package position

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

	"github.com/shopspring/decimal"

	"overnight-trading-bot/internal/domain"
	"overnight-trading-bot/internal/testutil"
)

func TestOnEntryFillKeepsBuyCommission(t *testing.T) {
	ctx := context.Background()
	manager := NewManager(testutil.NewMemoryRepository())
	pos, err := manager.OnEntryFill(ctx, "hash", domain.Instrument{Lot: 1}, domain.Order{
		InstrumentUID: "uid",
		TradeDate:     time.Now().UTC(),
		QuantityLots:  10,
		FilledLots:    10,
		AvgFillPrice:  decimal.NewFromInt(100),
		Commission:    decimal.NewFromInt(3),
	})
	if err != nil {
		t.Fatal(err)
	}
	if !pos.CommissionTotal.Equal(decimal.NewFromInt(3)) {
		t.Fatalf("commission=%s, want 3", pos.CommissionTotal)
	}
	if pos.Status != domain.PositionEntryFilled {
		t.Fatalf("status=%s, want ENTRY_FILLED", pos.Status)
	}
}

func TestOnEntryFillAggregatesRepostedPartialFills(t *testing.T) {
	ctx := context.Background()
	manager := NewManager(testutil.NewMemoryRepository())
	tradeDate := time.Date(2026, 6, 6, 0, 0, 0, 0, time.UTC)
	first, err := manager.OnEntryFill(ctx, "hash", domain.Instrument{Lot: 1}, domain.Order{
		InstrumentUID: "uid",
		TradeDate:     tradeDate,
		QuantityLots:  10,
		FilledLots:    4,
		AvgFillPrice:  decimal.NewFromInt(100),
		Commission:    decimal.NewFromInt(1),
	})
	if err != nil {
		t.Fatal(err)
	}
	if first.Status != domain.PositionEntryPartiallyFilled || first.Lots != 4 {
		t.Fatalf("first position=%+v, want partial 4 lots", first)
	}
	second, err := manager.OnEntryFill(ctx, "hash", domain.Instrument{Lot: 1}, domain.Order{
		InstrumentUID: "uid",
		TradeDate:     tradeDate,
		QuantityLots:  6,
		FilledLots:    6,
		AvgFillPrice:  decimal.NewFromInt(110),
		Commission:    decimal.NewFromInt(2),
	})
	if err != nil {
		t.Fatal(err)
	}
	wantAvg := decimal.NewFromInt(106)
	if second.Lots != 10 || second.Status != domain.PositionEntryFilled {
		t.Fatalf("aggregated position=%+v, want 10 lots ENTRY_FILLED", second)
	}
	if !second.AvgBuyPrice.Equal(wantAvg) {
		t.Fatalf("avg buy=%s, want %s", second.AvgBuyPrice, wantAvg)
	}
	if !second.CommissionTotal.Equal(decimal.NewFromInt(3)) {
		t.Fatalf("commission=%s, want 3", second.CommissionTotal)
	}
}

func TestOnExitFillPartialUsesExecutedLots(t *testing.T) {
	ctx := context.Background()
	manager := NewManager(testutil.NewMemoryRepository())
	openAt := time.Now().UTC()
	pos := domain.Position{
		AccountIDHash:   "hash",
		InstrumentUID:   "uid",
		OpenTradeDate:   openAt,
		Lots:            10,
		Lot:             1,
		AvgBuyPrice:     decimal.NewFromInt(100),
		Status:          domain.PositionHoldingOvernight,
		CommissionTotal: decimal.NewFromInt(2),
		OpenedAt:        &openAt,
	}
	updated, err := manager.OnExitFill(ctx, pos, domain.Order{
		InstrumentUID: "uid",
		FilledLots:    4,
		AvgFillPrice:  decimal.NewFromInt(110),
		Commission:    decimal.NewFromInt(1),
	})
	if err != nil {
		t.Fatal(err)
	}
	if updated.Status != domain.PositionExitPartiallyFilled || updated.ClosedAt != nil {
		t.Fatalf("unexpected partial status/closed_at: %+v", updated)
	}
	if updated.Lots != 6 {
		t.Fatalf("remaining lots=%d, want 6", updated.Lots)
	}
	if !updated.GrossPnL.Equal(decimal.NewFromInt(40)) {
		t.Fatalf("gross pnl=%s, want 40", updated.GrossPnL)
	}
	if updated.ExitFilledLots != 4 || !updated.AvgSellPrice.Equal(decimal.NewFromInt(110)) {
		t.Fatalf("exit aggregation lots=%d avg=%s", updated.ExitFilledLots, updated.AvgSellPrice)
	}
	second, err := manager.OnExitFill(ctx, updated, domain.Order{
		InstrumentUID: "uid",
		FilledLots:    3,
		AvgFillPrice:  decimal.NewFromInt(120),
	})
	if err != nil {
		t.Fatal(err)
	}
	wantAvg := decimal.NewFromInt(800).Div(decimal.NewFromInt(7))
	if second.ExitFilledLots != 7 || !second.AvgSellPrice.Equal(wantAvg) {
		t.Fatalf("weighted avg sell=%s lots=%d, want %s/7", second.AvgSellPrice, second.ExitFilledLots, wantAvg)
	}
}

