//
//  PolicyRuleStore.swift
//  punchnet
//  1. 需要增加规则基于轮训更新的逻辑
//  Created by 安礼成 on 2026/2/5.
//
import Foundation
import NIO

actor PolicyRuleStore {
    
    // 处理权限的请求问题
    nonisolated private let cooldown: Duration = .seconds(5)
    // identityId
    private var coolingDown: Set<UInt32> = []
    // 处理各个请求的版本问题, map[identityId] = version
    private var versions: [UInt32: UInt32] = [:]
    
    nonisolated private let alloctor = ByteBufferAllocator()
    
    private let publisher: SnapshotPublisher<PolicyRuleSnapshot>
    private var ruleMapByIdentity: [UInt32: PolicyRuleMap] = [:]
    
    init(publisher: SnapshotPublisher<PolicyRuleSnapshot>) {
        self.publisher = publisher
    }

    func makeBatchPolicyRequests(dstIdentityID: UInt32) -> [Data] {
        return self.ruleMapByIdentity.keys.compactMap { identityId in
            var policyRequest = SDLPolicyRequest()
            policyRequest.srcIdentityID = identityId
            policyRequest.dstIdentityID = dstIdentityID
            policyRequest.version = self.nextVersion(identityId: identityId)
            return try? policyRequest.serializedData()
        }
    }

    func makePolicyRequest(srcIdentityId: UInt32, dstIdentityId: UInt32) -> Data? {
        guard !coolingDown.contains(srcIdentityId) else {
            return nil
        }

        var policyRequest = SDLPolicyRequest()
        policyRequest.srcIdentityID = srcIdentityId
        policyRequest.dstIdentityID = dstIdentityId
        policyRequest.version = self.nextVersion(identityId: srcIdentityId)

        coolingDown.insert(srcIdentityId)

        Task { [weak self] in
            try? await Task.sleep(for: .seconds(5))
            await self?.endCooldown(for: srcIdentityId)
        }

        return try? policyRequest.serializedData()
    }
    
    // 处理权限的响应
    func applyPolicyResponse(_ policyResponse: SDLPolicyResponse) {
        let id = policyResponse.srcIdentityID
        let version = policyResponse.version
        
        guard self.ruleMapByIdentity[id] == nil || ((self.ruleMapByIdentity[id]?.version ?? 0) < version) else {
            return
        }
        
        // 判断一下是否接受完成
        var buffer = alloctor.buffer(bytes: policyResponse.rules)
        var ruleMap: [UInt8: [UInt16: Bool]] = [:]
        while true {
            guard let proto = buffer.readInteger(endianness: .big, as: UInt8.self),
                  let port = buffer.readInteger(endianness: .big, as: UInt16.self) else {
                break
            }
            ruleMap[proto, default: [:]][port] = true
        }
        self.ruleMapByIdentity[id] = PolicyRuleMap(version: version, ruleMap: ruleMap)
        
        // 发布新的快照信息
        let snapshot = compileSnapshot()
        publisher.publish(snapshot)
    }

    func clear() {
        self.coolingDown.removeAll()
        self.versions.removeAll()
        self.ruleMapByIdentity.removeAll()
        self.publisher.publish(PolicyRuleSnapshot.empty())
    }
    
    private func compileSnapshot() -> PolicyRuleSnapshot {
        return PolicyRuleSnapshot(ruleMapByIdentity: ruleMapByIdentity)
    }

    private func endCooldown(for key: UInt32) {
        self.coolingDown.remove(key)
    }
    
    private func nextVersion(identityId: UInt32) -> UInt32 {
        let version = self.versions[identityId, default: 1]
        // 更新请求的版本问题
        self.versions[identityId] = version + 1
        
        return version
    }
}