package api

import (
	"net/http"
	"strings"

	"github.com/owen/vibedns/internal/app"
	"github.com/owen/vibedns/internal/database"
	"github.com/owen/vibedns/internal/models"
	"github.com/owen/vibedns/internal/validate"
	"github.com/owen/vibedns/internal/zonefile"
)

// --- Zones --------------------------------------------------------------

func (s *Server) listZones(w http.ResponseWriter, r *http.Request) error {
	zones, err := s.app.Zones(r.Context(), database.ZoneFilter{
		Kind:   query(r, "kind"),
		Search: query(r, "search"),
	})
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, listBody{Items: nonNil(zones), Total: len(zones)})
	return nil
}

func (s *Server) getZone(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	zone, err := s.app.Zone(r.Context(), id)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, zone)
	return nil
}

func (s *Server) createZone(w http.ResponseWriter, r *http.Request) error {
	var in app.ZoneInput
	if err := decode(r, &in); err != nil {
		return err
	}
	zone, err := s.app.CreateZone(r.Context(), s.actor(r), in)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusCreated, zone)
	return nil
}

func (s *Server) updateZone(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in app.ZoneInput
	if err := decode(r, &in); err != nil {
		return err
	}
	zone, err := s.app.UpdateZone(r.Context(), s.actor(r), id, in)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, zone)
	return nil
}

func (s *Server) deleteZone(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	if err := s.app.DeleteZone(r.Context(), s.actor(r), id); err != nil {
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

func (s *Server) cloneZone(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in struct {
		Name        string `json:"name"`
		Description string `json:"description"`
	}
	if err := decode(r, &in); err != nil {
		return err
	}
	zone, err := s.app.CloneZone(r.Context(), s.actor(r), id, in.Name, in.Description)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusCreated, zone)
	return nil
}

func (s *Server) exportZone(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	zone, body, err := s.app.ExportZoneFile(r.Context(), id)
	if err != nil {
		return err
	}
	w.Header().Set("Content-Type", "text/dns; charset=utf-8")
	w.Header().Set("Content-Disposition", "attachment; filename=\""+zonefile.SuggestFilename(zone.Name)+"\"")
	_, _ = w.Write(body)
	return nil
}

// importZone accepts a zone file as the raw request body, which is what
// `curl --data-binary @example.zone` sends.
func (s *Server) importZone(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	mode := app.ImportMode(query(r, "mode"))
	if mode == "" {
		mode = app.ImportMerge
	}
	result, err := s.app.ImportZoneFile(r.Context(), s.actor(r), id, r.Body, mode)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, result)
	return nil
}

// --- Records ------------------------------------------------------------

func (s *Server) recordFilter(r *http.Request, zoneID int64) database.RecordFilter {
	limit, offset := limitOffset(r, 100)
	return database.RecordFilter{
		ZoneID:  zoneID,
		Search:  query(r, "search"),
		Type:    query(r, "type"),
		Enabled: query(r, "status"),
		Limit:   limit,
		Offset:  offset,
	}
}

func (s *Server) listRecords(w http.ResponseWriter, r *http.Request) error {
	f := s.recordFilter(r, queryInt64(r, "zone_id"))
	records, total, err := s.app.Records(r.Context(), f)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, listBody{
		Items: nonNil(records), Total: total, Limit: f.Limit, Offset: f.Offset,
	})
	return nil
}

func (s *Server) listZoneRecords(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	if _, err := s.app.Zone(r.Context(), id); err != nil {
		return err
	}
	f := s.recordFilter(r, id)
	records, total, err := s.app.Records(r.Context(), f)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, listBody{
		Items: nonNil(records), Total: total, Limit: f.Limit, Offset: f.Offset,
	})
	return nil
}

func (s *Server) getRecord(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	rec, err := s.app.Record(r.Context(), id)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, rec)
	return nil
}

func (s *Server) createRecord(w http.ResponseWriter, r *http.Request) error {
	zoneID, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in app.RecordInput
	if err := decode(r, &in); err != nil {
		return err
	}
	rec, err := s.app.CreateRecord(r.Context(), s.actor(r), zoneID, in)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusCreated, rec)
	return nil
}

func (s *Server) updateRecord(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in app.RecordInput
	if err := decode(r, &in); err != nil {
		return err
	}
	rec, err := s.app.UpdateRecord(r.Context(), s.actor(r), id, in)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, rec)
	return nil
}

func (s *Server) deleteRecord(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	if err := s.app.DeleteRecord(r.Context(), s.actor(r), id); err != nil {
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

