--
-- PhotoGpsData.lua
-- http://regex.info/blog/lightroom-goodies/gps/
-- jfriedl@yahoo.com
--
-- Version 20100726.2
--
--
-- Import this file into your code, and call
--      TieShadowGPS(photo)
-- on your LrPhoto object, and subsequent calls for GPS metadata will
-- reflect the shadow GPS metadata maintained by my plugin.
--
--
-- In addition to the latitude and longitude normally found in the table returned by
--      photo:getRawMetadata('gps')
-- if there is shadow data available, all data is returned:
--
--       {
--            latitude  = 23.456,
--            longitude = 78.91011,
--            altitude  = 123,       -- in meters
--            speed     = 45.6,      -- in kph
--            bearing   = 123,       -- in degrees
--            time      = 184784722, -- Coco timestamp for the image, possibly adjusted for clock skew
--            isShadow  = true,
--       }
--
-- Note: all non-nil fields are of type == 'number' except isShadow.
--
local TARGET_PLUGIN_ID = "info.regex.lightroom.gps"
local TARGET_PLUGIN = _PLUGIN.id == TARGET_PLUGIN_ID and _PLUGIN or TARGET_PLUGIN_ID

local LR2 = (import 'LrApplication'.versionTable().major == 2)
local LrTasks = import 'LrTasks'

local function my_getRawMetadata(self, key)

   if key == 'gps' or key == 'gpsAltitude' then
      --
      -- Need to trap errors in Lr2. In Lr3, final arg of true means don't throw
      --
      local success, shadow 
      if LR2 then
         success, shadow = LrTasks.pcall(self.getPropertyForPlugin, self, TARGET_PLUGIN, 'data')
      else
         success = true
         shadow = self:getPropertyForPlugin(TARGET_PLUGIN, 'data', nil, true)
      end

      if success and shadow then
         if not shadow.latitude or not shadow.longitude then
            -- present-but-empty shadow data: override the "real" GPS data with nothingness
            return nil 
         else
            if key == 'gpsAltitude' then
               return shadow.altitude
            else
               shadow.isShadow = true
               return shadow
            end
         end
      end
   end

   return self:orig_getRawMetadata(key)
end

local function pretty_degree(value, whenPos, whenNeg)
   local dir

   value = tonumber(value)
   if value >= 0 then
      dir = whenPos
   else
      dir = whenNeg
      value = -value
   end

   local D, Mx = math.modf(value)
   local M, Sx = math.modf(Mx * 60)
   local S     = tonumber(string.format("%.2f", Sx * 60))

   return LOC("$$$/x1613=^1^D^2\'^3\" ^4", D, M, S, dir)
end

local function my_getFormattedMetadata(self, key)

   if key == 'gps' then
      local gps = my_getRawMetadata(self, 'gps')
      if gps and gps.latitude and gps.longitude then
         return pretty_degree(gps.latitude,  "N", "S") .. " " .. pretty_degree(gps.longitude, "E", "W")
      else
         return nil
      end
   
   elseif key == 'gpsAltitude' then

      local altitude = my_getRawMetadata(self, 'gpsAltitude')
      if altitude then
         return LOC("$$$/xxx=^1 m", string.format('%.1f', altitude))
      else
         return nil
      end

   else
      return self:orig_getFormattedMetadata(key)
   end

end


--
-- returns an error string on error, or nil on success
--
function TieShadowGPS(photo)

   if type(photo) ~= 'table' or not photo.getRawMetadata then
      return "argument to TieShadowGPS() should be an LrPhoto object"
   end

   if not photo.orig_getRawMetadata then
      photo.orig_getRawMetadata       = photo.getRawMetadata
      photo.orig_getFormattedMetadata = photo.getFormattedMetadata
   end

   photo.getRawMetadata       = my_getRawMetadata
   photo.getFormattedMetadata = my_getFormattedMetadata

   return nil
end