; This asychronous download example code is adapted to OS4Depot where HTTP
; redirection is in place and must be adapted if the host site doesn't use
; HTTP redirection.
 
Global base, data$, count, done, host$
 
host$ = "www.os4depot.net"
 
base = {}
 
; Userdata, FilePort, Remote Archive, Bytes Received, Total Filesize
DimStr connections[30][2][1][1][1]
 
For Local c = 0 to 29
    connections[c][0] = ""
    connections[c][1] = c
    connections[c][2] = ""
    connections[c][3] = 0
    connections[c][4] = 0
Next
 
Function base:AllocateFindFilePort(userdata)
 
    Local c, available, found
 
    If userdata = nil ; Allocate File Port
       For c = 0 to 29
             If GetType(connections[c][0]) <> #LIGHTUSERDATA
                 available = True
                 Break
             EndIf
       Next
 
       ; If no connections available return Nil, maxconnections set in DimStr connections[]
       If available = False
           c = Nil
       EndIf
 
   Else ; Find File Port via userdata
 
      For c = 0 to 29
             If GetType(connections[c][0]) = #LIGHTUSERDATA
                 If connections[c][0] = userdata
                    found = True
                    Break
                EndIf
             EndIf
      Next
 
      If found = False
          c = Nil
      EndIf
    EndIf
 
    Return (c)
EndFunction
 
Function base:DownloadFile(server$, url$, downloadpath$, filename$, filesize)
 
    Local id = base:AllocateFindFilePort()
 
    Local data$, count, done
 
   connections[id][0] = OpenConnection(nil, server$, 80)
 
   SendData(connections[id][0], "GET " .. url$ .. " HTTP/1.0\r\n\r\n")
 
   ; This line here will not work if the site doesn't use redirection, you will need to
   ; adapt this accordingly.
   data$, count, done = ReceiveData(connections[id][0], #RECEIVEALL)
 
   ; Redirect
   If FindStr(data$,"302 Found") > -1
       CloseConnection(connections[id][0])
       redirection$ = MidStr(data$,FindStr(data$,"Location: "),StrLen(data$))
       redirection$ = MidStr(redirection$,10,FindStr(redirection$,"\n")-11)
 
       server$ = ReplaceStr(redirection$, "http://", "")
       server$ = MidStr(server$,0,FindStr(server$,"/"))
 
       connections[id][0] = OpenConnection(nil, server$, 80)
 
       SendData(connections[id][0], "GET " .. redirection$ .. " HTTP/1.0\r\n\r\n")
 
      data$ = nil
 
      ; Skip HTTP Headers
       While data$ = nil Or FindStr(data$,"Content-Type:") = -1
          data$, count, done = ReceiveData(connections[id][0], #RECEIVELINE)
         Wend
 
         data$, count, done = ReceiveData(connections[id][0], #RECEIVELINE) ; Skip blank line
 
   ; Adapt this for sites that don't use HTTP rdirection                    
   Else   
)
   EndIf
 
   ; Not Found
   If FindStr(data$,"404 Found") > -1
       Return(False)
 
   ; Found - Download it
   Else
 
      connections[id][1] = OpenFile(nil,downloadpath$ .. filename$, #MODE_READWRITE)
      connections[id][2] = filename$
      connections[id][4] = filesize
 
       Return(True)
   EndIf
EndFunction
 
Function base:BuildFile(userdata)   
   Local segment$
   segment$, count, done = ReceiveData(userdata.id, #RECEIVEBYTES, 65536) ; Read file data
 
   Local port = base:AllocateFindFilePort(userdata.id)
 
      WriteString(connections[port][1],segment$)
 
   connections[port][3] = connections[port][3] + StrLen(segment$)
 
   If connections[port][3] = connections[port][4] Then SaveToDisk(userdata.id,port)
EndFunction
 
Function base:Keyboard(msg)
   Switch msg.action
       Case "OnKeyDown"
          If msg.key = "ESC"
              End()
          EndIf
   EndSwitch
EndFunction
 
Function base_BuildFile(msg) base:BuildFile(msg) EndFunction
Function base_KeyboarD(msg) base:Keyboard(msg) EndFunction
 
InstallEventHandler({OnReceiveData = base_BuildFile, OnKeyDown = base_Keyboard})
 
debugprint("Asynchronous file download demo by Richard Lake (richard@lakemarketingandevents.co.uk)")
debugprint("\nWorks with sites like OS4Depot where HTTP Redirect is in place.")
debugprint("\nOne limitation in this demo is that you must know beforehand the filesize of each download in advance.")
debugprint("\nDownloading 3 files from OS4Depot asynchronously...")
 
success = base:DownloadFile(host$,"http://" .. host$ .. "/share/game/board/africa.lha","RAM:","africa.lha",297517)
success = base:DownloadFile(host$,"http://" .. host$ .. "/share/utility/misc/ipqalc.lha","RAM:","ipqalc.lha",114081)
success = base:DownloadFile(host$,"http://" .. host$ .. "/share/emulation/gamesystem/amiarcadia.lha","RAM:","amiarcadia.lha",3454033)
 
Function SaveToDisk(userdata,port)
      CloseConnection(userdata)
   CloseFile(connections[port][1])
 
   debugprint(connections[port][2] .. " saved to RAM:")
 
    connections[port][0] = ""
    connections[port][2] = ""
    connections[port][3] = 0
    connections[port][4] = 0
Endfunction
 
Repeat
    WaitEvent()
Forever