package pgstore

import (
	"context"
	"encoding/json"
	"errors"
	"sync"
	"testing"
	"time"

	"textmachine/platform/internal/ingest"
	"textmachine/platform/internal/money"
)

// The claim on an attempt can be taken, given back and taken again — that is what happens when a
// unit could not be created — and the SECOND claim must not overwrite what the first decided. The
// caller passes the stored values back on a retry, so this pins the guard the DATABASE keeps
// underneath it: two answers to "what limit did that process have" is one too many.
func TestASecondClaimOnOneAttemptKeepsWhatTheFirstRecorded(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 10,
		Ceiling: money.MicroUSD(300_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	first := SpawnRecord{AttemptID: run.AttemptID, Unit: "tm-run-x-1", Binary: "/opt/engine/1/tmctl",
		Ceiling: 300_000, CeilingArg: 3_000_000, Baseline: 1_000_000}
	if claimed, err := s.RecordSpawn(ctx, first); err != nil || !claimed {
		t.Fatalf("first claim: %v %v", claimed, err)
	}
	if err := s.ReleaseSpawnClaim(ctx, run.AttemptID); err != nil {
		t.Fatal(err)
	}
	// The meter has moved since — by the engine the first claim may well have started.
	second := first
	second.CeilingArg, second.Baseline = 3_400_000, 1_400_000
	if claimed, err := s.RecordSpawn(ctx, second); err != nil || !claimed {
		t.Fatalf("second claim: %v %v", claimed, err)
	}
	var baseline, arg int64
	if err := s.pool.QueryRow(ctx, `
		select spend_baseline_micro_usd, ceiling_arg_micro_usd from run_attempts where id = $1`,
		run.AttemptID).Scan(&baseline, &arg); err != nil {
		t.Fatal(err)
	}
	if money.MicroUSD(baseline) != first.Baseline {
		t.Errorf("baseline %s after a re-claim, want the one the first claim recorded (%s)",
			money.MicroUSD(baseline).USD(), first.Baseline.USD())
	}
	if money.MicroUSD(arg) != first.CeilingArg {
		t.Errorf("recorded limit %s after a re-claim, want %s",
			money.MicroUSD(arg).USD(), first.CeilingArg.USD())
	}
}

func seedBook(t *testing.T, s *Store, ctx context.Context, id, owner string, chapters int) {
	t.Helper()
	exec(t, s, ctx, `insert into books (id, owner_id, title, source_lang, target_lang, status,
	                                    chapter_count, workdir, engine_book_id)
	                 values ($1,$2,'蛊真人','zh','ru','not_started',$3,'/srv/books/'||$1,$1)`, id, owner, chapters)
}

func fundedAccount(t *testing.T, s *Store, ctx context.Context, user string, usd string) time.Time {
	t.Helper()
	now := time.Now().UTC().Truncate(time.Millisecond)
	seedUser(t, s, ctx, user)
	amount, err := money.ParseUSD(usd)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := s.Grant(ctx, user, amount, "test", "seed-"+user, "", now); err != nil {
		t.Fatal(err)
	}
	return now
}

// Admission is ONE transaction, and this is the assertion that says so: the run row, its attempt,
// the hold and the queue entry either all exist or none of them do. A hold that outlived a failed
// admission is credit reserved for a run that does not exist, and nothing would ever release it.
func TestAdmittingARunWritesTheRunTheAttemptAndTheHoldTogether(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)

	var enqueued string
	run, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", VerifyBank: true, CeilingChapters: 100,
		Ceiling: money.MicroUSD(3_000_000), Now: now,
	}, 0, func(_ context.Context, _ Tx, id string) error { enqueued = id; return nil })
	if err != nil {
		t.Fatal(err)
	}
	if enqueued != run.ID {
		t.Errorf("the queue was handed %q, the run is %q", enqueued, run.ID)
	}
	acct, err := s.ReadAccount(ctx, "u1")
	if err != nil {
		t.Fatal(err)
	}
	// The hold is a DEBIT at the moment it is taken: the balance already excludes it, and Reserved is
	// a separate, informational sum. Subtracting Reserved again is the arithmetic D39.115 §2a
	// corrected — it would halve the run-ceiling scale.
	if acct.Balance != money.MicroUSD(7_000_000) || acct.Reserved != money.MicroUSD(3_000_000) {
		t.Fatalf("balance %s, reserved %s; want 7.000000 and 3.000000", acct.Balance.USD(), acct.Reserved.USD())
	}
	if acct.LedgerSum != acct.Balance {
		t.Errorf("the cached balance and the ledger disagree: %s vs %s", acct.Balance.USD(), acct.LedgerSum.USD())
	}
	live, err := s.ListLiveRuns(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if len(live) != 1 || live[0].RunID != run.ID || live[0].AttemptNo != 1 {
		t.Fatalf("live runs: %+v", live)
	}
	if live[0].Ceiling != money.MicroUSD(3_000_000) {
		t.Errorf("the attempt's ceiling is %s, want the amount that was held", live[0].Ceiling.USD())
	}
}

