package view

import (
	"context"
	"fmt"
	"time"

	"github.com/derailed/k9s/internal/render"
	"github.com/derailed/k9s/internal/ui"
	"github.com/gdamore/tcell"
	"github.com/rs/zerolog/log"
	rbacv1 "k8s.io/api/rbac/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/runtime"
)

const (
	policyTitle = "Policy"
	group       = "Group"
	user        = "User"
	sa          = "ServiceAccount"
)

type (
	namespacedRole struct {
		ns, role string
	}

	// Policy presents a RBAC policy viewer.
	Policy struct {
		*Table

		cancel      context.CancelFunc
		subjectKind string
		subjectName string
		cache       render.RowEvents
	}
)

// NewPolicy returns a new viewer.
func NewPolicy(app *App, subject, name string) *Policy {
	return &Policy{
		Table:       NewTable(policyTitle),
		subjectKind: mapSubject(subject),
		subjectName: name,
	}
}

// Init the view.
func (p *Policy) Init(ctx context.Context) error {
	p.Table.Path = p.subjectKind + ":" + p.subjectName
	if err := p.Table.Init(ctx); err != nil {
		return err
	}
	p.SetColorerFn(render.Policy{}.ColorerFunc())
	p.bindKeys()
	p.SetSortCol(1, len(render.Policy{}.Header(render.AllNamespaces)), false)
	p.refresh()
	p.SelectRow(1, true)

	return nil
}

func (p *Policy) Name() string {
	return "policy"
}

func (p *Policy) Start() {
	p.Stop()
	ctx, cancel := context.WithCancel(context.Background())
	p.cancel = cancel
	go func(ctx context.Context) {
		for {
			select {
			case <-ctx.Done():
				return
			case <-time.After(time.Duration(p.app.Config.K9s.GetRefreshRate()) * time.Second):
				p.refresh()
			}
		}
	}(ctx)
}

func (p *Policy) bindKeys() {
	p.Actions().Delete(ui.KeyShiftA, tcell.KeyCtrlSpace, ui.KeySpace)
	p.Actions().Add(ui.KeyActions{
		tcell.KeyEscape: ui.NewKeyAction("Back", p.resetCmd, false),
		ui.KeySlash:     ui.NewKeyAction("Filter", p.activateCmd, false),
		ui.KeyShiftP:    ui.NewKeyAction("Sort Namespace", p.SortColCmd(0, true), false),
		ui.KeyShiftN:    ui.NewKeyAction("Sort Name", p.SortColCmd(1, true), false),
		ui.KeyShiftO:    ui.NewKeyAction("Sort Group", p.SortColCmd(2, true), false),
		ui.KeyShiftB:    ui.NewKeyAction("Sort Binding", p.SortColCmd(3, true), false),
	})
}

func (p *Policy) getTitle() string {
	return fmt.Sprintf(rbacTitleFmt, policyTitle, p.subjectKind+":"+p.subjectName, p.GetRowCount())
}

func (p *Policy) refresh() {
	log.Debug().Msgf(">>>>>>>>>>>>>>> Refreshing Policies")
	// BOZO!!
	defer func(t time.Time) {
		log.Debug().Msgf("Policy Refresh elapsed %v", time.Since(t))
	}(time.Now())

	data, err := p.reconcile()
	if err != nil {
		log.Error().Err(err).Msgf("Refresh for %s:%s", p.subjectKind, p.subjectName)
		p.app.Flash().Err(err)
	}
	p.app.QueueUpdateDraw(func() {
		p.Update(data)
	})
}

func (p *Policy) resetCmd(evt *tcell.EventKey) *tcell.EventKey {
	if !p.SearchBuff().Empty() {
		p.SearchBuff().Reset()
		return nil
	}

	return p.backCmd(evt)
}

func (p *Policy) backCmd(evt *tcell.EventKey) *tcell.EventKey {
	if p.cancel != nil {
		p.cancel()
	}

	if p.SearchBuff().IsActive() {
		p.SearchBuff().Reset()
		return nil
	}

	return p.app.PrevCmd(evt)
}

func (p *Policy) reconcile() (render.TableData, error) {
	// BOZO!!
	defer func(t time.Time) {
		log.Debug().Msgf("Policy Reconcile elapsed %v", time.Since(t))
	}(time.Now())

	var table render.TableData

	evts, errs := p.fetchClusterRoleBindings()
	if len(errs) > 0 {
		for _, err := range errs {
			log.Error().Err(err).Msg("Unable to find cluster policies")
		}
		return table, errs[0]
	}

	nevts, errs := p.namespacedPolicies()
	if len(errs) > 0 {
		for _, err := range errs {
			log.Error().Err(err).Msg("Unable to find cluster policies")
		}
		return table, errs[0]
	}

	for _, v := range nevts {
		evts = append(evts, v)
	}

	return buildTable(p, evts), nil
}

// Protocol...

