Imports System.IO
Imports System.Net
Imports System.Net.Http

Imports ModpackUpdater.Model

Public Class ModpackInstaller

    Public Event InstallProgessUpdated(result As UpdateCheckResult, processedSyncs As Integer)
    Public Event CheckingProgressUpdated(toCheck As Integer, processed As Integer)

    Private ReadOnly updateConfig As ModpackConfig
    Private ReadOnly localPath As String
    Private httpClient As New HttpClient

    Public Sub New(updateConfig As ModpackConfig, localPath As String)
        Me.updateConfig = updateConfig
        Me.localPath = localPath
    End Sub

    Protected Overrides Sub Finalize()
        httpClient.Dispose()
        MyBase.Finalize()
    End Sub

    Private Async Function DownloadUpdateInfos() As Task(Of UpdateInfos)
        Dim content As String = Await httpClient.GetStringAsync(updateConfig.UpdateUrl)
        Return UpdateInfos.Parse(content)
    End Function

    Public Async Function CheckForUpdates(ignoreRevmoedFiles As Boolean) As Task(Of UpdateCheckResult)
        Dim infos As UpdateInfos = Await DownloadUpdateInfos()
        Dim result As New UpdateCheckResult

        If infos IsNot Nothing AndAlso infos.Updates.Any Then
            Dim updatesOrderes = infos.Updates.OrderByDescending(Function(n) n.Version)
            result.LatestVersion = updatesOrderes.First.Version

            If ModpackInfo.HasModpackInfo(localPath) Then
                Dim modpackInfo As ModpackInfo = ModpackInfo.Load(localPath)
                result.CurrentVersion = modpackInfo.Version

                Dim checkingVersionIndex As Integer = 0
                Dim checkingVersion As UpdateInfo = updatesOrderes(checkingVersionIndex)

                Do While checkingVersion IsNot Nothing AndAlso checkingVersion.Version > result.CurrentVersion
                    Dim actionsToAdd As New List(Of UpdateAction)

                    For Each action In checkingVersion.Actions
                        If Not result.UpdateActions.Any(Function(n) n.DestPath = action.DestPath) Then
                            actionsToAdd.Add(action)
                        End If
                    Next

                    result.UpdateActions.InsertRange(0, actionsToAdd)

                    checkingVersionIndex += 1
                    checkingVersion = updatesOrderes.ElementAtOrDefault(checkingVersionIndex)
                Loop
            End If
        End If

        Return result
    End Function

    Public Async Function InstallUpdates(checkResult As UpdateCheckResult) As Task(Of Boolean?)
        Dim modpackInfo As ModpackInfo

        If ModpackInfo.HasModpackInfo(localPath) Then
            modpackInfo = ModpackInfo.Load(localPath)
        Else
            modpackInfo = New ModpackInfo
        End If

        Dim processed As Integer = 0
        For Each action As UpdateAction In checkResult.UpdateActions
            Dim destFilePath As String = Path.Combine(localPath, action.DestPath)

            Select Case action.Type
                Case UpdateActionType.Update
                    Directory.CreateDirectory(Path.GetDirectoryName(destFilePath))
                    Dim sRemote As Stream = Await httpClient.GetStreamAsync(action.DownloadUrl)
                    Dim fs As New FileStream(destFilePath, FileMode.Create, FileAccess.ReadWrite)
                    Await sRemote.CopyToAsync(fs)
                    sRemote.Close()
                    fs.Close()
                Case UpdateActionType.Delete
                    If action.IsDirectory Then
                        If Directory.Exists(destFilePath) Then
                            Directory.Delete(destFilePath, True)
                        End If
                    Else
                        If File.Exists(destFilePath) Then
                            File.Delete(destFilePath)
                        End If
                    End If
                Case UpdateActionType.Copy
                    Dim srcFilePath As String = Path.Combine(localPath, action.SrcPath)
                    If File.Exists(srcFilePath) Then
                        Directory.CreateDirectory(Path.GetDirectoryName(destFilePath))
                        File.Copy(srcFilePath, destFilePath, True)
                    End If
                Case UpdateActionType.Move
                    Dim srcFilePath As String = Path.Combine(localPath, action.SrcPath)
                    If File.Exists(srcFilePath) Then
                        Directory.CreateDirectory(Path.GetDirectoryName(destFilePath))
                        File.Move(srcFilePath, destFilePath, True)
                    End If
            End Select

            processed += 1
            RaiseEvent InstallProgessUpdated(checkResult, processed)
        Next

        modpackInfo.Version = checkResult.LatestVersion
        modpackInfo.Save(localPath)

        Return True
    End Function

End Class