// Nothing partial survives a refusal. The interesting half is the ROLLBACK: the run row is inserted
// before the hold is attempted, so a broke account must not leave one behind.
func TestARunThatCannotBePaidForLeavesNothingBehind(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "1")
	seedBook(t, s, ctx, "bk1", "u1", 500)

	_, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", CeilingChapters: 100, Ceiling: money.MicroUSD(5_000_000), Now: now,
	}, 0, nil)
	if !errors.Is(err, ErrInsufficientCredit) {
		t.Fatalf("started a run on an account that cannot pay: %v", err)
	}
	live, err := s.ListLiveRuns(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if len(live) != 0 {
		t.Fatalf("a refused admission left %d live runs", len(live))
	}
	var attempts int
	if err := s.pool.QueryRow(ctx, `select count(*) from run_attempts`).Scan(&attempts); err != nil {
		t.Fatal(err)
	}
	if attempts != 0 {
		t.Errorf("a refused admission left %d attempts", attempts)
	}
	acct, err := s.ReadAccount(ctx, "u1")
	if err != nil {
		t.Fatal(err)
	}
	if acct.Balance != money.MicroUSD(1_000_000) || acct.Reserved != 0 {
		t.Errorf("money moved on a refused admission: balance %s reserved %s", acct.Balance.USD(), acct.Reserved.USD())
	}
}

// The engine holds an EXCLUSIVE lock on the project file, so two live runs on one book is not a
// state to explain — it is one the database refuses. The guard is a partial unique index, and the
// point of this test is that the refusal surfaces as a DOMAIN error a handler can turn into 409,
// not as a raw SQLSTATE.
func TestABookCannotHaveTwoLiveRuns(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	in := StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 10, Ceiling: money.MicroUSD(300_000), Now: now}
	if _, err := s.StartRun(ctx, in, 0, nil); err != nil {
		t.Fatal(err)
	}
	if _, err := s.StartRun(ctx, in, 0, nil); !errors.Is(err, ErrRunInFlight) {
		t.Fatalf("a second live run gave %v, want ErrRunInFlight", err)
	}
	acct, err := s.ReadAccount(ctx, "u1")
	if err != nil {
		t.Fatal(err)
	}
	if acct.Reserved != money.MicroUSD(300_000) {
		t.Errorf("the refused second run reserved money: %s", acct.Reserved.USD())
	}
}

// A book that is not the caller's is indistinguishable from one that does not exist.
func TestARunCannotBeStartedOnSomeoneElsesBook(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	fundedAccount(t, s, ctx, "u2", "10")
	seedBook(t, s, ctx, "bk1", "u2", 500)
	_, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", CeilingChapters: 10, Ceiling: money.MicroUSD(300_000), Now: now,
	}, 0, nil)
	if !errors.Is(err, ErrNoBook) {
		t.Fatalf("starting a run on another account's book gave %v, want ErrNoBook", err)
	}
}

// The cursor and the effect move in ONE transaction. The assertion that matters is the second Apply
// of the same event: at-least-once delivery is the ratified norm (PD-105), so a duplicate must be a
// no-op rather than a second increment.
func TestAnEventAndItsCursorMoveTogetherAndADuplicateChangesNothing(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", CeilingChapters: 10, Ceiling: money.MicroUSD(300_000), Now: now,
	}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	sink := s.NewRunSink(run.AttemptID, run.ID, "bk1")
	if err := sink.Begin(ctx, ingest.Hello{EngineRunID: "eng-1", ChunkerVersion: "chunk-7"}); err != nil {
		t.Fatal(err)
	}
	ev := ingest.Envelope{Seq: 2, Type: ingest.TypeProgress,
		Data: json.RawMessage(`{"draft":{"done":3,"total":10},"edit":{"done":1,"total":10},"eta_seconds":42}`)}
	cur := ingest.Cursor{Offset: 128, SHA256: []byte("0123456789abcdef0123456789abcdef")}
	if err := sink.Apply(ctx, ev, cur); err != nil {
		t.Fatal(err)
	}
	var lastSeq, offset int64
	var draftDone, editDone int
	var eta *int
	read := func() {
		t.Helper()
		if err := s.pool.QueryRow(ctx, `select last_seq, last_offset from run_attempts where id = $1`,
			run.AttemptID).Scan(&lastSeq, &offset); err != nil {
			t.Fatal(err)
		}
		if err := s.pool.QueryRow(ctx, `select draft_done, edit_done, eta_seconds from runs where id = $1`,
			run.ID).Scan(&draftDone, &editDone, &eta); err != nil {
			t.Fatal(err)
		}
	}
	read()
	if lastSeq != 2 || offset != 128 || draftDone != 3 || editDone != 1 || eta == nil || *eta != 42 {
		t.Fatalf("after one event: seq=%d offset=%d draft=%d edit=%d eta=%v", lastSeq, offset, draftDone, editDone, eta)
	}
	// The same line again — the ordinary consequence of a reader restart.
	if err := sink.Apply(ctx, ev, cur); err != nil {
		t.Fatalf("a redelivered event was refused: %v", err)
	}
	before := draftDone
	read()
	if draftDone != before || lastSeq != 2 {
		t.Errorf("a duplicate moved something: draft %d→%d, seq %d", before, draftDone, lastSeq)
	}
	// The handshake's chunker version is what tells the platform its chapter numbering was produced
	// by a different chunker (row 100).
	var chunker string
	if err := s.pool.QueryRow(ctx, `select chunker_version from books where id='bk1'`).Scan(&chunker); err != nil {
		t.Fatal(err)
	}
	if chunker != "chunk-7" {
		t.Errorf("chunker version %q", chunker)
	}
}