// listRecordTypes publishes the record type catalogue, including the field
// definitions the UI builds its editors from.
func (s *Server) listRecordTypes(w http.ResponseWriter, r *http.Request) error {
	types := s.app.RecordTypes()
	writeJSON(w, http.StatusOK, listBody{Items: types, Total: len(types)})
	return nil
}

// --- Networks -----------------------------------------------------------

func (s *Server) listNetworks(w http.ResponseWriter, r *http.Request) error {
	nets, err := s.app.Networks(r.Context(), query(r, "search"))
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, listBody{Items: nonNil(nets), Total: len(nets)})
	return nil
}

func (s *Server) getNetwork(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	n, err := s.app.Network(r.Context(), id)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, n)
	return nil
}

func (s *Server) createNetwork(w http.ResponseWriter, r *http.Request) error {
	var in app.NetworkInput
	if err := decode(r, &in); err != nil {
		return err
	}
	n, err := s.app.CreateNetwork(r.Context(), s.actor(r), in)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusCreated, n)
	return nil
}

func (s *Server) updateNetwork(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in app.NetworkInput
	if err := decode(r, &in); err != nil {
		return err
	}
	n, err := s.app.UpdateNetwork(r.Context(), s.actor(r), id, in)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, n)
	return nil
}

func (s *Server) deleteNetwork(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	if err := s.app.DeleteNetwork(r.Context(), s.actor(r), id); err != nil {
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

// --- Policies -----------------------------------------------------------

func (s *Server) listPolicies(w http.ResponseWriter, r *http.Request) error {
	p, err := s.app.Policies(r.Context())
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, listBody{Items: nonNil(p), Total: len(p)})
	return nil
}

func (s *Server) getPolicy(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	p, err := s.app.Policy(r.Context(), id)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, p)
	return nil
}

func (s *Server) createPolicy(w http.ResponseWriter, r *http.Request) error {
	var in app.PolicyInput
	if err := decode(r, &in); err != nil {
		return err
	}
	p, err := s.app.CreatePolicy(r.Context(), s.actor(r), in)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusCreated, p)
	return nil
}

func (s *Server) updatePolicy(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in app.PolicyInput
	if err := decode(r, &in); err != nil {
		return err
	}
	p, err := s.app.UpdatePolicy(r.Context(), s.actor(r), id, in)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, p)
	return nil
}

func (s *Server) deletePolicy(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	if err := s.app.DeletePolicy(r.Context(), s.actor(r), id); err != nil {
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

// --- Domain lists -------------------------------------------------------

// kindFor maps the URL segment to the stored list kind.
func kindFor(segment string) string {
	if segment == "allowlists" {
		return models.KindAllowlist
	}
	return models.KindBlacklist
}

func (s *Server) listListsFor(segment string) handler {
	kind := kindFor(segment)
	return func(w http.ResponseWriter, r *http.Request) error {
		lists, err := s.app.DomainLists(r.Context(), kind, query(r, "search"))
		if err != nil {
			return err
		}
		writeJSON(w, http.StatusOK, listBody{Items: nonNil(lists), Total: len(lists)})
		return nil
	}
}

func (s *Server) createListFor(segment string) handler {
	kind := kindFor(segment)
	return func(w http.ResponseWriter, r *http.Request) error {
		var in app.ListInput
		if err := decode(r, &in); err != nil {
			return err
		}
		in.Kind = kind // the URL decides the kind, not the body
		l, err := s.app.CreateDomainList(r.Context(), s.actor(r), in)
		if err != nil {
			return err
		}
		writeJSON(w, http.StatusCreated, l)
		return nil
	}
}

func (s *Server) getList(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	l, err := s.app.DomainList(r.Context(), id)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, l)
	return nil
}

func (s *Server) updateList(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in app.ListInput
	if err := decode(r, &in); err != nil {
		return err
	}
	l, err := s.app.UpdateDomainList(r.Context(), s.actor(r), id, in)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, l)
	return nil
}

