package runs

import (
	"errors"
	"slices"
	"strings"
	"testing"
	"time"

	"textmachine/platform/internal/money"
	"textmachine/platform/internal/pgstore"
	"textmachine/platform/internal/pricing"
	"textmachine/platform/internal/runner"
)

// argvOf is the argv of the LAST unit this fixture started.
func argvOf(t *testing.T, f *fixture) []string {
	t.Helper()
	starts := f.runner.starts()
	if len(starts) == 0 {
		t.Fatal("no unit was started")
	}
	return starts[len(starts)-1].Args
}

// flagValue reads the value of a `--flag value` pair, or "" when the flag is absent.
func flagValue(args []string, flag string) string {
	if i := slices.Index(args, flag); i >= 0 && i+1 < len(args) {
		return args[i+1]
	}
	return ""
}

// ⛔ THE ORDER REACHES THE ENGINE, and until this pack it did not. The platform sold CHAPTERS and
// handed the engine a DOLLAR bound alone — so «buy ten chapters» arrived as a sum, and a sum buys
// whatever it buys: measured on real ledgers, ten chapters' worth of money bought sixteen to
// twenty-six (D39.165 §1). The knob said chapters and meant money.
//
// `--max-units` is the same quantity on both sides of the seam: the manifest's unit count is where
// this platform's per-chapter figure comes from, so the conversion is exact rather than estimated.
//
// Mutation caught: dropping maxUnits from TranslateArgs, or from spec.
func TestAPartialOrderReachesTheEngineAsAVolumeAndNotOnlyAsMoney(t *testing.T) {
	f := newFixture(t, "10", 500)
	run, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t), Chapters: order(7)})
	if err != nil {
		t.Fatal(err)
	}
	if err := f.svc.Spawn(f.ctx, run.ID); err != nil {
		t.Fatal(err)
	}
	args := argvOf(t, f)
	// The fixture ships one unit per chapter, so seven chapters are seven units.
	if got := flagValue(args, "--max-units"); got != "7" {
		t.Fatalf("the engine was given --max-units %q, want 7: %q", got, strings.Join(args, " "))
	}
	// And the MONEY bound is still there beside it: the two are orthogonal, one caps this run's work
	// and the other the book's cumulative spend.
	if !slices.Contains(args, "--ceiling-usd") {
		t.Errorf("the volume bound replaced the money bound: %q", strings.Join(args, " "))
	}
}

// The WHOLE-BOOK order carries no volume bound at all, and zero is the flag's own word for
// «unbounded» — so it must not be passed as a number either. A `--max-units 0` would be an order for
// nothing.
func TestAWholeBookOrderCarriesNoVolumeBound(t *testing.T) {
	f := newFixture(t, "10", 5)
	run, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t)})
	if err != nil {
		t.Fatal(err)
	}
	if err := f.svc.Spawn(f.ctx, run.ID); err != nil {
		t.Fatal(err)
	}
	if args := argvOf(t, f); slices.Contains(args, "--max-units") {
		t.Errorf("a whole-book order was bounded by volume: %q", strings.Join(args, " "))
	}
	// …and the book row says so in the only way that survives a re-cut: no boundary at all.
	var chapterID, unitID *string
	if err := f.store.Pool().QueryRow(f.ctx,
		`select ordered_through_chapter_id, ordered_through_unit_id from books where id = $1`,
		f.bookID(t)).Scan(&chapterID, &unitID); err != nil {
		t.Fatal(err)
	}
	if chapterID != nil || unitID != nil {
		t.Errorf("the whole book froze a boundary: chapter %v unit %v", chapterID, unitID)
	}
}

// The allowance is what is LEFT of the order, recomputed at every spawn. Frozen at admission, a run
// respawned after a restart would be handed its whole order a second time and the promise «you
// bought N units» would stop being about N.
//
// Mutation caught: maxUnitsFor ignoring DeliveredUnits.
func TestTheVolumeAllowanceIsWhatIsLeftOfTheOrderAtEverySpawn(t *testing.T) {
	f := newFixture(t, "10", 500)
	run, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t), Chapters: order(10)})
	if err != nil {
		t.Fatal(err)
	}
	if err := f.svc.Spawn(f.ctx, run.ID); err != nil {
		t.Fatal(err)
	}
	if got := flagValue(argvOf(t, f), "--max-units"); got != "10" {
		t.Fatalf("the first spawn was given %q, want 10", got)
	}
	// Four chapters of the order come back delivered, and the machine reboots.
	//
	// ⚠ Written as RESOLUTION ROWS and not as chapter counters, because the rows are what the
	// allowance is computed from and the counters are derived from them: a fixture that moved only
	// the counter would describe a state the materializer cannot produce, and would pass while the
	// arithmetic read something else.
	if _, err := f.store.Pool().Exec(f.ctx, `
		insert into unit_resolutions (book_id, chapter, unit, wave, shipped, flagged, at)
		select $1, g, 0, 'edit', true, false, now() from generate_series(1, 4) g`, f.bookID(t)); err != nil {
		t.Fatal(err)
	}
	f.engine.set(statusSpending(money.MicroUSD(100_000)), nil)
	f.runner.alive = false
	f.svc.Now = func() time.Time { return f.now.Add(2 * time.Hour) }
	if err := f.svc.Sweep(f.ctx); err != nil {
		t.Fatal(err)
	}
	got := flagValue(argvOf(t, f), "--max-units")
	if got != "6" {
		t.Fatalf("the respawn was given --max-units %q, want the six units of the order still owed", got)
	}
}

