package reconcile

// Expected values verified against scripts/match_payments.py on 2026-05-06:
//
//	PYTHONPATH=scripts:. python3 -m unittest tests.test_reconcile_exceptions tests.test_match_payments -v
//
// All Python test cases are ported below. Additional Go-only cases are marked with [Go].

import (
	"math"
	"testing"
)

const defaultYear = 2026

// tx builds a pre-matched Transaction (person+purpose already filled in).
// InferredAmount is left nil so Amount is used directly, matching the Python
// _tx helper where inferred_amount == amount.
func tx(person, purpose string, amount float64) Transaction {
	return Transaction{
		Date:    "2026-01-01",
		Amount:  amount,
		Person:  person,
		Purpose: purpose,
		Sender:  "Sender",
		Message: "fee",
	}
}

func TestReconcileExceptionOverride(t *testing.T) {
	t.Parallel()
	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 4}}}}
	exceptions := map[ExceptionKey]Exception{
		{Name: "alice", Period: "2026-01"}: {Amount: 400, Note: "Test exception"},
	}
	txs := []Transaction{{
		Date: "2026-01-05", Amount: 400,
		Person: "Alice", Purpose: "2026-01", Sender: "Alice Sender", Message: "fee",
	}}

	result := Reconcile(members, []string{"2026-01"}, txs, exceptions, defaultYear)

	jan := result.Members["Alice"].Months["2026-01"]
	if jan.Expected != 400 {
		t.Errorf("Expected override to 400, got %d", jan.Expected)
	}
	if jan.Paid != 400 {
		t.Errorf("Paid want 400, got %f", jan.Paid)
	}
	if result.Members["Alice"].TotalBalance != 0 {
		t.Errorf("TotalBalance want 0, got %d", result.Members["Alice"].TotalBalance)
	}
}

func TestReconcileFallbackToAttendance(t *testing.T) {
	t.Parallel()
	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 4}}}}

	result := Reconcile(members, []string{"2026-01"}, nil, nil, defaultYear)

	if result.Members["Alice"].Months["2026-01"].Expected != 750 {
		t.Errorf("Expected 750 when no exception, got %d", result.Members["Alice"].Months["2026-01"].Expected)
	}
}

func TestReconcileGreedyExactMatch(t *testing.T) {
	t.Parallel()
	members := []Member{{
		Name: "Alice", Tier: "A",
		Fees: map[string]FeeData{
			"2026-02": {Expected: 750, Attendance: 3},
			"2026-03": {Expected: 350, Attendance: 3},
			"2026-04": {Expected: 150, Attendance: 2},
		},
	}}
	sortedMonths := []string{"2026-02", "2026-03", "2026-04"}

	result := Reconcile(members, sortedMonths, []Transaction{tx("Alice", "2026-02, 2026-03, 2026-04", 1250)}, nil, defaultYear)

	months := result.Members["Alice"].Months
	if int(months["2026-02"].Paid) != 750 {
		t.Errorf("2026-02 paid want 750, got %f", months["2026-02"].Paid)
	}
	if int(months["2026-03"].Paid) != 350 {
		t.Errorf("2026-03 paid want 350, got %f", months["2026-03"].Paid)
	}
	if int(months["2026-04"].Paid) != 150 {
		t.Errorf("2026-04 paid want 150, got %f", months["2026-04"].Paid)
	}
}

func TestReconcileGreedyOverpaymentGoesToCredit(t *testing.T) {
	t.Parallel()
	members := []Member{{
		Name: "Alice", Tier: "A",
		Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}, "2026-02": {Expected: 750, Attendance: 3}},
	}}
	sortedMonths := []string{"2026-01", "2026-02"}

	result := Reconcile(members, sortedMonths, []Transaction{tx("Alice", "2026-01, 2026-02", 2000)}, nil, defaultYear)

