add functionality to respond to pings

bot.ps1

@@ -45,7 +45,7 @@ function Send-MatrixEvent {
 
     $response = Invoke-RestMethod @header_splat @http_splat
     if($response.event_id) {
-        Write-Output ('Event {0} sent to room {1}' -f $response.event_id,$RoomId)
+        Write-Host ('Event {0} sent to room {1}' -f $response.event_id,$RoomId)
     }
 }
 function Send-MatrixNotice {
@@ -56,15 +56,169 @@ function Send-MatrixNotice {
 
         [Parameter(Mandatory=$true)]
         [string]
-        $Message
+        $Body,
+
+        [Parameter(Mandatory=$false)]
+        [string]
+        $FormattedBody
     )
 
     $event = @{
         msgtype = 'm.notice'
-        body = $Message
+        body = $Body
-    } | ConvertTo-Json -Compress
-
-    Send-MatrixEvent -RoomId $RoomId -Event $event -EventType 'm.room.message'
     }
 
-Send-MatrixNotice -RoomId '!amKUIaaKdERatZsJgB:matrix.org' -Message ('asef :) {0}' -f (Get-Date))
+    if($FormattedBody) {
+        $event += @{
+            format = 'org.matrix.custom.html'
+            formatted_body = $FormattedBody
+        }
+    }
+
+    $event_json = $event | ConvertTo-Json -Compress
+
+    Send-MatrixEvent -RoomId $RoomId -Event $event_json -EventType 'm.room.message'
+}
+function Compare-Timestamps {
+    param (
+        [Parameter(Mandatory=$true)]
+        [Int64]
+        $OriginServerTs
+    )
+
+    $current_time = (Get-Date).ToUniversalTime()
+
+    #$OriginServerTs is milliseconds since 1970-01-01 (epoch time in milliseconds)
+    $original_time = Get-Date -Date ((Get-Date -Date '1970-01-01') + [timespan]::FromMilliseconds($OriginServerTs))
+
+    #return the difference
+    Write-Output ($current_time - $original_time)
+}
+function ConvertTo-HumanReadableTimespan {
+    param (
+        [parameter(Mandatory=$true)]
+        [timespan]
+        $TimeSpan
+    )
+
+    switch($TimeSpan) {
+        Default {
+            $output = '{0} days' -f [System.Math]::Round($TimeSpan.TotalDays, 2)
+        }
+        {$PSItem.TotalHours -lt 24} {
+            $output = '{0} h' -f [System.Math]::Round($TimeSpan.TotalHours, 2)
+        }
+        {$PSItem.TotalMinutes -lt 120} {
+            $output = '{0} min' -f [System.Math]::Round($TimeSpan.TotalMinutes, 2)
+        }
+        {$PSItem.TotalSeconds -lt 120} {
+            $output = '{0} s' -f [System.Math]::Round($TimeSpan.TotalSeconds, 2)
+        }
+        {$PSItem.TotalMilliseconds -lt 10000} {
+            $output = '{0} ms' -f [System.Math]::Round($TimeSpan.TotalMilliseconds, 0)
+        }
+    }
+
+    Write-Output $output
+}
+function Join-Pong {
+    param (
+        [Parameter(Mandatory=$true)]
+        [string]
+        $RoomId,
+
+        [Parameter(Mandatory=$true)]
+        [string]
+        $PingEventId,
+
+        [Parameter(Mandatory=$true)]
+        [string]
+        $SenderMxId,
+
+        [Parameter(Mandatory=$true)]
+        [string]
+        $ReadableTimespan,
+
+        [Parameter(Mandatory=$false)]
+        [string]
+        $Ball
+    )
+
+    if($Ball) {
+        $padded_ball = $Ball+' '
+    }
+
+    $body = '{0}: Pong! (ping {1}took {2} to arrive)' -f $SenderMxId,$padded_ball,$ReadableTimespan
+    $formatted_body  = '<a href=''https://matrix.to/#/{0}''>{0}</a>: Pong! ' -f $SenderMxId
+    $formatted_body += '(<a href="https://matrix.to/#/{0}/{1}">ping</a> {2}took {3} to arrive)' -f $RoomId,$PingEventId,$padded_ball,$ReadableTimespan
+
+    return @{
+        Body = $body
+        FormattedBody = $formatted_body
+    }
+}
+function Open-MatrixEvent {
+    param (
+        [Parameter(Mandatory=$true)]
+        $Event,
+
+        [Parameter(Mandatory=$true)]
+        $RoomId
+    )
+
+    #the "ball" is a string returned by the bot
+    if($Event.content.msgtype -eq 'm.text' -and $Event.content.body -match '!ping( (?<ball>.*))?') {
+        $difference = Compare-Timestamps -OriginServerTs $Event.origin_server_ts
+        $readable_timespan = ConvertTo-HumanReadableTimespan -TimeSpan $difference
+
+        #$bodies contains a hashtable with keys Body and FormattedBody
+        $bodies = Join-Pong -RoomId $RoomId -PingEventId $Event.event_id -SenderMxId $Event.sender -ReadableTimespan $readable_timespan -Ball $Matches.ball
+
+        Send-MatrixNotice -RoomId $RoomId @bodies
+    }
+}
+function Start-MatrixSync {
+    param (
+        [string]
+        $Token,
+
+        [int]
+        $Timeout = 30000
+    )
+
+    $uri = '{0}/_matrix/client/r0/sync?timeout={1}' -f $HomeServer,$Timeout
+    if($Token) {
+        $uri += '&since={0}' -f $Token
+    }
+
+    $header_splat = @{
+        Authentication = 'Bearer'
+        Token = $AccessToken
+        ContentType = 'application/json'
+    }
+    $http_splat = @{
+        Uri = $uri
+    }
+
+    $response = Invoke-RestMethod @header_splat @http_splat
+
+    #.PSObject.Properties because the rooms under .join are [NoteProperty]
+    $room_ids = $response.rooms.join.PSObject.Properties.Name
+    foreach($room_id in $room_ids) {
+        $events = $response.rooms.join.$room_id.timeline.events
+        foreach($event in $events) {
+            Open-MatrixEvent -Event $event -RoomId $room_id
+        }
+    }
+
+    Write-Output $response.next_batch
+}
+
+#Send-MatrixNotice -RoomId '!amKUIaaKdERatZsJgB:matrix.org' -Message ('asef :) {0}' -f (Get-Date))
+
+#start sync loop
+while($true) {
+    #use the token of the last sync
+    #initial token is $null
+    $token = Start-MatrixSync -Token $token
+}