// ⛔ AND IT NEVER FALLS TO ZERO BY ARITHMETIC, because zero is the flag's word for «no bound». A run
// respawned after its order was fully delivered would otherwise be handed the whole book.
func TestAFullyDeliveredOrderIsRespawnedWithOneUnitAndNotWithNoBoundAtAll(t *testing.T) {
	l := pgstore.LiveRun{RunID: "run_1", OrderedChapters: 10}
	o := pgstore.SpawnOrder{Resolved: true, Units: 10, Delivered: 10,
		Order: pgstore.BookOrder{ThroughChapterID: "c10"}}
	n, err := maxUnitsFor(l, o)
	if err != nil {
		t.Fatal(err)
	}
	if n != 1 {
		t.Fatalf("a fully delivered order was given --max-units %d; zero means UNBOUNDED", n)
	}
	o.Delivered = 40 // more delivered than ordered: free and carried units ride outside the grant
	if n, err := maxUnitsFor(l, o); err != nil || n != 1 {
		t.Fatalf("an over-delivered order was given %d (%v)", n, err)
	}
}

// ⛔ A BOOK CUT AGAIN UNDER A PURCHASE IS A REFUSAL, not a substituted number. The order's boundary is
// stored as an IDENTITY so that a re-cut makes it stop resolving; reading the dangling reference as
// «the whole book» would sell MORE than was bought and as «nothing» would sell less. Both are the
// silent change of a paid order that the identity form exists to prevent.
func TestAnOrderThatNoLongerNamesABoundaryRefusesToSpawn(t *testing.T) {
	l := pgstore.LiveRun{RunID: "run_1", OrderedChapters: 10}
	dangling := pgstore.SpawnOrder{Resolved: false, Units: 0,
		Order: pgstore.BookOrder{ThroughChapterID: "a chapter this cut does not have"}}
	if _, err := maxUnitsFor(l, dangling); !errors.Is(err, ErrOrderUnresolvable) {
		t.Fatalf("an unresolvable order answered %v, want ErrOrderUnresolvable", err)
	}
	// The whole-book order has no boundary to lose and is unaffected by any re-cut, which is the
	// other half of why it stores none. On a FIRST run it takes no volume bound at all.
	if n, err := maxUnitsFor(l, pgstore.SpawnOrder{Resolved: true}); err != nil || n != 0 {
		t.Fatalf("a whole-book order answered %d (%v)", n, err)
	}
	// ⛔ AND THE RE-PASS, which is the one shape that buys no volume: the book's own order says
	// nothing about it, and bounding it by that order would leave a re-pass the buyer paid a whole
	// book's projection for re-making a single unit.
	repass := pgstore.LiveRun{RunID: "run_1", OrderedChapters: 0}
	if n, err := maxUnitsFor(repass, pgstore.SpawnOrder{Resolved: true, Units: 4, Delivered: 4,
		Order: pgstore.BookOrder{ThroughChapterID: "c2"}}); err != nil || n != 0 {
		t.Fatalf("a re-pass was bounded by the book's order: %d (%v)", n, err)
	}
}