// The high-water mark inside the transaction, pinned on the one effect that COUNTS.
//
// ⚠ Written after a mutation survived: the first version of this pin used a progress event, whose
// effect is an absolute assignment, so applying it twice produces the same row whether the guard is
// there or not. A `unit_done` increments, and that is where a redelivered line — the ordinary
// consequence of at-least-once delivery — turns into a chapter that reports more finished units than
// it has.
func TestARedeliveredCountingEventDoesNotCountTwice(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	exec(t, s, ctx, `insert into chapters (id, book_id, number, units_total) values ('c1','bk1',1,5)`)
	run, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", CeilingChapters: 10, Ceiling: money.MicroUSD(300_000), Now: now,
	}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	sink := s.NewRunSink(run.AttemptID, run.ID, "bk1")
	if err := sink.Begin(ctx, ingest.Hello{EngineRunID: "eng-1"}); err != nil {
		t.Fatal(err)
	}
	body, err := json.Marshal(ingest.UnitDone{Chapter: 1, Unit: 1, Wave: "edit", Shipped: true})
	if err != nil {
		t.Fatal(err)
	}
	ev := ingest.Envelope{Seq: 2, Type: ingest.TypeUnitDone, Data: body}
	cur := ingest.Cursor{Offset: 64}
	for range 3 {
		if err := sink.Apply(ctx, ev, cur); err != nil {
			t.Fatalf("a redelivered event was refused: %v", err)
		}
	}
	var editDone, unitsDone int
	if err := s.pool.QueryRow(ctx,
		`select units_edit_done, units_done from chapters where id='c1'`).Scan(&editDone, &unitsDone); err != nil {
		t.Fatal(err)
	}
	if editDone != 1 || unitsDone != 1 {
		t.Errorf("one unit delivered three times counted as %d edit / %d done", editDone, unitsDone)
	}
}

// The spend counter is CUMULATIVE, so the materializer keeps the maximum instead of adding: a
// redelivered line that was summed would inflate what the account is charged.
func TestSpendKeepsTheHighestFigureRatherThanASum(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", CeilingChapters: 10, Ceiling: money.MicroUSD(300_000), Now: now,
	}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	sink := s.NewRunSink(run.AttemptID, run.ID, "bk1")
	if err := sink.Begin(ctx, ingest.Hello{EngineRunID: "eng-1"}); err != nil {
		t.Fatal(err)
	}
	spend := func(seq int64, micro int64) {
		t.Helper()
		body, _ := json.Marshal(ingest.Spend{CommittedMicroUSD: micro})
		if err := sink.Apply(ctx, ingest.Envelope{Seq: seq, Type: ingest.TypeSpend, Data: body}, ingest.Cursor{Offset: seq * 10}); err != nil {
			t.Fatal(err)
		}
	}
	spend(2, 120_000)
	spend(3, 90_000) // an out-of-order or stale figure must not lower it either
	var got int64
	if err := s.pool.QueryRow(ctx, `select spend_micro_usd from run_attempts where id=$1`, run.AttemptID).Scan(&got); err != nil {
		t.Fatal(err)
	}
	if got != 120_000 {
		t.Errorf("spend %d, want the highest seen (120000)", got)
	}
}

// A ceiling halt is `paused` and never `failed` (contract §BookStatus): the stop is resumable, and
// calling it a failure lies about that.
func TestACeilingHaltPausesTheRunWithItsReason(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", CeilingChapters: 10, Ceiling: money.MicroUSD(300_000), Now: now,
	}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	sink := s.NewRunSink(run.AttemptID, run.ID, "bk1")
	if err := sink.Begin(ctx, ingest.Hello{EngineRunID: "eng-1"}); err != nil {
		t.Fatal(err)
	}
	body, _ := json.Marshal(ingest.Ceiling{Halted: true})
	if err := sink.Apply(ctx, ingest.Envelope{Seq: 2, Type: ingest.TypeCeiling, Data: body}, ingest.Cursor{Offset: 10}); err != nil {
		t.Fatal(err)
	}
	var status, reason string
	if err := s.pool.QueryRow(ctx, `select status, coalesce(paused_reason,'') from runs where id=$1`, run.ID).
		Scan(&status, &reason); err != nil {
		t.Fatal(err)
	}
	if status != "paused" || reason != PausedCreditExhausted {
		t.Errorf("after a ceiling halt: status=%q reason=%q", status, reason)
	}
}

