import Foundation
import CryptoKit

/// 错误指纹计算
public enum Fingerprint {

    /// 计算错误指纹
    public static func compute(type: String, message: String, stacktrace: String) -> String {
        let normalizedMessage = normalizeMessage(message)
        let topFrames = extractTopFrames(stacktrace, count: 3)

        let payload = "\(type):\(normalizedMessage):\(topFrames)"
        let data = Data(payload.utf8)
        let hash = SHA256.hash(data: data)
        return hash.map { String(format: "%02x", $0) }.joined()
    }

    /// 归一化消息（数字替换为 N，长 hex 替换为 H）
    private static func normalizeMessage(_ message: String) -> String {
        var result = message
        // 替换数字
        result = result.replacingOccurrences(of: #"\d+"#, with: "N", options: .regularExpression)
        // 替换长 hex 字符串
        result = result.replacingOccurrences(of: #"[0-9a-fA-F]{8,}"#, with: "H", options: .regularExpression)
        return result
    }

    /// 提取堆栈顶部帧
    private static func extractTopFrames(_ stacktrace: String, count: Int) -> String {
        let lines = stacktrace.split(separator: "\n").prefix(count)
        return lines.joined(separator: "|")
    }
}