package store

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

	_ "modernc.org/sqlite"
)

// Store handles SQLite persistence for customer reports.
type Store struct {
	db     *sql.DB
	logger *log.Logger
}

// CustomerSummary holds the latest status for a customer (for dashboard).
type CustomerSummary struct {
	CustomerID        string
	CustomerName      string
	ControllerVersion string
	ReceivedAt        time.Time
	HealthStatus      string
	CPUPercent        float64
	MemoryPercent     float64
	ContainerTotal    int
	ContainerRunning  int
	BackupLastSnapshot *time.Time
	ReportJSON        string

	// Computed fields (not stored)
	TimeSinceReport time.Duration
	DiskSummary     string
}

// New creates a new store and initializes the schema.
func New(dbPath string, logger *log.Logger) (*Store, error) {
	db, err := sql.Open("sqlite", dbPath+"?_journal_mode=WAL&_busy_timeout=5000")
	if err != nil {
		return nil, fmt.Errorf("opening database: %w", err)
	}

	s := &Store{db: db, logger: logger}
	if err := s.migrate(); err != nil {
		db.Close()
		return nil, fmt.Errorf("migrating database: %w", err)
	}

	return s, nil
}

func (s *Store) migrate() error {
	_, err := s.db.Exec(`
		CREATE TABLE IF NOT EXISTS reports (
			id INTEGER PRIMARY KEY AUTOINCREMENT,
			customer_id TEXT NOT NULL,
			received_at DATETIME NOT NULL DEFAULT (datetime('now')),
			report_json TEXT NOT NULL,
			health_status TEXT,
			cpu_percent REAL,
			memory_percent REAL,
			container_total INTEGER,
			container_running INTEGER,
			backup_last_snapshot DATETIME,
			controller_version TEXT
		);

		CREATE INDEX IF NOT EXISTS idx_reports_customer
			ON reports(customer_id, received_at DESC);

		CREATE TABLE IF NOT EXISTS customer_notifications (
			customer_id TEXT PRIMARY KEY,
			email TEXT NOT NULL DEFAULT '',
			enabled_events TEXT NOT NULL DEFAULT '[]',
			created_at DATETIME DEFAULT (datetime('now')),
			updated_at DATETIME DEFAULT (datetime('now'))
		);

		CREATE TABLE IF NOT EXISTS notification_log (
			id INTEGER PRIMARY KEY AUTOINCREMENT,
			customer_id TEXT NOT NULL,
			event_type TEXT NOT NULL,
			severity TEXT NOT NULL,
			message TEXT NOT NULL,
			status TEXT NOT NULL DEFAULT 'pending',
			error_message TEXT,
			created_at DATETIME DEFAULT (datetime('now'))
		);

		CREATE INDEX IF NOT EXISTS idx_notification_log_customer
			ON notification_log(customer_id, created_at DESC);
	`)
	return err
}

// NotificationPrefs holds per-customer notification preferences.
type NotificationPrefs struct {
	CustomerID    string
	Email         string
	EnabledEvents []string
}

// GetNotificationPrefs returns notification preferences for a customer.
func (s *Store) GetNotificationPrefs(customerID string) (*NotificationPrefs, error) {
	var email, eventsJSON string
	err := s.db.QueryRow(
		"SELECT email, enabled_events FROM customer_notifications WHERE customer_id = ?",
		customerID,
	).Scan(&email, &eventsJSON)
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, nil
		}
		return nil, err
	}

	var events []string
	json.Unmarshal([]byte(eventsJSON), &events)

	return &NotificationPrefs{
		CustomerID:    customerID,
		Email:         email,
		EnabledEvents: events,
	}, nil
}

// SaveNotificationPrefs creates or updates notification preferences for a customer.
func (s *Store) SaveNotificationPrefs(customerID, email string, enabledEvents []string) error {
	eventsJSON, _ := json.Marshal(enabledEvents)
	_, err := s.db.Exec(`
		INSERT INTO customer_notifications (customer_id, email, enabled_events, updated_at)
		VALUES (?, ?, ?, datetime('now'))
		ON CONFLICT(customer_id) DO UPDATE SET
			email = excluded.email,
			enabled_events = excluded.enabled_events,
			updated_at = datetime('now')`,
		customerID, email, string(eventsJSON),
	)
	return err
}

