package store

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"reflect"

	"jarl/internal/model"
)

const settingsKey = "settings"

// LoadState loads the complete configuration.
func (s *Store) LoadState(ctx context.Context) (*model.State, error) {
	return loadState(ctx, s.db)
}

func loadState(ctx context.Context, e execer) (*model.State, error) {
	st := model.NewState()
	var raw string
	err := e.QueryRowContext(ctx, `SELECT value FROM meta WHERE key = ?`, settingsKey).Scan(&raw)
	switch {
	case errors.Is(err, sql.ErrNoRows):
	case err != nil:
		return nil, err
	default:
		if err := json.Unmarshal([]byte(raw), &st.Settings); err != nil {
			return nil, err
		}
	}

	rows, err := e.QueryContext(ctx, `SELECT id, name, position, match_clients, match_destinations, match_recursive_only, comment, version, created_at, updated_at, created_by, updated_by FROM views`)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		v := &model.View{}
		var mc, md, ca, ua string
		var mro sql.NullInt64
		if err := rows.Scan(&v.ID, &v.Name, &v.Position, &mc, &md, &mro, &v.Comment, &v.Version, &ca, &ua, &v.CreatedBy, &v.UpdatedBy); err != nil {
			rows.Close()
			return nil, err
		}
		json.Unmarshal([]byte(mc), &v.MatchClients)
		json.Unmarshal([]byte(md), &v.MatchDestinations)
		if mro.Valid {
			v.MatchRecursiveOnly = model.Ptr(mro.Int64 != 0)
		}
		v.CreatedAt, v.UpdatedAt = parseTS(ca), parseTS(ua)
		st.Views[v.ID] = v
	}
	if err := closeRows(rows); err != nil {
		return nil, err
	}

	rows, err = e.QueryContext(ctx, `SELECT id, name, elements, comment, version, created_at, updated_at, created_by, updated_by FROM acls`)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		a := &model.ACL{}
		var el, ca, ua string
		if err := rows.Scan(&a.ID, &a.Name, &el, &a.Comment, &a.Version, &ca, &ua, &a.CreatedBy, &a.UpdatedBy); err != nil {
			rows.Close()
			return nil, err
		}
		json.Unmarshal([]byte(el), &a.Elements)
		a.CreatedAt, a.UpdatedAt = parseTS(ca), parseTS(ua)
		st.ACLs[a.ID] = a
	}
	if err := closeRows(rows); err != nil {
		return nil, err
	}

	rows, err = e.QueryContext(ctx, `SELECT id, name, algorithm, secret, comment, version, created_at, updated_at, created_by, updated_by FROM tsig_keys`)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		k := &model.TSIGKey{}
		var ca, ua string
		if err := rows.Scan(&k.ID, &k.Name, &k.Algorithm, &k.Secret, &k.Comment, &k.Version, &ca, &ua, &k.CreatedBy, &k.UpdatedBy); err != nil {
			rows.Close()
			return nil, err
		}
		k.CreatedAt, k.UpdatedAt = parseTS(ca), parseTS(ua)
		st.Keys[k.ID] = k
	}
	if err := closeRows(rows); err != nil {
		return nil, err
	}

	rows, err = e.QueryContext(ctx, `SELECT id, name, view_id, type, in_view, file, soa_mname, soa_rname, soa_serial, soa_refresh, soa_retry, soa_expire, soa_minimum, default_ttl, serial_policy, dnssec_policy, comment, version, created_at, updated_at, created_by, updated_by FROM zones`)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		z := &model.Zone{}
		var ca, ua string
		if err := rows.Scan(&z.ID, &z.Name, &z.ViewID, &z.Type, &z.InView, &z.File, &z.SOA.MName, &z.SOA.RName, &z.SOA.Serial, &z.SOA.Refresh, &z.SOA.Retry, &z.SOA.Expire, &z.SOA.Minimum, &z.DefaultTTL, &z.SerialPolicy, &z.DNSSECPolicy, &z.Comment, &z.Version, &ca, &ua, &z.CreatedBy, &z.UpdatedBy); err != nil {
			rows.Close()
			return nil, err
		}
		z.CreatedAt, z.UpdatedAt = parseTS(ca), parseTS(ua)
		st.Zones[z.ID] = z
	}
	if err := closeRows(rows); err != nil {
		return nil, err
	}

