package server

import (
	"encoding/json"
	"net/http"
	"slices"
	"sort"
	"strconv"
	"strings"

	"jarl/internal/api"
	"jarl/internal/auth"
	"jarl/internal/catalog"
	"jarl/internal/dnsname"
	"jarl/internal/engine"
	"jarl/internal/iprange"
	"jarl/internal/model"
	"jarl/internal/render"
	"jarl/internal/rr"
)

// state returns the configuration a request works on: the current one,
// or, when the request names an open changeset (?changeset= or the
// X-Jarl-Changeset header), the configuration as it will be after that
// changeset, so staged objects can be referred to.
func (s *Server) state(r *http.Request) (*model.State, error) {
	st, _, err := s.states(r)
	return st, err
}

// states is like state but also returns the current configuration when a
// changeset is involved (base is nil otherwise).
func (s *Server) states(r *http.Request) (work, base *model.State, err error) {
	if csID, _ := changesetTarget(r); csID > 0 {
		if p, ok := r.Context().Value(keyPrincipal).(*auth.Principal); ok {
			if w, b, err := s.eng.WorkingState(r.Context(), csID, p); err == nil {
				return w, b, nil
			}
		}
	}
	st, err := s.store.LoadState(r.Context())
	return st, nil, err
}

// ---- views

func (s *Server) listViews(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	colors, err := s.store.ViewColors(r.Context())
	if err != nil {
		return err
	}
	out := []api.View{}
	for _, v := range st.OrderedViews() {
		if p.Can(auth.Action{Resource: auth.ResViews, View: v.Name}) {
			out = append(out, presentView(st, v, colors))
		}
	}
	writeJSON(w, http.StatusOK, out)
	return nil
}

func (s *Server) viewByPath(r *http.Request, st *model.State, p *auth.Principal) (*model.View, error) {
	ref := r.PathValue("id")
	var v *model.View
	if id, err := strconv.ParseInt(ref, 10, 64); err == nil {
		v = st.Views[id]
	} else {
		v = st.ViewByName(ref)
	}
	if v == nil || !p.Can(auth.Action{Resource: auth.ResViews, View: v.Name}) {
		return nil, notFound("view %s not found", ref)
	}
	return v, nil
}

func (s *Server) getView(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	v, err := s.viewByPath(r, st, p)
	if err != nil {
		return err
	}
	colors, err := s.store.ViewColors(r.Context())
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, presentView(st, v, colors))
	return nil
}

// viewKey: GET /views/{id}/key is the TSIG key that selects the view
// (render/viewkeys.go), with its secret: like revealing a TSIG key's, it
// needs tsig:write and is audited.
func (s *Server) viewKey(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	v, err := s.viewByPath(r, st, p)
	if err != nil {
		return err
	}
	if err := require(p, auth.Action{Resource: auth.ResTSIG, Write: true}); err != nil {
		return forbidden("showing a view's key needs tsig:write")
	}
	seed, err := engine.ViewKeySeed(r.Context(), s.store)
	if err != nil {
		return err
	}
	name := render.ViewKeyName(v.Name)
	s.eng.Audit(r.Context(), p, "tsig.reveal", "view", v.ID, v.Name, "success", "view key "+name+" shown")
	writeJSON(w, http.StatusOK, map[string]string{"name": name, "algorithm": render.ViewKeyAlgorithm, "secret": render.ViewKeySecret(seed, v.ID)})
	return nil
}

func (s *Server) viewObject(r *http.Request) func(st *model.State, id int64) any {
	return func(st *model.State, id int64) any {
		if v := st.Views[id]; v != nil {
			colors, _ := s.store.ViewColors(r.Context())
			return presentView(st, v, colors)
		}
		return nil
	}
}

// setViewColor sets the colour the web UI shows a view in. It is not part
// of the configuration, so it applies at once, outside changesets.
func (s *Server) setViewColor(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	v, err := s.viewByPath(r, st, p)
	if err != nil {
		return err
	}
	if err := require(p, auth.Action{Resource: auth.ResViews, Write: true, View: v.Name}); err != nil {
		return err
	}
	var in api.ViewColor
	if err := decodeJSON(r, &in); err != nil {
		return err
	}
	if in.Color != "" && !slices.Contains(model.ViewColors, in.Color) {
		return badRequest("unknown colour %q: use one of %s, or \"\" for the default", in.Color, strings.Join(model.ViewColors, ", "))
	}
	if err := s.store.SetViewColor(r.Context(), v.ID, in.Color); err != nil {
		return err
	}
	detail := in.Color
	if detail == "" {
		detail = "default"
	}
	s.eng.Audit(r.Context(), p, "view.color", "view", v.ID, v.Name, "success", detail)
	colors, err := s.store.ViewColors(r.Context())
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, presentView(st, v, colors))
	return nil
}

