package recovery

import (
	"context"
	"log"
	"os"
	"path/filepath"
	"strconv"
	"testing"
	"time"

	"git.k6n.net/mats/go-cart-actor/pkg/actor"
	"git.k6n.net/mats/go-cart-actor/pkg/cart"
	messages "git.k6n.net/mats/go-cart-actor/proto/cart"
	"google.golang.org/protobuf/proto"
)

// writeFixtureLog writes a synthetic `<id>.events.log` to dir with the given
// mutations, then pins the file's mtime AFTER Close so the canonical
// DiskStorage.SaveLoop flush can't overwrite it on test machines that run
// the inner save() during teardown.
func writeFixtureLog(t *testing.T, dir string, id uint64, mtime time.Time, muts []proto.Message) {
	t.Helper()
	path := filepath.Join(dir, strconv.FormatUint(id, 10)+".events.log")

	reg := cart.NewCartMultationRegistry(cart.NewCartMutationContext(nil))
	storage := actor.NewDiskStorage[cart.CartGrain](dir, reg)
	if err := storage.AppendMutations(id, muts...); err != nil {
		t.Fatalf("AppendMutations for fixture %d: %v", id, err)
	}
	// DiskStorage.Close runs save() which opens+appends the file; that
	// updates mtime. Pin AFTER Close so the test mtime wins.
	storage.Close()
	if err := os.Chtimes(path, mtime, mtime); err != nil {
		t.Fatalf("Chtimes %s: %v", path, err)
	}
}

// silenceLogs redirects the standard logger while the scanner runs so test
// output stays readable.
func silenceLogs(t *testing.T) {
	t.Helper()
	orig := log.Writer()
	prevFlags := log.Flags()
	log.SetOutput(devNull{})
	log.SetFlags(0)
	t.Cleanup(func() {
		log.SetOutput(orig)
		log.SetFlags(prevFlags)
	})
}

type devNull struct{}

func (devNull) Write(p []byte) (int, error) { return len(p), nil }

func TestScanner_FindsCandidateInWindow(t *testing.T) {
	silenceLogs(t)
	dir := t.TempDir()
	now := time.Date(2026, 7, 1, 12, 0, 0, 0, time.UTC)

	reg := cart.NewCartMultationRegistry(cart.NewCartMutationContext(nil))
	storage := actor.NewDiskStorage[cart.CartGrain](dir, reg)

	// Cart that became eligible exactly in the middle of the window:
	// delay 1h, window 1h → eligible mtime ∈ [now-2h, now-1h].
	mtime := now.Add(-90 * time.Minute)
	writeFixtureLog(t, dir, 42, mtime, []proto.Message{
		&messages.AddItem{ItemId: 1, Quantity: 1, Price: 1000, Sku: "A"},
		&messages.SetRecoveryContact{Email: "abandoned@example.com"},
	})
	defer storage.Close()

	scanner := NewScanner(dir, storage)
	got, err := scanner.Scan(context.Background(), time.Hour, time.Hour, now)
	if err != nil {
		t.Fatalf("Scan: %v", err)
	}
	if len(got) != 1 {
		t.Fatalf("candidates = %d, want 1; full result=%+v", len(got), got)
	}
	c := got[0]
	if c.CartID != cart.CartId(42) {
		t.Errorf("CartID = %d, want 42", c.CartID)
	}
	if c.Email != "abandoned@example.com" {
		t.Errorf("Email = %q, want abandoned@example.com", c.Email)
	}
	if c.ItemCount != 1 {
		t.Errorf("ItemCount = %d, want 1", c.ItemCount)
	}
	if c.TotalIncVat != 1000 {
		t.Errorf("TotalIncVat = %d, want 1000 (AddItem price 1000)", c.TotalIncVat)
	}
}

func TestScanner_SkipsCartsOutsideWindow(t *testing.T) {
	silenceLogs(t)
	dir := t.TempDir()
	now := time.Date(2026, 7, 1, 12, 0, 0, 0, time.UTC)

	reg := cart.NewCartMultationRegistry(cart.NewCartMutationContext(nil))
	storage := actor.NewDiskStorage[cart.CartGrain](dir, reg)

	// Too fresh (mtime = now-30m, inside the 1h "still active" cutoff).
	fresh := now.Add(-30 * time.Minute)
	writeFixtureLog(t, dir, 7, fresh, []proto.Message{
		&messages.AddItem{ItemId: 1, Quantity: 1, Price: 1000},
		&messages.SetRecoveryContact{Email: "fresh@example.com"},
	})
	// Too old (mtime = now-25h, past the 2h window upper bound).
	old := now.Add(-25 * time.Hour)
	writeFixtureLog(t, dir, 8, old, []proto.Message{
		&messages.AddItem{ItemId: 1, Quantity: 1, Price: 1000},
		&messages.SetRecoveryContact{Email: "old@example.com"},
	})
	// Inside window with NO contact (eligibility gate).
	mid := now.Add(-90 * time.Minute)
	writeFixtureLog(t, dir, 9, mid, []proto.Message{
		&messages.AddItem{ItemId: 1, Quantity: 1, Price: 1000},
		// no SetRecoveryContact
	})
	defer storage.Close()

	scanner := NewScanner(dir, storage)
	got, err := scanner.Scan(context.Background(), time.Hour, time.Hour, now)
	if err != nil {
		t.Fatalf("Scan: %v", err)
	}
	if len(got) != 0 {
		t.Fatalf("candidates = %d, want 0 (all filtered out); result=%+v", len(got), got)
	}
}

