package cluster

import (
	"context"
	"errors"
	"fmt"
	"os"
	"time"

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

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

var ErrNotFound = errors.New("ha_node not found")

// Store wraps the ha_nodes table — used by the cluster handler and by
// EnsureSelfRegistered. v1 only ever has one row (the local node);
// the table is in place so Phase 3.1 multi-node lands without
// schema churn.
type Store struct {
	Pool *pgxpool.Pool
}

func NewStore(pool *pgxpool.Pool) *Store { return &Store{Pool: pool} }

const baseSelect = `
SELECT id, name, fqdn, api_url, public_ip, internal_ip, mgmt_ip, role,
       version, config_hash, status,
       last_seen, joined_at, created_at, updated_at
FROM ha_nodes
`

func (s *Store) List(ctx context.Context) ([]models.HANode, error) {
	rows, err := s.Pool.Query(ctx, baseSelect+" ORDER BY joined_at ASC")
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := make([]models.HANode, 0, 4)
	for rows.Next() {
		n, err := scanNode(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, *n)
	}
	return out, rows.Err()
}

func (s *Store) Get(ctx context.Context, id string) (*models.HANode, error) {
	row := s.Pool.QueryRow(ctx, baseSelect+" WHERE id = $1", id)
	n, err := scanNode(row)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	return n, nil
}

// UpsertSelf writes the local node's row using the database-side
// ON CONFLICT DO UPDATE so the call is safe to make on every boot.
// last_seen is also bumped — handy for the heartbeat-by-restart
// pattern even before periodic heartbeats land. Phase-3-Felder
// (mgmt_ip, version, config_hash, status) werden mit COALESCE
// erhalten falls der Caller sie nicht setzt.
func (s *Store) UpsertSelf(ctx context.Context, n models.HANode) (*models.HANode, error) {
	now := time.Now().UTC()
	if n.Status == "" {
		n.Status = "online"
	}
	row := s.Pool.QueryRow(ctx, `
INSERT INTO ha_nodes (id, name, fqdn, api_url, public_ip, internal_ip, mgmt_ip,
                      role, version, config_hash, status, last_seen, joined_at)
VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13)
ON CONFLICT (id) DO UPDATE SET
   name = EXCLUDED.name,
   fqdn = EXCLUDED.fqdn,
   api_url = EXCLUDED.api_url,
   public_ip   = COALESCE(EXCLUDED.public_ip,   ha_nodes.public_ip),
   internal_ip = COALESCE(EXCLUDED.internal_ip, ha_nodes.internal_ip),
   mgmt_ip     = COALESCE(EXCLUDED.mgmt_ip,     ha_nodes.mgmt_ip),
   role        = EXCLUDED.role,
   version     = COALESCE(EXCLUDED.version,     ha_nodes.version),
   config_hash = COALESCE(EXCLUDED.config_hash, ha_nodes.config_hash),
   status      = EXCLUDED.status,
   last_seen   = EXCLUDED.last_seen,
   updated_at  = NOW()
RETURNING id, name, fqdn, api_url, public_ip, internal_ip, mgmt_ip,
          role, version, config_hash, status,
          last_seen, joined_at, created_at, updated_at`,
		n.ID, n.Name, n.FQDN, n.APIURL,
		n.PublicIP, n.InternalIP, n.MgmtIP,
		n.Role, n.Version, n.ConfigHash, n.Status,
		now, now,
	)
	return scanNode(row)
}

// EnsureSelfRegistered mints the node-id if needed, builds the row
// from setup.json + os.Hostname + node.conf, and upserts it. Called
// on edgeguard-api boot AFTER the DB pool is reachable.
//
// fqdn = setup-store fqdn (preferred) or hostname.
// apiURL = "https://<fqdn>".
// version = edgeguard-api-Version (für Drift-Banner).
// mgmtIP = aus /etc/edgeguard/node.conf wenn vorhanden, sonst Auto.
func EnsureSelfRegistered(ctx context.Context, store *Store, fqdn, role, version string) (*models.HANode, error) {
	id, err := EnsureNodeID("")
	if err != nil {
		// Even when persistence failed (read-only /var/lib in dev),
		// EnsureNodeID returns the in-memory id alongside the error
		// — so we can still register, but the id will rotate on
		// every boot.
		_ = err
	}
	if id == "" {
		return nil, fmt.Errorf("could not derive node id")
	}
	host, hostErr := os.Hostname()
	if hostErr != nil {
		host = "unknown"
	}
	if fqdn == "" {
		fqdn = host
	}
	cfg, _ := LoadLocalConfig("")
	var mgmtIP *string
	if cfg != nil && cfg.MgmtIP != "" {
		v := cfg.MgmtIP
		mgmtIP = &v
	}
	var ver *string
	if version != "" {
		v := version
		ver = &v
	}
	n := models.HANode{
		ID:      id,
		Name:    host,
		FQDN:    fqdn,
		APIURL:  "https://" + fqdn,
		MgmtIP:  mgmtIP,
		Role:    role,
		Version: ver,
		Status:  "online",
	}
	return store.UpsertSelf(ctx, n)
}

func scanNode(row interface{ Scan(...any) error }) (*models.HANode, error) {
	var n models.HANode
	if err := row.Scan(
		&n.ID, &n.Name, &n.FQDN, &n.APIURL,
		&n.PublicIP, &n.InternalIP, &n.MgmtIP,
		&n.Role, &n.Version, &n.ConfigHash, &n.Status,
		&n.LastSeen, &n.JoinedAt,
		&n.CreatedAt, &n.UpdatedAt,
	); err != nil {
		return nil, err
	}
	return &n, nil
}