func TestOnExitFillUsesInstrumentLotForAbsolutePnL(t *testing.T) {
	ctx := context.Background()
	manager := NewManager(testutil.NewMemoryRepository())
	openAt := time.Now().UTC()
	pos := domain.Position{
		AccountIDHash:   "hash",
		InstrumentUID:   "uid",
		OpenTradeDate:   openAt,
		Lots:            4,
		Lot:             10,
		AvgBuyPrice:     decimal.NewFromInt(100),
		Status:          domain.PositionHoldingOvernight,
		CommissionTotal: decimal.NewFromInt(2),
		OpenedAt:        &openAt,
	}
	updated, err := manager.OnExitFill(ctx, pos, domain.Order{
		InstrumentUID: "uid",
		FilledLots:    4,
		AvgFillPrice:  decimal.NewFromInt(105),
		Commission:    decimal.NewFromInt(3),
	})
	if err != nil {
		t.Fatal(err)
	}
	if !updated.GrossPnL.Equal(decimal.NewFromInt(200)) {
		t.Fatalf("gross pnl=%s, want 200", updated.GrossPnL)
	}
	if !updated.NetPnL.Equal(decimal.NewFromInt(195)) {
		t.Fatalf("net pnl=%s, want 195", updated.NetPnL)
	}
}

func TestOnExitFillUsesLotInRealizedEdgeCommissionBase(t *testing.T) {
	ctx := context.Background()
	manager := NewManager(testutil.NewMemoryRepository())
	openAt := time.Now().UTC()
	pos := domain.Position{
		AccountIDHash: "hash",
		InstrumentUID: "uid",
		OpenTradeDate: openAt,
		Lots:          1,
		Lot:           100,
		AvgBuyPrice:   decimal.NewFromInt(100),
		Status:        domain.PositionHoldingOvernight,
		OpenedAt:      &openAt,
	}
	updated, err := manager.OnExitFill(ctx, pos, domain.Order{
		InstrumentUID: "uid",
		FilledLots:    1,
		AvgFillPrice:  decimal.NewFromInt(100),
		Commission:    decimal.NewFromInt(10),
	})
	if err != nil {
		t.Fatal(err)
	}
	if !updated.RealizedEdgeBps.Equal(decimal.NewFromInt(-10)) {
		t.Fatalf("realized edge=%s, want -10 bps", updated.RealizedEdgeBps)
	}
}

func TestOnExitFillRejectsOverfillWithCriticalRiskEvent(t *testing.T) {
	ctx := context.Background()
	repo := testutil.NewMemoryRepository()
	manager := NewManager(repo)
	openAt := time.Now().UTC()
	pos := domain.Position{
		AccountIDHash: "hash",
		InstrumentUID: "uid",
		OpenTradeDate: openAt,
		Lots:          3,
		Lot:           1,
		AvgBuyPrice:   decimal.NewFromInt(100),
		Status:        domain.PositionHoldingOvernight,
		OpenedAt:      &openAt,
	}
	updated, err := manager.OnExitFill(ctx, pos, domain.Order{
		InstrumentUID: "uid",
		FilledLots:    5,
		AvgFillPrice:  decimal.NewFromInt(110),
	})
	if !errors.Is(err, ErrExitFillExceedsPositionLots) {
		t.Fatalf("err=%v, want ErrExitFillExceedsPositionLots", err)
	}
	if updated.Lots != 3 || updated.Status != domain.PositionHoldingOvernight {
		t.Fatalf("position was mutated despite overfill: %+v", updated)
	}
	if len(repo.RiskEvents) != 1 || repo.RiskEvents[0].Severity != domain.SeverityCritical || repo.RiskEvents[0].EventType != "exit_overfill" {
		t.Fatalf("risk events=%+v, want one critical exit_overfill", repo.RiskEvents)
	}
}