func TestScanner_FindsPushOnlyCandidate(t *testing.T) {
	silenceLogs(t)
	dir := t.TempDir()
	now := time.Date(2026, 7, 1, 12, 0, 0, 0, time.UTC)

	reg := cart.NewCartMultationRegistry(cart.NewCartMutationContext(nil))
	storage := actor.NewDiskStorage[cart.CartGrain](dir, reg)

	mtime := now.Add(-75 * time.Minute)
	writeFixtureLog(t, dir, 11, mtime, []proto.Message{
		&messages.AddItem{ItemId: 1, Quantity: 1, Price: 1000},
		&messages.SetRecoveryContact{
			PushTokens: []*messages.PushToken{
				{Platform: "fcm", Token: "tok-1"},
				{Platform: "apns", Token: "tok-2"},
			},
		},
	})
	defer storage.Close()

	scanner := NewScanner(dir, storage)
	got, err := scanner.Scan(context.Background(), time.Hour, time.Hour, now)
	if err != nil {
		t.Fatalf("Scan: %v", err)
	}
	if len(got) != 1 {
		t.Fatalf("candidates = %d, want 1", len(got))
	}
	if got[0].Email != "" {
		t.Errorf("Email = %q, want empty (push-only)", got[0].Email)
	}
	if len(got[0].PushTokens) != 2 {
		t.Fatalf("PushTokens = %d, want 2", len(got[0].PushTokens))
	}
}

func TestScanner_IgnoresWishlistCarts(t *testing.T) {
	silenceLogs(t)
	dir := t.TempDir()
	now := time.Date(2026, 7, 1, 12, 0, 0, 0, time.UTC)

	reg := cart.NewCartMultationRegistry(cart.NewCartMutationContext(nil))
	storage := actor.NewDiskStorage[cart.CartGrain](dir, reg)

	mtime := now.Add(-90 * time.Minute)
	writeFixtureLog(t, dir, 13, mtime, []proto.Message{
		&messages.AddItem{ItemId: 1, Quantity: 1, Price: 1000},
		&messages.SetRecoveryContact{Email: "wishlist@example.com"},
		&messages.SetCartType{Type: messages.CartType_WISHLIST},
	})
	defer storage.Close()

	scanner := NewScanner(dir, storage)
	got, err := scanner.Scan(context.Background(), time.Hour, time.Hour, now)
	if err != nil {
		t.Fatalf("Scan: %v", err)
	}
	if len(got) != 0 {
		t.Fatalf("wishlist candidate leaked: got %+v", got)
	}
}

// TestScanner_TotalPostReplay verifies the bug fix: replay does not run the
// post-mutation processor, so the scanner MUST call UpdateTotals to surface
// an accurate TotalIncVat.
func TestScanner_TotalPostReplay(t *testing.T) {
	silenceLogs(t)
	dir := t.TempDir()
	now := time.Date(2026, 7, 1, 12, 0, 0, 0, time.UTC)

	reg := cart.NewCartMultationRegistry(cart.NewCartMutationContext(nil))
	storage := actor.NewDiskStorage[cart.CartGrain](dir, reg)

	mtime := now.Add(-75 * time.Minute)
	writeFixtureLog(t, dir, 21, mtime, []proto.Message{
		&messages.AddItem{ItemId: 1, Quantity: 2, Price: 500, Sku: "A"},
		&messages.AddItem{ItemId: 2, Quantity: 1, Price: 1500, Sku: "B"},
		&messages.SetRecoveryContact{Email: "totals@example.com"},
	})
	defer storage.Close()

	scanner := NewScanner(dir, storage)
	got, err := scanner.Scan(context.Background(), time.Hour, time.Hour, now)
	if err != nil {
		t.Fatalf("Scan: %v", err)
	}
	if len(got) != 1 {
		t.Fatalf("candidates = %d, want 1", len(got))
	}
	// 2*500 + 1*1500 = 2500 inc-vat
	if got[0].TotalIncVat != 2500 {
		t.Errorf("TotalIncVat = %d, want 2500 (1000+1500 across two lines)", got[0].TotalIncVat)
	}
	if got[0].ItemCount != 2 {
		t.Errorf("ItemCount = %d, want 2", got[0].ItemCount)
	}
}

// TestIsValidEmail sanity for the optional helper exported for notifiers.
func TestIsValidEmail(t *testing.T) {
	if !IsValidEmail("user@example.com") {
		t.Errorf("user@example.com should be valid")
	}
	if IsValidEmail("not-an-email") {
		t.Errorf("not-an-email should be invalid")
	}
}

// TestFileIDFor verifies the helper that parses <id>.events.log filenames.
func TestFileIDFor(t *testing.T) {
	if id, ok := fileIDFor("12345.events.log"); !ok || id != 12345 {
		t.Errorf("12345.events.log -> %d, %v; want 12345, true", id, ok)
	}
	if _, ok := fileIDFor("not-a-number.events.log"); ok {
		t.Errorf("non-numeric should fail")
	}
	if _, ok := fileIDFor("0.events.log"); ok {
		t.Errorf("id=0 should fail (no implicit zero-cart grain)")
	}
	if _, ok := fileIDFor("garbage.txt"); ok {
		t.Errorf("non-event-log suffix should fail")
	}
}