// Package routingrules implements CRUD against the `routing_rules`
// table. A rule maps (domain, path_prefix) → backend; higher priority
// wins, ties broken by id.
package routingrules

import (
	"context"
	"errors"

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

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

var ErrNotFound = errors.New("routing rule not found")

type Repo struct {
	Pool *pgxpool.Pool
}

func New(pool *pgxpool.Pool) *Repo { return &Repo{Pool: pool} }

const baseSelect = `
SELECT id, domain_id, path_prefix, backend_id, priority, active,
       created_at, updated_at
FROM routing_rules
`

// List returns rules ordered by domain_id then priority desc — the
// shape the config-renderer wants when building haproxy/nginx vhosts.
func (r *Repo) List(ctx context.Context) ([]models.RoutingRule, error) {
	rows, err := r.Pool.Query(ctx, baseSelect+
		" ORDER BY domain_id ASC, priority DESC, id ASC")
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]models.RoutingRule, 0, 16)
	for rows.Next() {
		rr, err := scanRule(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, *rr)
	}
	return out, rows.Err()
}

// ListForDomain narrows List to a single domain — handlers expose this
// as GET /domains/:id/routing-rules so the UI only fetches what it needs.
func (r *Repo) ListForDomain(ctx context.Context, domainID int64) ([]models.RoutingRule, error) {
	rows, err := r.Pool.Query(ctx, baseSelect+
		" WHERE domain_id = $1 ORDER BY priority DESC, id ASC", domainID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]models.RoutingRule, 0, 4)
	for rows.Next() {
		rr, err := scanRule(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, *rr)
	}
	return out, rows.Err()
}

func (r *Repo) Get(ctx context.Context, id int64) (*models.RoutingRule, error) {
	row := r.Pool.QueryRow(ctx, baseSelect+" WHERE id = $1", id)
	rr, err := scanRule(row)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	return rr, nil
}

func (r *Repo) Create(ctx context.Context, rr models.RoutingRule) (*models.RoutingRule, error) {
	row := r.Pool.QueryRow(ctx, `
INSERT INTO routing_rules (domain_id, path_prefix, backend_id, priority, active)
VALUES ($1, $2, $3, $4, $5)
RETURNING id, domain_id, path_prefix, backend_id, priority, active,
          created_at, updated_at`,
		rr.DomainID, rr.PathPrefix, rr.BackendID, rr.Priority, rr.Active)
	return scanRule(row)
}

func (r *Repo) Update(ctx context.Context, id int64, rr models.RoutingRule) (*models.RoutingRule, error) {
	row := r.Pool.QueryRow(ctx, `
UPDATE routing_rules SET
   domain_id = $1,
   path_prefix = $2,
   backend_id = $3,
   priority = $4,
   active = $5,
   updated_at = NOW()
WHERE id = $6
RETURNING id, domain_id, path_prefix, backend_id, priority, active,
          created_at, updated_at`,
		rr.DomainID, rr.PathPrefix, rr.BackendID, rr.Priority, rr.Active, id)
	out, err := scanRule(row)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	return out, nil
}

func (r *Repo) Delete(ctx context.Context, id int64) error {
	tag, err := r.Pool.Exec(ctx, `DELETE FROM routing_rules WHERE id = $1`, id)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return ErrNotFound
	}
	return nil
}

func scanRule(row interface{ Scan(...any) error }) (*models.RoutingRule, error) {
	var rr models.RoutingRule
	if err := row.Scan(
		&rr.ID, &rr.DomainID, &rr.PathPrefix, &rr.BackendID,
		&rr.Priority, &rr.Active,
		&rr.CreatedAt, &rr.UpdatedAt,
	); err != nil {
		return nil, err
	}
	return &rr, nil
}