func (s *Server) createView(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	body, err := readBody(r)
	if err != nil {
		return err
	}
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpViewCreate, 0, body)}, s.viewObject(r))
}

func (s *Server) updateView(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	v, err := s.viewByPath(r, st, p)
	if err != nil {
		return err
	}
	body, err := readBody(r)
	if err != nil {
		return err
	}
	id := v.ID
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpViewUpdate, id, body)}, func(st *model.State, _ int64) any { return s.viewObject(r)(st, id) })
}

func (s *Server) deleteView(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	v, err := s.viewByPath(r, st, p)
	if err != nil {
		return err
	}
	data, _ := json.Marshal(engine.DeleteInput{Cascade: queryBool(r, "cascade")})
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpViewDelete, v.ID, data)}, nil)
}

func (s *Server) reorderViews(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	body, err := readBody(r)
	if err != nil {
		return err
	}
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpViewReorder, 0, body)}, nil)
}

// ---- ACLs

func (s *Server) listACLs(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.Action{Resource: auth.ResACLs}); err != nil {
		return err
	}
	st, err := s.state(r)
	if err != nil {
		return err
	}
	out := []api.ACL{}
	for _, a := range st.SortedACLs() {
		out = append(out, presentACL(st, a))
	}
	writeJSON(w, http.StatusOK, out)
	return nil
}

func (s *Server) aclByPath(r *http.Request, st *model.State) (*model.ACL, error) {
	ref := r.PathValue("id")
	var a *model.ACL
	if id, err := strconv.ParseInt(ref, 10, 64); err == nil {
		a = st.ACLs[id]
	} else {
		a = st.ACLByName(ref)
	}
	if a == nil {
		return nil, notFound("ACL %s not found", ref)
	}
	return a, nil
}

func (s *Server) getACL(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.Action{Resource: auth.ResACLs}); err != nil {
		return err
	}
	st, err := s.state(r)
	if err != nil {
		return err
	}
	a, err := s.aclByPath(r, st)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, presentACL(st, a))
	return nil
}

func aclObject(st *model.State, id int64) any {
	if a := st.ACLs[id]; a != nil {
		return presentACL(st, a)
	}
	return nil
}

func (s *Server) createACL(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	body, err := readBody(r)
	if err != nil {
		return err
	}
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpACLCreate, 0, body)}, aclObject)
}

func (s *Server) updateACL(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	a, err := s.aclByPath(r, st)
	if err != nil {
		return err
	}
	body, err := readBody(r)
	if err != nil {
		return err
	}
	id := a.ID
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpACLUpdate, id, body)}, func(st *model.State, _ int64) any { return aclObject(st, id) })
}

func (s *Server) deleteACL(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	a, err := s.aclByPath(r, st)
	if err != nil {
		return err
	}
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpACLDelete, a.ID, nil)}, nil)
}

// ---- TSIG keys

func (s *Server) listKeys(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.Action{Resource: auth.ResTSIG}); err != nil {
		return err
	}
	st, err := s.state(r)
	if err != nil {
		return err
	}
	out := []api.TSIGKey{}
	for _, k := range st.SortedKeys() {
		out = append(out, presentKey(st, k, false))
	}
	writeJSON(w, http.StatusOK, out)
	return nil
}

func (s *Server) keyByPath(r *http.Request, st *model.State) (*model.TSIGKey, error) {
	ref := r.PathValue("id")
	var k *model.TSIGKey
	if id, err := strconv.ParseInt(ref, 10, 64); err == nil {
		k = st.Keys[id]
	} else {
		k = st.KeyByName(ref)
	}
	if k == nil {
		return nil, notFound("TSIG key %s not found", ref)
	}
	return k, nil
}

func (s *Server) getKey(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.Action{Resource: auth.ResTSIG}); err != nil {
		return err
	}
	st, err := s.state(r)
	if err != nil {
		return err
	}
	k, err := s.keyByPath(r, st)
	if err != nil {
		return err
	}
	withSecret := queryBool(r, "secret")
	if withSecret {
		if err := require(p, auth.Action{Resource: auth.ResTSIG, Write: true}); err != nil {
			return forbidden("showing a TSIG secret needs tsig:write")
		}
		s.eng.Audit(r.Context(), p, "tsig.reveal", "tsig", k.ID, k.Name, "success", "secret shown")
	}
	writeJSON(w, http.StatusOK, presentKey(st, k, withSecret))
	return nil
}