// ⛔ PD-422: `--resnapshot` RIDES EVERY CONTINUATION, not only a run over an edited bank.
//
// The auto-bank grows by MINING during an ordinary run; mining moves the ENRICHED memory version;
// the enriched version is folded into the EDIT wave's snapshot alone. So the SECOND purchase of a
// mining book meets its own already-pinned edit jobs under a moved snapshot, the drift guard stops
// the engine with exit 1 — which this platform can only report as `failed` — and it does so AFTER
// the hold was taken, with nothing translated. The condition used to be the correction door's flag
// alone, which no amount of mining ever sets.
//
// Mutation caught: `resnapshot := book.BankMoved` — the condition as it shipped.
func TestASecondPurchaseCarriesResnapshotEvenWithoutABankCorrection(t *testing.T) {
	f := newFixture(t, "10", 500)
	first, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t), Chapters: order(3)})
	if err != nil {
		t.Fatal(err)
	}
	if err := f.svc.Spawn(f.ctx, first.ID); err != nil {
		t.Fatal(err)
	}
	// The FIRST purchase carries none: there is nothing pinned yet to be re-pinned, and a flag that
	// rode every run would be a consent nobody needed.
	if args := argvOf(t, f); slices.Contains(args, "--resnapshot") {
		t.Fatalf("the first purchase of a book carries --resnapshot: %q", strings.Join(args, " "))
	}
	// It ends cleanly. NO bank correction happens — this is the ordinary path, which is the whole
	// point: mining moved the bank and nothing recorded that fact.
	live := f.live(t)
	if err := runner.WriteMarker(f.svc.markerPath(live.RunID, live.AttemptNo),
		runner.Marker{Unit: live.UnitName, Result: "exit-code", Code: "exited", Status: "0"}); err != nil {
		t.Fatal(err)
	}
	if err := f.svc.Sweep(f.ctx); err != nil {
		t.Fatal(err)
	}
	second, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t), Chapters: order(3)})
	if err != nil {
		t.Fatal(err)
	}
	if err := f.svc.Spawn(f.ctx, second.ID); err != nil {
		t.Fatal(err)
	}
	args := argvOf(t, f)
	if !slices.Contains(args, "--resnapshot") {
		t.Fatalf("the second purchase of a book carries no --resnapshot, so the drift guard kills it "+
			"after the hold (PD-422): %q", strings.Join(args, " "))
	}
	// …and the consent that rides with it is FUNDED — the run's own hold, never the blanket form: a
	// projection grown past what the buyer saw must refuse, not be bought silently.
	if want := "--accept-rebill=" + fixtureHold(3).USD(); !slices.Contains(args, want) {
		t.Errorf("the continuation's consent is not its own hold (%s): %q", want, strings.Join(args, " "))
	}
}

// ⛔ A BOOK THE ENGINE HAS NOT PRICED IS NOT SOLD. This is the line the per-chapter constant used to
// stand on: $0.03 was measured 4.47× low and made the last chapters of every book unbuyable at any
// balance, so replacing it with a quieter guess would keep the shape of the defect. There is one
// source for what a book costs, and when it has not spoken the platform says so.
//
// Mutation caught: any fallback in Order or Start when Priced is false.
func TestAnUnpricedBookIsRefusedRatherThanSoldAtAGuess(t *testing.T) {
	f := newFixture(t, "10", 5)
	if _, err := f.store.Pool().Exec(f.ctx, `
		update books set expected_micro_usd = null, book_once_micro_usd = null, step_max_micro_usd = null
		 where id = $1`, f.bookID(t)); err != nil {
		t.Fatal(err)
	}
	if _, err := f.svc.Order(f.ctx, "u1", f.bookID(t)); !errors.Is(err, ErrNotPriced) {
		t.Errorf("the order form over an unpriced book answered %v, want ErrNotPriced", err)
	}
	if _, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t), Chapters: order(2)}); !errors.Is(err, ErrNotPriced) {
		t.Errorf("a purchase of an unpriced book answered %v, want ErrNotPriced", err)
	}
	// Nothing moved: a refusal before the hold is the only kind worth having.
	if acct := f.account(t); acct.Reserved != 0 {
		t.Errorf("a refused purchase reserved %s", acct.Reserved.USD())
	}
	// ⚠ A book carrying only PART of a projection is refused for the same reason and by the same
	// answer: two of three figures is a document this build did not read whole, and the one that
	// would be missing is exactly the one whose absence is silent.
	if _, err := f.store.Pool().Exec(f.ctx, `
		update books set expected_micro_usd = 150000, book_once_micro_usd = 0 where id = $1`,
		f.bookID(t)); err != nil {
		t.Fatal(err)
	}
	if _, err := f.svc.Order(f.ctx, "u1", f.bookID(t)); !errors.Is(err, ErrNotPriced) {
		t.Errorf("a book missing only its step_max was priced: %v", err)
	}
}

