package server

import (
	"fmt"
	"net/http"
	"strings"

	"housecarl/internal/api"
	"housecarl/internal/auth"
	"housecarl/internal/engine"
	"housecarl/internal/importer"
	"housecarl/internal/model"
)

// importNft makes an nftables ruleset Housecarl's configuration
// (internal/importer); ?dry_run=1 shows the result without applying it.
func (s *Server) importNft(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.ResConfig, true); err != nil {
		return err
	}
	if err := notStaged(r, "an import"); err != nil {
		return err
	}
	var in api.ImportInput
	if err := decodeJSON(r, &in); err != nil {
		return err
	}
	res, err := importer.Import(importer.Input{JSON: in.JSON, Text: in.Text, Defines: in.Defines, Table: in.Table, Zones: in.Zones})
	if err != nil {
		return badRequest("%v", err)
	}
	cur := s.eng.State()
	if !in.Replace && hasConfig(cur) {
		return conflict("Housecarl already has a configuration; import with replace (--replace) to replace it")
	}
	// The importer numbers objects from 1; give them IDs of their own.
	if err := s.renumber(r, res.State); err != nil {
		return err
	}
	opts := engine.Options{DryRun: queryBool(r, "dry_run"), Via: via(r, p)}
	er, err := s.eng.Replace(r.Context(), p, "import from nftables ("+tableName(in.Table)+")", opts, res.State)
	out := api.ImportResult{State: res.State, Notes: res.Notes, Raw: res.Raw}
	if out.Notes == nil {
		out.Notes = []string{}
	}
	if out.Raw == nil {
		out.Raw = []string{}
	}
	if err != nil {
		s.writeErr(w, r, err, out)
		return nil
	}
	s.afterChange(r.Context(), p, er)
	if er.Applied {
		// Until it is taken over, the old table still applies too: the
		// status warns (takeover_pending).
		s.store.SetMeta(r.Context(), importedTableKey, res.Table)
	}
	out.MutationResponse = api.MutationResponse{Applied: er.Applied, DryRun: er.DryRun, HistoryID: er.HistoryID, Changes: er.Changes, Warnings: er.Warnings}
	if out.Changes == nil {
		out.Changes = []model.Change{}
	}
	if pr := s.probationStatus(); er.Applied && len(pr.Pending) > 0 {
		out.ConfirmBy = &pr.Deadline
	}
	out.ConfirmToken = s.issueCheck(w, r, p, er)
	writeJSON(w, http.StatusOK, out)
	return nil
}

func tableName(t string) string {
	if t == "" {
		return "the ruleset"
	}
	return t
}

func hasConfig(st *model.State) bool {
	for _, k := range model.Kinds {
		if len(st.Objects(k)) > 0 {
			return true
		}
	}
	return false
}

// renumber gives every object of an imported state a fresh ID.
func (s *Server) renumber(r *http.Request, st *model.State) error {
	n := 0
	for _, k := range model.Kinds {
		n += len(st.Objects(k))
	}
	if n == 0 {
		return nil
	}
	ids, err := s.store.AllocateIDs(r.Context(), n)
	if err != nil {
		return err
	}
	i := 0
	for _, k := range model.Kinds {
		for _, o := range st.Objects(k) {
			setID(o, ids[i])
			i++
		}
	}
	return nil
}

// takeover deletes the tables Housecarl replaces (the ruleset imported).
// Over the network it is on probation: unless confirmed, the tables come
// back.
func (s *Server) takeover(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := requireAdmin(p); err != nil {
		return err
	}
	if err := notStaged(r, "a takeover"); err != nil {
		return err
	}
	var in api.TakeoverInput
	if err := decodeJSON(r, &in); err != nil {
		return err
	}
	if len(in.Tables) == 0 {
		return badRequest("name the tables to delete (\"inet main\")")
	}
	var done []string
	for _, t := range in.Tables {
		fam, name, ok := strings.Cut(strings.TrimSpace(t), " ")
		if !ok || name == "" {
			return badRequest("%q: write a table as FAMILY NAME (\"inet main\")", t)
		}
		if fam == "inet" && name == "housecarl" {
			return badRequest("that is Housecarl's own table")
		}
		script, err := s.fw.TableText(r.Context(), fam, name)
		if err != nil {
			return notFound("there is no table %s %s", fam, name)
		}
		if queryBool(r, "dry_run") {
			done = append(done, t)
			continue
		}
		if err := s.fw.DeleteTable(r.Context(), fam, name); err != nil {
			return fmt.Errorf("deleting table %s: %w", t, err)
		}
		s.startProbation(r.Context(), p, 0, script)
		s.eng.Audit(r.Context(), p, "takeover", t, "success", "")
		done = append(done, t)
	}
	msg := "deleted " + strings.Join(done, ", ")
	if queryBool(r, "dry_run") {
		msg = "would delete " + strings.Join(done, ", ")
	} else if pr := s.probationStatus(); pr.Takeovers > 0 {
		msg += fmt.Sprintf("; confirm with 'hc confirm' within %ds, or they come back", pr.SecondsLeft)
	}
	answer := map[string]any{"deleted": done, "message": msg}
	if !queryBool(r, "dry_run") && len(done) > 0 {
		if tok := s.issueCheck(w, r, p, nil); tok != "" {
			answer["confirm_token"] = tok
		}
	}
	writeJSON(w, http.StatusOK, answer)
	return nil
}