package db

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"time"

	"github.com/cynfo/rmm-backend/models"

	_ "modernc.org/sqlite"
)

type Database struct {
	db *sql.DB
}

func New(dbPath string) (*Database, error) {
	db, err := sql.Open("sqlite", dbPath)
	if err != nil {
		return nil, fmt.Errorf("Datenbank oeffnen: %w", err)
	}

	// WAL-Modus fuer bessere Performance
	if _, err := db.Exec("PRAGMA journal_mode=WAL"); err != nil {
		return nil, err
	}

	d := &Database{db: db}
	if err := d.migrate(); err != nil {
		return nil, fmt.Errorf("Migration fehlgeschlagen: %w", err)
	}

	return d, nil
}

func (d *Database) migrate() error {
	schema := `
	CREATE TABLE IF NOT EXISTS agents (
		id TEXT PRIMARY KEY,
		name TEXT NOT NULL,
		hostname TEXT NOT NULL,
		ip TEXT NOT NULL,
		opnsense_version TEXT NOT NULL DEFAULT '',
		registered_at TEXT NOT NULL,
		last_heartbeat TEXT
	);

	CREATE TABLE IF NOT EXISTS config_backups (
		id INTEGER PRIMARY KEY AUTOINCREMENT,
		agent_id TEXT NOT NULL,
		hash TEXT NOT NULL,
		size INTEGER NOT NULL,
		config_xml TEXT NOT NULL,
		created_at TEXT NOT NULL,
		FOREIGN KEY (agent_id) REFERENCES agents(id) ON DELETE CASCADE
	);

	CREATE INDEX IF NOT EXISTS idx_config_backups_agent ON config_backups(agent_id, created_at DESC);
	CREATE INDEX IF NOT EXISTS idx_config_backups_hash ON config_backups(agent_id, hash);

	CREATE TABLE IF NOT EXISTS system_data (
		agent_id TEXT PRIMARY KEY,
		data_json TEXT NOT NULL,
		updated_at TEXT NOT NULL,
		FOREIGN KEY (agent_id) REFERENCES agents(id) ON DELETE CASCADE
	);
	`
	_, err := d.db.Exec(schema)
	return err
}

func (d *Database) Close() error {
	return d.db.Close()
}

// RegisterAgent - Neuen Agent registrieren oder bestehenden aktualisieren
func (d *Database) RegisterAgent(agent *models.Agent) error {
	_, err := d.db.Exec(`
		INSERT INTO agents (id, name, hostname, ip, opnsense_version, registered_at)
		VALUES (?, ?, ?, ?, ?, ?)
		ON CONFLICT(id) DO UPDATE SET
			name=excluded.name,
			hostname=excluded.hostname,
			ip=excluded.ip,
			opnsense_version=excluded.opnsense_version
	`, agent.ID, agent.Name, agent.Hostname, agent.IP, agent.OPNsenseVersion, agent.RegisteredAt.UTC().Format(time.RFC3339))
	return err
}

// SaveSystemData - Systemdaten speichern und Heartbeat aktualisieren
func (d *Database) SaveSystemData(agentID string, data *models.SystemData) error {
	now := time.Now().UTC().Format(time.RFC3339)

	jsonData, err := json.Marshal(data)
	if err != nil {
		return fmt.Errorf("JSON Marshal: %w", err)
	}

	tx, err := d.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	// Heartbeat Zeitstempel aktualisieren
	res, err := tx.Exec("UPDATE agents SET last_heartbeat = ? WHERE id = ?", now, agentID)
	if err != nil {
		return err
	}
	rows, _ := res.RowsAffected()
	if rows == 0 {
		return fmt.Errorf("Agent %s nicht gefunden", agentID)
	}