func (s *Server) deleteList(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	if err := s.app.DeleteDomainList(r.Context(), s.actor(r), id); err != nil {
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

func (s *Server) listDomains(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	limit, offset := limitOffset(r, 100)
	entries, total, err := s.app.DomainEntries(r.Context(), id, query(r, "search"), limit, offset)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, listBody{
		Items: nonNil(entries), Total: total, Limit: limit, Offset: offset,
	})
	return nil
}

func (s *Server) addDomain(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in struct {
		Domain          string `json:"domain"`
		MatchSubdomains *bool  `json:"match_subdomains"`
		Comment         string `json:"comment"`
	}
	if err := decode(r, &in); err != nil {
		return err
	}
	// Subdomain matching is the useful default: it is what makes a blocklist
	// of a few hundred thousand names cover the millions of hosts beneath them.
	match := true
	if in.MatchSubdomains != nil {
		match = *in.MatchSubdomains
	}
	entry, err := s.app.AddDomain(r.Context(), s.actor(r), id, in.Domain, match, in.Comment)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusCreated, entry)
	return nil
}

func (s *Server) deleteDomain(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	if err := s.app.DeleteDomain(r.Context(), s.actor(r), id); err != nil {
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

func (s *Server) clearDomains(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	n, err := s.app.ClearDomains(r.Context(), s.actor(r), id)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, map[string]any{"removed": n})
	return nil
}

// importDomains reads the list from the raw request body, so a caller can pipe
// a multi-megabyte hosts file straight in with --data-binary.
func (s *Server) importDomains(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	match := true
	if v := query(r, "match_subdomains"); v != "" {
		match = queryBool(r, "match_subdomains")
	}
	summary, err := s.app.ImportDomains(r.Context(), s.actor(r), id, r.Body, match)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, summary)
	return nil
}

func (s *Server) exportDomains(w http.ResponseWriter, r *http.Request) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	if _, err := s.app.ExportDomains(r.Context(), id, w); err != nil {
		return err
	}
	return nil
}

// --- Cache --------------------------------------------------------------

func (s *Server) getCache(w http.ResponseWriter, r *http.Request) error {
	writeJSON(w, http.StatusOK, s.app.CacheView())
	return nil
}

func (s *Server) flushCache(w http.ResponseWriter, r *http.Request) error {
	if name := query(r, "name"); name != "" {
		n, err := s.app.FlushCacheName(r.Context(), s.actor(r), name)
		if err != nil {
			return err
		}
		writeJSON(w, http.StatusOK, map[string]any{"removed": n, "name": name})
		return nil
	}
	n, err := s.app.FlushCache(r.Context(), s.actor(r))
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, map[string]any{"removed": n})
	return nil
}

func (s *Server) listCacheEntries(w http.ResponseWriter, r *http.Request) error {
	limit, offset := limitOffset(r, 100)
	entries, total := s.app.CacheEntries(query(r, "search"), limit, offset)
	writeJSON(w, http.StatusOK, listBody{
		Items: nonNil(entries), Total: total, Limit: limit, Offset: offset,
	})
	return nil
}

func (s *Server) deleteCacheEntry(w http.ResponseWriter, r *http.Request) error {
	name := query(r, "name")
	qtype := query(r, "type")
	if name == "" || qtype == "" {
		return app.Invalid("Both the name and type query parameters are required.")
	}
	if err := s.app.DeleteCacheEntry(r.Context(), s.actor(r), name, qtype, queryBool(r, "dnssec")); err != nil {
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

// --- Settings -----------------------------------------------------------

func (s *Server) getSettings(w http.ResponseWriter, r *http.Request) error {
	writeJSON(w, http.StatusOK, s.app.Settings())
	return nil
}

// updateSettings merges the submitted fields over the current settings, so a
// caller can change one value without restating the whole configuration.
func (s *Server) updateSettings(w http.ResponseWriter, r *http.Request) error {
	next := s.app.Settings()
	if err := decode(r, &next); err != nil {
		return err
	}
	if err := s.app.SaveSettings(r.Context(), s.actor(r), app.GroupDNS, next); err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, s.app.Settings())
	return nil
}