	months := result.Members["Alice"].Months
	if int(months["2026-01"].Paid) != 750 {
		t.Errorf("2026-01 paid want 750, got %f", months["2026-01"].Paid)
	}
	if int(months["2026-02"].Paid) != 750 {
		t.Errorf("2026-02 paid want 750, got %f", months["2026-02"].Paid)
	}
	if result.Credits["Alice"] != 500 {
		t.Errorf("credits want 500, got %d", result.Credits["Alice"])
	}
}

func TestReconcileProportionalUnderpayment(t *testing.T) {
	t.Parallel()
	members := []Member{{
		Name: "Alice", Tier: "A",
		Fees: map[string]FeeData{"2026-02": {Expected: 750, Attendance: 3}, "2026-03": {Expected: 350, Attendance: 3}, "2026-04": {Expected: 750, Attendance: 3}},
	}}
	sortedMonths := []string{"2026-02", "2026-03", "2026-04"}
	amount := 1250.0

	result := Reconcile(members, sortedMonths, []Transaction{tx("Alice", "2026-02, 2026-03, 2026-04", amount)}, nil, defaultYear)

	months := result.Members["Alice"].Months
	paid02 := months["2026-02"].Paid
	paid03 := months["2026-03"].Paid
	paid04 := months["2026-04"].Paid

	if paid02 >= 750 {
		t.Errorf("2026-02 should be underpaid, got %f", paid02)
	}
	if paid03 >= 350 {
		t.Errorf("2026-03 should be underpaid, got %f", paid03)
	}
	if paid04 >= 750 {
		t.Errorf("2026-04 should be underpaid, got %f", paid04)
	}
	if math.Abs(paid02+paid03+paid04-amount) > 0.01 {
		t.Errorf("sum of paid want %f, got %f", amount, paid02+paid03+paid04)
	}
	if math.Abs(paid02-paid04) > 0.01 {
		t.Errorf("02 and 04 have equal expected, want equal paid: %f vs %f", paid02, paid04)
	}
}

func TestReconcileSingleMonthUnchanged(t *testing.T) {
	t.Parallel()
	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}}}}

	result := Reconcile(members, []string{"2026-01"}, []Transaction{tx("Alice", "2026-01", 750)}, nil, defaultYear)

	if math.Abs(result.Members["Alice"].Months["2026-01"].Paid-750) > 0.01 {
		t.Errorf("single month want 750, got %f", result.Members["Alice"].Months["2026-01"].Paid)
	}
}

func TestReconcileTwoMembersMultiMonth(t *testing.T) {
	t.Parallel()
	members := []Member{
		{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}, "2026-02": {Expected: 350, Attendance: 3}}},
		{Name: "Bob", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}, "2026-02": {Expected: 350, Attendance: 3}}},
	}
	sortedMonths := []string{"2026-01", "2026-02"}

	result := Reconcile(members, sortedMonths, []Transaction{tx("Alice, Bob", "2026-01, 2026-02", 2200)}, nil, defaultYear)

	for _, name := range []string{"Alice", "Bob"} {
		months := result.Members[name].Months
		if math.Abs(months["2026-01"].Paid-750) > 0.01 {
			t.Errorf("%s 2026-01 paid want 750, got %f", name, months["2026-01"].Paid)
		}
		if math.Abs(months["2026-02"].Paid-350) > 0.01 {
			t.Errorf("%s 2026-02 paid want 350, got %f", name, months["2026-02"].Paid)
		}
	}
}

func TestReconcileEvenSplitFallbackWhenNoExpected(t *testing.T) {
	t.Parallel()
	members := []Member{{
		Name: "Alice", Tier: "A",
		Fees: map[string]FeeData{"2026-01": {Expected: 0, Attendance: 0}, "2026-02": {Expected: 0, Attendance: 0}},
	}}
	sortedMonths := []string{"2026-01", "2026-02"}

	result := Reconcile(members, sortedMonths, []Transaction{tx("Alice", "2026-01, 2026-02", 300)}, nil, defaultYear)