	rows, err = e.QueryContext(ctx, `SELECT id, zone_id, name, type, ttl, data, comment, disabled, version, created_at, updated_at, created_by, updated_by FROM records`)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		r := &model.Record{}
		var ttl sql.NullInt64
		var ca, ua string
		if err := rows.Scan(&r.ID, &r.ZoneID, &r.Name, &r.Type, &ttl, &r.Data, &r.Comment, &r.Disabled, &r.Version, &ca, &ua, &r.CreatedBy, &r.UpdatedBy); err != nil {
			rows.Close()
			return nil, err
		}
		if ttl.Valid {
			r.TTL = model.Ptr(uint32(ttl.Int64))
		}
		r.CreatedAt, r.UpdatedAt = parseTS(ca), parseTS(ua)
		st.Records[r.ID] = r
	}
	if err := closeRows(rows); err != nil {
		return nil, err
	}

	rows, err = e.QueryContext(ctx, `SELECT id, scope, scope_id, name, value, position, comment, version, created_at, updated_at, created_by, updated_by FROM options`)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		o := &model.Option{}
		var ca, ua string
		if err := rows.Scan(&o.ID, &o.Scope, &o.ScopeID, &o.Name, &o.Value, &o.Position, &o.Comment, &o.Version, &ca, &ua, &o.CreatedBy, &o.UpdatedBy); err != nil {
			rows.Close()
			return nil, err
		}
		o.CreatedAt, o.UpdatedAt = parseTS(ca), parseTS(ua)
		st.Options[o.ID] = o
	}
	if err := closeRows(rows); err != nil {
		return nil, err
	}

	rows, err = e.QueryContext(ctx, `SELECT id, name, url, view_ids, disabled, comment, version, created_at, updated_at, created_by, updated_by FROM blocklists`)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		b := &model.Blocklist{}
		var views, ca, ua string
		if err := rows.Scan(&b.ID, &b.Name, &b.URL, &views, &b.Disabled, &b.Comment, &b.Version, &ca, &ua, &b.CreatedBy, &b.UpdatedBy); err != nil {
			rows.Close()
			return nil, err
		}
		json.Unmarshal([]byte(views), &b.ViewIDs)
		b.CreatedAt, b.UpdatedAt = parseTS(ca), parseTS(ua)
		st.Blocklists[b.ID] = b
	}
	if err := closeRows(rows); err != nil {
		return nil, err
	}

	rows, err = e.QueryContext(ctx, `SELECT id, name, action, exact, view_ids, comment, version, created_at, updated_at, created_by, updated_by FROM block_rules`)
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		r := &model.BlockRule{}
		var views, ca, ua string
		if err := rows.Scan(&r.ID, &r.Name, &r.Action, &r.Exact, &views, &r.Comment, &r.Version, &ca, &ua, &r.CreatedBy, &r.UpdatedBy); err != nil {
			rows.Close()
			return nil, err
		}
		json.Unmarshal([]byte(views), &r.ViewIDs)
		r.CreatedAt, r.UpdatedAt = parseTS(ca), parseTS(ua)
		st.BlockRules[r.ID] = r
	}
	if err := closeRows(rows); err != nil {
		return nil, err
	}
	return st, nil
}

func closeRows(rows *sql.Rows) error {
	err := rows.Err()
	rows.Close()
	return err
}

// SaveState writes the differences between old and new.
func (t *Tx) SaveState(old, new *model.State) error {
	return saveState(t.ctx, t.tx, old, new)
}

