Implemented adaptive fetching using IDEC extensions

tiifetch.tcl

@@ -154,7 +154,9 @@ proc getfile {url} {
     }
     https - http {
       set hs [::http::geturl $url -binary 1 -keepalive 1 -timeout 5000]
+      if {[::http::ncode $hs] eq "200"} {
         return [::http::data $hs]
+      } else {return {}}
     }
     default {return {}}
   }
@@ -211,16 +213,41 @@ proc fetchiidb {url echos dbfile dolog maxids} {
     set echos [split $echos "/,;"]
   }
   if {$dolog eq 1} {puts "Echos to fetch: $echos"}
-  # pass the echo list and fetch the message IDs
   set echos [lmap s $echos {string trim $s}]
+  # get the IDEC extended feature list
+  set featurelist ""
+  catch {set featurelist [getfile [string cat $url "/x/features"]]}
+  set featurelist [lmap s [split $featurelist \n] {string trim $s}]
+  set datalines ""
+  if {([lsearch $featurelist x/c] > -1 ) && ([lsearch $featurelist u/e] > -1)} {
+    # get message count in every echo of our choice  
+    set countdata [getfile [string cat $url "/x/c/" [join $echos "/"]]]
+    foreach cd $countdata {
+      set cdparts [split $cd :]
+      if {[llength $cdparts] > 1} {
+        set ename [lindex $cdparts 0]
+        set rcount [lindex $cdparts 1]
+        set lcount [msgdb eval {SELECT COUNT (DISTINCT `id`) FROM `msg` WHERE `echoname` = $ename;}]
+        # get the difference between remote and local counts
+        set diff [expr {$rcount - $lcount}]
+        if {$diff > 0} { # we have something to fetch
+          set localdata [getfile [string cat $url "/u/e/" $ename "/-$diff:$diff"]]
+          append datalines [string trim $localdata] \n
+        }
+      }
+    }
+
+  } else { # no extended feature support, pass the echo list and fetch the message IDs
     set echodata [getfile [string cat $url "/u/e/" [join $echos "/"]]]
+    set datalines [split $echodata \n]
+  }
   # iterate over the fetched data and fetch corresponding messages
   set curecho ""
-  set datalines [split $echodata "\n"]
   set echomap ""
   # build the map of lists of message IDs
   foreach line $datalines {
     set line [string trim $line]
+    if {$line ne ""} {
       # detect if the line is related to echo name or message ID 
       if {[string first "." $line] eq -1} { # message ID
         if {[string length $line] == 20} { # filter out invalid IDs
@@ -233,6 +260,7 @@ proc fetchiidb {url echos dbfile dolog maxids} {
         dict set echomap $curecho ""
       }
     }
+  }
   if {$dolog eq 1} {puts "Echomap built"}
   # pass the echo list and fetch the message IDs
   # now, process the map we've built