require 'rails_helper'

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

  describe 'validations' do
    it 'requires a source pattern' do
      rule = described_class.new(priority: 10, source_pattern: nil, replacement: '')

      expect(rule).to be_invalid
      expect(rule.errors.details.fetch(:source_pattern)).to eq([{ error: :blank }])
    end

    it 'requires a unique source pattern' do
      described_class.create!(priority: 10, source_pattern: 'source', replacement: 'first')
      rule = described_class.new(
        priority: 20,
        source_pattern: 'source',
        replacement: 'second'
      )

      expect(rule).to be_invalid
      expect(rule.errors.details.fetch(:source_pattern)).to include(
        error: :taken,
        value: 'source'
      )
    end

    it 'rejects an invalid regexp' do
      rule = described_class.new(priority: 10, source_pattern: '[', replacement: '')

      expect(rule).to be_invalid
      expect(rule.errors[:source_pattern]).to include('変な正規表現だね〜（笑）')
    end
  end

  describe '.sanitise' do
    it 'applies each active rule once in priority order' do
      described_class.create!(priority: 30, source_pattern: 'c', replacement: 'd')
      described_class.create!(priority: 10, source_pattern: 'a', replacement: 'aa')
      described_class.create!(priority: 20, source_pattern: 'aa', replacement: 'c')
      discarded = described_class.create!(
        priority: 5,
        source_pattern: '.',
        replacement: 'discarded'
      )
      discarded.discard!

      expect(described_class.sanitise('a')).to eq('d')
    end

    it 'canonicalises the initial YouTube and Nico URL forms' do
      create_initial_rules

      urls = {
        'https://youtu.be/abc123?si=share' => youtube_url('abc123'),
        'https://www.youtube.com/live/abc123?t=10' => youtube_url('abc123'),
        'https://youtube.com/shorts/abc123?feature=share' => youtube_url('abc123'),
        'https://m.youtube.com/embed/abc123' => youtube_url('abc123'),
        'https://youtube.com/watch?feature=share&v=abc123&t=10' => youtube_url('abc123'),
        'https://nico.ms/sm123?from=share#fragment' => nico_url('sm123'),
        'https://www.nicovideo.jp/watch/sm123?ref=share#fragment' => nico_url('sm123')
      }

      urls.each do |url, canonical_url|
        expect(described_class.sanitise(url)).to eq(canonical_url)
      end
    end
  end

  describe '.apply!' do
    it 'locks posts in ID order and updates through temporary URLs' do
      first = create(:post, url: 'https://example.com/source/1')
      second = create(:post, url: 'https://example.com/source/2')
      create_source_rule
      sql = capture_sql { described_class.apply! }

      lock_sql = sql.find { _1.match?(/SELECT .*posts.*FOR UPDATE/i) }
      expect(lock_sql).to match(/ORDER BY .*posts.*id.* ASC/i)
      expect(sql.grep(/post-url-sanitising\.invalid/).size).to eq(2)
      expect(first.reload.url).to eq('https://example.com/canonical/1')
      expect(second.reload.url).to eq('https://example.com/canonical/2')
    end

    it 'loads and compiles rules only once' do
      create(:post, url: 'https://example.com/source/1')
      create(:post, url: 'https://example.com/source/2')
      create_source_rule

      expect(described_class).to receive(:rules).once.and_call_original

      described_class.apply!
    end

    it 'does not change post versions, version_no, or updated_at' do
      post = create(:post, url: 'https://example.com/source/1')
      post.update_columns(version_no: 7, updated_at: 1.day.ago)
      original_updated_at = post.reload.updated_at
      create_source_rule

      expect { described_class.apply! }.not_to change(PostVersion, :count)

      post.reload
      expect(post.url).to eq('https://example.com/canonical/1')
      expect(post.version_no).to eq(7)
      expect(post.updated_at).to eq(original_updated_at)
    end

    invalid_urls = {
      'a blank URL' => '',
      'an unparseable URL' => 'https://[',
      'a non-HTTP URL' => 'ftp://example.com/file',
      'an HTTP URL without a host' => 'https:/path'
    }

    invalid_urls.each do |description, sanitised_url|
      it "rolls back every update when sanitisation produces #{ description }" do
        valid_post = create(:post, url: 'https://example.com/source/1')
        invalid_post = create(:post, url: 'https://example.com/invalid')
        create_source_rule
        described_class.create!(
          priority: 20,
          source_pattern: '\\Ahttps://example\\.com/invalid\\z',
          replacement: sanitised_url
        )

        expect { described_class.apply! }
            .to raise_error(described_class::InvalidUrlError) { |error|
          expect(error.invalid_rows).to eq([
            { post_id: invalid_post.id,
              original_url: 'https://example.com/invalid',
              sanitised_url: }
          ])
        }
        expect(valid_post.reload.url).to eq('https://example.com/source/1')
        expect(invalid_post.reload.url).to eq('https://example.com/invalid')
      end
    end

