modules/luci-base/luasrc/http/protocol/date.lua

   1 -- Copyright 2008 Freifunk Leipzig / Jo-Philipp Wich <xm@leipzig.freifunk.net>
   2 -- Licensed to the public under the Apache License 2.0.
   3
   4 --- LuCI http protocol implementation - date helper class.
   5 -- This class contains functions to parse, compare and format http dates.
   6 module("luci.http.protocol.date", package.seeall)
   7
   8 require("luci.sys.zoneinfo")
   9
  10
  11 MONTHS = {
  12         "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug",
  13         "Sep", "Oct", "Nov", "Dec"
  14 }
  15
  16 --- Return the time offset in seconds between the UTC and given time zone.
  17 -- @param tz    Symbolic or numeric timezone specifier
  18 -- @return              Time offset to UTC in seconds
  19 function tz_offset(tz)
  20
  21         if type(tz) == "string" then
  22
  23                 -- check for a numeric identifier
  24                 local s, v = tz:match("([%+%-])([0-9]+)")
  25                 if s == '+' then s = 1 else s = -1 end
  26                 if v then v = tonumber(v) end
  27
  28                 if s and v then
  29                         return s * 60 * ( math.floor( v / 100 ) * 60 + ( v % 100 ) )
  30
  31                 -- lookup symbolic tz
  32                 elseif luci.sys.zoneinfo.OFFSET[tz:lower()] then
  33                         return luci.sys.zoneinfo.OFFSET[tz:lower()]
  34                 end
  35
  36         end
  37
  38         -- bad luck
  39         return 0
  40 end
  41
  42 --- Parse given HTTP date string and convert it to unix epoch time.
  43 -- @param data  String containing the date
  44 -- @return              Unix epoch time
  45 function to_unix(date)
  46
  47         local wd, day, mon, yr, hr, min, sec, tz = date:match(
  48                 "([A-Z][a-z][a-z]), ([0-9]+) " ..
  49                 "([A-Z][a-z][a-z]) ([0-9]+) " ..
  50                 "([0-9]+):([0-9]+):([0-9]+) " ..
  51                 "([A-Z0-9%+%-]+)"
  52         )
  53
  54         if day and mon and yr and hr and min and sec then
  55                 -- find month
  56                 local month = 1
  57                 for i = 1, 12 do
  58                         if MONTHS[i] == mon then
  59                                 month = i
  60                                 break
  61                         end
  62                 end
  63
  64                 -- convert to epoch time
  65                 return tz_offset(tz) + os.time( {
  66                         year  = yr,
  67                         month = month,
  68                         day   = day,
  69                         hour  = hr,
  70                         min   = min,
  71                         sec   = sec
  72                 } )
  73         end
  74
  75         return 0
  76 end
  77
  78 --- Convert the given unix epoch time to valid HTTP date string.
  79 -- @param time  Unix epoch time
  80 -- @return              String containing the formatted date
  81 function to_http(time)
  82         return os.date( "%a, %d %b %Y %H:%M:%S GMT", time )
  83 end
  84
  85 --- Compare two dates which can either be unix epoch times or HTTP date strings.
  86 -- @param d1    The first date or epoch time to compare
  87 -- @param d2    The first date or epoch time to compare
  88 -- @return              -1  -  if d1 is lower then d2
  89 -- @return              0   -  if both dates are equal
  90 -- @return              1   -  if d1 is higher then d2
  91 function compare(d1, d2)
  92
  93         if d1:match("[^0-9]") then d1 = to_unix(d1) end
  94         if d2:match("[^0-9]") then d2 = to_unix(d2) end
  95
  96         if d1 == d2 then
  97                 return 0
  98         elseif d1 < d2 then
  99                 return -1
 100         else
 101                 return 1
 102         end
 103 end