func keyObject(withSecret bool) func(st *model.State, id int64) any {
	return func(st *model.State, id int64) any {
		if k := st.Keys[id]; k != nil {
			return presentKey(st, k, withSecret)
		}
		return nil
	}
}

func (s *Server) createKey(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	body, err := readBody(r)
	if err != nil {
		return err
	}
	// The creator gets to see a generated secret once.
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpTSIGCreate, 0, body)}, keyObject(true))
}

func (s *Server) updateKey(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	k, err := s.keyByPath(r, st)
	if err != nil {
		return err
	}
	body, err := readBody(r)
	if err != nil {
		return err
	}
	id := k.ID
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpTSIGUpdate, id, body)}, func(st *model.State, _ int64) any { return keyObject(false)(st, id) })
}

func (s *Server) deleteKey(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	k, err := s.keyByPath(r, st)
	if err != nil {
		return err
	}
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpTSIGDelete, k.ID, nil)}, nil)
}

// ---- options

func (s *Server) listOptions(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	scope := r.URL.Query().Get("scope")
	scopeID := int64(queryInt(r, "scope_id", 0))
	out := []api.Option{}
	var list []*model.Option
	if scope != "" {
		list = st.ScopedOptions(scope, scopeID)
	} else {
		for _, sc := range []string{model.ScopeTopLevel, model.ScopeOptions} {
			list = append(list, st.ScopedOptions(sc, 0)...)
		}
		for _, v := range st.OrderedViews() {
			list = append(list, st.ScopedOptions(model.ScopeView, v.ID)...)
		}
		for _, z := range st.SortedZones() {
			list = append(list, st.ScopedOptions(model.ScopeZone, z.ID)...)
		}
	}
	for _, o := range list {
		if canReadOption(p, st, o) {
			out = append(out, presentOption(st, o))
		}
	}
	writeJSON(w, http.StatusOK, out)
	return nil
}

func (s *Server) optionByPath(r *http.Request, st *model.State, p *auth.Principal) (*model.Option, error) {
	id, err := pathID(r, "id")
	if err != nil {
		return nil, err
	}
	o := st.Options[id]
	if o == nil || !canReadOption(p, st, o) {
		return nil, notFound("option %d not found", id)
	}
	return o, nil
}

func (s *Server) getOption(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	o, err := s.optionByPath(r, st, p)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, presentOption(st, o))
	return nil
}

func optionObject(st *model.State, id int64) any {
	if o := st.Options[id]; o != nil {
		return presentOption(st, o)
	}
	return nil
}

func (s *Server) createOption(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	body, err := readBody(r)
	if err != nil {
		return err
	}
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpOptionCreate, 0, body)}, optionObject)
}

func (s *Server) updateOption(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	o, err := s.optionByPath(r, st, p)
	if err != nil {
		return err
	}
	body, err := readBody(r)
	if err != nil {
		return err
	}
	id := o.ID
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpOptionUpdate, id, body)}, func(st *model.State, _ int64) any { return optionObject(st, id) })
}

func (s *Server) deleteOption(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	o, err := s.optionByPath(r, st, p)
	if err != nil {
		return err
	}
	return s.mutate(w, r, p, "", []engine.Request{request(engine.OpOptionDelete, o.ID, nil)}, nil)
}

// ---- settings

func (s *Server) getSettings(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.state(r)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, st.Settings)
	return nil
}

func (s *Server) updateSettings(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	body, err := readBody(r)
	if err != nil {
		return err
	}
	return s.mutate(w, r, p, "update settings", []engine.Request{request(engine.OpSettingsUpdate, 0, body)}, func(st *model.State, _ int64) any { return st.Settings })
}

// ---- catalogs

func (s *Server) catalogOptions(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	cat := catalog.Default()
	scope := r.URL.Query().Get("scope")
	if scope == "" {
		writeJSON(w, http.StatusOK, map[string]any{"scopes": cat.Scopes(), "zone_types": cat.ZoneTypes()})
		return nil
	}
	list := cat.List(scope)
	if list == nil {
		return notFound("unknown scope %q (use one of %s)", scope, strings.Join(cat.Scopes(), ", "))
	}
	out := []*catalog.Statement{}
	for _, st := range list {
		if !st.Managed || queryBool(r, "all") {
			out = append(out, st)
		}
	}
	writeJSON(w, http.StatusOK, out)
	return nil
}

func (s *Server) catalogRRTypes(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	writeJSON(w, http.StatusOK, rr.Types())
	return nil
}

