package masterdb

import (
	"database/sql"
	"fmt"
	"time"
)

// Node represents a registered node in the cluster.
type Node struct {
	Name          string
	Address       string
	Role          string
	Arch          string
	Status        string
	Containers    int
	LastHeartbeat *time.Time
}

// UpsertNode inserts or updates a node in the registry.
func UpsertNode(db *sql.DB, name, address, role, arch string) error {
	_, err := db.Exec(`
		INSERT INTO nodes (name, address, role, arch, updated_at)
		VALUES (?, ?, ?, ?, datetime('now'))
		ON CONFLICT(name) DO UPDATE SET
			address = excluded.address,
			role = excluded.role,
			arch = excluded.arch,
			updated_at = datetime('now')
	`, name, address, role, arch)
	if err != nil {
		return fmt.Errorf("upsert node %s: %w", name, err)
	}
	return nil
}

// GetNode returns a single node by name.
func GetNode(db *sql.DB, name string) (*Node, error) {
	var n Node
	var lastHB sql.NullString
	err := db.QueryRow(`
		SELECT name, address, role, arch, status, containers, last_heartbeat
		FROM nodes WHERE name = ?
	`, name).Scan(&n.Name, &n.Address, &n.Role, &n.Arch, &n.Status, &n.Containers, &lastHB)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("get node %s: %w", name, err)
	}
	if lastHB.Valid {
		t, _ := time.Parse("2006-01-02 15:04:05", lastHB.String)
		n.LastHeartbeat = &t
	}
	return &n, nil
}

// ListNodes returns all nodes.
func ListNodes(db *sql.DB) ([]*Node, error) {
	return queryNodes(db, `SELECT name, address, role, arch, status, containers, last_heartbeat FROM nodes ORDER BY name`)
}

// ListWorkerNodes returns nodes with role "worker" or "master" (master is also a worker).
func ListWorkerNodes(db *sql.DB) ([]*Node, error) {
	return queryNodes(db, `SELECT name, address, role, arch, status, containers, last_heartbeat FROM nodes WHERE role IN ('worker', 'master') ORDER BY name`)
}

// ListEdgeNodes returns nodes with role "edge".
func ListEdgeNodes(db *sql.DB) ([]*Node, error) {
	return queryNodes(db, `SELECT name, address, role, arch, status, containers, last_heartbeat FROM nodes WHERE role = 'edge' ORDER BY name`)
}

func queryNodes(db *sql.DB, query string) ([]*Node, error) {
	rows, err := db.Query(query)
	if err != nil {
		return nil, fmt.Errorf("query nodes: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var nodes []*Node
	for rows.Next() {
		var n Node
		var lastHB sql.NullString
		if err := rows.Scan(&n.Name, &n.Address, &n.Role, &n.Arch, &n.Status, &n.Containers, &lastHB); err != nil {
			return nil, fmt.Errorf("scan node: %w", err)
		}
		if lastHB.Valid {
			t, _ := time.Parse("2006-01-02 15:04:05", lastHB.String)
			n.LastHeartbeat = &t
		}
		nodes = append(nodes, &n)
	}
	return nodes, rows.Err()
}

// UpdateNodeStatus updates a node's status field.
func UpdateNodeStatus(db *sql.DB, name, status string) error {
	_, err := db.Exec(`UPDATE nodes SET status = ?, updated_at = datetime('now') WHERE name = ?`, status, name)
	if err != nil {
		return fmt.Errorf("update node status %s: %w", name, err)
	}
	return nil
}