let genericArgCount = function
                | IsGeneric t -> t.GetGenericTypeDefinition().GetGenericArguments().Length
                | _ ->  0
            (type' |> nonGenericName, type' |> genericArgCount)
        let wrappedNamespaces (escape:string -> string) (types : Type seq) =
            let overload = nameOverloads escape (fun t -> (t:Type).Name |> trimGeneric)
            types |> Seq.sortBy genericArgs |> Seq.fold overload overloadAcc |> snd
            
    let types namespace' = assemblies() |> findTypesIn namespace'
    let overloadedTypes (config:Config) namespace' = namespace' |> (types >> wrappedNamespaces config.NameOverload)
    let typeNames namespace' = namespace' |> (types >> findNames)


module private Generate =

    [<AutoOpen>]
    module private utility =

        let (||>) s sb = (sb:StringBuilder).AppendLine s |> ignore
        let (++) x y = x + y
        let write writeTo = 
            let sb = new StringBuilder()
            writeTo sb
            sb.ToString()
        
    [<AutoOpen>]
    module private generic =

        let typeDef = function | t when (t:Type).IsGenericType -> t.GetGenericTypeDefinition() | t -> t
        let args t = (t:Type).GetGenericArguments()
        let paramConstraints t = (t:Type).GetGenericParameterConstraints()
        let typeArgs t = 
            (t:Type) 
            |> (typeDef >> args)
            |> Seq.map (name >> tickEscape)
            |> String.concat ","
        let typeConstraints t = (t:Type) |> (typeDef >> args) |> Array.map paramConstraints
        let typeNameWithContraints t (name:string) = 
            let constraints = ""
            let array = if (name.EndsWith("[]")) then "[]" else "" 
            sprintf "%s<%s%s>%s" (name |> trimGeneric) (t |> typeArgs) constraints array
        let typeName t name = sprintf "%s<%s>" (name |> trimGeneric) (t |> typeArgs)
        let typeFullName t = typeName t t.FullName

    [<AutoOpen>]
    module private type' =        
        
        let fullname = function
            | IsGeneric t -> t |> generic.typeFullName
            | t -> t.FullName
        let name  = function
            | IsGeneric t -> t.Name |> trimGeneric
            | t -> t.Name        
        let isEquatable (t:Type) = (t |> safeTypeName) = "System.Collections.Generic.IEqualityComparer`1"
        let nameOfGenericParam t = t |> (safeTypeName >> generic.typeNameWithContraints t)
        let nameOfTypeParam = name >> (safeName >> tickEscape)
        let fullTypeName = function 
            | HasGenericName t -> 
                match t with
                | IsGeneric t -> t |> nameOfGenericParam
                | t           -> t |> nameOfTypeParam
            | t -> t.FullName
        let isBool p = (p:PropertyInfo).PropertyType = typeof<bool>
        let boolProps (t:Type) = t.GetProperties() |> Array.filter isBool
        let patt = function
            | IsStaticProp p -> fmt "    let (|%s|_|) = if %s.%s then Some () else None" p.Name (p.DeclaringType |> fullname) p.Name 
            | p ->              fmt "    let (|%s|_|) this = if (this:%s).%s then Some this else None" p.Name (p.DeclaringType |> fullname) p.Name
        let activePatterns (t:Type) (write:StringBuilder) = 
            let write s = s ||> write
            let writePatterns = Seq.map (patt >> write)
            t |> (boolProps >> writePatterns) |> ignore

    [<AutoOpen>]
    module private param' =
          
        let typeName (p:ParameterInfo) = p.ParameterType |> fullTypeName |> safeName
        let name (p:ParameterInfo) = p.Name |> cleanName
        let call = function
            | IsRefParam p -> sprintf "ref(%s)" (p |> name)
            | p            -> p |> name
        let argumentName p = sprintf "(%s:%s)" (p |> name) (p |> typeName)
        let map (map:ParameterInfo -> string) concatWith (m:MethodBase) =  
            m.GetParameters() |> Array.map map |> String.concat concatWith
        let curriedArgs  = function
            | HasParams m -> m |> map argumentName " "
            | IsStatic _ -> "() "
            | _ -> ""
        let callArgs = map call ", "
             
