package book

import (
	"fmt"
	"testing"

	"github.com/edwardtay/injective-booklab/dec"
)

var D = dec.MustParse

func lv(p, q string) Level { return Level{D(p), D(q)} }

// Snapshot shape taken from INJ/USDT on mainnet, 2026-11-07.
func sample() *Book {
	return &Book{
		Seq:  73443633,
		Bids: []Level{lv("8.105", "53.846"), lv("8.084", "13.785"), lv("8.057", "17.81")},
		Asks: []Level{lv("8.27", "52.766"), lv("8.291", "13.306"), lv("8.318", "17.034")},
	}
}

func TestValidate(t *testing.T) {
	if err := sample().Validate(); err != nil {
		t.Fatal(err)
	}
	b := sample()
	b.Bids[0].Price = D("8.3")
	if err := b.Validate(); err == nil {
		t.Error("crossed or unsorted book accepted")
	}
	b = sample()
	b.Asks[1], b.Asks[2] = b.Asks[2], b.Asks[1]
	if err := b.Validate(); err == nil {
		t.Error("unsorted asks accepted")
	}
}

func TestMidSpread(t *testing.T) {
	b := sample()
	mid, _ := b.Mid()
	if mid.String() != "8.1875" {
		t.Errorf("mid %s", mid)
	}
	bps, _ := b.SpreadBps()
	if got := bps.Round(4).String(); got != "201.5267" {
		t.Errorf("spread bps %s", got)
	}
}

func TestSimulateTaker(t *testing.T) {
	cases := []struct {
		name                    string
		side                    Side
		qty, limit              string
		filled, unfilled, worst string
		levels                  int
	}{
		{"inside top level", Buy, "10", "0", "10", "0", "8.27", 1},
		{"walks two levels", Buy, "60", "0", "60", "0", "8.291", 2},
		{"exhausts book", Buy, "100", "0", "83.106", "16.894", "8.318", 3},
		{"limit stops walk", Buy, "100", "8.291", "66.072", "33.928", "8.291", 2},
		{"sell side", Sell, "60", "0", "60", "0", "8.084", 2},
	}
	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			r := SimulateTaker(sample(), c.side, D(c.qty), D(c.limit), D("0.0005"))
			if r.Filled.String() != c.filled || r.Unfilled.String() != c.unfilled ||
				r.WorstPrice.String() != c.worst || r.LevelsUsed != c.levels {
				t.Fatalf("got filled=%s unfilled=%s worst=%s levels=%d", r.Filled, r.Unfilled, r.WorstPrice, r.LevelsUsed)
			}
			if r.SlippageBps.IsNegative() {
				t.Errorf("negative slippage %s", r.SlippageBps)
			}
		})
	}
	r := SimulateTaker(sample(), Buy, D("60"), dec.Zero(), D("0.0005"))
	// 52.766*8.27 + 7.234*8.291 = 436.37482 + 59.977094 = 496.351914
	if r.Notional.String() != "496.351914" || r.Fee.String() != "0.248175957" {
		t.Errorf("notional %s fee %s", r.Notional, r.Fee)
	}
}

func TestCheckOrder(t *testing.T) {
	m := Market{PriceTick: D("0.001"), QtyTick: D("0.001"), MinNotional: D("1")}
	if errs := m.CheckOrder(D("8.105"), D("1")); len(errs) != 0 {
		t.Errorf("valid order rejected: %v", errs)
	}
	if errs := m.CheckOrder(D("8.1055"), D("0.0005")); len(errs) != 3 {
		t.Errorf("want 3 violations (price tick, qty tick, notional), got %v", errs)
	}
}

func TestDiff(t *testing.T) {
	a := sample()
	b := sample()
	b.Bids = []Level{lv("8.11", "1"), lv("8.105", "50"), lv("8.057", "17.81")} // add, change, remove
	ch := Diff(a, b)
	if len(ch) != 3 {
		t.Fatalf("want 3 changes, got %d: %+v", len(ch), ch)
	}
	if !ch[0].Price.Equal(D("8.11")) || !ch[0].Old.IsZero() {
		t.Errorf("first change should be the new 8.11 level: %+v", ch[0])
	}
	if len(Diff(a, sample())) != 0 {
		t.Error("identical books should diff empty")
	}
}

func deepBook(n int) *Book {
	b := &Book{}
	for i := 0; i < n; i++ {
		b.Bids = append(b.Bids, lv(fmt.Sprintf("%d.5", 10000-i), "1.25"))
		b.Asks = append(b.Asks, lv(fmt.Sprintf("%d.5", 10001+i), "1.25"))
	}
	return b
}

func BenchmarkSimulateTaker500Levels(b *testing.B) {
	bk := deepBook(500)
	q := D("400")
	b.ReportAllocs()
	for i := 0; i < b.N; i++ {
		SimulateTaker(bk, Buy, q, dec.Zero(), D("0.0005"))
	}
}

func BenchmarkDiff500Levels(b *testing.B) {
	x, y := deepBook(500), deepBook(500)
	y.Bids[10].Qty = D("2")
	b.ReportAllocs()
	for i := 0; i < b.N; i++ {
		Diff(x, y)
	}
}