>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #3615214. --> Reported by: [mably](https://www.drupal.org/user/3375160) Related to !179 >>> <h3>Problem</h3> <p>The only seating strategy is 1455 lines and 35 methods. That is not a complaint about its length: three questions genuinely live there, the ladder that places a party has six rungs, and every one of them earned its place from a reported fault. The problem is that two of the things holding it up are not about seating at all, and a second strategy cannot have them.</p> <p><strong>The row geometry.</strong> <code>rows()</code>, <code>run()</code>, <code>runsOf()</code>, <code>fragments()</code>, <code>isolation()</code> and <code>apart()</code> answer questions about a hall: group these places into rows, find a stretch this long, find the unbroken runs a set of places sits in, say how far one place is from another. None of it knows what a party is or which rung is asking. About 120 lines.</p> <p><strong>The rate matching.</strong> <code>shareOut()</code> and its four helpers decide which seat goes to which rate when the rates price different grades, by augmenting paths. That is a bipartite matcher, roughly 170 lines, and it is a plugin's private method. It is also the part with a real algorithm in it, the one most worth testing on its own and least worth reading past to reach the seating rules.</p> <p>Two consequences, and the second is the one that matters:</p> <ul> <li>Anybody writing a second strategy starts from nothing. There is no base class and no trait, so "seat a party in one row" and "spread a party across a section" would each need their own copy of the geometry and their own matcher, and a copied matcher is a matcher that drifts.</li> <li>The three questions the interface asks are 160 of the 1455 lines, so what the class <em>is</em> reads as a tenth of what it contains.</li> </ul> <p>Filed off the back of <a href="https://www.drupal.org/project/yoyaku/issues/3615212">#3615212</a>, which added the third question and made the shape hard to keep ignoring: <code>consolidate()</code> needed a new geometry method (<code>runsOf()</code>, because <code>run()</code> answers with the first run only) and reused the matcher through a private call, both of which a strategy outside this file could not have done.</p> <h3>Proposed resolution</h3> <p>Extract the two collaborators, leave the seating rules where they are, and change no behavior at all.</p> <ul> <li>A row geometry service or value-object helper in <code>yoyaku_placement</code>, holding the six methods above. It takes places and returns places; it never sees a request, a rate or an anchor.</li> <li>A rate matcher, holding <code>shareOut()</code> and its helpers, plus <code>uniformlyPriced()</code>, <code>prices()</code>, <code>gradeIds()</code> and <code>rateKey()</code>. It takes places and wanted counts and answers with an assignment or nothing.</li> <li><code>Together</code> keeps <code>propose()</code>, <code>giveUpFirst()</code>, <code>consolidate()</code>, the six rungs and the reduction's two passes, and reads the two collaborators. It should come out near 700 lines, which is what the seating rules honestly cost.</li> <li>Whether a base class or trait follows is a separate decision and should not be made in the same issue. Two collaborators a strategy can inject may well be enough, and a base class invented for one implementation is a guess.</li> </ul> <p>This is a refactor with no user-visible change, and the safety net is already there: the reported faults each pinned a rule, so a rule that moves and breaks is caught by a test naming the case it came from.</p> <h3>Remaining tasks</h3> <ul> <li>Extract the geometry, unchanged, and point <code>Together</code> at it.</li> <li>Extract the matcher, unchanged, and point <code>Together</code> at it.</li> <li>Cover both directly, at the level they now sit: a stretch shorter than the run asked for, a row with a gap in it, overlapping windows of one stretch, a party in a pool with no row at all; and for the matcher, rates pricing the same grades, rates pricing disjoint grades, an arrangement only the matching finds, and one that exists for no share-out. Some of these are asserted today only through a whole hold, which is a slow and indirect way to test arithmetic.</li> <li>Keep every existing test passing untouched. A refactor that needs its tests edited is not a refactor, so any test that has to change is a behavior change and belongs in its own issue.</li> <li><code>docs/seating.md</code>, whose "Writing your own strategy" section describes what a strategy is handed, and the cost section, which explains why the geometry reads nothing.</li> </ul> <h3>User interface changes</h3> <p>None.</p>