// An interrupted run gets a NEW attempt with what is LEFT of its budget. Reserving the full ceiling
// again would let one run spend it twice.
func TestARestartedRunOnlyGetsTheBudgetItHasNotSpent(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", CeilingChapters: 100, Ceiling: money.MicroUSD(3_000_000), Now: now,
	}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	// The first attempt is settled at what the engine actually spent.
	if err := s.Settle(ctx, ReservationKey(run.ID, 1), money.MicroUSD(1_000_000), now); err != nil {
		t.Fatal(err)
	}
	spent, err := s.RunSpent(ctx, run.ID)
	if err != nil {
		t.Fatal(err)
	}
	if spent != money.MicroUSD(1_000_000) {
		t.Fatalf("run spend %s, want 1.000000", spent.USD())
	}
	next, err := s.RestartRun(ctx, RestartInput{
		RunID: run.ID, AttemptID: run.AttemptID, UserID: "u1", BookID: "bk1",
		Ceiling: money.MicroUSD(3_000_000) - spent, Offset: 512, Now: now,
	})
	if err != nil {
		t.Fatal(err)
	}
	if next.AttemptNo != 2 || next.Position.Offset != 512 {
		t.Fatalf("next attempt: %+v", next)
	}
	acct, err := s.ReadAccount(ctx, "u1")
	if err != nil {
		t.Fatal(err)
	}
	// $10 granted − $1 spent − $2 reserved for the new attempt.
	if acct.Balance != money.MicroUSD(7_000_000) || acct.Reserved != money.MicroUSD(2_000_000) {
		t.Fatalf("balance %s reserved %s", acct.Balance.USD(), acct.Reserved.USD())
	}
	live, err := s.ListLiveRuns(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if len(live) != 1 || live[0].AttemptNo != 2 {
		t.Fatalf("live runs after a restart: %+v", live)
	}
}

// Finishing is idempotent by refusal: the reconciler retries, and a second pass must not move a
// finished run or reopen its attempt.
func TestFinishingARunTwiceChangesNothingTheSecondTime(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", CeilingChapters: 10, Ceiling: money.MicroUSD(300_000), Now: now,
	}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	code := 0
	if _, err := s.FinishRun(ctx, run.ID, run.AttemptID, "ready", "success", &code, now); err != nil {
		t.Fatal(err)
	}
	later := now.Add(time.Hour)
	if _, err := s.FinishRun(ctx, run.ID, run.AttemptID, "failed", "exit-code", nil, later); err != nil {
		t.Fatal(err)
	}
	var status string
	var finished time.Time
	if err := s.pool.QueryRow(ctx, `select status, finished_at from runs where id=$1`, run.ID).Scan(&status, &finished); err != nil {
		t.Fatal(err)
	}
	if status != "ready" || !finished.Equal(now) {
		t.Errorf("a second finish rewrote the run: status=%q finished=%s", status, finished)
	}
	if _, err := s.ListLiveRuns(ctx); err != nil {
		t.Fatal(err)
	}
	var bookStatus string
	if err := s.pool.QueryRow(ctx, `select status from books where id='bk1'`).Scan(&bookStatus); err != nil {
		t.Fatal(err)
	}
	if bookStatus != "ready" {
		t.Errorf("book status %q", bookStatus)
	}
}

// The unsettled list is what keeps a hold from being reserved forever when the settlement figure
// could not be read.
func TestAFinishedRunWithAnOpenHoldIsListedAsUnsettled(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", CeilingChapters: 10, Ceiling: money.MicroUSD(300_000), Now: now,
	}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	code := 0
	if _, err := s.FinishRun(ctx, run.ID, run.AttemptID, "ready", "success", &code, now); err != nil {
		t.Fatal(err)
	}
	open, err := s.UnsettledRuns(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if len(open) != 1 || open[0].RunID != run.ID {
		t.Fatalf("unsettled: %+v", open)
	}
	if err := s.Settle(ctx, ReservationKey(run.ID, 1), money.MicroUSD(120_000), now); err != nil {
		t.Fatal(err)
	}
	if err := s.MarkSettled(ctx, run.ID, now); err != nil {
		t.Fatal(err)
	}
	open, err = s.UnsettledRuns(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if len(open) != 0 {
		t.Fatalf("a settled run is still listed: %+v", open)
	}
}

// Quarantine stops the PROJECTION and leaves the run alone: the engine is spending money the account
// already reserved, and our inability to read its journal is not a reason to throw that away.
func TestQuarantineStopsTheProjectionAndNotTheRun(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{
		UserID: "u1", BookID: "bk1", CeilingChapters: 10, Ceiling: money.MicroUSD(300_000), Now: now,
	}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	if err := s.Quarantine(ctx, run.AttemptID, "a seq was re-read with a different payload"); err != nil {
		t.Fatal(err)
	}
	live, err := s.ListLiveRuns(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if len(live) != 1 || !live[0].Quarantined {
		t.Fatalf("after quarantine: %+v", live)
	}
	// The first reason is kept: a later sweep must not overwrite why materialization stopped.
	if err := s.Quarantine(ctx, run.AttemptID, "something else"); err != nil {
		t.Fatal(err)
	}
	var reason string
	if err := s.pool.QueryRow(ctx, `select quarantine_reason from run_attempts where id=$1`, run.AttemptID).Scan(&reason); err != nil {
		t.Fatal(err)
	}
	if reason != "a seq was re-read with a different payload" {
		t.Errorf("quarantine reason was overwritten: %q", reason)
	}
}

