module Fable.Compiler.ProjectParser

open Fable.Compiler.Platform
open System.Collections.Generic
open System.Text.RegularExpressions

type ReferenceType =
    | ProjectReference of string
    | PackageReference of string * string

let (|Regex|_|) (pattern: string) (input: string) =
    let m = Regex.Match(input, pattern)

    if m.Success then
        Some [ for x in m.Groups -> x.Value ]
    else
        None

let getXmlWithoutComments xml =
    Regex.Replace(xml, @"<!--[\s\S]*?-->", "")

let getXmlTagContents tag xml =
    let pattern = $"""<%s{tag}[^>]*>([^<]*)<\/%s{tag}[^>]*>"""
    Regex.Matches(xml, pattern) |> Seq.map (fun m -> m.Groups[1].Value.Trim())

let getXmlTagContentsFirstOrDefault tag defaultValue xml =
    defaultArg (getXmlTagContents tag xml |> Seq.tryHead) defaultValue

let getXmlTagAttributes1 tag attr1 xml =
    let pattern = $"""<%s{tag}\s+[^>]*%s{attr1}\s*=\s*("[^"]*|'[^']*)"""

    Regex.Matches(xml, pattern)
    |> Seq.map (fun m -> m.Groups[1].Value.TrimStart('"').TrimStart(''').Trim())

let getXmlTagAttributes2 tag attr1 attr2 xml =
    let pattern =
        $"""<%s{tag}\s+[^>]*%s{attr1}\s*=\s*("[^"]*|'[^']*)[^>]*%s{attr2}\s*=\s*("[^"]*|'[^']*)"""

    Regex.Matches(xml, pattern)
    |> Seq.map (fun m ->
        m.Groups[1].Value.TrimStart('"').TrimStart(''').Trim(), m.Groups[2].Value.TrimStart('"').TrimStart(''').Trim()
    )

let isSystemPackage (pkgName: string) =
    pkgName.StartsWith("System.")
    || pkgName.StartsWith("Microsoft.")
    || pkgName.StartsWith("runtime.")
    || pkgName = "NETStandard.Library"
    || pkgName = "FSharp.Core"
    || pkgName = "Fable.Core"

let parsePackageSpec nuspecPath =
    // get package spec xml
    let packageXml = readAllText nuspecPath
    // get package dependencies
    let references =
        packageXml
        |> getXmlWithoutComments
        |> getXmlTagAttributes2 "dependency" "id" "version"
        |> Seq.map PackageReference
        |> Seq.toArray

    references

let resolvePackage (pkgName, pkgVersion) =
    if not (isSystemPackage pkgName) then
        let homePath = getHomePath().Replace('\\', '/')
        let nugetPath = $".nuget/packages/%s{pkgName}/%s{pkgVersion}"
        let pkgPath = Path.Combine(homePath, nugetPath.ToLowerInvariant())
        let libPath = Path.Combine(pkgPath, "lib")
        let fablePath = Path.Combine(pkgPath, "fable")
        let binaryPaths = getDirFiles libPath ".dll"
        let nuspecPaths = getDirFiles pkgPath ".nuspec"
        let fsprojPaths = getDirFiles fablePath ".fsproj"

        if Array.isEmpty nuspecPaths then
            printfn "ERROR: Cannot find package %s" pkgPath

        let binaryOpt = binaryPaths |> Array.tryLast

        let dependOpt = nuspecPaths |> Array.tryLast |> Option.map parsePackageSpec

        let fsprojOpt = fsprojPaths |> Array.tryLast |> Option.map ProjectReference

        let pkgRefs, dllPaths =
            match binaryOpt, dependOpt, fsprojOpt with
            | _, _, Some projRef -> [| projRef |], [||]
            | Some dllRef, Some dependencies, _ -> dependencies, [| dllRef |]
            | _, _, _ -> [||], [||]

        pkgRefs, dllPaths
    else
        [||], [||]

let parseCompilerOptions projectXml =
    // get project settings,
    let target = projectXml |> getXmlTagContentsFirstOrDefault "OutputType" ""

    let langVersion = projectXml |> getXmlTagContentsFirstOrDefault "LangVersion" ""

    let warnLevel = projectXml |> getXmlTagContentsFirstOrDefault "WarningLevel" ""

    let treatWarningsAsErrors =
        projectXml |> getXmlTagContentsFirstOrDefault "TreatWarningsAsErrors" ""

