package engine

import (
	"context"
	"net/netip"
	"strings"
	"testing"

	"steward/internal/auth"
	"steward/internal/model"
	"steward/internal/store"
)

func newEngine(t *testing.T) *Engine {
	t.Helper()
	st, err := store.Open(":memory:")
	if err != nil {
		t.Fatal(err)
	}
	e, err := New(context.Background(), st, nil)
	if err != nil {
		t.Fatal(err)
	}
	return e
}

var admin = &auth.Principal{User: &model.User{ID: 1, Username: "admin", Admin: true}, Method: "session"}

func addOffice(t *testing.T, e *Engine) int64 {
	t.Helper()
	var id int64
	res, err := e.Apply(context.Background(), admin, "", Options{Via: "cli"}, func(st *model.State, newID func() int64) error {
		p, _ := model.ParsePool("10.0.10.100-10.0.10.199")
		id = newID()
		st.Subnets = append(st.Subnets, &model.Subnet{ID: id, Name: "office", Interface: "eth0", Prefix: netip.MustParsePrefix("10.0.10.0/24"),
			Pools: []model.Pool{p}, Options: []model.OptionValue{{Code: 6, Value: "10.0.10.2,10.0.10.3"}}})
		return nil
	})
	if err != nil || !res.Applied || res.HistoryID == 0 {
		t.Fatalf("apply: %+v %v", res, err)
	}
	return id
}

func TestApplyNormalizesAndRecords(t *testing.T) {
	e := newEngine(t)
	id := addOffice(t, e)
	s := e.State().SubnetByID(id)
	if s.Options[0].Value != "10.0.10.2, 10.0.10.3" || s.Options[0].Name != "domain-name-servers" {
		t.Errorf("options not normalized: %+v", s.Options)
	}
	h, _ := e.Store().ListHistory(context.Background(), 10, 0)
	if len(h) != 1 || h[0].Description != "create subnet office (10.0.10.0/24)" || h[0].Via != "cli" || h[0].Username != "admin" {
		t.Errorf("history %+v", h[0])
	}
	// Nothing changed: nothing recorded.
	res, err := e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, _ func() int64) error { return nil })
	if err != nil || res.Applied || len(res.Changes) != 0 {
		t.Errorf("empty change: %+v %v", res, err)
	}
	// Reloading from the database gives the same state.
	e2, err := New(context.Background(), e.Store(), nil)
	if err != nil {
		t.Fatal(err)
	}
	if d := Diff(e.State(), e2.State()); len(d) != 0 {
		t.Errorf("reloaded state differs: %+v", d)
	}
}

func TestValidationRefuses(t *testing.T) {
	e := newEngine(t)
	addOffice(t, e)
	_, err := e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, newID func() int64) error {
		st.Subnets = append(st.Subnets, &model.Subnet{ID: newID(), Interface: "eth1", Prefix: netip.MustParsePrefix("10.0.0.0/16")})
		return nil
	})
	ee, ok := AsError(err)
	if !ok || ee.Kind != KindValidation || !strings.Contains(ee.Message, "overlaps subnet office") {
		t.Fatalf("got %v", err)
	}
	if len(e.State().Subnets) != 1 {
		t.Error("refused change was kept")
	}
}

func TestDryRun(t *testing.T) {
	e := newEngine(t)
	res, err := e.Apply(context.Background(), admin, "", Options{DryRun: true}, func(st *model.State, newID func() int64) error {
		st.Subnets = append(st.Subnets, &model.Subnet{ID: newID(), Interface: "eth0", Prefix: netip.MustParsePrefix("10.0.10.0/24")})
		return nil
	})
	if err != nil || res.Applied || len(res.Changes) != 1 || len(res.Warnings) != 1 || res.Warnings[0].Code != "subnet_no_pools" {
		t.Fatalf("dry run: %+v %v", res, err)
	}
	if len(e.State().Subnets) != 0 {
		t.Error("dry run changed the state")
	}
}

func TestRevert(t *testing.T) {
	ctx := context.Background()
	e := newEngine(t)
	var got *model.State
	e.OnChange = func(st *model.State) { got = st }
	id := addOffice(t, e)
	res, err := e.Apply(ctx, admin, "longer leases", Options{}, func(st *model.State, _ func() int64) error {
		st.SubnetByID(id).LeaseTime = 86400
		return nil
	})
	if err != nil {
		t.Fatal(err)
	}
	if got == nil || got.SubnetByID(id).LeaseTime != 86400 {
		t.Error("OnChange didn't get the new state")
	}
	// Undoing the creation conflicts: the subnet changed since.
	if _, err := e.Revert(ctx, admin, 1, Options{}); err == nil || !strings.Contains(err.Error(), "has changed since entry 1") {
		t.Fatalf("revert of an older entry: %v", err)
	}
	if _, err := e.Revert(ctx, admin, res.HistoryID, Options{}); err != nil {
		t.Fatal(err)
	}
	if e.State().SubnetByID(id).LeaseTime != 0 {
		t.Error("revert didn't restore the lease time")
	}
	if _, err := e.Revert(ctx, admin, res.HistoryID, Options{}); err == nil || !strings.Contains(err.Error(), "already undone") {
		t.Errorf("second revert: %v", err)
	}
	if _, err := e.Revert(ctx, admin, 1, Options{}); err != nil {
		t.Fatalf("revert of the creation: %v", err)
	}
	if len(e.State().Subnets) != 0 {
		t.Error("subnet still there")
	}
	h, _ := e.Store().GetHistory(ctx, 1)
	if h.RevertedBy == 0 {
		t.Error("entry 1 not marked undone")
	}
}