// The order form answers the buyer's question over a REAL book, end to end: the verdict, what the
// balance covers, and the pair «expected / reserved».
func TestTheOrderFormAnswersOverARealBook(t *testing.T) {
	// Five chapters at the fixture's $0.03: the whole book is affordable at $10 and not at $0.10.
	rich := newFixture(t, "10", 5)
	got, err := rich.svc.Order(rich.ctx, "u1", rich.bookID(t))
	if err != nil {
		t.Fatal(err)
	}
	if got.Verdict != pricing.VerdictCoversAll || got.ChaptersLeft != 5 || got.AffordableChapters != 5 {
		t.Fatalf("a $10 balance over a $0.15 book: %+v", got.Options)
	}
	if got.Whole.Hold != fixtureHold(5) || got.Whole.Expected != fixtureChapterUSD*5 {
		t.Errorf("the estimate is %s expected / %s held, want %s / %s",
			got.Whole.Expected.USD(), got.Whole.Hold.USD(),
			(fixtureChapterUSD * 5).USD(), fixtureHold(5).USD())
	}
	if got.MinHold != fixtureStepMaxUSD {
		t.Errorf("the money slider's minimum is %s, want the engine's own step", got.MinHold.USD())
	}
	if !got.ChapterOrders || got.Structure != "detected" {
		t.Errorf("a detected cut was not offered in chapters: %+v", got)
	}

	poor := newFixture(t, "0.15", 5)
	got, err = poor.svc.Order(poor.ctx, "u1", poor.bookID(t))
	if err != nil {
		t.Fatal(err)
	}
	if got.Verdict != pricing.VerdictCoversPart || got.AffordableChapters == 0 ||
		got.AffordableChapters >= 5 {
		t.Fatalf("a $0.15 balance over a book that reserves %s: %+v", fixtureHold(5).USD(), got.Options)
	}
}

// The three kinds of order end up as three DIFFERENT boundaries on the book row, and each is an
// identity. The chapter number rides beside its identity as a LABEL — which is what makes a shifted
// number visible rather than authoritative.
func TestEachKindOfOrderStoresItsOwnBoundaryAsAnIdentity(t *testing.T) {
	f := newFixture(t, "10", 5)
	book := f.bookID(t)
	read := func() (chapterID, unitID *string, number *int) {
		t.Helper()
		if err := f.store.Pool().QueryRow(f.ctx, `
			select ordered_through_chapter_id, ordered_through_unit_id, ordered_through_chapter_number
			  from books where id = $1`, book).Scan(&chapterID, &unitID, &number); err != nil {
			t.Fatal(err)
		}
		return
	}
	run, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: book, Chapters: order(3)})
	if err != nil {
		t.Fatal(err)
	}
	chapterID, unitID, number := read()
	if chapterID == nil || *chapterID != "c3" || unitID != nil || number == nil || *number != 3 {
		t.Fatalf("a chapter order stored chapter=%v unit=%v number=%v", chapterID, unitID, number)
	}
	f.finish(t, run.ID)

	// A CHARACTER order: the fixture's units are 1000 runes each, so 2500 buys three of them —
	// rounded UP to the unit that contains the 2500th rune.
	chars := int64(2500)
	run, err = f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: book, Characters: &chars})
	if err != nil {
		t.Fatal(err)
	}
	chapterID, unitID, number = read()
	if unitID == nil || *unitID != "u3" || chapterID != nil {
		t.Fatalf("a character order stored chapter=%v unit=%v", chapterID, unitID)
	}
	if number != nil {
		t.Errorf("a character order invented a chapter label: %v", number)
	}
	f.finish(t, run.ID)

	// The WHOLE BOOK: no boundary of any kind, which is the only form that keeps meaning the whole
	// book after a re-cut.
	if _, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: book}); err != nil {
		t.Fatal(err)
	}
	if chapterID, unitID, _ = read(); chapterID != nil || unitID != nil {
		t.Errorf("the whole book stored chapter=%v unit=%v", chapterID, unitID)
	}
}

// A character order over a book whose chapters ARE recognised still resolves to units, and an order
// in CHAPTERS over a book whose cut cannot be sold against is refused with its own word rather than
// silently rounded to the whole book.
func TestAChapterOrderIsRefusedOnACutThatCannotBeSoldAgainst(t *testing.T) {
	for _, structure := range []string{"none", "declared", "a word a later engine grew"} {
		f := newFixture(t, "10", 5)
		if _, err := f.store.Pool().Exec(f.ctx,
			`update books set structure = $2 where id = $1`, f.bookID(t), structure); err != nil {
			t.Fatal(err)
		}
		_, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t), Chapters: order(2)})
		if !errors.Is(err, ErrChapterOrdersUnavailable) {
			t.Errorf("structure %q accepted a chapter order: %v", structure, err)
		}
		if acct := f.account(t); acct.Reserved != 0 {
			t.Errorf("structure %q: a refused order reserved %s", structure, acct.Reserved.USD())
		}
		// The whole book and a character order are both still available — the refusal is of the UNIT
		// the order is phrased in, not of the book.
		chars := int64(1500)
		if _, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t), Characters: &chars}); err != nil {
			t.Errorf("structure %q refused a character order too: %v", structure, err)
		}
	}
}