	// Systemdaten upsert
	_, err = tx.Exec(`
		INSERT INTO system_data (agent_id, data_json, updated_at)
		VALUES (?, ?, ?)
		ON CONFLICT(agent_id) DO UPDATE SET
			data_json=excluded.data_json,
			updated_at=excluded.updated_at
	`, agentID, string(jsonData), now)
	if err != nil {
		return err
	}

	return tx.Commit()
}

// GetAgents - Alle Agents auflisten
func (d *Database) GetAgents() ([]models.Agent, error) {
	rows, err := d.db.Query("SELECT id, name, hostname, ip, opnsense_version, registered_at, last_heartbeat FROM agents ORDER BY name")
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var agents []models.Agent
	for rows.Next() {
		var a models.Agent
		var regAt string
		var lastHB sql.NullString

		if err := rows.Scan(&a.ID, &a.Name, &a.Hostname, &a.IP, &a.OPNsenseVersion, &regAt, &lastHB); err != nil {
			return nil, err
		}
		a.RegisteredAt, _ = time.Parse(time.RFC3339, regAt)
		if lastHB.Valid {
			t, _ := time.Parse(time.RFC3339, lastHB.String)
			a.LastHeartbeat = &t
		}
		agents = append(agents, a)
	}
	return agents, rows.Err()
}

// GetAgent - Einzelnen Agent mit Systemdaten
func (d *Database) GetAgentByHostname(hostname string) (*models.Agent, error) {
	var a models.Agent
	var regAt string
	var lastHB sql.NullString

	err := d.db.QueryRow("SELECT id, name, hostname, ip, opnsense_version, registered_at, last_heartbeat FROM agents WHERE hostname = ? LIMIT 1", hostname).
		Scan(&a.ID, &a.Name, &a.Hostname, &a.IP, &a.OPNsenseVersion, &regAt, &lastHB)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	a.RegisteredAt, _ = time.Parse(time.RFC3339, regAt)
	if lastHB.Valid {
		t, _ := time.Parse(time.RFC3339, lastHB.String)
		a.LastHeartbeat = &t
	}
	return &a, nil
}

func (d *Database) GetAgent(id string) (*models.Agent, *models.SystemData, error) {
	var a models.Agent
	var regAt string
	var lastHB sql.NullString

	err := d.db.QueryRow("SELECT id, name, hostname, ip, opnsense_version, registered_at, last_heartbeat FROM agents WHERE id = ?", id).
		Scan(&a.ID, &a.Name, &a.Hostname, &a.IP, &a.OPNsenseVersion, &regAt, &lastHB)
	if err == sql.ErrNoRows {
		return nil, nil, nil
	}
	if err != nil {
		return nil, nil, err
	}
	a.RegisteredAt, _ = time.Parse(time.RFC3339, regAt)
	if lastHB.Valid {
		t, _ := time.Parse(time.RFC3339, lastHB.String)
		a.LastHeartbeat = &t
	}

	// Systemdaten laden
	var dataJSON sql.NullString
	err = d.db.QueryRow("SELECT data_json FROM system_data WHERE agent_id = ?", id).Scan(&dataJSON)
	if err != nil && err != sql.ErrNoRows {
		return nil, nil, err
	}

	var sysData *models.SystemData
	if dataJSON.Valid {
		sysData = &models.SystemData{}
		if err := json.Unmarshal([]byte(dataJSON.String), sysData); err != nil {
			return &a, nil, nil
		}
	}

	return &a, sysData, nil
}

// GetSystemData - Nur Systemdaten eines Agents
func (d *Database) GetSystemData(agentID string) (*models.SystemData, error) {
	var dataJSON string
	err := d.db.QueryRow("SELECT data_json FROM system_data WHERE agent_id = ?", agentID).Scan(&dataJSON)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}

	var data models.SystemData
	if err := json.Unmarshal([]byte(dataJSON), &data); err != nil {
		return nil, err
	}
	return &data, nil
}

