#399

backend/app/services/post_metadata_fetcher.rb

@@ -1,4 +1,5 @@
 require 'time'
+require 'date'
 
 class PostMetadataFetcher
   TIMESTAMP_PATTERN =
@@ -30,7 +31,7 @@ class PostMetadataFetcher
           Preview::KnownSiteExtractor.thumbnail_url(uri) || metadata[:image_url],
       original_created_from: serialise_time(created_range&.first),
       original_created_before: serialise_time(created_range&.last),
-      duration: duration&.to_f&.then { _1.positive? ? (_1 * 1_000).round : nil },
+      duration: serialise_duration(duration),
       tags: platform_tags.join(' ') }
   end
 
@@ -54,12 +55,16 @@ class PostMetadataFetcher
         when /\A(\d{4})-(\d{2})\z/
           year = Regexp.last_match(1).to_i
           month = Regexp.last_match(2).to_i
+          return nil unless month.between?(1, 12)
+
           from = Time.zone.local(year, month, 1)
           [from, from + 1.month]
         when /\A(\d{4})-(\d{2})-(\d{2})\z/
           year = Regexp.last_match(1).to_i
           month = Regexp.last_match(2).to_i
           day = Regexp.last_match(3).to_i
+          return nil unless Date.valid_date?(year, month, day)
+
           from = Time.zone.local(year, month, day)
           [from, from + 1.day]
         else
@@ -84,6 +89,9 @@ class PostMetadataFetcher
     second = match[6]&.to_i || 0
     fraction = match[7]
     offset = match[8]
+    return nil unless valid_timestamp_components?(year, month, day, hour, minute, second)
+    return nil unless valid_offset?(offset)
+
     nanoseconds = parse_nanoseconds(fraction)
     timestamp =
         if offset.present?
@@ -117,6 +125,37 @@ class PostMetadataFetcher
     value.match?(/\A[+-]\d{2}:\d{2}\z/) ? value : "#{ value[0, 3] }:#{ value[3, 2] }"
   end
 
+  def self.serialise_duration value
+    seconds = Float(value)
+    return nil unless seconds.positive?
+
+    milliseconds = (seconds * 1_000).round
+    seconds_string = (milliseconds / 1_000.0).to_s
+    seconds_string.end_with?('.0') ? seconds_string.delete_suffix('.0') : seconds_string
+  rescue ArgumentError, TypeError
+    nil
+  end
+
+  def self.valid_timestamp_components? year, month, day, hour, minute, second
+    return false unless Date.valid_date?(year, month, day)
+    return false unless hour.between?(0, 23)
+    return false unless minute.between?(0, 59)
+    return false unless second.between?(0, 59)
+
+    true
+  end
+
+  def self.valid_offset? value
+    return true if value.nil? || value == 'Z'
+
+    match = value.match(/\A([+-])(\d{2}):?(\d{2})\z/)
+    return false if match.nil?
+
+    hours = match[2].to_i
+    minutes = match[3].to_i
+    hours.between?(0, 23) && minutes.between?(0, 59)
+  end
+
   def self.serialise_time value
     return nil if value.nil?
 
@@ -128,5 +167,8 @@ class PostMetadataFetcher
                        :parse_timestamp_range,
                        :parse_nanoseconds,
                        :parse_offset,
+                       :serialise_duration,
+                       :valid_timestamp_components?,
+                       :valid_offset?,
                        :serialise_time
 end