package rules

import (
	"path/filepath"
	"testing"

	"git.petrovv.com/nikola/money/internal/config"
	"git.petrovv.com/nikola/money/internal/model"
	"git.petrovv.com/nikola/money/internal/store"
)

func testDB(t *testing.T) *store.DB {
	t.Helper()
	db, err := store.Open(filepath.Join(t.TempDir(), "index.db"))
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { db.Close() })
	return db
}

// seed inserts transactions with no rule verdict yet.
func seed(t *testing.T, db *store.DB, descriptions ...string) int64 {
	t.Helper()
	accountID, err := db.UpsertAccount(model.Account{
		Slug: "checking", Name: "Checking", Currency: "EUR", MinorDigits: 2,
	})
	if err != nil {
		t.Fatal(err)
	}
	sourceID, err := db.SourceFile(accountID, "checking/st.csv", "sha", "2026-01-01T00:00:00Z", 0)
	if err != nil {
		t.Fatal(err)
	}
	for i, d := range descriptions {
		added, err := db.InsertTransaction(model.Transaction{
			AccountID:    accountID,
			SourceFileID: sourceID,
			Fingerprint:  d,
			Date:         "2026-01-0" + string(rune('1'+i)),
			Description:  d,
			AmountMinor:  -1000,
		})
		if err != nil {
			t.Fatal(err)
		}
		if !added {
			t.Fatalf("seed %q was not inserted", d)
		}
	}
	return accountID
}

func byDescription(t *testing.T, db *store.DB, desc string) model.Transaction {
	t.Helper()
	txns, err := db.Transactions(store.Filter{})
	if err != nil {
		t.Fatal(err)
	}
	for _, x := range txns {
		if x.Description == desc {
			return x
		}
	}
	t.Fatalf("no transaction with description %q", desc)
	return model.Transaction{}
}

// A tag is derived state: rules.toml is the only thing that decides it, so
// retagging rewrites every tag from the current rules however often it runs,
// including back to nothing when no rule matches any more.
func TestRetagRewritesEveryTag(t *testing.T) {
	db := testDB(t)
	seed(t, db, "LIDL SOFIA", "SOME RANDOM SHOP")

	engine := New(&config.Rules{Rule: []config.Rule{
		{Match: "*LIDL*", Tag: "groceries"},
		{Match: "*SHOP*", Tag: "shopping"},
	}})
	n, err := engine.Retag(db)
	if err != nil {
		t.Fatal(err)
	}
	if n != 2 {
		t.Errorf("retagged %d rows, want 2", n)
	}
	if got := byDescription(t, db, "LIDL SOFIA").RuleTag; got != "groceries" {
		t.Errorf("tag = %q, want groceries", got)
	}

	// Re-running with the same rules changes nothing and says so.
	if n, err := engine.Retag(db); err != nil || n != 0 {
		t.Errorf("second retag: %d rows, %v; want 0 and no error", n, err)
	}

	// New rules win, and a row no rule matches loses its tag entirely.
	engine = New(&config.Rules{Rule: []config.Rule{
		{Match: "*LIDL*", Tag: "food"},
	}})
	if _, err := engine.Retag(db); err != nil {
		t.Fatal(err)
	}
	if got := byDescription(t, db, "LIDL SOFIA").RuleTag; got != "food" {
		t.Errorf("tag = %q, want food", got)
	}
	if got := byDescription(t, db, "SOME RANDOM SHOP").RuleTag; got != "" {
		t.Errorf("tag = %q, want empty once no rule matches", got)
	}
}

// The narrower rule claims what it names wherever it sits in the file: the
// catch-all above it must not swallow the exception written below.
func TestMoreSpecificRuleWins(t *testing.T) {
	both := [][]config.Rule{
		{{Match: "NIK*", Tag: "misc"}, {Match: "NIKOLA*", Tag: "family"}},
		{{Match: "NIKOLA*", Tag: "family"}, {Match: "NIK*", Tag: "misc"}},
	}
	for _, rs := range both {
		engine := New(&config.Rules{Rule: rs})
		if tag := engine.Apply("checking", "NIKOLA PETROV"); tag != "family" {
			t.Errorf("%q first: tag = %q, want family", rs[0].Match, tag)
		}
		if tag := engine.Apply("checking", "NIKI TODOROV"); tag != "misc" {
			t.Errorf("%q first: tag = %q, want misc", rs[0].Match, tag)
		}
	}
}

// Specificity is measured on what the pattern spells out, so the wildcards
// around a literal do not buy it precedence, and a bare "*" is always last.
func TestSpecificityOrder(t *testing.T) {
	engine := New(&config.Rules{Rule: []config.Rule{
		{Match: "*", Tag: "other"},
		{Match: "*LIDL*", Tag: "groceries"},
		{Match: "*LIDL EXPRESS*", Tag: "snacks"},
	}})
	for _, c := range []struct{ desc, want string }{
		{"CARD LIDL EXPRESS 12", "snacks"},
		{"CARD LIDL 12", "groceries"},
		{"SOMETHING ELSE", "other"},
	} {
		if tag := engine.Apply("checking", c.desc); tag != c.want {
			t.Errorf("%q: tag = %q, want %q", c.desc, tag, c.want)
		}
	}
}