// PD-82: a mistyped account id used to come back as "insufficient credit", which reads as "this
// account is broke" — the one answer an operator acts on differently.
func TestMoneyOperationsTellAMissingAccountFromAnEmptyOne(t *testing.T) {
	s, ctx := testDB(t)
	seedUser(t, s, ctx, "u1")
	seedBook(t, s, ctx, "bk1", "u1", 10)
	now := time.Now().UTC()
	if err := s.Hold(ctx, "nobody", "bk1", "r#1", money.MicroUSD(1), now); !errors.Is(err, ErrNoAccount) {
		t.Errorf("hold on a missing account gave %v, want ErrNoAccount", err)
	}
	if err := s.Hold(ctx, "u1", "bk1", "r#1", money.MicroUSD(1), now); !errors.Is(err, ErrInsufficientCredit) {
		t.Errorf("hold on an account with no credit gave %v, want ErrInsufficientCredit", err)
	}
}

// PD-81: with a LIVE reservation the second hold collides on the primary key, and the declared error
// was reachable only through a shape nobody produces. A worker cannot act on a raw SQLSTATE.
func TestASecondHoldOnALiveReservationIsADuplicateNotASqlstate(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 10)
	if err := s.Hold(ctx, "u1", "bk1", "r#1", money.MicroUSD(1_000_000), now); err != nil {
		t.Fatal(err)
	}
	err := s.Hold(ctx, "u1", "bk1", "r#1", money.MicroUSD(1_000_000), now)
	if !errors.Is(err, ErrDuplicateHold) {
		t.Fatalf("a second hold on a live reservation gave %v, want ErrDuplicateHold", err)
	}
	acct, err := s.ReadAccount(ctx, "u1")
	if err != nil {
		t.Fatal(err)
	}
	if acct.Reserved != money.MicroUSD(1_000_000) || acct.Balance != acct.LedgerSum {
		t.Errorf("the refused duplicate moved money: %+v", acct)
	}
}

// PD-97: the release of a hold used to discard whether it applied, so a spent release key closed the
// reservation and returned nothing — a silent no-op on the money path.
func TestAReleaseWhoseKeyWasSpentIsRefusedRatherThanSilent(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 10)
	if err := s.Hold(ctx, "u1", "bk1", "r#1", money.MicroUSD(1_000_000), now); err != nil {
		t.Fatal(err)
	}
	if err := s.Release(ctx, "r#1", now); err != nil {
		t.Fatal(err)
	}
	// The out-of-band sequence the register named: the reservation row is gone but the release key is
	// spent, and the same attempt id is opened again.
	if err := s.Hold(ctx, "u1", "bk1", "r#1", money.MicroUSD(1_000_000), now); !errors.Is(err, ErrDuplicateHold) {
		t.Fatalf("re-opening a spent attempt id gave %v", err)
	}
	// The surgery removes the reservation and the HOLD's ledger key while leaving the RELEASE key
	// spent — the state the register describes and no code path produces. The cached balance is
	// recomputed with it, or the fixture itself would break `balance == SUM(ledger)` and the
	// assertion below would be measuring the test rather than the code.
	exec(t, s, ctx, `delete from reservations where engine_run_id='r#1'`)
	exec(t, s, ctx, `delete from credit_ledger where source='run' and source_id='r#1'`)
	exec(t, s, ctx, `update account_balances b set balance_micro_usd =
	                   (select coalesce(sum(amount_micro_usd),0) from credit_ledger where user_id = b.user_id)`)
	if err := s.Hold(ctx, "u1", "bk1", "r#1", money.MicroUSD(1_000_000), now); err != nil {
		t.Fatal(err)
	}
	if err := s.Release(ctx, "r#1", now); !errors.Is(err, ErrReleaseKeySpent) {
		t.Fatalf("a release against a spent key gave %v, want ErrReleaseKeySpent", err)
	}
	// The refusal rolls the whole transaction back: the reservation stays OPEN and visible to an
	// operator, instead of being closed while the money never came back.
	acct, err := s.ReadAccount(ctx, "u1")
	if err != nil {
		t.Fatal(err)
	}
	if acct.Balance != acct.LedgerSum {
		t.Errorf("balance %s and ledger %s disagree after the refusal", acct.Balance.USD(), acct.LedgerSum.USD())
	}
	if acct.Reserved != money.MicroUSD(1_000_000) {
		t.Errorf("the reservation was closed by a release that returned nothing: reserved %s", acct.Reserved.USD())
	}
}