// A character order that reaches the end of the book IS the whole book, and is recorded as such: a
// boundary on the last unit would freeze an order that a re-cut then breaks for no reason.
func TestACharacterOrderThatReachesTheEndIsTheWholeBook(t *testing.T) {
	f := newFixture(t, "10", 5)
	chars := int64(999_999)
	if _, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t), Characters: &chars}); err != nil {
		t.Fatal(err)
	}
	var unitID *string
	if err := f.store.Pool().QueryRow(f.ctx,
		`select ordered_through_unit_id from books where id = $1`, f.bookID(t)).Scan(&unitID); err != nil {
		t.Fatal(err)
	}
	if unitID != nil {
		t.Errorf("an order for more characters than the book has froze a boundary at %q", *unitID)
	}
}

// finish closes a live run so the fixture can buy again: one live run per book by construction.
func (f *fixture) finish(t *testing.T, runID string) {
	t.Helper()
	if _, err := f.store.Pool().Exec(f.ctx,
		`update runs set finished_at = now(), status = 'stopped' where id = $1`, runID); err != nil {
		t.Fatal(err)
	}
	if _, err := f.store.Pool().Exec(f.ctx,
		`update reservations set state = 'released', closed_at = now()
		  where engine_run_id like $1 and state = 'open'`, runID+"#%"); err != nil {
		t.Fatal(err)
	}
}

// ⛔ THE SERVER RE-JUDGES THE ORDER, and this is the half PD-375 found untested under the previous
// shape: the bound that decides HOW MUCH MONEY IS RESERVED can never be one the caller chose
// unilaterally. The options read is a READ, the balance moves under it, and a client is forbidden to
// clamp on its own account.
//
// Two halves, and both are asserted because removing either used to pass the whole battery:
//   - an order the balance CANNOT carry is refused, before the hold, with nothing moved;
//   - an order LARGER than the book is the whole book, not an error and not a larger reservation.
//
// Mutation caught: dropping the `quote.Hold > acct.Balance` refusal in Start; letting Quote reserve
// for more chapters than the book has.
func TestAnOrderTheBalanceCannotCarryIsRefusedBeforeTheHold(t *testing.T) {
	// $0.10 against a five-chapter book whose whole order reserves more than that.
	f := newFixture(t, "0.10", 5)
	if fixtureHold(5) <= money.MicroUSD(100_000) {
		t.Fatalf("the fixture does not test what it claims: five chapters reserve %s, which $0.10 covers",
			fixtureHold(5).USD())
	}
	before := f.account(t)
	_, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t), Chapters: order(5)})
	// ⚠ ITS OWN ERROR, and not ErrCeilingOutOfBounds. That one means «the options moved between the
	// read and the call» and reaches the wire as `bounds_moved`, which promises a client that
	// re-reading and retrying will work. Here nothing moved and retrying is futile: what is missing
	// is money, and the remedy is to top up. This is the refusal the whole order form exists to make
	// honest, and it used to travel under the other word.
	if !errors.Is(err, ErrBalanceCannotCarry) {
		t.Fatalf("an unaffordable order answered %v, want ErrBalanceCannotCarry", err)
	}
	if after := f.account(t); after.Reserved != before.Reserved || after.Balance != before.Balance {
		t.Fatalf("money moved on a refused order: before %+v, after %+v", before, after)
	}
	if live, err := f.store.ListLiveRuns(f.ctx); err != nil || len(live) != 0 {
		t.Fatalf("a refused order left a live run: %+v (%v)", live, err)
	}
	// And an order LARGER than the book is the whole book — the reservation is the book's, never the
	// number the caller typed.
	rich := newFixture(t, "10", 5)
	if _, err := rich.svc.Start(rich.ctx, StartRequest{UserID: "u1", BookID: rich.bookID(t), Chapters: order(9999)}); err != nil {
		t.Fatal(err)
	}
	if got := rich.account(t).Reserved; got != fixtureHold(5) {
		t.Errorf("an order for 9999 chapters of a five-chapter book reserved %s, want the book's own %s",
			got.USD(), fixtureHold(5).USD())
	}
}