// catalogRanges: GET /catalog/ranges?r=A-B,C-D shows the prefixes each
// address range is written to named.conf as (the web UI shows them while
// you type). Text that isn't a range is left out; a range with a mistake
// comes back with its error.
func (s *Server) catalogRanges(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	type rangeInfo struct {
		Input    string   `json:"input"`
		Range    string   `json:"range,omitempty"`
		Prefixes []string `json:"prefixes,omitempty"`
		Size     string   `json:"size,omitempty"`
		Error    string   `json:"error,omitempty"`
	}
	out := []rangeInfo{}
	for _, in := range strings.Split(r.URL.Query().Get("r"), ",") {
		in = strings.TrimSpace(in)
		if in == "" || len(out) >= 100 {
			continue
		}
		rg, ok, err := iprange.Parse(strings.TrimSpace(strings.TrimPrefix(in, "!")))
		switch {
		case !ok:
			continue
		case err != nil:
			out = append(out, rangeInfo{Input: in, Error: err.Error()})
		default:
			ri := rangeInfo{Input: in, Range: rg.String(), Size: rg.SizeText()}
			for _, pf := range rg.Prefixes() {
				ri.Prefixes = append(ri.Prefixes, pf.String())
			}
			out = append(out, ri)
		}
	}
	writeJSON(w, http.StatusOK, out)
	return nil
}

func (s *Server) catalogGrants(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	roles := map[string][]string{}
	for name, gs := range auth.RoleTemplates {
		for _, g := range gs {
			roles[name] = append(roles[name], auth.FormatGrant(g))
		}
	}
	writeJSON(w, http.StatusOK, map[string]any{"resources": auth.Resources, "access": []string{auth.Read, auth.Write}, "roles": roles,
		"syntax": "resource:access [zones=a,b] [views=x] [names=pattern] [types=TXT,CNAME]"})
	return nil
}

// ---- search

func (s *Server) search(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	q := strings.ToLower(strings.TrimSpace(r.URL.Query().Get("q")))
	if len(q) < 2 {
		return badRequest("search for at least 2 characters")
	}
	st, err := s.state(r)
	if err != nil {
		return err
	}
	limit := queryInt(r, "limit", 200)
	out := []api.SearchResult{}
	add := func(res api.SearchResult) bool {
		out = append(out, res)
		return len(out) >= limit
	}
	for _, z := range st.SortedZones() {
		if strings.Contains(z.Name, q) && p.CanSeeZone(z.Name, st.ViewName(z)) {
			if add(api.SearchResult{Kind: "zone", ID: z.ID, ZoneID: z.ID, Label: engine.ZoneLabel(st, z), Detail: z.Type}) {
				break
			}
		}
	}
	var recs []*model.Record
	for _, r := range st.Records {
		if strings.Contains(r.Name, q) || strings.Contains(strings.ToLower(r.Data), q) || strings.Contains(strings.ToLower(r.Comment), q) {
			recs = append(recs, r)
		}
	}
	sort.Slice(recs, func(i, j int) bool {
		if recs[i].Name != recs[j].Name {
			return model.CanonicalLess(recs[i].Name, recs[j].Name)
		}
		return recs[i].ID < recs[j].ID
	})
	for _, rec := range recs {
		if len(out) >= limit {
			break
		}
		if !canReadRecord(p, st, rec) {
			continue
		}
		z := st.Zones[rec.ZoneID]
		add(api.SearchResult{Kind: "record", ID: rec.ID, ZoneID: rec.ZoneID, Label: dnsname.Display(rec.Name) + " " + rec.Type + " " + rec.Data, Detail: engine.ZoneLabel(st, z)})
	}
	if p.Can(auth.Action{Resource: auth.ResACLs}) {
		for _, a := range st.SortedACLs() {
			if strings.Contains(strings.ToLower(a.Name), q) || strings.Contains(strings.ToLower(strings.Join(a.Elements, " ")), q) {
				add(api.SearchResult{Kind: "acl", ID: a.ID, Label: "ACL " + a.Name, Detail: strings.Join(a.Elements, "; ")})
			}
		}
	}
	writeJSON(w, http.StatusOK, out)
	return nil
}