package tools

import (
	"context"
	"errors"
	"strings"
	"testing"
	"time"

	"nearle/models"
)

const cardSecret = "a-test-signing-key-long-enough"

// writingApprovals records every write, so a test can assert that nothing
// happened as easily as that something did.
type writingApprovals struct {
	fakeApprovals
	wrote  []int
	status string
	err    error
}

func (w *writingApprovals) UpdateStockRequest(requestID int, status string) error {
	if w.err != nil {
		return w.err
	}
	w.wrote = append(w.wrote, requestID)
	w.status = status
	return nil
}

func pendingRequest(id, qty int, product, branch string) models.StockRequest {
	return models.StockRequest{
		Requestid: id, Qty: qty, Productname: product, Locationname: branch,
		Status: "Pending", Created: time.Date(2026, 9, 20, 9, 0, 0, 0, time.UTC),
	}
}

func approvalSetup(t *testing.T, rows ...models.StockRequest) (*Registry, *writingApprovals, Agent) {
	t.Helper()
	t.Setenv("POS_TOKEN_SECRET", cardSecret)

	store := &writingApprovals{}
	store.rows = rows
	r := New(nil)
	if err := r.Register(ApproveStockRequest(store, store)); err != nil {
		t.Fatalf("registering: %v", err)
	}
	return r, store, Agent{Name: "inventory", Tools: []string{"approve_stock_request"}}
}

var owner = Caller{Userid: 904, Tenantid: 1147}

// propose runs the model's half and returns the card.
func propose(t *testing.T, r *Registry, agent Agent, id int, caller Caller) (Proposal, error) {
	t.Helper()
	result, err := r.Call(context.Background(), agent, "approve_stock_request",
		map[string]any{"requestid": id}, caller)
	if err != nil {
		return Proposal{}, err
	}
	proposal, ok := result.Rows.(Proposal)
	if !ok {
		t.Fatalf("a write returned %T, not a proposal", result.Rows)
	}
	return proposal, nil
}

/* ── Nothing auto-executes ─────────────────────────────────────────────── */

func TestAskingForAWriteChangesNothing(t *testing.T) {
	// The whole phase in one test. The model asked; the database did not move.
	r, store, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))

	proposal, err := propose(t, r, agent, 41, owner)
	if err != nil {
		t.Fatalf("proposing: %v", err)
	}
	if len(store.wrote) != 0 {
		t.Fatalf("a write happened on the model's say so: %v", store.wrote)
	}
	if proposal.Card == "" {
		t.Fatal("no card came back, so nothing can be approved")
	}
}

func TestTheModelIsToldItHasNotDoneTheThing(t *testing.T) {
	// Without this it reports the action in the past tense, and the person
	// believes it.
	r, _, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))

	result, err := r.Call(context.Background(), agent, "approve_stock_request",
		map[string]any{"requestid": 41}, owner)
	if err != nil {
		t.Fatalf("proposing: %v", err)
	}
	note := strings.ToLower(result.Note)
	if !strings.Contains(note, "not been done") || !strings.Contains(note, "do not say it is done") {
		t.Fatalf("the model was not told to hold off: %q", result.Note)
	}
}

func TestAWriteToolCannotBeBuiltWithAPlainHandler(t *testing.T) {
	// The structural half: there is no shape of Tool a caller can construct
	// that writes when the model asks for it.
	r := New(nil)
	err := r.Register(Tool{
		Name: "sneaky", Description: strings.Repeat("a write pretending to be ordinary ", 3),
		Scope: ScopeWrite,
		Handler: func(context.Context, Request) (Result, error) {
			t.Fatal("a hand-built write tool ran")
			return Result{}, nil
		},
	})
	if err == nil {
		t.Fatal("a write tool was registered without a propose/execute pair")
	}
}

/* ── Approving ─────────────────────────────────────────────────────────── */

func TestAnApprovedCardPerformsTheWriteExactlyOnce(t *testing.T) {
	r, store, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))
	proposal, _ := propose(t, r, agent, 41, owner)

	result, err := r.Approve(context.Background(), agent, proposal.Card, owner)
	if err != nil {
		t.Fatalf("approving: %v", err)
	}
	if len(store.wrote) != 1 || store.wrote[0] != 41 {
		t.Fatalf("the write did not happen as expected: %v", store.wrote)
	}
	if store.status != "Approved" {
		t.Fatalf("wrote status %q — the column expects the capitalised word", store.status)
	}
	if result.Count != 1 {
		t.Fatalf("the result does not describe the change: %+v", result)
	}
}

func TestAnUnapprovedCardIsTheOnlyWayInAndAForgedOneFails(t *testing.T) {
	r, store, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))

