From ae9b9f1ab79e4bb3e3ca8a23412ce1384dc0ee0e Mon Sep 17 00:00:00 2001
From: Guillaume Virlet <github@virlet.org>
Date: Sat, 18 Sep 2021 10:15:50 +0200
Subject: [PATCH] add ability to set time offset with loading file + enhance
 spec for Local time

---
 README.md                   | 20 ++++++++++++++++++++
 lib/fit.rb                  |  3 ++-
 lib/fit/file/types.rb       | 13 ++++++++++++-
 spec/fit/file/types_spec.rb |  9 +++++++--
 4 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index f60a5b9..b75cd0b 100644
--- a/README.md
+++ b/README.md
@@ -14,6 +14,26 @@ fit_file = Fit.load_file(ARGV[0])
 records = fit_file.records.select{ |r| r.content.record_type != :definition }.map{ |r| r.content }
 ```
 
+If some times returned for your file are around 1989 or 1990, then you need to get the offset and pass it to the `load_file` method
+This requires loading the file 2 times (1 to get the offset, and 1 to read the file with the offseted date)
+```ruby
+require 'fit'
+
+fit_file = Fit.load_file(ARGV[0])
+
+offset = nil
+records = fit_file.records.select { |r| r.content.record_type == :activity }.map(&:content)
+rec = records[0]
+local_ts = rec.send(:raw_timestamp).to_i
+offset = rec.send(:raw_local_timestamp).to_i if local_ts < 268435456
+
+
+fit_file = Fit.load_file(ARGV[0], offset)
+
+records = fit_file.records.select{ |r| r.content.record_type != :definition }.map{ |r| r.content }
+
+```
+
 ## Supported files
 
 This library has been tested with files coming from the following devices:
diff --git a/lib/fit.rb b/lib/fit.rb
index 3a452ee..0ef22c2 100644
--- a/lib/fit.rb
+++ b/lib/fit.rb
@@ -17,7 +17,8 @@
 require 'fit/version'
 
 module Fit
-  def self.load_file(path)
+  def self.load_file(path, time_offset = nil)
+    Fit::File::Types.time_offset = time_offset
     File.read ::File.open(path)
   end
 end
diff --git a/lib/fit/file/types.rb b/lib/fit/file/types.rb
index 4efc3d3..384fafa 100644
--- a/lib/fit/file/types.rb
+++ b/lib/fit/file/types.rb
@@ -4,6 +4,7 @@ module Fit
   class File
     module Types
       @@types = {}
+      @@time_offset = nil
 
       class << self
         def add_type(name, type, option = {})
@@ -16,10 +17,20 @@ def get_type_definition(name)
           nil
         end
 
+        def time_offset=(time_offset)
+          @@time_offset = time_offset
+        end
+
         def date_time_value(time, values, parameters)
           val = values.invert
           if time < val['min']
-            time.to_s
+            if @@time_offset
+              offsetted_time = @@time_offset + time
+              res = parameters[:utc] ? Time.utc(1989, 12, 31) + offsetted_time : Time.local(1989, 12, 31) + offsetted_time
+              res.to_s
+            else
+              time.to_s
+            end
           else
             res = parameters[:utc] ? Time.utc(1989, 12, 31) + time : Time.local(1989, 12, 31) + time
             res.to_s
diff --git a/spec/fit/file/types_spec.rb b/spec/fit/file/types_spec.rb
index 2b580e6..1e93af8 100644
--- a/spec/fit/file/types_spec.rb
+++ b/spec/fit/file/types_spec.rb
@@ -37,6 +37,12 @@
         expect(described_class.date_time_value(9999, { 268435456 => 'min' }, { utc: true })).to eql '9999'
         expect(described_class.date_time_value(9999, { 268435456 => 'min' }, { utc: false })).to eql '9999'
       end
+
+      it 'returns offsetted system time when offset is defined' do
+        described_class.time_offset = 788392680
+        expect(described_class.date_time_value(738748, { 268435456 => 'min' },
+                                               { utc: true })).to eql '2015-01-02 11:10:28 UTC'
+      end
     end
 
     context 'when value is above min' do
@@ -49,9 +55,8 @@
 
       context 'with local mode' do
         it 'returns exact date in locale time zone' do
-          # TODO: manage answer based on current system local
           expect(described_class.date_time_value(790509304, { 268435456 => 'min' },
-                                                 { utc: false })).not_to match(/UTC$/)
+                                                 { utc: false })).to match(/^2015-01-18 09:55:04 [+-]\d{4}$/)
         end
       end
     end