LUA HTTP Interface: Implementation of missing seeking funtionality when using...

LUA HTTP Interface: Implementation of missing seeking funtionality when using status.xml from the lua http interface.

Seeking is now possible with relative values instead of just absolute ones.
Also the time format as mentioned in the readme file is now recognized:
[+ or -][<int><H or h>:][<int><M or m or '>:][<int><nothing or S or s or ">]
Signed-off-by: Rémi Duraffort <ivoire@videolan.org>

share/lua/intf/modules/common.lua

@@ -86,13 +86,56 @@ function realpath(path)
     return string.gsub(string.gsub(string.gsub(string.gsub(path,"/%.%./[^/]+","/"),"/[^/]+/%.%./","/"),"/%./","/"),"//","/")
 end
 
+-- parse the time from a string and return the seconds
+-- time format: [+ or -][<int><H or h>:][<int><M or m or '>:][<int><nothing or S or s or ">]
+function parsetime(timestring)
+    local seconds = 0
+    local hourspattern = "(%d+)[hH]"
+    local minutespattern = "(%d+)[mM']"
+    local secondspattern = "(%d+)[sS\"]?$"
+
+    local _, _, hoursmatch = string.find(timestring, hourspattern)
+    if hoursmatch ~= nil then
+        seconds = seconds + tonumber(hoursmatch) * 3600
+    end
+    local _, _, minutesmatch = string.find(timestring, minutespattern)
+    if minutesmatch ~= nil then
+        seconds = seconds + tonumber(minutesmatch) * 60
+    end
+    local _, _, secondsmatch = string.find(timestring, secondspattern)
+    if secondsmatch ~= nil then
+        seconds = seconds + tonumber(secondsmatch)
+    end
+
+    if string.sub(timestring,1,1) == "-" then
+        seconds = seconds * -1
+    end
+
+    return seconds
+end
+
 -- seek
 function seek(value)
     local input = vlc.object.input()
-    if string.sub(value,#value)=="%" then
-        vlc.var.set(input,"position",tonumber(string.sub(value,1,#value-1))/100.)
-    else
-        vlc.var.set(input,"time",tonumber(value))
+    if input ~= nil and value ~= nil then
+        if string.sub(value,-1) == "%" then
+            local number = tonumber(string.sub(value,1,-2))
+            if number ~= nil then
+                local posPercent = tonumber( string.sub(value,1,-2))/100.
+                if string.sub(value,1,1) == "+" or string.sub(value,1,1) == "-" then
+                    vlc.var.set(input,"position",vlc.var.get(input,"position") + posPercent)
+                else
+                    vlc.var.set(input,"position",posPercent)
+                end
+            end
+        else
+            local posTime = parsetime(value)
+            if string.sub(value,1,1) == "+" or string.sub(value,1,1) == "-" then
+                vlc.var.set(input,"time",vlc.var.get(input,"time") + posTime)
+            else
+                vlc.var.set(input,"time",posTime)
+            end
+        end
     end
 end