// LogNotification records a notification attempt.
func (s *Store) LogNotification(customerID, eventType, severity, message, status, errorMsg string) error {
	_, err := s.db.Exec(`
		INSERT INTO notification_log (customer_id, event_type, severity, message, status, error_message)
		VALUES (?, ?, ?, ?, ?, ?)`,
		customerID, eventType, severity, message, status, errorMsg,
	)
	return err
}

// SaveReport stores a new report. The reportJSON should be the raw JSON payload.
func (s *Store) SaveReport(customerID string, reportJSON []byte) error {
	// Parse denormalized fields from the JSON
	var parsed struct {
		ControllerVersion string `json:"controller_version"`
		System            struct {
			CPUPercent    float64 `json:"cpu_percent"`
			MemoryPercent float64 `json:"memory_percent"`
		} `json:"system"`
		Containers struct {
			Total   int `json:"total"`
			Running int `json:"running"`
		} `json:"containers"`
		Backup struct {
			LastSnapshot *time.Time `json:"last_snapshot"`
		} `json:"backup"`
		Health struct {
			Status string `json:"status"`
		} `json:"health"`
	}
	json.Unmarshal(reportJSON, &parsed)

	var backupSnapshot *string
	if parsed.Backup.LastSnapshot != nil {
		t := parsed.Backup.LastSnapshot.Format(time.RFC3339)
		backupSnapshot = &t
	}

	_, err := s.db.Exec(`
		INSERT INTO reports (customer_id, report_json, health_status, cpu_percent,
			memory_percent, container_total, container_running,
			backup_last_snapshot, controller_version)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		customerID, string(reportJSON),
		parsed.Health.Status, parsed.System.CPUPercent,
		parsed.System.MemoryPercent, parsed.Containers.Total,
		parsed.Containers.Running, backupSnapshot,
		parsed.ControllerVersion,
	)
	return err
}

// GetCustomers returns the latest report summary for each customer.
func (s *Store) GetCustomers() ([]CustomerSummary, error) {
	rows, err := s.db.Query(`
		SELECT r.customer_id, r.received_at, r.report_json,
			r.health_status, r.cpu_percent, r.memory_percent,
			r.container_total, r.container_running,
			r.backup_last_snapshot, r.controller_version
		FROM reports r
		INNER JOIN (
			SELECT customer_id, MAX(received_at) as max_time
			FROM reports
			GROUP BY customer_id
		) latest ON r.customer_id = latest.customer_id
			AND r.received_at = latest.max_time
		ORDER BY r.customer_id`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var customers []CustomerSummary
	for rows.Next() {
		var c CustomerSummary
		var receivedAt string
		var backupSnapshot sql.NullString

		if err := rows.Scan(&c.CustomerID, &receivedAt, &c.ReportJSON,
			&c.HealthStatus, &c.CPUPercent, &c.MemoryPercent,
			&c.ContainerTotal, &c.ContainerRunning,
			&backupSnapshot, &c.ControllerVersion); err != nil {
			return nil, err
		}

		c.ReceivedAt = parseSQLiteTime(receivedAt)
		c.TimeSinceReport = time.Since(c.ReceivedAt)

		if backupSnapshot.Valid {
			t, err := time.Parse(time.RFC3339, backupSnapshot.String)
			if err == nil {
				c.BackupLastSnapshot = &t
			}
		}

		// Parse customer_name from JSON
		var report struct {
			CustomerName string `json:"customer_name"`
		}
		json.Unmarshal([]byte(c.ReportJSON), &report)
		c.CustomerName = report.CustomerName

		// Parse disk summary
		c.DiskSummary = parseDiskSummary(c.ReportJSON)

		customers = append(customers, c)
	}
	return customers, rows.Err()
}

// GetCustomer returns the latest report for a specific customer.
func (s *Store) GetCustomer(customerID string) (*CustomerSummary, error) {
	row := s.db.QueryRow(`
		SELECT customer_id, received_at, report_json,
			health_status, cpu_percent, memory_percent,
			container_total, container_running,
			backup_last_snapshot, controller_version
		FROM reports
		WHERE customer_id = ?
		ORDER BY received_at DESC
		LIMIT 1`, customerID)