	for _, forged := range []string{
		"", "c1.", "c1.rubbish.signature", "not-a-card",
		"c1.eyJ0IjoiYXBwcm92ZV9zdG9ja19yZXF1ZXN0In0.wrongsignature",
	} {
		if _, err := r.Approve(context.Background(), agent, forged, owner); err == nil {
			t.Fatalf("a forged card was accepted: %q", forged)
		}
	}
	if len(store.wrote) != 0 {
		t.Fatalf("a forged card wrote something: %v", store.wrote)
	}
}

func TestACardIsNotTransferable(t *testing.T) {
	// Without this, one person's approval could be replayed by another —
	// including somebody in a different shop.
	r, store, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))
	proposal, _ := propose(t, r, agent, 41, owner)

	someoneElse := Caller{Userid: 905, Tenantid: 1147}
	if _, err := r.Approve(context.Background(), agent, proposal.Card, someoneElse); !errors.Is(err, ErrNotYourCard) {
		t.Fatalf("another user approved somebody else's card: %v", err)
	}

	anotherShop := Caller{Userid: 904, Tenantid: 916}
	if _, err := r.Approve(context.Background(), agent, proposal.Card, anotherShop); !errors.Is(err, ErrNotYourCard) {
		t.Fatalf("another shop approved this card: %v", err)
	}

	if len(store.wrote) != 0 {
		t.Fatalf("a transferred card wrote something: %v", store.wrote)
	}
}

func TestApprovalDoesNotCarryForward(t *testing.T) {
	// Approving one request is not consent for the next. A second card has to
	// be resolved and approved on its own.
	r, store, agent := approvalSetup(t,
		pendingRequest(41, 12, "Rice", "R Mart"),
		pendingRequest(42, 3, "Oil", "R Mart"))

	first, _ := propose(t, r, agent, 41, owner)
	if _, err := r.Approve(context.Background(), agent, first.Card, owner); err != nil {
		t.Fatalf("approving: %v", err)
	}
	if len(store.wrote) != 1 || store.wrote[0] != 41 {
		t.Fatalf("approving one request touched another: %v", store.wrote)
	}
}

/* ── Re-validated at execution ─────────────────────────────────────────── */

func TestACardApprovedTwiceDoesNotWriteTwice(t *testing.T) {
	// A signed card carries no nonce. Replay is refused where it belongs —
	// against the live database, which no longer has the request pending.
	r, store, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))
	proposal, _ := propose(t, r, agent, 41, owner)

	if _, err := r.Approve(context.Background(), agent, proposal.Card, owner); err != nil {
		t.Fatalf("first approval: %v", err)
	}
	// The request is no longer pending, exactly as the database would report.
	store.rows = nil

	if _, err := r.Approve(context.Background(), agent, proposal.Card, owner); err == nil {
		t.Fatal("the same card wrote a second time")
	}
	if len(store.wrote) != 1 {
		t.Fatalf("the write happened %d times", len(store.wrote))
	}
}

func TestACardExpires(t *testing.T) {
	// A card resolved against a shop half an hour ago is a card about a shop
	// that has moved on.
	r, _, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))
	proposal, _ := propose(t, r, agent, 41, owner)

	r.now = func() time.Time { return time.Now().Add(2 * CardExpiryForTests) }
	if _, err := r.Approve(context.Background(), agent, proposal.Card, owner); err == nil {
		t.Fatal("an expired card was approved")
	}
}

func TestAFailedWriteIsReportedNotSwallowed(t *testing.T) {
	r, store, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))
	proposal, _ := propose(t, r, agent, 41, owner)
	store.err = errors.New("the database is down")

	if _, err := r.Approve(context.Background(), agent, proposal.Card, owner); err == nil {
		t.Fatal("a failed write reported success")
	}
}

/* ── Ownership is re-derived, never compared ───────────────────────────── */

func TestARequestFromAnotherShopIsNotFound(t *testing.T) {
	// The lookup is scoped to the caller's tenant, so another merchant's id is
	// simply absent. "Not found" and "not yours" are deliberately the same
	// message — distinguishing them would make this a way to ask whether an id
	// exists somewhere else on the platform.
	r, store, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))

	if _, err := propose(t, r, agent, 999, owner); err == nil {
		t.Fatal("a request that is not this shop's was resolved")
	}
	if len(store.wrote) != 0 {
		t.Fatalf("something was written: %v", store.wrote)
	}
}

func TestTheModelCannotNameAShop(t *testing.T) {
	tool := ApproveStockRequest(&writingApprovals{}, &writingApprovals{})
	for _, field := range tool.Schema.Fields {
		if scopingArguments[strings.ToLower(field.Name)] {
			t.Fatalf("the write offers %q for the model to set", field.Name)
		}
	}
}