// ReplaceState replaces the stored configuration with st (used by import
// and tests).
func (t *Tx) ReplaceState(st *model.State) error {
	for _, tbl := range []string{"views", "acls", "tsig_keys", "zones", "records", "options", "blocklists", "block_rules"} {
		if _, err := t.tx.ExecContext(t.ctx, "DELETE FROM "+tbl); err != nil {
			return err
		}
	}
	return saveState(t.ctx, t.tx, model.NewState(), st)
}

// LoadState loads the configuration inside the transaction.
func (t *Tx) LoadState() (*model.State, error) { return loadState(t.ctx, t.tx) }

func saveState(ctx context.Context, e execer, old, new *model.State) error {
	if !reflect.DeepEqual(old.Settings, new.Settings) {
		if err := setMeta(ctx, e, settingsKey, jsonText(new.Settings)); err != nil {
			return err
		}
	}
	if err := diffMap(old.Views, new.Views, func(v *model.View) error {
		var mro any
		if v.MatchRecursiveOnly != nil {
			mro = boolInt(*v.MatchRecursiveOnly)
		}
		_, err := e.ExecContext(ctx, `INSERT OR REPLACE INTO views (id, name, position, match_clients, match_destinations, match_recursive_only, comment, version, created_at, updated_at, created_by, updated_by) VALUES (?,?,?,?,?,?,?,?,?,?,?,?)`,
			v.ID, v.Name, v.Position, jsonText(nonNil(v.MatchClients)), jsonText(nonNil(v.MatchDestinations)), mro, v.Comment, v.Version, ts(v.CreatedAt), ts(v.UpdatedAt), v.CreatedBy, v.UpdatedBy)
		return err
	}, func(id int64) error { return del(ctx, e, "views", id) }); err != nil {
		return err
	}
	if err := diffMap(old.ACLs, new.ACLs, func(a *model.ACL) error {
		_, err := e.ExecContext(ctx, `INSERT OR REPLACE INTO acls (id, name, elements, comment, version, created_at, updated_at, created_by, updated_by) VALUES (?,?,?,?,?,?,?,?,?)`,
			a.ID, a.Name, jsonText(nonNil(a.Elements)), a.Comment, a.Version, ts(a.CreatedAt), ts(a.UpdatedAt), a.CreatedBy, a.UpdatedBy)
		return err
	}, func(id int64) error { return del(ctx, e, "acls", id) }); err != nil {
		return err
	}
	if err := diffMap(old.Keys, new.Keys, func(k *model.TSIGKey) error {
		_, err := e.ExecContext(ctx, `INSERT OR REPLACE INTO tsig_keys (id, name, algorithm, secret, comment, version, created_at, updated_at, created_by, updated_by) VALUES (?,?,?,?,?,?,?,?,?,?)`,
			k.ID, k.Name, k.Algorithm, k.Secret, k.Comment, k.Version, ts(k.CreatedAt), ts(k.UpdatedAt), k.CreatedBy, k.UpdatedBy)
		return err
	}, func(id int64) error { return del(ctx, e, "tsig_keys", id) }); err != nil {
		return err
	}
	if err := diffMap(old.Zones, new.Zones, func(z *model.Zone) error {
		_, err := e.ExecContext(ctx, `INSERT OR REPLACE INTO zones (id, name, view_id, type, in_view, file, soa_mname, soa_rname, soa_serial, soa_refresh, soa_retry, soa_expire, soa_minimum, default_ttl, serial_policy, dnssec_policy, comment, version, created_at, updated_at, created_by, updated_by) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)`,
			z.ID, z.Name, z.ViewID, z.Type, z.InView, z.File, z.SOA.MName, z.SOA.RName, z.SOA.Serial, z.SOA.Refresh, z.SOA.Retry, z.SOA.Expire, z.SOA.Minimum, z.DefaultTTL, z.SerialPolicy, z.DNSSECPolicy, z.Comment, z.Version, ts(z.CreatedAt), ts(z.UpdatedAt), z.CreatedBy, z.UpdatedBy)