// ⛔ THE ORDER FORM'S PROMISE HAS TO SURVIVE THE CLICK, and until an adversarial pass looked it did
// not. The form answers, before the click, whether the book-wide consistency pass is funded; the
// form is a READ and the balance moves under it — another book's hold, a correction — and the hold
// taken at admission is computed against the balance AS IT IS. So a buyer shown «funded» could be
// sold a run that was not, and the passes DEGRADE rather than halt: the book arrives and only its
// terms wander. Consistency of terms across a book is the owner's first stated priority (D39.198),
// and a refusal shaped like normal work is the class D39.202 §3 names.
//
// The run carries what it actually got, so the question is answerable after the click too.
//
// Mutation caught: dropping BondFunded from the StartRunInput, or reading it from anything but the
// quote the admission acted on.
func TestWhatTheRunActuallyGotIsRecordedAndNotOnlyWhatTheFormPromised(t *testing.T) {
	// A book-level bound the balance CAN carry: the run is sold with the pass funded.
	f := newFixture(t, "10", 3)
	if _, err := f.store.Pool().Exec(f.ctx,
		`update books set book_once_micro_usd = 2000000 where id = $1`, f.bookID(t)); err != nil {
		t.Fatal(err)
	}
	form, err := f.svc.Order(f.ctx, "u1", f.bookID(t))
	if err != nil {
		t.Fatal(err)
	}
	if !form.Whole.BondFunded {
		t.Fatalf("a $10 balance does not fund a $2 book-level pass: %+v", form.Options)
	}
	run, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t)})
	if err != nil {
		t.Fatal(err)
	}
	if !f.run(t, run.ID).BondFunded {
		t.Error("a run sold with the pass funded does not say so")
	}

	// …and the case the form CANNOT promise: a balance that carries the chapters and not the bound.
	poor := newFixture(t, "0.5", 3)
	if _, err := poor.store.Pool().Exec(poor.ctx,
		`update books set book_once_micro_usd = 2000000 where id = $1`, poor.bookID(t)); err != nil {
		t.Fatal(err)
	}
	form, err = poor.svc.Order(poor.ctx, "u1", poor.bookID(t))
	if err != nil {
		t.Fatal(err)
	}
	if form.Verdict != pricing.VerdictCoversAll || form.Whole.BondFunded {
		t.Fatalf("the chapters are covered and the bound is not: %+v", form.Options)
	}
	run, err = poor.svc.Start(poor.ctx, StartRequest{UserID: "u1", BookID: poor.bookID(t)})
	if err != nil {
		t.Fatal(err)
	}
	if poor.run(t, run.ID).BondFunded {
		t.Error("a run sold WITHOUT the book-wide pass claims it is funded, which is the silence " +
			"this column exists to break")
	}
}

// ⛔ A WHOLE-BOOK CONTINUATION IS BOUNDED BY VOLUME TOO, and the reason is the engine's, not this
// platform's caution: with no ceiling in force the engine builds NO volume scope, and the scope is
// what carries its protective order of work — new book before re-made book. Without one, a
// continuation carrying `--resnapshot` walks the edit wave in BOOK order and re-pays the beginning
// of the book before editing the chapters just bought.
//
// That is exactly the argument this platform made for riding `--resnapshot` on every continuation
// (PD-422), and it held only for PARTIAL orders until this bound existed. Found by an adversarial
// pass reading the engine, not by a failure here.
//
// The FIRST run of a book gets no bound: nothing is delivered, so nothing can be re-made.
//
// Mutation caught: returning 0 for a whole-book order unconditionally.
func TestAWholeBookContinuationIsGivenTheRemainderAsItsVolume(t *testing.T) {
	f := newFixture(t, "10", 5)
	first, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t)})
	if err != nil {
		t.Fatal(err)
	}
	if err := f.svc.Spawn(f.ctx, first.ID); err != nil {
		t.Fatal(err)
	}
	if args := argvOf(t, f); slices.Contains(args, "--max-units") {
		t.Fatalf("the FIRST whole-book run is bounded by volume: %q", strings.Join(args, " "))
	}
	// It delivers two of the five chapters and ends.
	if _, err := f.store.Pool().Exec(f.ctx, `
		insert into unit_resolutions (book_id, chapter, unit, wave, shipped, flagged, at)
		select $1, g, 0, 'edit', true, false, now() from generate_series(1, 2) g`, f.bookID(t)); err != nil {
		t.Fatal(err)
	}
	live := f.live(t)
	if err := runner.WriteMarker(f.svc.markerPath(live.RunID, live.AttemptNo),
		runner.Marker{Unit: live.UnitName, Result: "exit-code", Code: "exited", Status: "0"}); err != nil {
		t.Fatal(err)
	}
	if err := f.svc.Sweep(f.ctx); err != nil {
		t.Fatal(err)
	}
	second, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: f.bookID(t)})
	if err != nil {
		t.Fatal(err)
	}
	if err := f.svc.Spawn(f.ctx, second.ID); err != nil {
		t.Fatal(err)
	}
	args := argvOf(t, f)
	if got := flagValue(args, "--max-units"); got != "3" {
		t.Fatalf("a whole-book CONTINUATION was given --max-units %q, want the three units still "+
			"owed — without a ceiling the engine builds no scope and re-pays the beginning of the "+
			"book before editing what was bought: %q", got, strings.Join(args, " "))
	}
	if !slices.Contains(args, "--resnapshot") {
		t.Errorf("the continuation carries no --resnapshot: %q", strings.Join(args, " "))
	}
}