	var c CustomerSummary
	var receivedAt string
	var backupSnapshot sql.NullString

	if err := row.Scan(&c.CustomerID, &receivedAt, &c.ReportJSON,
		&c.HealthStatus, &c.CPUPercent, &c.MemoryPercent,
		&c.ContainerTotal, &c.ContainerRunning,
		&backupSnapshot, &c.ControllerVersion); err != nil {
		if err == sql.ErrNoRows {
			return nil, nil
		}
		return nil, err
	}

	c.ReceivedAt = parseSQLiteTime(receivedAt)
	c.TimeSinceReport = time.Since(c.ReceivedAt)

	if backupSnapshot.Valid {
		t, err := time.Parse(time.RFC3339, backupSnapshot.String)
		if err == nil {
			c.BackupLastSnapshot = &t
		}
	}

	var report struct {
		CustomerName string `json:"customer_name"`
	}
	json.Unmarshal([]byte(c.ReportJSON), &report)
	c.CustomerName = report.CustomerName

	c.DiskSummary = parseDiskSummary(c.ReportJSON)

	return &c, nil
}

// GetCustomerHistory returns report history for a customer.
func (s *Store) GetCustomerHistory(customerID string, since time.Duration) ([]CustomerSummary, error) {
	cutoff := time.Now().Add(-since).Format("2006-01-02 15:04:05")

	rows, err := s.db.Query(`
		SELECT customer_id, received_at, report_json,
			health_status, cpu_percent, memory_percent,
			container_total, container_running,
			backup_last_snapshot, controller_version
		FROM reports
		WHERE customer_id = ? AND received_at >= ?
		ORDER BY received_at DESC`, customerID, cutoff)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var history []CustomerSummary
	for rows.Next() {
		var c CustomerSummary
		var receivedAt string
		var backupSnapshot sql.NullString

		if err := rows.Scan(&c.CustomerID, &receivedAt, &c.ReportJSON,
			&c.HealthStatus, &c.CPUPercent, &c.MemoryPercent,
			&c.ContainerTotal, &c.ContainerRunning,
			&backupSnapshot, &c.ControllerVersion); err != nil {
			return nil, err
		}

		c.ReceivedAt = parseSQLiteTime(receivedAt)
		c.TimeSinceReport = time.Since(c.ReceivedAt)

		if backupSnapshot.Valid {
			t, err := time.Parse(time.RFC3339, backupSnapshot.String)
			if err == nil {
				c.BackupLastSnapshot = &t
			}
		}

		history = append(history, c)
	}
	return history, rows.Err()
}

// Prune deletes reports older than the given number of days.
func (s *Store) Prune(maxDays int) (int64, error) {
	cutoff := time.Now().AddDate(0, 0, -maxDays).Format("2006-01-02 15:04:05")
	res, err := s.db.Exec("DELETE FROM reports WHERE received_at < ?", cutoff)
	if err != nil {
		return 0, err
	}
	return res.RowsAffected()
}

// Close closes the database connection.
func (s *Store) Close() error {
	return s.db.Close()
}

// parseSQLiteTime tries multiple formats that modernc.org/sqlite may return.
func parseSQLiteTime(s string) time.Time {
	formats := []string{
		"2006-01-02 15:04:05",          // SQLite datetime('now')
		"2006-01-02T15:04:05Z",         // RFC3339 without fractional
		time.RFC3339,                    // 2006-01-02T15:04:05Z07:00
		time.RFC3339Nano,               // with fractional seconds
		"2006-01-02 15:04:05+00:00",    // with explicit UTC offset
		"2006-01-02 15:04:05.999999999", // with fractional, no TZ
	}
	for _, f := range formats {
		if t, err := time.Parse(f, s); err == nil {
			return t
		}
	}
	// Last resort: if string is non-empty, log it for debugging
	if s != "" {
		log.Printf("[WARN] Could not parse timestamp: %q", s)
	}
	return time.Time{} // zero time
}

func parseDiskSummary(reportJSON string) string {
	var report struct {
		Storage []struct {
			Mount   string  `json:"mount"`
			Percent float64 `json:"percent"`
		} `json:"storage"`
	}
	json.Unmarshal([]byte(reportJSON), &report)

	var parts []string
	for _, s := range report.Storage {
		parts = append(parts, fmt.Sprintf("%.0f%%", s.Percent))
	}
	if len(parts) == 0 {
		return "–"
	}
	result := parts[0]
	for _, p := range parts[1:] {
		result += "/" + p
	}
	return result
}