package server

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"strconv"
	"time"

	"jarl/internal/api"
	"jarl/internal/auth"
	"jarl/internal/engine"
	"jarl/internal/model"
	"jarl/internal/store"
	"jarl/internal/version"
)

func toRequests(in []api.ChangeRequest) []engine.Request {
	out := make([]engine.Request, len(in))
	for i, c := range in {
		out[i] = engine.Request{Op: c.Op, ID: c.ID, BaseVersion: c.BaseVersion, Data: c.Data}
	}
	return out
}

func presentChangeset(cs *model.Changeset) api.Changeset {
	c := *cs
	c.Ops = engine.RedactOps(cs.Ops)
	undoable := false
	if cs.Status == model.ChangesetApplied && len(cs.Result) > 0 {
		var r struct {
			Undo []json.RawMessage `json:"undo"`
		}
		if json.Unmarshal(cs.Result, &r) == nil {
			undoable = len(r.Undo) > 0
		}
		// The undo operations hold old TSIG secrets; don't send them.
		var m map[string]json.RawMessage
		if json.Unmarshal(cs.Result, &m) == nil {
			delete(m, "undo")
			c.Result, _ = json.Marshal(m)
		}
	}
	return api.Changeset{Changeset: c, Undoable: undoable}
}

// applyBatch: POST /apply applies several requests atomically.
func (s *Server) applyBatch(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	var in api.BatchRequest
	if err := decodeJSON(r, &in); err != nil {
		return err
	}
	if len(in.Ops) == 0 {
		return badRequest("no operations given")
	}
	q := r.URL.Query()
	if in.DryRun {
		q.Set("dry_run", "1")
	}
	if in.Force {
		q.Set("force", "1")
	}
	if in.AcceptRisk {
		q.Set("accept_risk", "1")
	}
	r.URL.RawQuery = q.Encode()
	return s.mutate(w, r, p, in.Description, toRequests(in.Ops), nil)
}

func (s *Server) listChangesets(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	f := store.ChangesetFilter{Status: r.URL.Query().Get("status"), Limit: queryInt(r, "limit", 100), Before: int64(queryInt(r, "before", 0))}
	all := p.IsAdmin() || p.Can(auth.Action{Resource: auth.ResAudit})
	if !all || queryBool(r, "mine") {
		f.UserID = p.User.ID
	}
	list, err := s.store.ListChangesets(r.Context(), f)
	if err != nil {
		return err
	}
	out := []api.Changeset{}
	for _, cs := range list {
		out = append(out, presentChangeset(cs))
	}
	writeJSON(w, http.StatusOK, out)
	return nil
}

func (s *Server) createChangeset(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	var in api.BatchRequest
	body, err := readBody(r)
	if err != nil {
		return err
	}
	if len(body) > 0 {
		if err := json.Unmarshal(body, &in); err != nil {
			return badRequest("invalid JSON: %v", err)
		}
	}
	cs, err := s.eng.CreateChangeset(r.Context(), p, via(r, p), in.Description)
	if err != nil {
		return err
	}
	if len(in.Ops) > 0 {
		res, err := s.eng.Stage(r.Context(), cs.ID, toRequests(in.Ops), p)
		if err != nil {
			s.eng.Discard(r.Context(), cs.ID, p)
			return err
		}
		cs = res.Changeset
		if in.Apply {
			out, err := s.eng.Apply(r.Context(), cs.ID, p, engine.ApplyOptions{DryRun: in.DryRun, Force: in.Force, AcceptRisk: in.AcceptRisk})
			if err != nil {
				s.writeErr(w, r, err, out)
				return nil
			}
			writeJSON(w, http.StatusCreated, api.MutationResponse{Applied: out.Applied, DryRun: out.DryRun, ChangesetID: cs.ID, Result: raw(out), Warnings: out.Warnings})
			return nil
		}
		writeJSON(w, http.StatusCreated, api.MutationResponse{Staged: true, ChangesetID: cs.ID, Changeset: raw(presentChangeset(cs)), Added: engine.RedactOps(res.Added), Warnings: res.Warnings, Problems: raw(res.Problems)})
		return nil
	}
	writeJSON(w, http.StatusCreated, presentChangeset(cs))
	return nil
}

func (s *Server) changesetByPath(r *http.Request, p *auth.Principal) (*model.Changeset, error) {
	id, err := pathID(r, "id")
	if err != nil {
		return nil, err
	}
	cs, err := s.store.GetChangeset(r.Context(), id)
	if errors.Is(err, store.ErrNotFound) || err == nil && !engine.CanAccessChangeset(p, cs, false) {
		return nil, notFound("changeset %d not found", id)
	}
	return cs, err
}