// A stranger's book is INDISTINGUISHABLE from a missing one on the order form, exactly as it is
// everywhere else in this package: telling the two apart is what would let anyone enumerate other
// people's libraries by asking what a book costs.
//
// Pinned here because the form is a NEW path with its own query, and ownership on it is that query's
// own `where b.owner_id = $2` rather than a guard somebody remembered to put in front of it — a
// guard is exactly the thing a later refactor drops.
//
// Mutation caught: dropping `b.owner_id = $2` from ReadBookForOrder or RemainingUnits.
func TestTheOrderFormDoesNotAnswerAboutSomebodyElsesBook(t *testing.T) {
	f := newFixture(t, "10", 5)
	if _, err := f.store.Pool().Exec(f.ctx,
		`insert into users (id, email) values ('u2','u2@example.org')`); err != nil {
		t.Fatal(err)
	}
	if _, err := f.svc.Order(f.ctx, "u2", f.bookID(t)); !errors.Is(err, pgstore.ErrNoBook) {
		t.Errorf("the order form over a stranger's book answered %v, want ErrNoBook", err)
	}
	if _, err := f.svc.Order(f.ctx, "u1", "bk_THISDOESNOTEXIST"); !errors.Is(err, pgstore.ErrNoBook) {
		t.Errorf("the order form over a missing book answered %v, want ErrNoBook", err)
	}
	// The purchase path too, and it must not move money on the way to refusing.
	before := f.account(t)
	if _, err := f.svc.Start(f.ctx, StartRequest{UserID: "u2", BookID: f.bookID(t)}); !errors.Is(err, pgstore.ErrNoBook) {
		t.Errorf("a stranger's purchase answered %v, want ErrNoBook", err)
	}
	if after := f.account(t); after.Reserved != before.Reserved {
		t.Errorf("a stranger's refused purchase moved the owner's money: %s → %s",
			before.Reserved.USD(), after.Reserved.USD())
	}
	// …and the character order's own read, which is a SECOND query with its own ownership clause.
	if got, err := f.store.RemainingUnits(f.ctx, "u2", f.bookID(t)); err != nil || len(got) != 0 {
		t.Errorf("a stranger read %d units of somebody else's book (%v)", len(got), err)
	}
}

// ⛔ THE ALLOWANCE IS IN UNITS AND THE ORDER IS IN CHAPTERS, and until this test nothing in the zone
// could tell the two apart: every other fixture gives a chapter exactly one unit, so `chapters` and
// `units` were the same number everywhere and swapping one for the other stayed green.
//
// Three chapters of four units each: an order of two chapters is EIGHT units, not two.
//
// Mutation caught: `maxUnitsFor` returning `l.OrderedChapters - o.Delivered` — the unit of measure
// swapped for the one beside it.
func TestTheVolumeAllowanceCountsUnitsAndNotChapters(t *testing.T) {
	f := newFixture(t, "10", 5)
	book := multiUnitBook(t, f, "multi", 3, 4)
	run, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: book, Chapters: order(2)})
	if err != nil {
		t.Fatal(err)
	}
	if err := f.svc.Spawn(f.ctx, run.ID); err != nil {
		t.Fatal(err)
	}
	if got := flagValue(argvOf(t, f), "--max-units"); got != "8" {
		t.Fatalf("an order of two four-unit chapters was given --max-units %q, want 8: the allowance "+
			"is counted in the unit the ENGINE ships, and two is what it would be if the chapter count "+
			"were handed over instead", got)
	}
	// …and what was SOLD is still counted in chapters, because that is what the buyer chose and what
	// the run's own bar is measured in.
	if got := f.run(t, run.ID).OrderedChapters; got != 2 {
		t.Errorf("the run says it bought %d chapters", got)
	}
	// The hold is the units' money, not the chapters': eight units at the fixture's rate.
	if got, want := f.account(t).Reserved, fixtureHold(8); got != want {
		t.Errorf("the order reserved %s, want %s — the price of eight units", got.USD(), want.USD())
	}
}

