package firewall

import (
	"context"
	"errors"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"

	"git.netcell-it.de/projekte/edgeguard-native/internal/models"
)

var ErrZoneNotFound = errors.New("zone not found")

type ZonesRepo struct {
	Pool *pgxpool.Pool
}

func NewZonesRepo(pool *pgxpool.Pool) *ZonesRepo { return &ZonesRepo{Pool: pool} }

const zoneBaseSelect = `
SELECT id, name, description, builtin, created_at, updated_at
FROM firewall_zones
`

func (r *ZonesRepo) List(ctx context.Context) ([]models.FirewallZone, error) {
	rows, err := r.Pool.Query(ctx, zoneBaseSelect+" ORDER BY name ASC")
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]models.FirewallZone, 0, 8)
	for rows.Next() {
		z, err := scanZone(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, *z)
	}
	return out, rows.Err()
}

func (r *ZonesRepo) Get(ctx context.Context, id int64) (*models.FirewallZone, error) {
	row := r.Pool.QueryRow(ctx, zoneBaseSelect+" WHERE id = $1", id)
	z, err := scanZone(row)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, ErrZoneNotFound
		}
		return nil, err
	}
	return z, nil
}

// Exists is used by the rules / nat / iface handlers to validate
// that the zone name they got from the operator references a real
// zone (or the special 'any' which the rule layer handles itself).
func (r *ZonesRepo) Exists(ctx context.Context, name string) (bool, error) {
	var n int
	err := r.Pool.QueryRow(ctx, `SELECT 1 FROM firewall_zones WHERE name = $1`, name).Scan(&n)
	if errors.Is(err, pgx.ErrNoRows) {
		return false, nil
	}
	if err != nil {
		return false, err
	}
	return true, nil
}

func (r *ZonesRepo) Create(ctx context.Context, z models.FirewallZone) (*models.FirewallZone, error) {
	row := r.Pool.QueryRow(ctx, `
INSERT INTO firewall_zones (name, description, builtin)
VALUES ($1, $2, FALSE)
RETURNING id, name, description, builtin, created_at, updated_at`,
		z.Name, z.Description)
	return scanZone(row)
}

// Update — builtin zones may have their description tweaked but
// not their name (the renderer + iface rows reference zones by
// name and a rename would silently dangle them). Custom zones can
// be renamed; the handler is responsible for cascading the new
// name into network_interfaces.role / firewall_rules.src_zone /
// dst_zone / firewall_nat_rules.in_zone / out_zone if needed.
func (r *ZonesRepo) Update(ctx context.Context, id int64, z models.FirewallZone) (*models.FirewallZone, error) {
	cur, err := r.Get(ctx, id)
	if err != nil {
		return nil, err
	}
	name := z.Name
	if cur.Builtin {
		name = cur.Name
	}
	row := r.Pool.QueryRow(ctx, `
UPDATE firewall_zones SET
   name = $1, description = $2, updated_at = NOW()
WHERE id = $3
RETURNING id, name, description, builtin, created_at, updated_at`,
		name, z.Description, id)
	return scanZone(row)
}

// Delete — builtin zones are non-deletable; for custom zones the
// caller must check for references in network_interfaces /
// firewall_rules / firewall_nat_rules first (handler concern).
func (r *ZonesRepo) Delete(ctx context.Context, id int64) error {
	cur, err := r.Get(ctx, id)
	if err != nil {
		return err
	}
	if cur.Builtin {
		return errors.New("builtin zone cannot be deleted")
	}
	tag, err := r.Pool.Exec(ctx, `DELETE FROM firewall_zones WHERE id = $1`, id)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return ErrZoneNotFound
	}
	return nil
}

// References returns the count of foreign uses of this zone (by
// name) so the handler can surface a "zone is still in use" error
// instead of letting a cascade go silent.
func (r *ZonesRepo) References(ctx context.Context, name string) (int, error) {
	var n int
	err := r.Pool.QueryRow(ctx, `
SELECT
  (SELECT COUNT(*) FROM network_interfaces WHERE role = $1) +
  (SELECT COUNT(*) FROM firewall_rules WHERE src_zone = $1 OR dst_zone = $1) +
  (SELECT COUNT(*) FROM firewall_nat_rules WHERE in_zone = $1 OR out_zone = $1)`,
		name).Scan(&n)
	return n, err
}

func scanZone(row interface{ Scan(...any) error }) (*models.FirewallZone, error) {
	var z models.FirewallZone
	if err := row.Scan(
		&z.ID, &z.Name, &z.Description, &z.Builtin,
		&z.CreatedAt, &z.UpdatedAt,
	); err != nil {
		return nil, err
	}
	return &z, nil
}