Imports System.IO
Imports System.Net
Imports Newtonsoft.Json
Imports Newtonsoft.Json.Linq

Module Module1

    ' The authentication key (API Key).
    ' Get your own by registering at https://app.pdf.co/documentation/api
    Const API_KEY As String = "***********************************"

    ' HTML template
    Dim template As String = File.ReadAllText(".\invoice_template.html")
    ' Data to fill the template
    Dim templateData As String = File.ReadAllText(".\invoice_data.json")
    ' Destination PDF file name
    Const DestinationFile As String = ".\result.pdf"

    Sub Main()

        ' Create standard .NET web client instance
        Dim webClient As WebClient = New WebClient()

        ' Set API Key
        webClient.Headers.Add("x-api-key", API_KEY)

        Try
            ' Prepare URL for HTML to PDF API call
            Dim request As String = Uri.EscapeUriString(String.Format(
                "https://api.pdf.co/v1/pdf/convert/from/html?name={0}",
                Path.GetFileName(DestinationFile)))

            ' Prepare request body in JSON format
            Dim jsonObject As JObject = New JObject(
                New JProperty("html", template),
                New JProperty("templateData", templateData))

            webClient.Headers.Add("Content-Type", "application/json")

            ' Execute request
            Dim response As String = webClient.UploadString(request, jsonObject.ToString())

            ' Parse JSON response
            Dim json As JObject = JObject.Parse(response)

            If json("error").ToObject(Of Boolean) = False Then

                ' Get URL of generated PDF file
                Dim resultFileUrl As String = json("url").ToString()

                webClient.Headers.Remove("Content-Type") ' remove the header required for only the previous request

                ' Download the PDF file
                webClient.DownloadFile(resultFileUrl, DestinationFile)

                Console.WriteLine("Generated PDF document saved as ""{0}"" file.", DestinationFile)

            End If

        Catch ex As WebException
            Console.WriteLine(ex.ToString())
        End Try

        webClient.Dispose()


        Console.WriteLine()
        Console.WriteLine("Press any key...")
        Console.ReadKey()

    End Sub

End Module