// ⛔ A CHARACTER ORDER'S BAR MOVES, and before this it could not: the order buys a PREFIX of a
// chapter, a chapter counts as done only once EVERY unit in it is done, so the run read `0/N` for
// its whole life and `delivered_chapters: 0` for ever.
//
// ⚠ THE PLATFORM ALREADY CALLS THAT STATE INADMISSIBLE — in its own words, in the admission that
// refuses a book with no materialised tree: «every counter the screen shows is a count over
// chapters, so the run would read 0/total for its entire life while spending» (PD-405). Introducing
// the same state through the character order would be this pack contradicting itself, and the
// character order is not a corner: `declared` is led as `none`, so today it is the ONLY partial
// purchase available for every EPUB and every non-CJK txt.
//
// Mutation caught: dropping the `r.ordered_units is not null` branch from runDone/runTotal, or
// leaving OrderedUnits nil on a character order.
func TestACharacterOrdersBarIsCountedInWhatItActuallyBought(t *testing.T) {
	f := newFixture(t, "10", 5)
	// One chapter of six units: the shape of a book whose chapters cannot be sold against.
	book := multiUnitBook(t, f, "one-chapter", 1, 6)
	chars := int64(2500) // 1000 runes a unit ⇒ three units
	run, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: book, Characters: &chars})
	if err != nil {
		t.Fatal(err)
	}
	got := f.run(t, run.ID)
	// Two passes over three units: the same shape the chapter bar has, one level finer.
	if got.Progress.Total != 6 || got.Progress.Done != 0 {
		t.Fatalf("a three-unit order opens at %d/%d, want 0/6", got.Progress.Done, got.Progress.Total)
	}
	if got.DeliveredChapters != nil {
		t.Errorf("a run that bought a prefix of a chapter reports %d chapters delivered; it has "+
			"delivered no CHAPTER, and 0 reads as «nothing happened»", *got.DeliveredChapters)
	}
	// The engine drafts the three it was sold. The chapter is NOT finished — three of six units — so
	// the chapter bar would still read zero here, and that is the whole defect.
	if _, err := f.store.Pool().Exec(f.ctx, `
		insert into unit_resolutions (book_id, chapter, unit, wave, shipped, flagged, at)
		select $1, 1, g - 1, 'draft', true, false, now() from generate_series(1, 3) g`, book); err != nil {
		t.Fatal(err)
	}
	got = f.run(t, run.ID)
	if got.Progress.Done != 3 {
		t.Fatalf("after the draft pass over all three units the bar reads %d/%d: counted in chapters "+
			"it can never move, because the chapter holds six", got.Progress.Done, got.Progress.Total)
	}
	if got.Progress.Stage != "editing" {
		t.Errorf("the draft pass over what was bought is done and the caption says %q", got.Progress.Stage)
	}
	// …and the edit pass closes it.
	if _, err := f.store.Pool().Exec(f.ctx, `
		insert into unit_resolutions (book_id, chapter, unit, wave, shipped, flagged, at)
		select $1, 1, g - 1, 'edit', true, false, now() from generate_series(1, 3) g`, book); err != nil {
		t.Fatal(err)
	}
	if got = f.run(t, run.ID); got.Progress.Done != 6 || got.Progress.Total != 6 {
		t.Errorf("a fully delivered three-unit order reads %d/%d", got.Progress.Done, got.Progress.Total)
	}
}

// The ORDINARY shape is untouched: a run that bought whole chapters keeps the bar it always had,
// counted in chapters, with `delivered_chapters` a number rather than null. Asserted beside the test
// above because the unit-shaped branch is a NEW first case in three SQL expressions every existing
// bar reads, and «the new branch is not entered» is the property that keeps thirty other tests true.
func TestAChapterOrderKeepsTheBarItAlwaysHad(t *testing.T) {
	f := newFixture(t, "10", 5)
	book := multiUnitBook(t, f, "chapters", 3, 2)
	run, err := f.svc.Start(f.ctx, StartRequest{UserID: "u1", BookID: book, Chapters: order(2)})
	if err != nil {
		t.Fatal(err)
	}
	got := f.run(t, run.ID)
	if got.Progress.Total != 4 {
		t.Fatalf("a two-chapter order over an editor pipeline opens with a total of %d, want 4 — two "+
			"passes over two CHAPTERS, not over their four units", got.Progress.Total)
	}
	if got.DeliveredChapters == nil || *got.DeliveredChapters != 0 {
		t.Errorf("a chapter order reports delivered chapters as %v, want 0 rather than null", got.DeliveredChapters)
	}
	// One whole chapter delivered moves both the bar and the delivered count.
	if _, err := f.store.Pool().Exec(f.ctx, `
		update chapters set units_draft_done = 2, units_edit_done = 2
		 where book_id = $1 and number = 1`, book); err != nil {
		t.Fatal(err)
	}
	got = f.run(t, run.ID)
	if got.DeliveredChapters == nil || *got.DeliveredChapters != 1 {
		t.Errorf("one whole chapter delivered reports %v", got.DeliveredChapters)
	}
	if got.Progress.Done != 2 {
		t.Errorf("one whole chapter through both passes reads %d/%d", got.Progress.Done, got.Progress.Total)
	}
}