// --- Config Backup Methoden ---

// SaveConfigBackup speichert ein Config-Backup (dedupliziert nach Hash)
func (d *Database) SaveConfigBackup(agentID, hash string, size int, configXML string) (int64, bool, error) {
	// Pruefen ob ein Backup mit gleichem Hash schon existiert
	var existingID int64
	err := d.db.QueryRow("SELECT id FROM config_backups WHERE agent_id = ? AND hash = ? LIMIT 1", agentID, hash).Scan(&existingID)
	if err == nil {
		// Gleicher Hash existiert bereits — kein neues Backup noetig
		return existingID, false, nil
	}

	now := time.Now().UTC().Format(time.RFC3339)
	res, err := d.db.Exec(
		"INSERT INTO config_backups (agent_id, hash, size, config_xml, created_at) VALUES (?, ?, ?, ?, ?)",
		agentID, hash, size, configXML, now,
	)
	if err != nil {
		return 0, false, fmt.Errorf("Backup speichern: %w", err)
	}
	id, _ := res.LastInsertId()
	return id, true, nil
}

// GetConfigBackups listet alle Backups eines Agents
func (d *Database) GetConfigBackups(agentID string, limit int) ([]map[string]interface{}, error) {
	if limit <= 0 {
		limit = 50
	}
	rows, err := d.db.Query(
		"SELECT id, hash, size, created_at FROM config_backups WHERE agent_id = ? ORDER BY created_at DESC LIMIT ?",
		agentID, limit,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var backups []map[string]interface{}
	for rows.Next() {
		var id int64
		var hash, createdAt string
		var size int
		if err := rows.Scan(&id, &hash, &size, &createdAt); err != nil {
			return nil, err
		}
		backups = append(backups, map[string]interface{}{
			"id":         id,
			"hash":       hash,
			"size":       size,
			"created_at": createdAt,
		})
	}
	if backups == nil {
		backups = []map[string]interface{}{}
	}
	return backups, rows.Err()
}

// GetConfigBackup holt ein einzelnes Backup inkl. config_xml
func (d *Database) GetConfigBackup(agentID string, backupID int64) (map[string]interface{}, error) {
	var hash, configXML, createdAt string
	var size int
	var id int64
	err := d.db.QueryRow(
		"SELECT id, hash, size, config_xml, created_at FROM config_backups WHERE agent_id = ? AND id = ?",
		agentID, backupID,
	).Scan(&id, &hash, &size, &configXML, &createdAt)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	return map[string]interface{}{
		"id":         id,
		"hash":       hash,
		"size":       size,
		"config_xml": configXML,
		"created_at": createdAt,
	}, nil
}

// GetLatestConfigBackup holt das neueste Backup
func (d *Database) GetLatestConfigBackup(agentID string) (map[string]interface{}, error) {
	var hash, configXML, createdAt string
	var size int
	var id int64
	err := d.db.QueryRow(
		"SELECT id, hash, size, config_xml, created_at FROM config_backups WHERE agent_id = ? ORDER BY created_at DESC LIMIT 1",
		agentID,
	).Scan(&id, &hash, &size, &configXML, &createdAt)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	return map[string]interface{}{
		"id":         id,
		"hash":       hash,
		"size":       size,
		"config_xml": configXML,
		"created_at": createdAt,
	}, nil
}

// DeleteConfigBackup loescht ein einzelnes Backup
func (d *Database) DeleteConfigBackup(agentID string, backupID int64) (bool, error) {
	res, err := d.db.Exec("DELETE FROM config_backups WHERE agent_id = ? AND id = ?", agentID, backupID)
	if err != nil {
		return false, err
	}
	rows, _ := res.RowsAffected()
	return rows > 0, nil
}

// DeleteAgent - Agent und zugehoerige Daten loeschen
func (d *Database) DeleteAgent(id string) (bool, error) {
	// Foreign Key Cascade aktivieren
	d.db.Exec("PRAGMA foreign_keys = ON")

	res, err := d.db.Exec("DELETE FROM agents WHERE id = ?", id)
	if err != nil {
		return false, err
	}
	rows, _ := res.RowsAffected()
	// Sicherheitshalber auch system_data loeschen (falls kein CASCADE)
	d.db.Exec("DELETE FROM system_data WHERE agent_id = ?", id)
	return rows > 0, nil
}