func (p *Policy) Header() render.HeaderRow {
	return render.Policy{}.Header(render.AllNamespaces)
}

func (p *Policy) GetCache() render.RowEvents {
	return p.cache
}

func (p *Policy) SetCache(evts render.RowEvents) {
	p.cache = evts
}

func (p *Policy) fetchClusterRoleBindings() (render.Rows, []error) {
	var errs []error
	oo, err := p.app.factory.List(render.ClusterWide, "rbac.authorization.k8s.io/v1/clusterrolebindings", labels.Everything())
	if err != nil {
		return nil, append(errs, err)
	}

	roles := make([]string, 0, len(oo))
	for _, o := range oo {
		var crb rbacv1.ClusterRoleBinding
		err = runtime.DefaultUnstructuredConverter.FromUnstructured(o.(*unstructured.Unstructured).Object, &crb)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		for _, s := range crb.Subjects {
			if s.Kind == p.subjectKind && s.Name == p.subjectName {
				roles = append(roles, crb.RoleRef.Name)
			}
		}
	}

	rows := make(render.Rows, 0, len(oo))
	for _, role := range roles {
		o, err := p.app.factory.Get(render.ClusterWide, "rbac.authorization.k8s.io/v1/clusterroles", role, labels.Everything())
		if err != nil {
			return nil, append(errs, err)
		}
		var cr rbacv1.ClusterRole
		err = runtime.DefaultUnstructuredConverter.FromUnstructured(o.(*unstructured.Unstructured).Object, &cr)
		if err != nil {
			errs = append(errs, err)
			continue
		}

		for _, v := range p.parseRules("*", "CR:"+role, cr.Rules) {
			rows = append(rows, v)
		}
	}

	return rows, errs
}

func (p *Policy) fetchRoleBindings() ([]namespacedRole, error) {
	oo, err := p.app.factory.List(render.AllNamespaces, "rbac.authorization.k8s.io/v1/rolebindings", labels.Everything())
	if err != nil {
		return nil, err
	}

	rr := make([]namespacedRole, 0, len(oo))
	for _, o := range oo {
		var rb rbacv1.RoleBinding
		err = runtime.DefaultUnstructuredConverter.FromUnstructured(o.(*unstructured.Unstructured).Object, &rb)
		if err != nil {
			return nil, err
		}
		for _, s := range rb.Subjects {
			if s.Kind == p.subjectKind && s.Name == p.subjectName {
				rr = append(rr, namespacedRole{rb.Namespace, rb.RoleRef.Name})
			}
		}
	}

	return rr, nil
}

func (p *Policy) fetchClusterRoles(errs []error, rr []namespacedRole) (render.Rows, []error) {
	rows := make(render.Rows, 0, len(rr))
	for _, r := range rr {
		o, err := p.app.factory.Get(r.ns, "rbac.authorization.k8s.io/v1/clusterroles", r.role, labels.Everything())
		if err != nil {
			return nil, append(errs, err)
		}

		var cr rbacv1.ClusterRole
		err = runtime.DefaultUnstructuredConverter.FromUnstructured(o.(*unstructured.Unstructured).Object, &cr)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		rows = append(rows, p.parseRules(r.ns, "RO:"+r.role, cr.Rules)...)
	}

	return rows, errs
}

func (p *Policy) namespacedPolicies() (render.Rows, []error) {
	var errs []error
	roles, err := p.fetchRoleBindings()
	if err != nil {
		errs = append(errs, err)
	}

	return p.fetchClusterRoles(errs, roles)
}

func (p *Policy) parseRules(ns, binding string, rules []rbacv1.PolicyRule) render.Rows {
	m := make(render.Rows, 0, len(rules))
	for _, r := range rules {
		for _, grp := range r.APIGroups {
			for _, res := range r.Resources {
				k := res
				if grp != "" {
					k = res + "." + grp
				}
				for _, na := range r.ResourceNames {
					n := fqn(k, na)
					m = append(m, render.Row{
						ID:     fqn(ns, n),
						Fields: append(policyRow(ns, n, grp, binding), asVerbs(r.Verbs...)...),
					})
				}
				m = append(m, render.Row{
					ID:     fqn(ns, k),
					Fields: append(policyRow(ns, k, grp, binding), asVerbs(r.Verbs...)...),
				})
			}
		}
		for _, nres := range r.NonResourceURLs {
			if nres[0] != '/' {
				nres = "/" + nres
			}
			m = append(m, render.Row{
				ID:     fqn(ns, nres),
				Fields: append(policyRow(ns, nres, "", binding), asVerbs(r.Verbs...)...),
			})
		}
	}

	return m
}

func policyRow(ns, res, grp, binding string) render.Fields {
	if grp != "" {
		grp = toGroup(grp)
	}

	r := make(render.Fields, 0, len(render.Policy{}.Header(render.AllNamespaces)))
	return append(r, ns, res, grp, binding)
}

func mapSubject(subject string) string {
	switch subject {
	case "g":
		return group
	case "s":
		return sa
	default:
		return user
	}
}

func showSAPolicy(app *App, _, _, selection string) {
	_, n := namespaced(selection)
	subject, err := mapFuSubject("ServiceAccount")
	if err != nil {
		app.Flash().Err(err)
		return
	}
	app.inject(NewPolicy(app, subject, n))
}