package repository

import (
	"baron-sso-backend/internal/domain"
	"context"
	"fmt"
	"time"

	"github.com/ClickHouse/clickhouse-go/v2"
	"github.com/ClickHouse/clickhouse-go/v2/lib/driver"
)

type ClickHouseRepository struct {
	conn driver.Conn
}

func NewClickHouseRepository(host string, port int, user, password, db string) (*ClickHouseRepository, error) {
	// 1. Connect to 'default' database first to ensure target DB exists
	tmpConn, err := clickhouse.Open(&clickhouse.Options{
		Addr: []string{fmt.Sprintf("%s:%d", host, port)},
		Auth: clickhouse.Auth{
			Database: "default",
			Username: user,
			Password: password,
		},
	})
	if err == nil {
		_ = tmpConn.Exec(context.Background(), fmt.Sprintf("CREATE DATABASE IF NOT EXISTS %s", db))
		_ = tmpConn.Close()
	}

	// 2. Now connect to the target database
	conn, err := clickhouse.Open(&clickhouse.Options{
		Addr: []string{fmt.Sprintf("%s:%d", host, port)},
		Auth: clickhouse.Auth{
			Database: db,
			Username: user,
			Password: password,
		},
		Debug: false,
	})
	if err != nil {
		return nil, fmt.Errorf("failed to open clickhouse connection: %w", err)
	}

	if err := conn.Ping(context.Background()); err != nil {
		return nil, fmt.Errorf("failed to ping clickhouse: %w", err)
	}

	// Ensure Table Exists
	// Note: In production, use migrations.
	query := `
	CREATE TABLE IF NOT EXISTS audit_logs (
		event_id String,
		timestamp DateTime DEFAULT now(),
		user_id String,
		tenant_id String,
		event_type String,
		status String,
		ip_address String,
		user_agent String,
		device_id String,
		details String
	) ENGINE = MergeTree()
	ORDER BY timestamp
	`
	if err := conn.Exec(context.Background(), query); err != nil {
		return nil, fmt.Errorf("failed to create table: %w", err)
	}

	alterQuery := `
		ALTER TABLE audit_logs
		ADD COLUMN IF NOT EXISTS tenant_id String,
		ADD COLUMN IF NOT EXISTS event_id String
	`
	if err := conn.Exec(context.Background(), alterQuery); err != nil {
		return nil, fmt.Errorf("failed to alter table: %w", err)
	}

	return &ClickHouseRepository{conn: conn}, nil
}

func (r *ClickHouseRepository) Create(log *domain.AuditLog) error {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	if log.Timestamp.IsZero() {
		log.Timestamp = time.Now()
	}

	query := `
		INSERT INTO audit_logs (event_id, timestamp, user_id, tenant_id, event_type, status, ip_address, user_agent, device_id, details)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
	`
	return r.conn.Exec(ctx, query,
		log.EventID,
		log.Timestamp,
		log.UserID,
		log.TenantID,
		log.EventType,
		log.Status,
		log.IPAddress,
		log.UserAgent,
		log.DeviceID,
		log.Details,
	)
}

func (r *ClickHouseRepository) FindPage(ctx context.Context, limit int, cursor *domain.AuditCursor, tenantID string) ([]domain.AuditLog, error) {
	if limit <= 0 {
		limit = 50
	}
	query := `
		SELECT event_id, timestamp, user_id, tenant_id, event_type, status, ip_address, user_agent, device_id, details
		FROM audit_logs
		WHERE 1=1
	`
	args := make([]any, 0, 5)

	if tenantID != "" {
		query += " AND tenant_id = ?"
		args = append(args, tenantID)
	}

	if cursor != nil {
		query += `
		AND ((timestamp < ?) OR (timestamp = ? AND event_id < ?))
		`
		args = append(args, cursor.Timestamp, cursor.Timestamp, cursor.EventID)
	}
	query += `
		ORDER BY timestamp DESC, event_id DESC
		LIMIT ?
	`
	args = append(args, limit)

	rows, err := r.conn.Query(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("failed to query audit logs: %w", err)
	}
	defer rows.Close()

	var logs []domain.AuditLog
	for rows.Next() {
		var log domain.AuditLog
		if err := rows.Scan(
			&log.EventID,
			&log.Timestamp,
			&log.UserID,
			&log.TenantID,
			&log.EventType,
			&log.Status,
			&log.IPAddress,
			&log.UserAgent,
			&log.DeviceID,
			&log.Details,
		); err != nil {
			return nil, fmt.Errorf("failed to scan audit log: %w", err)
		}
		logs = append(logs, log)
	}
	return logs, nil
}

func (r *ClickHouseRepository) FindByUserAndEvents(ctx context.Context, userID string, eventTypes []string, limit int) ([]domain.AuditLog, error) {
	if limit <= 0 {
		limit = 100
	}
	query := `
		SELECT event_id, timestamp, user_id, tenant_id, event_type, status, ip_address, user_agent, device_id, details
		FROM audit_logs
		WHERE user_id = ? AND event_type IN (?)
		ORDER BY timestamp DESC
		LIMIT ?
	`
	rows, err := r.conn.Query(ctx, query, userID, eventTypes, limit)
	if err != nil {
		return nil, fmt.Errorf("failed to query audit logs by user/events: %w", err)
	}
	defer rows.Close()

	var logs []domain.AuditLog
	for rows.Next() {
		var log domain.AuditLog
		if err := rows.Scan(
			&log.EventID,
			&log.Timestamp,
			&log.UserID,
			&log.TenantID,
			&log.EventType,
			&log.Status,
			&log.IPAddress,
			&log.UserAgent,
			&log.DeviceID,
			&log.Details,
		); err != nil {
			return nil, fmt.Errorf("failed to scan audit log: %w", err)
		}
		logs = append(logs, log)
	}
	return logs, nil
}

func (r *ClickHouseRepository) Ping(ctx context.Context) error {
	if r.conn == nil {
		return fmt.Errorf("clickhouse connection is nil")
	}
	return r.conn.Ping(ctx)
}

func (r *ClickHouseRepository) CountFailuresSince(ctx context.Context, since time.Time, tenantID string) (int64, error) {
	query := `
		SELECT count()
		FROM audit_logs
		WHERE status = 'failure' AND timestamp >= ?
	`
	args := []any{since}
	if tenantID != "" {
		query += " AND JSONExtractString(details, 'tenant_id') = ?"
		args = append(args, tenantID)
	}

	var count int64
	err := r.conn.QueryRow(ctx, query, args...).Scan(&count)
	if err != nil {
		return 0, fmt.Errorf("failed to count failures: %w", err)
	}
	return count, nil
}

func (r *ClickHouseRepository) CountActiveSessionsSince(ctx context.Context, since time.Time, tenantID string) (int64, error) {
	// We use uniqExact(session_id) to count unique sessions that had success events recently.
	query := `
		SELECT uniqExact(session_id)
		FROM audit_logs
		WHERE status = 'success' AND timestamp >= ? AND session_id != ''
	`
	args := []any{since}
	if tenantID != "" {
		query += " AND JSONExtractString(details, 'tenant_id') = ?"
		args = append(args, tenantID)
	}

	var count int64
	err := r.conn.QueryRow(ctx, query, args...).Scan(&count)
	if err != nil {
		return 0, fmt.Errorf("failed to count active sessions: %w", err)
	}
	return count, nil
}