func (s *Server) getChangeset(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	cs, err := s.changesetByPath(r, p)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, presentChangeset(cs))
	return nil
}

func (s *Server) updateChangeset(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in struct {
		Description string `json:"description"`
	}
	if err := decodeJSON(r, &in); err != nil {
		return err
	}
	cs, err := s.eng.UpdateDescription(r.Context(), id, in.Description, p)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, presentChangeset(cs))
	return nil
}

func (s *Server) stageOps(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in api.BatchRequest
	if err := decodeJSON(r, &in); err != nil {
		return err
	}
	res, err := s.eng.Stage(r.Context(), id, toRequests(in.Ops), p)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusAccepted, api.MutationResponse{Staged: true, ChangesetID: id, Changeset: raw(presentChangeset(res.Changeset)), Added: engine.RedactOps(res.Added), Warnings: res.Warnings, Problems: raw(res.Problems)})
	return nil
}

func (s *Server) unstageOp(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	seq, err := strconv.Atoi(r.PathValue("seq"))
	if err != nil {
		return badRequest("invalid operation number")
	}
	cs, err := s.eng.RemoveOps(r.Context(), id, []int{seq}, p)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, presentChangeset(cs))
	return nil
}

func (s *Server) previewChangeset(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	res, err := s.eng.Preview(r.Context(), id, p)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, res)
	return nil
}

func (s *Server) applyChangeset(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	var in struct {
		DryRun     bool `json:"dry_run"`
		Force      bool `json:"force"`
		AcceptRisk bool `json:"accept_risk"`
	}
	if body, err := readBody(r); err != nil {
		return err
	} else if len(body) > 0 {
		if err := json.Unmarshal(body, &in); err != nil {
			return badRequest("invalid JSON: %v", err)
		}
	}
	res, err := s.eng.Apply(r.Context(), id, p, engine.ApplyOptions{DryRun: in.DryRun || queryBool(r, "dry_run"), Force: in.Force || queryBool(r, "force"),
		AcceptRisk: in.AcceptRisk || queryBool(r, "accept_risk")})
	if err != nil {
		s.writeErr(w, r, err, res)
		return nil
	}
	writeJSON(w, http.StatusOK, api.MutationResponse{Applied: res.Applied, DryRun: res.DryRun, ChangesetID: res.ChangesetID, Result: raw(res), Warnings: res.Warnings})
	return nil
}

func (s *Server) discardChangeset(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	if err := s.eng.Discard(r.Context(), id, p); err != nil {
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

func (s *Server) revertChangeset(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	id, err := pathID(r, "id")
	if err != nil {
		return err
	}
	cs, err := s.eng.Revert(r.Context(), id, p)
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusCreated, presentChangeset(cs))
	return nil
}

// ---- status, system, audit

func (s *Server) status(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	st, err := s.eng.Status(r.Context())
	if err != nil {
		return err
	}
	if !p.IsAdmin() && !p.Can(auth.Action{Resource: auth.ResOptions}) {
		// Keep it to the essentials for restricted principals.
		st.Problems = nil
		st.Drift = nil
		if st.Named != nil {
			st.Named.Raw = ""
		}
	}
	now := time.Now()
	resp := api.StatusResponse{Version: s.cfg.Version, Build: version.Info(), Engine: raw(st), Time: now, ExpiringTokens: s.expiringTokens(r.Context(), p, now)}
	if p.IsAdmin() {
		resp.Backup = s.backupStatus(r.Context(), now)
		resp.TOTP = s.totpOverview(r.Context())
		resp.Certificates = s.certSummary(r.Context())
	}
	if p.Can(auth.Action{Resource: auth.ResOptions}) {
		if h := s.encryptedDNSHealth(); h != nil {
			sum := &api.EncDNSSummary{Checked: h.Checked, OK: h.OK(), Problems: []string{}, Warnings: []string{}}
			for _, pr := range h.Probes {
				where := fmt.Sprintf("%s on %s port %d", map[string]string{"dot": "DNS over TLS", "doh": "DNS over HTTPS"}[pr.Kind], pr.Address, pr.Port)
				if pr.Problem != "" {
					sum.Problems = append(sum.Problems, where+": "+pr.Problem)
				} else if pr.Warning != "" {
					sum.Warnings = append(sum.Warnings, where+": "+pr.Warning)
				}
			}
			resp.EncryptedDNS = sum
		}
	}
	if p.Can(auth.Action{Resource: auth.ResBlocking}) {
		resp.BlocklistErrors = s.blocklistErrors(r.Context())
		if st, err := s.store.LoadState(r.Context()); err == nil {
			resp.BlockingPausedUntil = st.Settings.BlockingPausedUntil
			resp.BlockingPausedIndefinitely = st.Settings.BlockingPausedIndefinitely
		}
	}
	writeJSON(w, http.StatusOK, resp)
	return nil
}

