libs/web/luasrc/http/protocol/date.lua

   1 --[[
   2
   3 HTTP protocol implementation for LuCI - date handling
   4 (c) 2008 Freifunk Leipzig / Jo-Philipp Wich <xm@leipzig.freifunk.net>
   5
   6 Licensed under the Apache License, Version 2.0 (the "License");
   7 you may not use this file except in compliance with the License.
   8 You may obtain a copy of the License at
   9
  10         http://www.apache.org/licenses/LICENSE-2.0
  11
  12 $Id$
  13
  14 ]]--
  15
  16 --- LuCI http protocol implementation - date helper class.
  17 -- This class contains functions to parse, compare and format http dates.
  18 module("luci.http.protocol.date", package.seeall)
  19
  20 require("luci.sys.zoneinfo")
  21
  22
  23 MONTHS = {
  24         "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug",
  25         "Sep", "Oct", "Nov", "Dec"
  26 }
  27
  28 --- Return the time offset in seconds between the UTC and given time zone.
  29 -- @param tz    Symbolic or numeric timezone specifier
  30 -- @return              Time offset to UTC in seconds
  31 function tz_offset(tz)
  32
  33         if type(tz) == "string" then
  34
  35                 -- check for a numeric identifier
  36                 local s, v = tz:match("([%+%-])([0-9]+)")
  37                 if s == '+' then s = 1 else s = -1 end
  38                 if v then v = tonumber(v) end
  39
  40                 if s and v then
  41                         return s * 60 * ( math.floor( v / 100 ) * 60 + ( v % 100 ) )
  42
  43                 -- lookup symbolic tz
  44                 elseif luci.sys.zoneinfo.OFFSET[tz:lower()] then
  45                         return luci.sys.zoneinfo.OFFSET[tz:lower()]
  46                 end
  47
  48         end
  49
  50         -- bad luck
  51         return 0
  52 end
  53
  54 --- Parse given HTTP date string and convert it to unix epoch time.
  55 -- @param data  String containing the date
  56 -- @return              Unix epoch time
  57 function to_unix(date)
  58
  59         local wd, day, mon, yr, hr, min, sec, tz = date:match(
  60                 "([A-Z][a-z][a-z]), ([0-9]+) " ..
  61                 "([A-Z][a-z][a-z]) ([0-9]+) " ..
  62                 "([0-9]+):([0-9]+):([0-9]+) " ..
  63                 "([A-Z0-9%+%-]+)"
  64         )
  65
  66         if day and mon and yr and hr and min and sec then
  67                 -- find month
  68                 local month = 1
  69                 for i = 1, 12 do
  70                         if MONTHS[i] == mon then
  71                                 month = i
  72                                 break
  73                         end
  74                 end
  75
  76                 -- convert to epoch time
  77                 return tz_offset(tz) + os.time( {
  78                         year  = yr,
  79                         month = month,
  80                         day   = day,
  81                         hour  = hr,
  82                         min   = min,
  83                         sec   = sec
  84                 } )
  85         end
  86
  87         return 0
  88 end
  89
  90 --- Convert the given unix epoch time to valid HTTP date string.
  91 -- @param time  Unix epoch time
  92 -- @return              String containing the formatted date
  93 function to_http(time)
  94         return os.date( "%a, %d %b %Y %H:%M:%S GMT", time )
  95 end
  96
  97 --- Compare two dates which can either be unix epoch times or HTTP date strings.
  98 -- @param d1    The first date or epoch time to compare
  99 -- @param d2    The first date or epoch time to compare
 100 -- @return              -1  -  if d1 is lower then d2
 101 -- @return              0   -  if both dates are equal
 102 -- @return              1   -  if d1 is higher then d2
 103 function compare(d1, d2)
 104
 105         if d1:match("[^0-9]") then d1 = to_unix(d1) end
 106         if d2:match("[^0-9]") then d2 = to_unix(d2) end
 107
 108         if d1 == d2 then
 109                 return 0
 110         elseif d1 < d2 then
 111                 return -1
 112         else
 113                 return 1
 114         end
 115 end