btrc-hub/backend/spec/models/post_spec.rb

require 'rails_helper'
require 'tempfile'

RSpec.describe Post, type: :model do
  before do
    PostUrlSanitisationRule.unscoped.delete_all
  end

  describe 'URL normalisation' do
    it 'normalises the HTTP URL before applying sanitisation rules' do
      PostUrlSanitisationRule.create!(
        priority: 10,
        source_pattern: '\\Ahttps://example\\.com/videos/([^/]+)\\z',
        replacement: 'https://example.com/watch/\\1'
      )

      post = described_class.create!(
        title: 'normalised URL',
        url: '  https://EXAMPLE.com/videos/123/  '
      )

      expect(post.url).to eq('https://example.com/watch/123')
    end

    it 'does not normalise an unchanged URL when another attribute changes' do
      post = create(:post)
      post.update_column(:url, 'https://EXAMPLE.com/unchanged/')

      post.update!(title: 'updated title')

      expect(post.reload.url).to eq('https://EXAMPLE.com/unchanged/')
    end

    it 'validates the sanitised URL length' do
      path = 'a' * 375

      PostUrlSanitisationRule.create!(
        priority: 10,
        source_pattern: '\\Ahttps://example\\.com/(a+)\\z',
        replacement: 'https://example.com/\\1\\1'
      )

      post = described_class.new(
        title: 'long URL',
        url: "https://example.com/#{ path }"
      )

      expect(post).to be_invalid
      expect(post.errors.details.fetch(:url)).to include(
        error: :too_long,
        count: 768
      )
    end

    it 'validates uniqueness after sanitisation' do
      PostUrlSanitisationRule.create!(
        priority: 10,
        source_pattern: '\\Ahttps://example\\.com/alias\\z',
        replacement: 'https://example.com/canonical'
      )
      create(:post, url: 'https://example.com/canonical')

      post = described_class.new(title: 'duplicate URL', url: 'https://example.com/alias')

      expect(post).to be_invalid
      expect(post.errors.details.fetch(:url)).to include(error: :taken, value: post.url)
    end
  end

  describe 'thumbnail processing' do
    def image_blob(width:, height:, background:, draw: nil)
      Tempfile.create(['post-thumbnail', '.png']) do |file|
        MiniMagick::Tool::Convert.new do |convert|
          convert.size "#{ width }x#{ height }"
          convert.xc background
          draw&.call(convert)
          convert << file.path
        end
        File.binread(file.path)
      end
    end

    def upload_for(blob)
      StringIO.new(blob).tap(&:rewind)
    end

    def read_image(attachment)
      blob =
          attachment.is_a?(Hash) ? attachment.fetch(:io).read : attachment.download
      MiniMagick::Image.read(blob)
    end

    def colour_at(image, x, y)
      image.get_pixels.fetch(y).fetch(x)
    end

    def expect_green(pixel)
      expect(pixel[1]).to be > pixel[0] + 40
      expect(pixel[1]).to be > pixel[2] + 40
    end

    def expect_red(pixel)
      expect(pixel[0]).to be > pixel[1] + 40
      expect(pixel[0]).to be > pixel[2] + 40
    end

    def expect_blue(pixel)
      expect(pixel[2]).to be > pixel[0] + 40
      expect(pixel[2]).to be > pixel[1] + 40
    end

    describe '.resized_thumbnail_attachment' do
      it 'centre-crops a wide image to 180x180 without distorting it' do
        blob = image_blob(
            width: 360,
            height: 180,
            background: 'red',
            draw: -> convert {
              convert.fill 'green'
              convert.draw 'rectangle 90,0 269,179'
            })

        resized = described_class.resized_thumbnail_attachment(upload_for(blob))
        image = read_image(resized)

        expect(image.dimensions).to eq([180, 180])
        expect_green(colour_at(image, 0, 90))
        expect_green(colour_at(image, 90, 90))
        expect_green(colour_at(image, 179, 90))
      end

      it 'centre-crops a tall image to 180x180 without distorting it' do
        blob = image_blob(
            width: 180,
            height: 360,
            background: 'red',
            draw: -> convert {
              convert.fill 'green'
              convert.draw 'rectangle 0,90 179,269'
            })

        resized = described_class.resized_thumbnail_attachment(upload_for(blob))
        image = read_image(resized)

        expect(image.dimensions).to eq([180, 180])
        expect_green(colour_at(image, 90, 0))
        expect_green(colour_at(image, 90, 90))
        expect_green(colour_at(image, 90, 179))
      end

      it 'keeps a square image square without distortion' do
        blob = image_blob(
            width: 180,
            height: 180,
            background: 'red',
            draw: -> convert {
              convert.fill 'blue'
              convert.draw 'rectangle 90,0 179,179'
            })

        resized = described_class.resized_thumbnail_attachment(upload_for(blob))
        image = read_image(resized)

        expect(image.dimensions).to eq([180, 180])
        expect_red(colour_at(image, 20, 90))
        expect_blue(colour_at(image, 160, 90))
      end
    end

    describe '#attach_thumbnail_from_url!' do
      it 'attaches a fetched remote image through the common resize path' do
        blob = image_blob(
            width: 240,
            height: 180,
            background: 'red',
            draw: -> convert {
              convert.fill 'green'
              convert.draw 'rectangle 30,0 209,179'
            })
        response = Preview::HttpFetcher::Response.new(
            blob,
            'image/png',
            'https://example.com/thumb.png')
        allow(Preview::ThumbnailFetcher).to receive(:fetch_image_response)
            .with('https://example.com/thumb.png')
            .and_return(response)

        post = described_class.create!(title: 'title', url: 'https://example.com/post')

        post.attach_thumbnail_from_url!('https://example.com/thumb.png')

        expect(post.thumbnail).to be_attached
        image = read_image(post.thumbnail)
        expect(image.dimensions).to eq([180, 180])
      end
    end
  end
end