// Readiness has to cover the QUEUE's schema too: River keeps its own migration ledger, so goose's
// version says nothing about it, and an instance that answers "ready" and then cannot accept a run
// has told the load balancer a falsehood (the class of PD-68).
func TestReadinessCoversTheQueueSchema(t *testing.T) {
	s, ctx := testDB(t)
	if err := s.Ready(ctx); err != nil {
		t.Fatalf("a fully migrated database is not ready: %v", err)
	}
	if _, err := s.pool.Exec(ctx, `drop table river_job cascade`); err != nil {
		t.Fatal(err)
	}
	if err := s.Ready(ctx); !errors.Is(err, ErrSchemaBehind) {
		t.Fatalf("readiness without the queue schema gave %v, want ErrSchemaBehind", err)
	}
}

// The high-water mark has to hold under CONCURRENCY, not only under repetition. Three sequential
// deliveries are absorbed by the seq check alone; two SIMULTANEOUS ones are absorbed only by the row
// lock, and this is the direct analogue of TestConcurrentHoldsCannotOvercommitAnAccount on the
// credits side, which had no counterpart here.
func TestConcurrentDeliveriesOfOneEventCountItOnce(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	exec(t, s, ctx, `insert into chapters (id, book_id, number, units_total) values ('c1','bk1',1,50)`)
	run, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 10,
		Ceiling: money.MicroUSD(300_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	sink := s.NewRunSink(run.AttemptID, run.ID, "bk1")
	if err := sink.Begin(ctx, ingest.Hello{EngineRunID: "eng-1"}); err != nil {
		t.Fatal(err)
	}
	body, err := json.Marshal(ingest.UnitDone{Chapter: 1, Unit: 1, Wave: "edit", Shipped: true})
	if err != nil {
		t.Fatal(err)
	}
	ev := ingest.Envelope{Seq: 2, Type: ingest.TypeUnitDone, Data: body}
	var wg sync.WaitGroup
	for range 8 {
		wg.Add(1)
		go func() {
			defer wg.Done()
			_ = sink.Apply(ctx, ev, ingest.Cursor{Offset: 64})
		}()
	}
	wg.Wait()
	var done int
	if err := s.pool.QueryRow(ctx, `select units_edit_done from chapters where id='c1'`).Scan(&done); err != nil {
		t.Fatal(err)
	}
	if done != 1 {
		t.Errorf("one event delivered by eight goroutines counted as %d", done)
	}
}

// An attempt already bound to one engine run must refuse a different one: two engine processes
// writing into one journal under one attempt would mix two runs' counters into one projection.
func TestAnAttemptRefusesASecondEnginesHandshake(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 10,
		Ceiling: money.MicroUSD(300_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	sink := s.NewRunSink(run.AttemptID, run.ID, "bk1")
	if err := sink.Begin(ctx, ingest.Hello{EngineRunID: "eng-1"}); err != nil {
		t.Fatal(err)
	}
	if err := sink.Begin(ctx, ingest.Hello{EngineRunID: "eng-1"}); err != nil {
		t.Fatalf("re-reading our own handshake was refused: %v", err)
	}
	if err := sink.Begin(ctx, ingest.Hello{EngineRunID: "eng-2"}); err == nil {
		t.Error("a second engine rebound the attempt")
	}
	var bound string
	if err := s.pool.QueryRow(ctx, `select engine_run_id from run_attempts where id=$1`, run.AttemptID).Scan(&bound); err != nil {
		t.Fatal(err)
	}
	if bound != "eng-1" {
		t.Errorf("the attempt is bound to %q", bound)
	}
}

// RunSpent decides how much budget a restarted run has left, so it must count THIS run's settlements
// and nothing else: not another run's, and not the holds and releases that cancel out only while an
// attempt is balanced.
func TestRunSpentCountsOnlyThisRunsSettlements(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "20")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	seedBook(t, s, ctx, "bk2", "u1", 500)
	mine, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 100,
		Ceiling: money.MicroUSD(3_000_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	other, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk2", CeilingChapters: 100,
		Ceiling: money.MicroUSD(3_000_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	if err := s.Settle(ctx, ReservationKey(mine.ID, 1), money.MicroUSD(1_000_000), now); err != nil {
		t.Fatal(err)
	}
	if err := s.Settle(ctx, ReservationKey(other.ID, 1), money.MicroUSD(2_000_000), now); err != nil {
		t.Fatal(err)
	}
	got, err := s.RunSpent(ctx, mine.ID)
	if err != nil {
		t.Fatal(err)
	}
	if got != money.MicroUSD(1_000_000) {
		t.Errorf("RunSpent = %s, want 1.000000 — another run's settlement leaked in", got.USD())
	}
	// An OPEN hold is not spend. This is the reachable case: settlement deferred, the hold still open,
	// and counting it would overstate the spend by the whole ceiling and pause a run with budget left.
	seedBook(t, s, ctx, "bk3", "u1", 500)
	third, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk3", CeilingChapters: 50,
		Ceiling: money.MicroUSD(1_500_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	if got, err = s.RunSpent(ctx, third.ID); err != nil || got != 0 {
		t.Errorf("a run with an open hold and no settlement reports %s spent (%v)", got.USD(), err)
	}
}