// backupStatus reports the newest backup, as 'jarld backup' recorded it,
// and whether it is older than backup.warn_after. No backup at all is
// reported but not flagged: backups may be made some other way.
func (s *Server) backupStatus(ctx context.Context, now time.Time) *api.BackupStatus {
	ok, failed := s.store.LastBackups(ctx)
	bs := &api.BackupStatus{Dir: s.cfg.BackupDir, WarnAfter: int64(s.cfg.BackupWarnAfter / time.Second)}
	if ok != nil {
		bs.LastAt, bs.LastFile, bs.LastSize = &ok.At, ok.File, ok.Size
		bs.Stale = s.cfg.BackupWarnAfter > 0 && now.Sub(ok.At) > s.cfg.BackupWarnAfter
	}
	if failed != nil && (ok == nil || failed.At.After(ok.At)) {
		bs.LastError, bs.LastErrorAt = failed.Error, &failed.At
	}
	return bs
}

// expiringTokens lists the tokens the dashboard warns about: those that
// expire within model.TokenExpiryWarning or expired less than that long
// ago. Administrators see everyone's, others their own.
func (s *Server) expiringTokens(ctx context.Context, p *auth.Principal, now time.Time) []api.Token {
	out := []api.Token{}
	uid := p.User.ID
	if p.IsAdmin() {
		uid = 0
	} else if uid == 0 {
		return out
	}
	ts, err := s.store.ListTokens(ctx, uid)
	if err != nil {
		s.log.Warn("listing tokens failed", "err", err)
		return out
	}
	for _, t := range ts {
		if t.ExpiresWithin(now, model.TokenExpiryWarning) && now.Sub(*t.ExpiresAt) < model.TokenExpiryWarning {
			out = append(out, presentToken(t))
		}
	}
	return out
}

func (s *Server) systemCheck(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := require(p, auth.Action{Resource: auth.ResOptions}); err != nil {
		return err
	}
	res, err := s.eng.CheckCurrent(r.Context())
	if err != nil {
		return err
	}
	writeJSON(w, http.StatusOK, res)
	return nil
}

func (s *Server) systemResync(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	if err := requireAdmin(p); err != nil {
		return err
	}
	var in struct {
		DryRun bool `json:"dry_run"`
		Force  bool `json:"force"`
	}
	if body, err := readBody(r); err != nil {
		return err
	} else if len(body) > 0 {
		if err := json.Unmarshal(body, &in); err != nil {
			return badRequest("invalid JSON: %v", err)
		}
	}
	res, err := s.eng.Resync(r.Context(), p, engine.ApplyOptions{DryRun: in.DryRun, Force: in.Force})
	if err != nil {
		s.writeErr(w, r, err, res)
		return nil
	}
	writeJSON(w, http.StatusOK, res)
	return nil
}

func (s *Server) listAudit(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
	q := r.URL.Query()
	f := store.AuditFilter{Username: q.Get("user"), Action: q.Get("action"), Outcome: q.Get("outcome"), ObjectType: q.Get("object_type"),
		ChangesetID: int64(queryInt(r, "changeset", 0)), Search: q.Get("q"), Before: int64(queryInt(r, "before", 0)), Limit: queryInt(r, "limit", 200)}
	for name, dst := range map[string]*time.Time{"since": &f.Since, "until": &f.Until} {
		if v := q.Get(name); v != "" {
			t, err := time.Parse(time.RFC3339, v)
			if err != nil {
				if d, derr := time.Parse("2006-01-02", v); derr == nil {
					t = d
				} else {
					return badRequest("invalid %s %q (use RFC 3339 or YYYY-MM-DD)", name, v)
				}
			}
			*dst = t
		}
	}
	if !p.IsAdmin() && !p.Can(auth.Action{Resource: auth.ResAudit}) {
		// Everyone may see their own activity.
		f.Username = p.User.Username
	}
	evs, err := s.store.ListAudit(r.Context(), f)
	if err != nil {
		return err
	}
	if evs == nil {
		evs = []*model.AuditEvent{}
	}
	writeJSON(w, http.StatusOK, evs)
	return nil
}