open System

open System.Collections

open System.IO

open System.Text

open Microsoft.Build.Framework

open Microsoft.Build.Utilities

type WriteCodeFragment() as this =

inherit Task()

let mutable _outputDirectory: ITaskItem MaybeNull = null

let mutable _outputFile: ITaskItem MaybeNull = null

let mutable _language: string = ""

let mutable _assemblyAttributes: ITaskItem[] = [||]

let failTask fmt =

Printf.ksprintf

(fun msg ->

this.Log.LogError msg

raise TaskFailed)

fmt

static let escapeString (str: string) =

let sb =

str.ToCharArray()

|> Seq.fold

(fun (sb: StringBuilder) (c: char) ->

match c with

| '\n'

| '\u2028'

| '\u2028' -> sb.Append("\\n")

| '\r' -> sb.Append("\\r")

| '\t' -> sb.Append("\\t")

| '\'' -> sb.Append("\\'")

| '\\' -> sb.Append("\\\\")

| '"' -> sb.Append("\\\"")

| '\u0000' -> sb.Append("\\0")

| _ -> sb.Append(c))

(StringBuilder().Append("\""))

sb.Append("\"").ToString()

member _.GenerateAttribute(item: ITaskItem, language: string) =

let attributeName = item.ItemSpec

let args =

// mimicking the behavior from https://github.com/Microsoft/msbuild/blob/70ce7e9ccb891b63f0859f1f7f0b955693ed3742/src/Tasks/WriteCodeFragment.cs#L355-L415

// Split parameters into unnamed positional (e.g., key is "_Parameter1", etc.) and proper named parameters.

let customMetadata = item.CloneCustomMetadata()

let parameterPairs =

// normalize everything to strings

seq { for entry in customMetadata -> entry :?> DictionaryEntry }

|> Seq.toList

|> List.map (fun entry ->

let key = entry.Key :?> string

let value =

match entry.Value with

| null -> "null"

| :? string as value -> escapeString value

| value -> value.ToString()

(key, value))

let orderedParameters, namedParameters =

parameterPairs |> List.partition (fun (key, _) -> key.StartsWith("_Parameter"))

let orderedParametersWithIndex =

orderedParameters

|> List.map (fun (key, value) ->

let indexString = key.Substring("_Parameter".Length)

match Int32.TryParse indexString with

| (true, index) -> (index, value)

| (false, _) -> failTask "Unable to parse '%s' as an index" indexString)

|> List.sortBy fst

// assign ordered parameters to array

let orderedParametersArray =

if List.isEmpty orderedParametersWithIndex then

[||]

else

Array.create (List.last orderedParametersWithIndex |> fst) "null"

List.iter (fun (index, value) -> orderedParametersArray.[index - 1] <- value) orderedParametersWithIndex

// construct ordered parameter lists

let combinedOrderedParameters = String.Join(", ", orderedParametersArray)

let combinedNamedParameters =

String.Join(", ", List.map (fun (key, value) -> sprintf "%s = %s" key value) namedParameters)

// construct the final argument string; positional arguments followed by named

match (combinedOrderedParameters.Length, combinedNamedParameters.Length) with

| (0, 0) -> "" // no arguments

| (0, _) -> combinedNamedParameters // only named arguments

| (_, 0) -> combinedOrderedParameters // only positional arguments

| (_, _) -> combinedOrderedParameters + ", " + combinedNamedParameters // both positional and named arguments

match language.ToLowerInvariant() with

| "f#" -> sprintf "[<assembly: %s(%s)>]" attributeName args

| "c#" -> sprintf "[assembly: %s(%s)]" attributeName args

| "vb" -> sprintf "<Assembly: %s(%s)>" attributeName args

| _ -> failTask "Language name must be one of F#, C# or VB"

// adding this property to maintain API equivalence with the MSBuild task

member _.Language

with get () = _language

and set (value) = _language <- value

member _.AssemblyAttributes

with get () = _assemblyAttributes

and set (value) = _assemblyAttributes <- value

member _.OutputDirectory

with get () = _outputDirectory

and set (value) = _outputDirectory <- value

[<Output>]

member _.OutputFile

with get () = _outputFile

and set (value) = _outputFile <- value

override this.Execute() =

try

match _outputFile with

| Null -> failTask "Output location must be specified"

| NonNull outputFile ->

let boilerplate =

match _language.ToLowerInvariant() with

| "f#" ->

"// <auto-generated>\n// Generated by the FSharp WriteCodeFragment class.\n// </auto-generated>\nnamespace FSharp\n\nopen System\nopen System.Reflection\n"

| "c#" ->

"// <auto-generated>\n// Generated by the FSharp WriteCodeFragment class.\n// </auto-generated>\n\nusing System;\nusing System.Reflection;"

| "vb" ->

"'------------------------------------------------------------------------------\n' <auto-generated>\n' Generated by the FSharp WriteCodeFragment class.\n' </auto-generated>\n'------------------------------------------------------------------------------\n\nOption Strict Off\nOption Explicit On\n\nImports System\nImports System.Reflection"

| _ -> failTask "Language name must be one of F#, C# or VB"

let sb = StringBuilder().AppendLine(boilerplate).AppendLine()

let code =

(sb, _assemblyAttributes)

||> Array.fold (fun (sb: StringBuilder) (item: ITaskItem) ->

sb.AppendLine(this.GenerateAttribute(item, _language.ToLowerInvariant())))

if _language.ToLowerInvariant() = "f#" then

code.AppendLine("do()") |> ignore

let fileName = outputFile.ItemSpec

let outputFileItem =

match _outputDirectory with

| Null -> outputFile

| NonNull outputDirectory ->

if Path.IsPathRooted(fileName) then

outputFile

else

TaskItem(Path.Combine(outputDirectory.ItemSpec, fileName)) :> ITaskItem

let codeText = code.ToString()

File.WriteAllText(fileName, codeText)

_outputFile <- outputFileItem

not this.Log.HasLoggedErrors

with TaskFailed ->

false