		return err
	}, func(id int64) error { return del(ctx, e, "zones", id) }); err != nil {
		return err
	}
	if err := diffMap(old.Records, new.Records, func(r *model.Record) error {
		var ttl any
		if r.TTL != nil {
			ttl = int64(*r.TTL)
		}
		_, err := e.ExecContext(ctx, `INSERT OR REPLACE INTO records (id, zone_id, name, type, ttl, data, comment, disabled, version, created_at, updated_at, created_by, updated_by) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?)`,
			r.ID, r.ZoneID, r.Name, r.Type, ttl, r.Data, r.Comment, r.Disabled, r.Version, ts(r.CreatedAt), ts(r.UpdatedAt), r.CreatedBy, r.UpdatedBy)
		return err
	}, func(id int64) error { return del(ctx, e, "records", id) }); err != nil {
		return err
	}
	if err := diffMap(old.Options, new.Options, func(o *model.Option) error {
		_, err := e.ExecContext(ctx, `INSERT OR REPLACE INTO options (id, scope, scope_id, name, value, position, comment, version, created_at, updated_at, created_by, updated_by) VALUES (?,?,?,?,?,?,?,?,?,?,?,?)`,
			o.ID, o.Scope, o.ScopeID, o.Name, o.Value, o.Position, o.Comment, o.Version, ts(o.CreatedAt), ts(o.UpdatedAt), o.CreatedBy, o.UpdatedBy)
		return err
	}, func(id int64) error { return del(ctx, e, "options", id) }); err != nil {
		return err
	}
	if err := diffMap(old.Blocklists, new.Blocklists, func(b *model.Blocklist) error {
		_, err := e.ExecContext(ctx, `INSERT OR REPLACE INTO blocklists (id, name, url, view_ids, disabled, comment, version, created_at, updated_at, created_by, updated_by) VALUES (?,?,?,?,?,?,?,?,?,?,?)`,
			b.ID, b.Name, b.URL, jsonText(nonNilIDs(b.ViewIDs)), b.Disabled, b.Comment, b.Version, ts(b.CreatedAt), ts(b.UpdatedAt), b.CreatedBy, b.UpdatedBy)
		return err
	}, func(id int64) error { return del(ctx, e, "blocklists", id) }); err != nil {
		return err
	}
	return diffMap(old.BlockRules, new.BlockRules, func(r *model.BlockRule) error {
		_, err := e.ExecContext(ctx, `INSERT OR REPLACE INTO block_rules (id, name, action, exact, view_ids, comment, version, created_at, updated_at, created_by, updated_by) VALUES (?,?,?,?,?,?,?,?,?,?,?)`,
			r.ID, r.Name, r.Action, r.Exact, jsonText(nonNilIDs(r.ViewIDs)), r.Comment, r.Version, ts(r.CreatedAt), ts(r.UpdatedAt), r.CreatedBy, r.UpdatedBy)
		return err
	}, func(id int64) error { return del(ctx, e, "block_rules", id) })
}

func nonNilIDs(ids []int64) []int64 {
	if ids == nil {
		return []int64{}
	}
	return ids
}

func nonNil(s []string) []string {
	if s == nil {
		return []string{}
	}
	return s
}

func del(ctx context.Context, e execer, table string, id int64) error {
	_, err := e.ExecContext(ctx, "DELETE FROM "+table+" WHERE id = ?", id)
	return err
}

// diffMap calls put for new or changed objects and remove for deleted ones.
func diffMap[T any](old, new map[int64]*T, put func(*T) error, remove func(int64) error) error {
	for id, n := range new {
		if o, ok := old[id]; ok && reflect.DeepEqual(o, n) {
			continue
		}
		if err := put(n); err != nil {
			return err
		}
	}
	for id := range old {
		if _, ok := new[id]; !ok {
			if err := remove(id); err != nil {
				return err
			}
		}
	}
	return nil
}