import Foundation

// MARK: - 二维码载荷（当前播放视频 URL + 频道信息）
//
// 扫码后直接把该条目保存进扫码方的媒体库，并带上频道/分组/台标等元数据。
//
// 编码格式：优先 JSON（携带频道信息），
// 若编码后过长（> ~900 字符，QR 版本会过大影响识别率），
// 退化为纯 URL —— 扫码方仍能添加，只是没有频道元数据。

public struct QRMediaPayload: Codable, Equatable {
    /// 媒体 URL（必填）
    public var url: String
    /// 频道/节目名称
    public var name: String?
    /// 类型："stream" / "url" / "file"
    public var type: String?
    /// 频道分组（M3U group-title）
    public var group: String?
    /// 台标 URL（M3U tvg-logo）
    public var logo: String?
    /// 发送方标识，便于扫码方区分来源
    public var from: String?

    public init(url: String, name: String? = nil, type: String? = nil,
                group: String? = nil, logo: String? = nil, from: String? = nil) {
        self.url = url
        self.name = name
        self.type = type
        self.group = group
        self.logo = logo
        self.from = from
    }

    /// 短键名，压缩二维码体积
    enum CodingKeys: String, CodingKey {
        case url = "u"
        case name = "n"
        case type = "t"
        case group = "g"
        case logo = "l"
        case from = "f"
    }

    /// 二维码中实际使用的文本：短负载用 JSON，超长退回纯 URL
    public static let maxJSONLength = 900

    public func encoded() -> String {
        let enc = JSONEncoder()
        enc.outputFormatting = [.withoutEscapingSlashes]
        if let data = try? enc.encode(self),
           let json = String(data: data, encoding: .utf8),
           json.count <= Self.maxJSONLength {
            return json
        }
        return url   // 退化：纯 URL
    }

    /// 解析扫码结果：支持 JSON 载荷，也兼容纯 URL（旧二维码/手输）
    public static func decode(_ text: String) -> QRMediaPayload? {
        let trimmed = text.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !trimmed.isEmpty else { return nil }

        if trimmed.hasPrefix("{") {
            if let data = trimmed.data(using: .utf8),
               let p = try? JSONDecoder().decode(QRMediaPayload.self, from: data),
               !p.url.isEmpty {
                return p
            }
            return nil   // 是 JSON 但解析失败 → 不当成 URL 处理
        }

        // 纯 URL 回退
        if let u = URL(string: trimmed), let scheme = u.scheme?.lowercased(),
           scheme == "http" || scheme == "https" || scheme == "file" {
            return QRMediaPayload(url: trimmed, name: u.lastPathComponent.isEmpty ? u.host : u.lastPathComponent)
        }
        return nil
    }
}