package engine

import (
	"context"
	"errors"
	"strings"
	"testing"

	"housecarl/internal/auth"
	"housecarl/internal/model"
	"housecarl/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"}

// fakeFirewall records what it was asked to apply.
type fakeFirewall struct {
	applied  []*model.State
	checkErr error
	applyErr error
}

func (f *fakeFirewall) Check(_ context.Context, st *model.State) error { return f.checkErr }
func (f *fakeFirewall) Apply(_ context.Context, st *model.State) error {
	if f.applyErr != nil {
		return f.applyErr
	}
	f.applied = append(f.applied, st.Clone())
	return nil
}

func addWAN(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 {
		id = newID()
		st.Zones = append(st.Zones, &model.Zone{ID: id, Name: "wan", Interfaces: []string{" wan ", "wan", "ppp*"}, External: true})
		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)
	fw := &fakeFirewall{}
	e.Firewall = fw
	id := addWAN(t, e)
	z := e.State().ByID(model.KindZone, id).(*model.Zone)
	if strings.Join(z.Interfaces, ",") != "wan,ppp*" {
		t.Errorf("interfaces not normalized: %q", z.Interfaces)
	}
	if len(fw.applied) != 1 || len(fw.applied[0].Zones) != 1 {
		t.Errorf("firewall got %+v", fw.applied)
	}
	h, _ := e.Store().ListHistory(context.Background(), 10, 0)
	if len(h) != 1 || h[0].Description != "create zone wan" || h[0].Via != "cli" || h[0].Username != "admin" {
		t.Errorf("history %+v", h[0])
	}
	// Nothing changed: nothing recorded or applied.
	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 || len(fw.applied) != 1 {
		t.Errorf("empty change: %+v %v", res, err)
	}
}

func TestValidationAndFirewallRefusals(t *testing.T) {
	e := newEngine(t)
	fw := &fakeFirewall{}
	e.Firewall = fw
	addWAN(t, e)
	addRule := func(r *model.Rule) (*Result, error) {
		return e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, newID func() int64) error {
			r.ID = newID()
			st.Rules = append(st.Rules, r)
			return nil
		})
	}
	// Validation: an unknown set.
	_, err := addRule(&model.Rule{Chain: model.ChainInput, Position: 1, Action: model.ActionAccept, Match: model.Match{Sources: []string{"trusted"}}})
	if ee, ok := AsError(err); !ok || ee.Kind != KindValidation || ee.Problems[0].Code != "unknown_set" {
		t.Errorf("unknown set: %v", err)
	}
	// nftables refuses: nothing applied or saved.
	fw.checkErr = errors.New("syntax error")
	_, err = addRule(&model.Rule{Chain: model.ChainInput, Position: 1, Action: model.ActionAccept, Raw: "bogus"})
	if ee, ok := AsError(err); !ok || ee.Kind != KindFirewall {
		t.Errorf("refused ruleset: %v", err)
	}
	// Applying fails: nothing saved.
	fw.checkErr, fw.applyErr = nil, errors.New("netlink: busy")
	_, err = addRule(&model.Rule{Chain: model.ChainInput, Position: 1, Action: model.ActionAccept, Match: model.Match{Services: []string{"ssh"}}})
	if ee, ok := AsError(err); !ok || ee.Kind != KindFirewall || !strings.Contains(ee.Message, "nothing was changed") {
		t.Errorf("failed apply: %v", err)
	}
	if len(e.State().Rules) != 0 {
		t.Errorf("rules saved after failures: %+v", e.State().Rules)
	}
	// A dry run is checked, but neither applied nor saved.
	fw.applyErr = nil
	before := len(fw.applied)
	res, err := e.Apply(context.Background(), admin, "", Options{DryRun: true}, func(st *model.State, newID func() int64) error {
		st.Rules = append(st.Rules, &model.Rule{ID: newID(), Chain: model.ChainInput, Position: 1, Action: model.ActionDrop})
		return nil
	})
	if err != nil || res.Applied || len(res.Changes) != 1 || len(fw.applied) != before {
		t.Errorf("dry run: %+v %v", res, err)
	}
}

func TestRevertAppliesThePreviousRuleset(t *testing.T) {
	e := newEngine(t)
	fw := &fakeFirewall{}
	e.Firewall = fw
	addWAN(t, e)
	res, err := e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, newID func() int64) error {
		st.Settings.ForwardPolicy = model.PolicyAccept
		return nil
	})
	if err != nil || !res.Applied {
		t.Fatal(err)
	}
	if _, err := e.Revert(context.Background(), admin, res.HistoryID, Options{}); err != nil {
		t.Fatal(err)
	}
	last := fw.applied[len(fw.applied)-1]
	if last.Settings.ForwardPolicy != model.PolicyDrop || e.State().Settings.ForwardPolicy != model.PolicyDrop {
		t.Errorf("after revert: applied %s, state %s", last.Settings.ForwardPolicy, e.State().Settings.ForwardPolicy)
	}
	// Undoing it twice is refused.
	if _, err := e.Revert(context.Background(), admin, res.HistoryID, Options{}); err == nil {
		t.Error("second undo accepted")
	}
}

func TestPositionsStayStableUntilCrowded(t *testing.T) {
	e := newEngine(t)
	for i := 0; i < 3; i++ {
		e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, newID func() int64) error {
			st.Rules = append(st.Rules, &model.Rule{ID: newID(), Chain: model.ChainInput, Position: float64(i + 1), Action: model.ActionAccept,
				Match: model.Match{Services: []string{"ssh"}}})
			return nil
		})
	}
	// Inserting between two rules changes only the new one.
	res, err := e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, newID func() int64) error {
		st.Rules = append(st.Rules, &model.Rule{ID: newID(), Chain: model.ChainInput, Position: 1.5, Action: model.ActionDrop})
		return nil
	})
	if err != nil || len(res.Changes) != 1 {
		t.Fatalf("insert: %+v %v", res, err)
	}
	var order []string
	for _, r := range e.State().Rules {
		order = append(order, r.Action)
	}
	if strings.Join(order, ",") != "accept,drop,accept,accept" {
		t.Errorf("order %v", order)
	}
}