/* ── What the person sees ──────────────────────────────────────────────── */

func TestTheCardShowsWhatWasResolvedNotWhatWasAsked(t *testing.T) {
	// A person approving "approve this request" must see which request, from
	// which branch, for what — the sentence and the action are produced by
	// different things and only one of them is checkable.
	r, _, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))
	proposal, _ := propose(t, r, agent, 41, owner)

	if !strings.Contains(proposal.Summary, "Rice") || !strings.Contains(proposal.Summary, "R Mart") {
		t.Fatalf("the summary names nothing checkable: %q", proposal.Summary)
	}

	labels := map[string]string{}
	for _, detail := range proposal.Details {
		labels[detail.Label] = detail.Value
	}
	if labels["Request"] != "#41" {
		t.Fatalf("the card does not name the request by id: %+v", proposal.Details)
	}
	for _, want := range []string{"Product", "Quantity", "Branch"} {
		if labels[want] == "" {
			t.Fatalf("the card is missing %q: %+v", proposal.Details, want)
		}
	}
}

func TestAnUnusualQuantityIsFlaggedAndAnOrdinaryOneIsNot(t *testing.T) {
	// A warning on every card is a warning on none.
	r, _, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))
	ordinary, _ := propose(t, r, agent, 41, owner)
	if ordinary.Warning != "" {
		t.Fatalf("an ordinary request was flagged: %q", ordinary.Warning)
	}

	r2, _, agent2 := approvalSetup(t, pendingRequest(42, 9000, "Rice", "R Mart"))
	large, _ := propose(t, r2, agent2, 42, owner)
	if large.Warning == "" {
		t.Fatal("nine thousand units passed without comment")
	}
}

/* ── The audit trail ───────────────────────────────────────────────────── */

func TestAnApprovalIsRecordedBeforeTheWriteLeaves(t *testing.T) {
	// A crash mid-write has to leave a trace that it was attempted. A row
	// written only on success is missing exactly when it is needed.
	t.Setenv("POS_TOKEN_SECRET", cardSecret)
	audit := &CollectAudit{}
	store := &writingApprovals{}
	store.rows = []models.StockRequest{pendingRequest(41, 12, "Rice", "R Mart")}
	store.err = errors.New("the database died mid-write")

	r := New(audit)
	_ = r.Register(ApproveStockRequest(store, store))
	agent := Agent{Name: "inventory", Tools: []string{"approve_stock_request"}}

	proposal, _ := propose(t, r, agent, 41, owner)
	_, _ = r.Approve(context.Background(), agent, proposal.Card, owner)

	var sawApproved, sawFailed bool
	for _, entry := range audit.Entries {
		if entry.Outcome == "approved" {
			sawApproved = true
		}
		if entry.Outcome == OutcomeFailed {
			sawFailed = true
		}
	}
	if !sawApproved {
		t.Fatal("a write that died left no record that it was attempted")
	}
	if !sawFailed {
		t.Fatal("the failure itself was not recorded")
	}
}

func TestARejectedCardLeavesNoSideEffect(t *testing.T) {
	// Rejection is the console never calling Approve. Nothing to undo, nothing
	// half-written — and the proposal itself is still in the trail.
	t.Setenv("POS_TOKEN_SECRET", cardSecret)
	audit := &CollectAudit{}
	store := &writingApprovals{}
	store.rows = []models.StockRequest{pendingRequest(41, 12, "Rice", "R Mart")}

	r := New(audit)
	_ = r.Register(ApproveStockRequest(store, store))
	agent := Agent{Name: "inventory", Tools: []string{"approve_stock_request"}}

	if _, err := propose(t, r, agent, 41, owner); err != nil {
		t.Fatalf("proposing: %v", err)
	}

	if len(store.wrote) != 0 {
		t.Fatalf("an unapproved proposal wrote something: %v", store.wrote)
	}
	last, _ := audit.Last()
	if last.Outcome != "proposed" {
		t.Fatalf("the proposal is not in the trail: %+v", last)
	}
}

/* ── The allow-list still applies at approval ──────────────────────────── */

func TestACardCannotOutliveAnAgentLosingTheTool(t *testing.T) {
	r, store, agent := approvalSetup(t, pendingRequest(41, 12, "Rice", "R Mart"))
	proposal, _ := propose(t, r, agent, 41, owner)

	narrowed := Agent{Name: "inventory", Tools: []string{"low_stock"}}
	if _, err := r.Approve(context.Background(), narrowed, proposal.Card, owner); !errors.Is(err, ErrNotAllowed) {
		t.Fatalf("a card was a way around the allow-list: %v", err)
	}
	if len(store.wrote) != 0 {
		t.Fatalf("something was written: %v", store.wrote)
	}
}