    [<AutoOpen>]
    module private method' =

        let constructorCall t = "", ""
        let staticCall t = "", t |> type'.fullname
        let curriedCall t = sprintf "fun (this:%s) -> " (t |> type'.fullname), "this"
        let memberCall = function
            | IsConstructor _ -> constructorCall
            | IsStatic _      -> staticCall
            | _               -> curriedCall
        let paramsSpace = function HasParams _ -> " " | _ -> ""
        let methodReturn = function IsInstanceVoid _ -> "; this" | _ -> ""
        let methodDeclaration t write ((name, m):string * MethodBase) =
                let call, instName = memberCall m t
                let sig'    = fmt "    let %s " name
                let params' = fmt "%s" (m |> curriedArgs) 
                let eq      = fmt "%s= " (m |> paramsSpace)
                let ref'    = fmt "%s.%s" instName m.Name
                let args    = fmt "(%s)%s" (m |> callArgs) (m |> methodReturn)

                sig' ++ params' ++ eq ++ call ++ ref' ++ args ||> write

        let curried config (moduleName, t) write =
            fmt "/// Autogenerated curry-wrapper for %s\r\nmodule %s =" (t |> type'.fullname) moduleName ||> write
            let writeMethods = methodDeclaration t write
            t |> Type'.methods config |> List.map writeMethods |> ignore
            sprintf "" ||> write

    let type' config t = t |> (curried config >> write)

    [<AutoOpen>]
    module private namespace' =

        let namespaceModule config namespace' write =
            let header namespace' =
                sprintf "namespace %s\r\n\r\n" (namespace' |> trimGeneric |> config.CurriedNamespace) ||> write
                namespace'
            let types namespace' = Namespace.overloadedTypes config namespace'
            let bodies types = 
                for t in types do curried config t write
                types
            let patterns types = for (moduleName, type') in types do activePatterns type' write
            namespace' |> (header >> types >> bodies >> patterns) 

    let namespace' config = namespaceModule config >> write


/// Creates curryable wrappers for POCO's in a given namespace or assembly
module Curry =

    /// Default configuration for code generation, allows customization
    let DefaultConfig = 
        { From = "System.Collections.Generic" 
          To   = "stdout" 
          NameOverload   = fun name -> name + "'"
          CurriedNamespace = fun namespace' -> namespace' + ".Curried" }

    [<AutoOpen>]
    module private shh =
        let load = function
            | Library path -> 
                query { for t in Assembly.LoadFrom(path).GetTypes() do
                        groupBy t.Namespace into g
                        select (if g.Key = null then "NO_NAMESPACE" else g.Key) } |> Seq.toList
            | from' -> [ from' ]
        let generate config = 
            let generation = Generate.namespace' config
            (List.map generation) >> String.concat ""
        let formatReference = 
            IO.Path.GetFileName >> sprintf """#r "%s" """
        let generateReferences = function
            | Library path -> 
                Assembly.LoadFrom(path).GetReferencedAssemblies()                 
                |> Array.map (fun referencedAssembly -> referencedAssembly.FullName) 
                |> Array.distinct
                |> Array.map formatReference
                |> String.concat "\r\n"
                |> function | "" -> "" | txt -> txt + (String.replicate 3 "\r\n")
            | from' -> ""
        let write referencesText typesText = function
            | SourceFile file ->
                    System.IO.File.WriteAllText (file, typesText)
                    sprintf "Curried output written to: %s" file
            | ScriptFile file ->
                    System.IO.File.WriteAllText (file, referencesText + typesText)
                    sprintf "Curried output written to: %s" file
            | _ -> typesText

    /// Generates curryable wrappers from the provided configuration
    let up' (config:Config) = 
        let namespaces = load config.From
        let typesText = namespaces |> generate config
        let referencesText = generateReferences config.From
        write referencesText typesText config.To

    /// Generates curryable wrappers to the provided location from a given library path or namespace/type name
    let up (to':string) (from':string) = up' { DefaultConfig with To = to'; From = from' }