// --- Statistics and logs ------------------------------------------------

func (s *Server) getStats(w http.ResponseWriter, r *http.Request) error {
	dash, err := s.app.Dashboard(r.Context(), queryInt(r, "top", 10))
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, dash)
	return nil
}

func (s *Server) listQueryLog(w http.ResponseWriter, r *http.Request) error {
	limit, offset := limitOffset(r, 100)
	f := database.QueryLogFilter{
		Domain:    query(r, "domain"),
		ClientIP:  query(r, "client"),
		QType:     query(r, "type"),
		Rcode:     query(r, "rcode"),
		Source:    query(r, "source"),
		Blocked:   query(r, "blocked"),
		NetworkID: queryInt64(r, "network_id"),
		Limit:     limit,
		Offset:    offset,
	}
	entries, total, err := s.app.QueryLogs(r.Context(), f)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, listBody{
		Items: nonNil(entries), Total: total, Limit: limit, Offset: offset,
	})
	return nil
}

func (s *Server) clearQueryLog(w http.ResponseWriter, r *http.Request) error {
	n, err := s.app.ClearQueryLog(r.Context(), s.actor(r))
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, map[string]any{"removed": n})
	return nil
}

func (s *Server) listAuditLog(w http.ResponseWriter, r *http.Request) error {
	limit, offset := limitOffset(r, 100)
	f := database.AuditFilter{
		Search:     query(r, "search"),
		ObjectType: query(r, "object_type"),
		Source:     query(r, "source"),
		Limit:      limit,
		Offset:     offset,
	}
	entries, total, err := s.app.AuditLogs(r.Context(), f)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, listBody{
		Items: nonNil(entries), Total: total, Limit: limit, Offset: offset,
	})
	return nil
}

// --- Operations ---------------------------------------------------------

func (s *Server) listBackups(w http.ResponseWriter, r *http.Request) error {
	backups, err := s.app.BackupList()
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, map[string]any{
		"status":  s.app.BackupStatus(),
		"backups": nonNil(backups),
	})
	return nil
}

func (s *Server) createBackup(w http.ResponseWriter, r *http.Request) error {
	info, err := s.app.RunBackup(r.Context(), s.actor(r))
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusCreated, info)
	return nil
}

func (s *Server) exportConfig(w http.ResponseWriter, r *http.Request) error {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	return s.app.WriteConfigExport(r.Context(), w, queryBool(r, "include_domains"))
}

func (s *Server) importConfig(w http.ResponseWriter, r *http.Request) error {
	report, err := s.app.ImportConfig(r.Context(), s.actor(r), r.Body, queryBool(r, "apply_settings"))
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, report)
	return nil
}

// --- Tools --------------------------------------------------------------

// reverseZone previews the zone apex a subnet maps to. The zone creation form
// calls this as the operator types.
func (s *Server) reverseZone(w http.ResponseWriter, r *http.Request) error {
	cidr := query(r, "cidr")
	if cidr == "" {
		return app.Invalid("The cidr query parameter is required.")
	}
	name, note, err := s.app.ReverseZoneName(cidr)
	if err != nil {
		return err
	}
	kind, _ := validate.ReverseZoneKindForCIDR(cidr)
	writeJSON(w, http.StatusOK, map[string]any{
		"cidr": cidr,
		"zone": strings.TrimSuffix(name, "."),
		"fqdn": name,
		"kind": kind,
		"note": note,
	})
	return nil
}

func (s *Server) lookup(w http.ResponseWriter, r *http.Request) error {
	name := query(r, "name")
	if name == "" {
		return app.Invalid("The name query parameter is required.")
	}
	result, err := s.app.Lookup(r.Context(), name, query(r, "type"), query(r, "client"), queryBool(r, "dnssec"))
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, result)
	return nil
}

// domainCheck reports which policy lists cover a name.
func (s *Server) domainCheck(w http.ResponseWriter, r *http.Request) error {
	name := query(r, "domain")
	if name == "" {
		return app.Invalid("The domain query parameter is required.")
	}
	hits, err := s.app.LookupDomain(r.Context(), name)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, map[string]any{
		"domain":  name,
		"matches": nonNil(hits),
	})
	return nil
}

// nonNil turns a nil slice into an empty one so JSON responses always carry
// [] rather than null, which is what most clients expect from a collection.
func nonNil[T any](v []T) []T {
	if v == nil {
		return []T{}
	}
	return v
}