parse posted_at from fa static file url

spec/helpers/fa_uri_helper_spec.rb

@@ -0,0 +1,38 @@
+# typed: false
+require "rails_helper"
+
+RSpec.describe FaUriHelper do
+  describe "#parse_fa_media_url" do
+    it "parses a media URL with same timestamps" do
+      url =
+        "https://d.furaffinity.net/art/zzreg/1740700581/1740700581.zzreg_stippling-crop.jpg"
+      parsed = described_class.parse_fa_media_url(url)
+      expect(parsed).to eq(
+        FaUriHelper::FaMediaUrlInfo.new(
+          url_name: "zzreg",
+          original_file_posted: 1_740_700_581,
+          latest_file_posted: 1_740_700_581,
+          filename: "zzreg_stippling-crop.jpg",
+        ),
+      )
+      expect(parsed.original_file_posted_at).to eq(Time.at(1_740_700_581))
+      expect(parsed.latest_file_posted_at).to eq(Time.at(1_740_700_581))
+    end
+
+    it "parses a media URL with different timestamps" do
+      url =
+        "https://d.furaffinity.net/art/zzreg/1753374875/1740700581.zzreg_stippling-crop.jpg"
+      parsed = described_class.parse_fa_media_url(url)
+      expect(parsed).to eq(
+        FaUriHelper::FaMediaUrlInfo.new(
+          url_name: "zzreg",
+          original_file_posted: 1_740_700_581,
+          latest_file_posted: 1_753_374_875,
+          filename: "zzreg_stippling-crop.jpg",
+        ),
+      )
+      expect(parsed.original_file_posted_at).to eq(Time.at(1_740_700_581))
+      expect(parsed.latest_file_posted_at).to eq(Time.at(1_753_374_875))
+    end
+  end
+end

spec/models/domain/post/fa_post_spec.rb

@@ -48,6 +48,53 @@ RSpec.describe Domain::Post::FaPost do
     end
   end
 
+  describe "posted_at" do
+    let(:post_url_str) do
+      "https://d.furaffinity.net/art/zzreg/1740700581/1740700581.zzreg_stippling-crop.jpg"
+    end
+    let(:post) { create(:domain_post_fa_post, posted_at: 1.day.ago) }
+    let(:post_file) do
+      create(:domain_post_file, post: post, url_str: post_url_str)
+    end
+
+    it "can be extracted from file uri if no explicit posted_at is set" do
+      post_file # ensure the file is created
+      post.posted_at = nil
+      post.save!
+      post.reload
+      expect(post.posted_at).to eq(Time.at(1_740_700_581))
+    end
+
+    it "uses the existing posted_at if it is set" do
+      post_file # ensure the file is created
+      expect(post.posted_at).to be_within(10.seconds).of(1.day.ago)
+    end
+
+    it "guesses it from the submission log entry if all else fails" do
+      # do not create the post file
+      post.posted_at = nil
+      post.last_submission_log_entry =
+        create(
+          :http_log_entry,
+          response:
+            create(
+              :blob_file,
+              contents:
+                File.read(
+                  Rails.root.join(
+                    "test/fixtures/files/domain/fa/submission/submission_page_59723907.html",
+                  ),
+                ),
+            ),
+        )
+      post.save!
+      post.reload
+      expect(post.posted_at).to be_within(1.minute).of(
+        Time.parse("Feb 1, 2025 07:15 AM PST"),
+      )
+    end
+  end
+
   describe "attributes" do
     let(:post) { build(:domain_post_fa_post) }
     let(:time) { Time.now }