    // get conditional defines
    let defines =
        projectXml
        |> getXmlTagContents "DefineConstants"
        |> Seq.collect (fun s -> s.Split(';'))
        |> Seq.append
            [
                "FABLE_COMPILER"
                "FABLE_COMPILER_4"
                "FABLE_COMPILER_JAVASCRIPT"
                "NPM_PACKAGE_FABLE_COMPILER_JAVASCRIPT"
            ]
        |> Seq.map (fun s -> s.Trim())
        |> Seq.distinct
        |> Seq.except [ "$(DefineConstants)"; "" ]
        |> Seq.toArray

    // get disabled warnings
    let nowarns =
        projectXml
        |> getXmlTagContents "NoWarn"
        |> Seq.collect (fun s -> s.Split(';'))
        |> Seq.map (fun s -> s.Trim())
        |> Seq.distinct
        |> Seq.except [ "$(NoWarn)"; "" ]
        |> Seq.toArray

    // get warnings as errors
    let warnAsErrors =
        projectXml
        |> getXmlTagContents "WarningsAsErrors"
        |> Seq.collect (fun s -> s.Split(';'))
        |> Seq.map (fun s -> s.Trim())
        |> Seq.distinct
        |> Seq.except [ "$(WarningsAsErrors)"; "" ]
        |> Seq.toArray

    // get other flags
    let otherFlags =
        projectXml
        |> getXmlTagContents "OtherFlags"
        |> Seq.collect (fun s -> s.Split(' '))
        |> Seq.map (fun s -> s.Trim())
        |> Seq.distinct
        |> Seq.except [ "$(OtherFlags)"; "" ]
        |> Seq.toArray

    let otherOptions =
        [|
            if target.Length > 0 then
                yield "--target:" + target
            if langVersion.Length > 0 then
                yield "--langversion:" + langVersion
            if warnLevel.Length > 0 then
                yield "--warn:" + warnLevel
            if treatWarningsAsErrors = "true" then
                yield "--warnaserror+"
            for d in defines do
                yield "-d:" + d
            for n in nowarns do
                yield "--nowarn:" + n
            for e in warnAsErrors do
                yield "--warnaserror:" + e
            for o in otherFlags do
                yield o
        |]

    otherOptions

let makeFullPath projectFileDir (path: string) =
    let path = path.Replace('\\', '/')

    let isAbsolutePath (path: string) =
        path.StartsWith('/') || path.IndexOf(':') = 1

    if isAbsolutePath path then
        path
    else
        Path.Combine(projectFileDir, path)
    |> normalizeFullPath

let parseProjectScript projectFilePath =
    let projectXml = readAllText projectFilePath
    let projectDir = Path.GetDirectoryName projectFilePath

    let dllRefs, srcFiles =
        (([||], [||]), projectXml.Split('\n'))
        ||> Array.fold (fun (dllRefs, srcFiles) line ->
            match line.Trim() with
            | Regex @"^#r\s+""(.*?)""$" [ _; path ] when not (path.EndsWith("Fable.Core.dll")) ->
                Array.append [| Path.Combine(projectDir, path) |] dllRefs, srcFiles
            | Regex @"^#load\s+""(.*?)""$" [ _; path ] ->
                dllRefs, Array.append [| Path.Combine(projectDir, path) |] srcFiles
            | _ -> dllRefs, srcFiles
        )

    let projectRefs = [||]

    let sourceFiles = Array.append srcFiles [| Path.GetFileName projectFilePath |]

    let otherOptions =
        [|
            "--define:FABLE_COMPILER"
            "--define:FABLE_COMPILER_4"
            "--define:FABLE_COMPILER_JAVASCRIPT"
            "--define:NPM_PACKAGE_FABLE_COMPILER_JAVASCRIPT"
        |]