// Two rules that are equally specific are still decided by the file: the
// earlier one wins, which is what makes appending a rule safe.
func TestEqualSpecificityKeepsFileOrder(t *testing.T) {
	engine := New(&config.Rules{Rule: []config.Rule{
		{Match: "*ACME*", Tag: "first"},
		{Match: "*ACME*", Tag: "second"},
	}})
	if tag := engine.Apply("checking", "ACME LTD"); tag != "first" {
		t.Errorf("tag = %q, want first", tag)
	}
	if tag := engine.Apply("checking", "SOMETHING ELSE"); tag != "" {
		t.Errorf("tag = %q, want empty for an unmatched description", tag)
	}
}

// A rule can be dead two ways: nothing matches it, or a rule that beats it
// already claimed everything it would have caught. Usage must report both as
// zero, indexed by file position however the rules are ordered for matching.
func TestUsageCountsWinnersOnly(t *testing.T) {
	engine := New(&config.Rules{Rule: []config.Rule{
		{Match: "*LIDL SOFIA*", Tag: "groceries"},  // the narrower of the two
		{Match: "*LIDL*", Tag: "shadowed"},         // every LIDL row here is Sofia
		{Match: "*NOTHING MATCHES ME*", Tag: "no"}, // matches nothing at all
		{Match: "*PAYROLL*", Tag: "salary"},        // claims one row
	}})

	txns := []model.Transaction{
		{AccountSlug: "checking", Description: "LIDL SOFIA 4412"},
		{AccountSlug: "checking", Description: "LIDL SOFIA 9911"},
		{AccountSlug: "checking", Description: "ACME PAYROLL"},
		{AccountSlug: "checking", Description: "UNMATCHED SHOP"},
	}

	usage := engine.Usage(txns)
	want := []int{2, 0, 0, 1}
	if len(usage) != len(want) {
		t.Fatalf("usage has %d entries, want %d", len(usage), len(want))
	}
	for i := range want {
		if usage[i] != want[i] {
			t.Errorf("rule %d used by %d transactions, want %d", i+1, usage[i], want[i])
		}
	}
}

// The index is the rule's position in rules.toml, not its position in the order
// it was tried in — that is the number the rules screen shows and deletes by.
func TestMatchIndex(t *testing.T) {
	engine := New(&config.Rules{Rule: []config.Rule{
		{Match: "*LIDL*", Tag: "groceries"},
		{Match: "*LIDL EXPRESS*", Tag: "snacks"},
	}})

	if got := engine.MatchIndex("checking", model.Transaction{Description: "LIDL EXPRESS 1"}); got != 1 {
		t.Errorf("index = %d, want 1", got)
	}
	if got := engine.MatchIndex("checking", model.Transaction{Description: "LIDL 1"}); got != 0 {
		t.Errorf("index = %d, want 0", got)
	}
	if got := engine.MatchIndex("checking", model.Transaction{Description: "OTHER"}); got != -1 {
		t.Errorf("index = %d, want -1 for no match", got)
	}
}

// Naming an account is itself a narrowing, so the scoped rule beats the
// identical unscoped one even when the unscoped one is written first.
func TestAccountScopedRule(t *testing.T) {
	engine := New(&config.Rules{Rule: []config.Rule{
		{Match: "*TRANSFER*", Tag: "misc"},
		{Match: "*TRANSFER*", Tag: "transfer", Account: "savings"},
	}})

	if tag := engine.Apply("savings", "TRANSFER FROM CHECKING"); tag != "transfer" {
		t.Errorf("savings: tag = %q, want transfer", tag)
	}
	if tag := engine.Apply("checking", "TRANSFER FROM CHECKING"); tag != "misc" {
		t.Errorf("checking: tag = %q, want misc", tag)
	}
}

// Besides the description, a rule can match the bank's own classification of
// the transaction, on its own or alongside a description glob.
func TestTypeRules(t *testing.T) {
	engine := New(&config.Rules{Rule: []config.Rule{
		{Type: "CARD_PAYMENT", Match: "*LIDL*", Tag: "groceries"},
		{Type: "ATM", Tag: "cash"},
	}})

	// A rule setting several patterns requires all of them to match.
	tag := engine.ApplyTxn("checking", model.Transaction{
		Description: "LIDL SOFIA", Type: "CARD_PAYMENT",
	})
	if tag != "groceries" {
		t.Errorf("tag = %q, want groceries", tag)
	}
	tag = engine.ApplyTxn("checking", model.Transaction{
		Description: "LIDL SOFIA", Type: "TRANSFER",
	})
	if tag != "" {
		t.Errorf("tag = %q, want empty: the type does not match", tag)
	}

	// Type alone works too.
	if tag := engine.ApplyTxn("checking", model.Transaction{
		Description: "WITHDRAWAL", Type: "ATM",
	}); tag != "cash" {
		t.Errorf("tag = %q, want cash", tag)
	}
}