// The settlement worklist must contain only money that is still reserved, and the settled stamp must
// be written once: a second stamp with a later clock would rewrite when the money resolved.
func TestTheSettlementWorklistAndItsStampAreBothIdempotent(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 10,
		Ceiling: money.MicroUSD(300_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	code := 0
	if _, err := s.FinishRun(ctx, run.ID, run.AttemptID, "ready", "success", &code, now); err != nil {
		t.Fatal(err)
	}
	if err := s.Settle(ctx, ReservationKey(run.ID, 1), money.MicroUSD(100_000), now); err != nil {
		t.Fatal(err)
	}
	open, err := s.UnsettledRuns(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if len(open) != 0 {
		t.Errorf("a run whose reservation is closed is still on the worklist: %+v", open)
	}
	if err := s.MarkSettled(ctx, run.ID, now); err != nil {
		t.Fatal(err)
	}
	later := now.Add(time.Hour)
	if err := s.MarkSettled(ctx, run.ID, later); err != nil {
		t.Fatal(err)
	}
	var at time.Time
	if err := s.pool.QueryRow(ctx, `select settled_at from runs where id=$1`, run.ID).Scan(&at); err != nil {
		t.Fatal(err)
	}
	if !at.Equal(now) {
		t.Errorf("the settled stamp was rewritten: %s, want %s", at, now)
	}
}

// A hold that debited NOTHING must be refused. The ordinary duplicate collides on the reservation's
// primary key one level up; this is the other shape — the reservation row gone and the ledger key
// spent — which is what a book deletion leaves behind for CLOSED reservations.
func TestAHoldThatDebitedNothingIsRefused(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	if err := s.Hold(ctx, "u1", "bk1", "r#1", money.MicroUSD(1_000_000), now); err != nil {
		t.Fatal(err)
	}
	before, err := s.ReadAccount(ctx, "u1")
	if err != nil {
		t.Fatal(err)
	}
	exec(t, s, ctx, `delete from reservations where engine_run_id='r#1'`)
	err = s.Hold(ctx, "u1", "bk1", "r#1", money.MicroUSD(1_000_000), now)
	if !errors.Is(err, ErrDuplicateHold) {
		t.Fatalf("a hold against a spent ledger key gave %v, want ErrDuplicateHold", err)
	}
	after, err := s.ReadAccount(ctx, "u1")
	if err != nil {
		t.Fatal(err)
	}
	if after.Balance != before.Balance {
		t.Errorf("the refused hold moved the balance: %s → %s", before.Balance.USD(), after.Balance.USD())
	}
}

// The byte hint is monotone: a stale sweep must not walk it back and re-read applied lines forever.
func TestTheByteHintNeverGoesBackwards(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 10,
		Ceiling: money.MicroUSD(300_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	if err := s.SaveCursor(ctx, run.AttemptID, Position{Offset: 1000}); err != nil {
		t.Fatal(err)
	}
	if err := s.SaveCursor(ctx, run.AttemptID, Position{Offset: 100}); err != nil {
		t.Fatal(err)
	}
	var got int64
	if err := s.pool.QueryRow(ctx, `select last_offset from run_attempts where id=$1`, run.AttemptID).Scan(&got); err != nil {
		t.Fatal(err)
	}
	if got != 1000 {
		t.Errorf("the byte hint went back to %d", got)
	}
}

// The store's own guard on the chapter ceiling, and the pause vocabulary: both are values the API
// layer also checks, and both must be refused here too — the store is what the reconciler calls.
func TestTheStoreRefusesAnImpossibleCeilingAndAnUnknownPauseReason(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	for _, n := range []int{0, -5} {
		if _, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: n,
			Ceiling: money.MicroUSD(300_000), Now: now}, 0, nil); err == nil {
			t.Errorf("a ceiling of %d chapters was accepted", n)
		}
	}
	var runs int
	if err := s.pool.QueryRow(ctx, `select count(*) from runs`).Scan(&runs); err != nil {
		t.Fatal(err)
	}
	if runs != 0 {
		t.Errorf("a refused start left %d run rows", runs)
	}
	run, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 10,
		Ceiling: money.MicroUSD(300_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	if err := s.PauseRun(ctx, run.ID, run.AttemptID, "because", now); err == nil {
		t.Error("an unknown pause reason was accepted; the contract enumerates them")
	}
}

// Only ONE sweep may restart an interrupted attempt: two that both succeeded would each open a next
// attempt and each take a hold.
func TestOnlyOneSweepCanRestartAnInterruptedAttempt(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 100,
		Ceiling: money.MicroUSD(3_000_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	if err := s.Settle(ctx, ReservationKey(run.ID, 1), money.MicroUSD(500_000), now); err != nil {
		t.Fatal(err)
	}
	in := RestartInput{RunID: run.ID, AttemptID: run.AttemptID, UserID: "u1", BookID: "bk1",
		Ceiling: money.MicroUSD(1_000_000), Now: now}
	var wg sync.WaitGroup
	results := make([]error, 4)
	for i := range results {
		wg.Add(1)
		go func() {
			defer wg.Done()
			_, results[i] = s.RestartRun(ctx, in)
		}()
	}
	wg.Wait()
	won := 0
	for _, err := range results {
		if err == nil {
			won++
		}
	}
	if won != 1 {
		t.Fatalf("%d of four concurrent restarts succeeded, want exactly 1", won)
	}
	var attempts int
	if err := s.pool.QueryRow(ctx, `select count(*) from run_attempts where run_id=$1`, run.ID).Scan(&attempts); err != nil {
		t.Fatal(err)
	}
	if attempts != 2 {
		t.Errorf("%d attempts after four concurrent restarts", attempts)
	}
}