	months := result.Members["Alice"].Months
	if math.Abs(months["2026-01"].Paid-150) > 0.01 {
		t.Errorf("2026-01 paid want 150, got %f", months["2026-01"].Paid)
	}
	if math.Abs(months["2026-02"].Paid-150) > 0.01 {
		t.Errorf("2026-02 paid want 150, got %f", months["2026-02"].Paid)
	}
}

func TestReconcileDiacriticsTolerantPersonMatching(t *testing.T) {
	t.Parallel()
	members := []Member{{Name: "Mária Maco", Tier: "A", Fees: map[string]FeeData{"2026-04": {Expected: 750, Attendance: 4}}}}
	txFn := func(person string) Transaction {
		return Transaction{
			Date: "2026-04-15", Amount: 750, Person: person, Purpose: "2026-04",
			Sender: "Maco Family", Message: "fee",
		}
	}

	cases := []struct {
		name   string
		person string
	}{
		{"without diacritics", "Maria Maco"},
		{"extra whitespace", "Mária  Maco"},
		{"lowercase", "mária maco"},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()
			result := Reconcile(members, []string{"2026-04"}, []Transaction{txFn(tc.person)}, nil, defaultYear)

			paid := result.Members["Mária Maco"].Months["2026-04"].Paid
			if paid != 750 {
				t.Errorf("%s: paid want 750, got %f", tc.name, paid)
			}
			if len(result.Unmatched) != 0 {
				t.Errorf("%s: want no unmatched, got %v", tc.name, result.Unmatched)
			}
		})
	}
}

func TestReconcileTrulyUnknownPersonIsUnmatched(t *testing.T) {
	t.Parallel()
	members := []Member{{Name: "Mária Maco", Tier: "A", Fees: map[string]FeeData{"2026-04": {Expected: 750, Attendance: 4}}}}
	txs := []Transaction{{
		Date: "2026-04-15", Amount: 750,
		Person: "Někdo Neznámý", Purpose: "2026-04",
		Sender: "Neznámý", Message: "fee",
	}}

	result := Reconcile(members, []string{"2026-04"}, txs, nil, defaultYear)

	if result.Members["Mária Maco"].Months["2026-04"].Paid != 0 {
		t.Errorf("unknown person must not credit the member")
	}
	if len(result.Unmatched) != 1 {
		t.Errorf("want 1 unmatched, got %d", len(result.Unmatched))
	}
}

// [Go] Test that [?] markers are stripped from the Person field before lookup.
func TestReconcileQuestionMarkMarkerStripped(t *testing.T) {
	t.Parallel()
	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}}}}
	txs := []Transaction{{
		Date: "2026-01-01", Amount: 750,
		Person: "[?] Alice", Purpose: "2026-01",
		Sender: "Bank", Message: "fee",
	}}

	result := Reconcile(members, []string{"2026-01"}, txs, nil, defaultYear)

	if result.Members["Alice"].Months["2026-01"].Paid != 750 {
		t.Errorf("[?] stripping: want 750 paid, got %f", result.Members["Alice"].Months["2026-01"].Paid)
	}
}

// [Go] Purpose "other:shirt" puts payment in OtherTransactions, not in month ledger.
func TestReconcileOtherPurpose(t *testing.T) {
	t.Parallel()
	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}}}}
	txs := []Transaction{{
		Date: "2026-01-01", Amount: 300,
		Person: "Alice", Purpose: "other:shirt",
		Sender: "Bank", Message: "shirt order",
	}}

	result := Reconcile(members, []string{"2026-01"}, txs, nil, defaultYear)

	if result.Members["Alice"].Months["2026-01"].Paid != 0 {
		t.Errorf("other: purpose must not touch month ledger")
	}
	others := result.Members["Alice"].OtherTransactions
	if len(others) != 1 {
		t.Fatalf("want 1 OtherTransaction, got %d", len(others))
	}
	if math.Abs(others[0].Amount-300) > 0.01 {
		t.Errorf("OtherEntry.Amount want 300, got %f", others[0].Amount)
	}
	if others[0].Purpose != "other:shirt" {
		t.Errorf("OtherEntry.Purpose want %q, got %q", "other:shirt", others[0].Purpose)
	}
}