    (projectRefs, dllRefs, sourceFiles, otherOptions)

let parseProjectFile projectFilePath =
    // get project xml without any comments
    let projectXml = readAllText projectFilePath |> getXmlWithoutComments
    let projectDir = Path.GetDirectoryName projectFilePath

    // get package references
    let packageRefs =
        projectXml
        |> getXmlTagAttributes2 "PackageReference" "Include" "Version"
        |> Seq.map PackageReference
        |> Seq.toArray

    // get project references
    let projectRefs =
        projectXml
        |> getXmlTagAttributes1 "ProjectReference" "Include"
        |> Seq.map (makeFullPath projectDir >> ProjectReference)
        |> Seq.toArray

    // replace some variables
    let projectXml = projectXml.Replace("$(MSBuildProjectDirectory)", ".")

    let sourceRoot =
        projectXml |> getXmlTagContentsFirstOrDefault "FSharpSourcesRoot" ""

    let projectXml =
        projectXml.Replace("$(FSharpSourcesRoot)", sourceRoot.Replace('\\', '/'))

    let yaccOutput =
        projectXml |> getXmlTagContentsFirstOrDefault "FsYaccOutputFolder" ""

    let projectXml =
        projectXml.Replace("$(FsYaccOutputFolder)", yaccOutput.Replace('\\', '/'))

    // get source files
    let sourceFiles =
        projectXml
        |> getXmlTagAttributes1 "Compile" "Include"
        |> Seq.map (makeFullPath projectDir)
        |> Seq.collect getGlobFiles
        |> Seq.toArray

    let dllRefs = [||]
    let projectRefs = Array.append projectRefs packageRefs
    let otherOptions = parseCompilerOptions projectXml
    (projectRefs, dllRefs, sourceFiles, otherOptions)

let makeHashSetIgnoreCase () =
    let equalityComparerIgnoreCase =
        { new IEqualityComparer<string> with
            member _.Equals(x, y) =
                x.ToLowerInvariant() = y.ToLowerInvariant()

            member _.GetHashCode(x) = hash (x.ToLowerInvariant())
        }

    HashSet<string>(equalityComparerIgnoreCase)

let dedupReferences (refSet: HashSet<string>) references =
    let refName =
        function
        | ProjectReference path -> path
        | PackageReference(pkgName, pkgVersion) -> pkgName + "," + pkgVersion

    let newRefs = references |> Array.filter (refName >> refSet.Contains >> not)
    refSet.UnionWith(newRefs |> Array.map refName)
    newRefs

let parseProject projectFilePath =

    let rec parseProject (refSet: HashSet<string>) (projectRef: ReferenceType) =
        let projectRefs, dllPaths, sourcePaths, otherOptions =
            match projectRef with
            | ProjectReference path ->
                if path.EndsWith("Fable.Core.fsproj") then
                    [||], [||], [||], [||]
                elif path.EndsWith(".fsx") then
                    parseProjectScript path
                else
                    parseProjectFile path
            | PackageReference(pkgName, pkgVersion) ->
                let pkgRefs, dllPaths = resolvePackage (pkgName, pkgVersion)
                pkgRefs, dllPaths, [||], [||]

        // parse and combine all referenced projects into one big project
        let parseResult =
            projectRefs |> dedupReferences refSet |> Array.map (parseProject refSet)

        let dllPaths =
            dllPaths |> Array.append (parseResult |> Array.collect (fun (x, _, _) -> x))

        let sourcePaths =
            sourcePaths |> Array.append (parseResult |> Array.collect (fun (_, x, _) -> x))

        let otherOptions =
            otherOptions |> Array.append (parseResult |> Array.collect (fun (_, _, x) -> x))

        (dllPaths, sourcePaths, otherOptions)

    let refSet = makeHashSetIgnoreCase ()
    let projectRef = ProjectReference projectFilePath
    let dllPaths, sourcePaths, otherOptions = parseProject refSet projectRef

    (dllPaths |> Array.distinct, sourcePaths |> Array.distinct, otherOptions |> Array.distinct)