    it 'rolls back every update when sanitisation produces a URL longer than 768 characters' do
      path = 'a' * 375
      original_url = "https://example.com/#{ path }"
      sanitised_url = "https://example.com/#{ path }#{ path }"
      valid_post = create(:post, url: 'https://example.com/source/1')
      invalid_post = create(:post, url: original_url)
      create_source_rule
      described_class.create!(
        priority: 20,
        source_pattern: '\\Ahttps://example\\.com/(a+)\\z',
        replacement: 'https://example.com/\\1\\1'
      )

      expect { described_class.apply! }
          .to raise_error(described_class::InvalidUrlError) { |error|
        expect(error.invalid_rows).to eq([
          { post_id: invalid_post.id,
            original_url:,
            sanitised_url: }
        ])
      }
      expect(valid_post.reload.url).to eq('https://example.com/source/1')
      expect(invalid_post.reload.url).to eq(original_url)
    end

    it 'rejects sanitised URL collisions case-insensitively without changing posts' do
      source = create(:post, url: 'https://example.com/source/Foo')
      canonical = create(:post, url: 'https://example.com/canonical/foo')
      create_source_rule

      expect { described_class.apply! }
          .to raise_error(described_class::UrlConflictError) { |error|
        expect(error.conflicts).to contain_exactly(
          { url: 'https://example.com/canonical/Foo',
            post_id: source.id,
            original_url: 'https://example.com/source/Foo' },
          { url: 'https://example.com/canonical/foo',
            post_id: canonical.id,
            original_url: 'https://example.com/canonical/foo' }
        )
      }
      expect(source.reload.url).to eq('https://example.com/source/Foo')
      expect(canonical.reload.url).to eq('https://example.com/canonical/foo')
      expect(Post.count).to eq(2)
    end

    it 'converts a persisted URL constraint race into UrlConflictError' do
      post = create(:post, url: 'https://example.com/source/1')
      create_source_rule
      conflict = { url: 'https://example.com/canonical/1',
                   post_id: post.id,
                   original_url: post.url }
      database_error = ActiveRecord::RecordNotUnique.new('duplicate URL')
      allow_any_instance_of(ActiveRecord::Relation)
          .to receive(:update_all).and_raise(database_error)
      allow(described_class).to receive(:build_persisted_conflicts).and_return([conflict])

      expect { described_class.apply! }
          .to raise_error(described_class::UrlConflictError) { |error|
        expect(error.conflicts).to eq([conflict])
        expect(error.cause).to equal(database_error)
      }
      expect(post.reload.url).to eq('https://example.com/source/1')
    end

    it 're-raises an unidentified RecordNotUnique error' do
      post = create(:post, url: 'https://example.com/source/1')
      create_source_rule
      database_error = ActiveRecord::RecordNotUnique.new('another unique constraint')
      allow_any_instance_of(ActiveRecord::Relation)
          .to receive(:update_all).and_raise(database_error)
      allow(described_class).to receive(:build_persisted_conflicts).and_return([])

      expect { described_class.apply! }.to raise_error(database_error)
      expect(post.reload.url).to eq('https://example.com/source/1')
    end
  end

  def capture_sql
    statements = []
    subscriber = lambda do |_name, _start, _finish, _id, payload|
      binds = payload.fetch(:binds, []).map { _1.value_for_database.to_s }
      statements << ([payload.fetch(:sql)] + binds).join(' ')
    end
    ActiveSupport::Notifications.subscribed(subscriber, 'sql.active_record') { yield }
    statements
  end

  def create_source_rule
    described_class.create!(
      priority: 10,
      source_pattern: '\\Ahttps://example\\.com/source/(.+)\\z',
      replacement: 'https://example.com/canonical/\\1'
    )
  end

  def create_initial_rules
    rules = [
      ['\\Ahttps?://youtu\\.be/([^/?#]+)(?:[?#].*)?\\z', youtube_url('\\1')],
      ['\\Ahttps?://(?:www\\.|m\\.)?youtube\\.com/live/([^/?#]+)(?:[?#].*)?\\z',
       youtube_url('\\1')],
      ['\\Ahttps?://(?:www\\.|m\\.)?youtube\\.com/shorts/([^/?#]+)(?:[?#].*)?\\z',
       youtube_url('\\1')],
      ['\\Ahttps?://(?:www\\.|m\\.)?youtube\\.com/embed/([^/?#]+)(?:[?#].*)?\\z',
       youtube_url('\\1')],
      ['\\Ahttps?://(?:www\\.|m\\.)?youtube\\.com/watch\\?(?:[^#&]+&)*' \
       'v=([^&#]+)(?:[&#].*)?\\z', youtube_url('\\1')],
      ['\\Ahttps?://nico\\.ms/([^/?#]+)(?:[?#].*)?\\z', nico_url('\\1')],
      ['\\Ahttps?://(?:www\\.)?nicovideo\\.jp/watch/([^?#/]+)(?:[?#].*)?\\z',
       nico_url('\\1')]
    ]
    rules.each_with_index do |(source_pattern, replacement), index|
      described_class.create!(
        priority: (index + 1) * 10,
        source_pattern:,
        replacement:
      )
    end
  end

  def youtube_url(video_id) = "https://www.youtube.com/watch?v=#{ video_id }"

  def nico_url(video_id) = "https://www.nicovideo.jp/watch/#{ video_id }"
end