// [Go] Months outside sortedMonths go to credit, not to the window ledger.
func TestReconcileOutOfWindowGoesToCredit(t *testing.T) {
	t.Parallel()
	// Window shows only 2026-01. Transaction references 2026-01 (in) and 2026-02 (out).
	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 600, Attendance: 3}}}}
	txs := []Transaction{{
		Date: "2026-01-01", Amount: 1200,
		Person: "Alice", Purpose: "2026-01, 2026-02",
		Sender: "Bank", Message: "Q1",
	}}

	result := Reconcile(members, []string{"2026-01"}, txs, nil, defaultYear)

	// member_share = 1200 (one member)
	// out_credit = 1200 / 2 * 1 = 600
	// in_window_share = 600
	// in_window = [(2026-01, 600)], total_expected = 600 → greedy: paid = 600, no overflow
	if math.Abs(result.Members["Alice"].Months["2026-01"].Paid-600) > 0.01 {
		t.Errorf("in-window paid want 600, got %f", result.Members["Alice"].Months["2026-01"].Paid)
	}
	// total_balance = int(600) - 600 (window) + 600 (out credit) = 600
	if result.Members["Alice"].TotalBalance != 600 {
		t.Errorf("TotalBalance want 600, got %d", result.Members["Alice"].TotalBalance)
	}
}

// [Go] No person/purpose → inference fallback resolves sender name and date month.
func TestReconcileInferenceFallback(t *testing.T) {
	t.Parallel()
	members := []Member{{Name: "Tomáš Němeček", Tier: "A", Fees: map[string]FeeData{"2026-04": {Expected: 750, Attendance: 3}}}}
	txs := []Transaction{{
		Date: "2026-04-15", Amount: 750,
		// Person and Purpose are empty → inference path
		Sender:  "Tomas Nemecek",
		Message: "clenske 04/2026",
	}}

	result := Reconcile(members, []string{"2026-04"}, txs, nil, defaultYear)

	if math.Abs(result.Members["Tomáš Němeček"].Months["2026-04"].Paid-750) > 0.01 {
		t.Errorf("inference fallback: want 750 paid, got %f", result.Members["Tomáš Němeček"].Months["2026-04"].Paid)
	}
}

// [Go] Transaction with no match at all ends up in Unmatched; ledger unchanged.
func TestReconcileNoMatchGoesToUnmatched(t *testing.T) {
	t.Parallel()
	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}}}}
	txs := []Transaction{{
		Date: "2026-01-01", Amount: 500,
		// empty person+purpose and sender name not matching any member
		Sender: "Unknown Corp", Message: "invoice",
	}}

	result := Reconcile(members, []string{"2026-01"}, txs, nil, defaultYear)

	if len(result.Unmatched) != 1 {
		t.Errorf("want 1 unmatched, got %d", len(result.Unmatched))
	}
	if result.Members["Alice"].Months["2026-01"].Paid != 0 {
		t.Errorf("unmatched tx must not touch ledger")
	}
}

// [Go] Empty transaction list leaves every month at paid=0 and balance=–expected.
func TestReconcileNoTransactionsAllUnpaid(t *testing.T) {
	t.Parallel()
	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}}}}

	result := Reconcile(members, []string{"2026-01"}, nil, nil, defaultYear)

	if result.Members["Alice"].Months["2026-01"].Paid != 0 {
		t.Errorf("no txs: want paid=0, got %f", result.Members["Alice"].Months["2026-01"].Paid)
	}
	if result.Members["Alice"].TotalBalance != -750 {
		t.Errorf("no txs: want balance -750, got %d", result.Members["Alice"].TotalBalance)
	}
	if len(result.Unmatched) != 0 {
		t.Errorf("no txs: want empty unmatched, got %v", result.Unmatched)
	}
}