import Foundation

struct PairingPayloadContext: Equatable {
    let deviceName: String
    let originHost: String
    let pairingToken: String
    let challenge: String?
    let challengeID: String?
    let tokenPreview: String
}

enum PairingPayloadParser {
    static func parse(_ payload: String) throws -> PairingPayloadContext {
        let trimmedPayload = payload.trimmingCharacters(in: .whitespacesAndNewlines)

        if let components = URLComponents(string: trimmedPayload),
           components.scheme == "idp.global",
           components.host == "pair" {
            let queryItems = components.queryItems ?? []
            let token = queryItems.first(where: { $0.name == "token" })?.value ?? "demo-token"
            let origin = queryItems.first(where: { $0.name == "origin" })?.value ?? "code.foss.global"
            let device = queryItems.first(where: { $0.name == "device" })?.value ?? "Web Session"

            return PairingPayloadContext(
                deviceName: device,
                originHost: origin,
                pairingToken: token,
                challenge: queryItems.first(where: { $0.name == "challenge" })?.value,
                challengeID: queryItems.first(where: { $0.name == "challenge_id" })?.value,
                tokenPreview: String(token.suffix(6))
            )
        }

        if trimmedPayload.contains("token") || trimmedPayload.contains("pair") {
            return PairingPayloadContext(
                deviceName: "Manual Session",
                originHost: "code.foss.global",
                pairingToken: trimmedPayload,
                challenge: nil,
                challengeID: nil,
                tokenPreview: String(trimmedPayload.suffix(6))
            )
        }

        throw AppError.invalidPairingPayload
    }
}