// Cross-family review of the acceptance dofix (M1): a pause is a CLOSING path, and every closing path
// must check that the attempt it closes is still a live attempt of this run. `FinishRun` and
// `FinishUnspawnedStop` do; `PauseRun` did not, so a pass holding a snapshot of the attempt that was
// already restarted answered "the credit ran out" for a run whose second attempt is spending right
// now — and that second hold then belongs to no list at all.
func TestAPauseFromAnOldSnapshotDoesNotCloseARunOverALiveAttempt(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	run, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 100,
		Ceiling: money.MicroUSD(3_000_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	if err := s.Settle(ctx, ReservationKey(run.ID, 1), money.MicroUSD(500_000), now); err != nil {
		t.Fatal(err)
	}
	next, err := s.RestartRun(ctx, RestartInput{RunID: run.ID, AttemptID: run.AttemptID, UserID: "u1",
		BookID: "bk1", Ceiling: money.MicroUSD(1_000_000), Now: now})
	if err != nil {
		t.Fatal(err)
	}
	if err := s.PauseRun(ctx, run.ID, run.AttemptID, PausedCreditExhausted, now); err != nil {
		t.Fatal(err)
	}
	var status string
	var finished *time.Time
	if err := s.pool.QueryRow(ctx,
		`select status, finished_at from runs where id = $1`, run.ID).Scan(&status, &finished); err != nil {
		t.Fatal(err)
	}
	if finished != nil {
		t.Fatalf("a stale pause closed the run as %q while attempt %d is live", status, next.AttemptID)
	}
	var ended *time.Time
	if err := s.pool.QueryRow(ctx,
		`select ended_at from run_attempts where id = $1`, next.AttemptID).Scan(&ended); err != nil {
		t.Fatal(err)
	}
	if ended != nil {
		t.Fatal("a stale pause ended the LIVE attempt")
	}
	// The money half of the same fact: the live attempt's hold must be findable. A closed run with an
	// open hold is in neither list — not in the live runs (the run is finished) and not in the
	// unsettled ones (the attempt is not) — which is how a hold is lost for good.
	live, err := s.ListLiveRuns(ctx)
	if err != nil {
		t.Fatal(err)
	}
	found := false
	for _, l := range live {
		if l.AttemptID == next.AttemptID {
			found = true
		}
	}
	if !found {
		t.Fatalf("the live attempt %d is not in ListLiveRuns after a stale pause", next.AttemptID)
	}
}

// Re-check of the dofix (FP5-11): the rule the intake writers got — take the LIBRARY's next number,
// not your own plus one — has to hold for the run's writers too. A book that is not the account's
// newest carries a counter below the library's, so `translating`, `paused` and `stopped` on it left
// `greatest(max, floor)` exactly where it was and the library screen never saw the run start.
func TestARunTransitionOnAnOlderBookStillMovesTheLibrary(t *testing.T) {
	s, ctx := testDB(t)
	now := fundedAccount(t, s, ctx, "u1", "10")
	seedBook(t, s, ctx, "bk1", "u1", 500)
	// A second, NEWER book carries the library's maximum, so bk1's own counter is not it.
	seedBook(t, s, ctx, "bk2", "u1", 500)
	exec(t, s, ctx, `update books set revision = 41 where id = 'bk2'`)
	before, err := s.ListBooks(ctx, "u1", 50, "")
	if err != nil {
		t.Fatal(err)
	}
	run, err := s.StartRun(ctx, StartRunInput{UserID: "u1", BookID: "bk1", CeilingChapters: 10,
		Ceiling: money.MicroUSD(300_000), Now: now}, 0, nil)
	if err != nil {
		t.Fatal(err)
	}
	after, err := s.ListBooks(ctx, "u1", 50, "")
	if err != nil {
		t.Fatal(err)
	}
	if after.Revision <= before.Revision {
		t.Fatalf("a run started on an older book and the library still answers %d (was %d): a client "+
			"obeying the contract drops that read and never sees the book start translating",
			after.Revision, before.Revision)
	}
	// And the same for the closing half of the lifecycle.
	mid := after.Revision
	if err := s.PauseRun(ctx, run.ID, run.AttemptID, PausedCreditExhausted, now); err != nil {
		t.Fatal(err)
	}
	end, err := s.ListBooks(ctx, "u1", 50, "")
	if err != nil {
		t.Fatal(err)
	}
	if end.Revision <= mid {
		t.Fatalf("the run was paused and the library still answers %d (was %d)", end.Revision, mid)
	}
}