package catalogue

import (
	"strings"
	"testing"
)

// **A seat's holder on record settles who holds it, and lets the next holder stand beside the
// current one** (novox/hq ADR 0131, design 28 task 5.3). Until the record existed, two assignments
// whose modules both claimed a seat were refused outright — which left no way to hand a seat over
// without a moment where nobody held it, and the control plane finds its own bus through one of
// these seats. That moment was the outage of 2026-09-27.

func busSeatDelivering(t *testing.T, delivers string) {
	t.Helper()
	was := Seats()
	t.Cleanup(func() { UseSeats(was) })
	UseSeats([]Seat{{Name: "mesh-broker", Scope: ScopeMesh, Delivers: delivers, Decision: "test"}})
}

func oldBroker() Manifest {
	return Manifest{Module: "old-broker", Provides: []Offer{{Name: "mesh-bus", Scope: ScopeMesh}},
		Claims: []Claim{{Name: "mesh-broker", Scope: ScopeMesh}}}
}

func newBroker() Manifest {
	return Manifest{Module: "new-broker", Provides: []Offer{{Name: "mesh-bus", Scope: ScopeMesh}},
		Claims: []Claim{{Name: "mesh-broker", Scope: ScopeMesh}}}
}

// Nothing on record: exactly the old rule. One claimant holds; two are refused.
func TestWithNoHolderOnRecordTheSoleClaimantHoldsAndTwoAreRefused(t *testing.T) {
	busSeatDelivering(t, "mesh-bus")
	node := Node{Name: "anchor"}

	held, problems := checkClaims([]Manifest{oldBroker()}, node, nil, nil)
	if len(problems) != 0 || len(held) != 1 || held[0].Module != "old-broker" {
		t.Fatalf("a sole claimant did not hold the seat: held=%v problems=%v", held, problems)
	}
	_, problems = checkClaims([]Manifest{oldBroker(), newBroker()}, node, nil, nil)
	if len(problems) != 1 || !strings.Contains(problems[0], "both claim") {
		t.Fatalf("two claimants with nothing on record were not refused: %v", problems)
	}
}

// With a holder on record, the other eligible assignment is silent: not refused, and not holding.
func TestTheHolderOnRecordHoldsAndTheOtherClaimantStandsBesideIt(t *testing.T) {
	busSeatDelivering(t, "mesh-bus")
	node := Node{Name: "anchor"}
	record := []Held{{Claim: "mesh-broker", Scope: ScopeMesh, Node: "anchor", Module: "new-broker"}}

	held, problems := checkClaims([]Manifest{oldBroker(), newBroker()}, node, nil, record)
	if len(problems) != 0 {
		t.Fatalf("the assignment beside the holder was refused: %v", problems)
	}
	if len(held) != 1 || held[0].Module != "new-broker" {
		t.Fatalf("the holder on record is not the one holding: %v", held)
	}
}

// The record names a node too: an eligible module on another machine holds nothing, and its
// machine's set still resolves.
func TestAHolderOnRecordElsewhereLeavesThisMachinesClaimantSilent(t *testing.T) {
	busSeatDelivering(t, "mesh-bus")
	record := []Held{{Claim: "mesh-broker", Scope: ScopeMesh, Node: "anchor", Module: "new-broker"}}

	held, problems := checkClaims([]Manifest{oldBroker()}, Node{Name: "laptop"}, nil, record)
	if len(problems) != 0 || len(held) != 0 {
		t.Fatalf("a claimant elsewhere than the recorded holder was not simply silent: held=%v problems=%v",
			held, problems)
	}
}

// A record naming a seat's former name still applies to it after a rename (ADR 0122).
func TestAHolderRecordedUnderAFormerNameStillHolds(t *testing.T) {
	busSeatDelivering(t, "mesh-bus")
	wasAliases := aliases
	t.Cleanup(func() { UseAliases(wasAliases) })
	UseAliases(map[string]string{"the-broker": "mesh-broker"})
	record := []Held{{Claim: "the-broker", Scope: ScopeMesh, Node: "anchor", Module: "new-broker"}}

	held, problems := checkClaims([]Manifest{oldBroker(), newBroker()}, Node{Name: "anchor"}, nil, record)
	if len(problems) != 0 || len(held) != 1 || held[0].Module != "new-broker" {
		t.Fatalf("a record under the former name did not settle the seat: held=%v problems=%v", held, problems)
	}
}

// CanHold is the one judgement registration and the handover share, against the store's row.
func TestCanHoldJudgesClaimScopeAndWhatTheSeatDelivers(t *testing.T) {
	busSeatDelivering(t, "mesh-bus")
	seat, _ := SeatNamed("mesh-broker")

	if err := CanHold(newBroker(), seat); err != nil {
		t.Fatalf("a module that claims the seat and provides what it delivers was refused: %v", err)
	}
	noClaim := Manifest{Module: "quiet", Provides: []Offer{{Name: "mesh-bus", Scope: ScopeMesh}}}
	if err := CanHold(noClaim, seat); err == nil || !strings.Contains(err.Error(), "does not claim") {
		t.Fatalf("a module that never claimed the seat was allowed to hold it: %v", err)
	}
	wrongScope := newBroker()
	wrongScope.Claims[0].Scope = ScopeNode
	if err := CanHold(wrongScope, seat); err == nil || !strings.Contains(err.Error(), "scope") {
		t.Fatalf("a claim at the wrong scope was allowed: %v", err)
	}
	cannotAnswer := Manifest{Module: "amqp-only", Provides: []Offer{{Name: "amqp", Scope: ScopeMesh}},
		Claims: []Claim{{Name: "mesh-broker", Scope: ScopeMesh}}}
	if err := CanHold(cannotAnswer, seat); err == nil || !strings.Contains(err.Error(), `does not provide "mesh-bus"`) {
		t.Fatalf("a holder that cannot answer for the seat was allowed: %v", err)
	}
	// And the judgement follows the store's row, not a compiled copy.
	busSeatDelivering(t, "amqp")
	seat, _ = SeatNamed("mesh-broker")
	if err := CanHold(cannotAnswer, seat); err != nil {
		t.Fatalf("with the row saying amqp, an amqp provider was refused: %v", err)
	}
}