package com.xuqm.sdk.license

import android.content.Context
import com.xuqm.sdk.license.api.LicenseApiService
import com.xuqm.sdk.license.internal.DeviceInfoProvider
import com.xuqm.sdk.license.internal.LicenseContextHolder
import com.xuqm.sdk.license.internal.LicenseFileReader
import com.xuqm.sdk.license.internal.LicenseHttpClient
import com.xuqm.sdk.license.model.RegisterRequest
import com.xuqm.sdk.license.model.LicenseUserInfo
import com.xuqm.sdk.license.model.VerifyRequest
import com.xuqm.sdk.license.store.LicenseStore
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.SupervisorJob
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext

object LicenseSDK {

    private const val STATUS_OK = "ok"
    private const val STATUS_DENIED = "denied"
    private const val DEFAULT_BASE_URL = "https://auth.dev.xuqinmin.com/"

    private var initialized = false
    private lateinit var appContext: Context
    private lateinit var config: LicenseConfig
    private lateinit var store: LicenseStore
    private lateinit var apiService: LicenseApiService
    private val sdkScope = CoroutineScope(SupervisorJob() + Dispatchers.IO)

    /**
     * Optional manual initialization. Normal apps only need to place the encrypted
     * license file under assets/xuqm/license.xuqm and call checkLicense().
     *
     * @param context Application context
     * @param appKey The company appKey (e.g., "f713d051-0fbe-4f2d-bec9-bf7b96fc9ce4")
     * @param deviceName Optional device name for identification
     * @param baseUrl Optional custom license server base URL. Defaults to https://auth.dev.xuqinmin.com/
     */
    @JvmStatic
    @JvmOverloads
    fun initialize(
        context: Context,
        appKey: String,
        deviceName: String? = null,
        baseUrl: String? = null,
    ) {
        synchronized(this) {
            val ctx = context.applicationContext
            appContext = ctx
            store = LicenseStore(ctx)

            // If appKey changed, clear old data to force re-registration
            if (store.appKey != null && store.appKey != appKey) {
                store.clear()
            }
            store.appKey = appKey

            config = LicenseConfig(
                appKey = appKey,
                baseUrl = normalizeBaseUrl(baseUrl ?: DEFAULT_BASE_URL),
                deviceName = deviceName ?: DeviceInfoProvider.getDeviceName(),
            )

            apiService = LicenseHttpClient.create(LicenseApiService::class.java, config.baseUrl)
            initialized = true
        }
    }

    @JvmStatic
    @JvmOverloads
    fun checkLicense(userInfo: LicenseUserInfo? = null, callback: LicenseCallback) {
        sdkScope.launch {
            val valid = when (checkLicense(userInfo)) {
                is LicenseResult.Success -> true
                is LicenseResult.Error -> false
            }
            withContext(Dispatchers.Main) {
                callback.onResult(valid)
            }
        }
    }

    /**
     * Check license status. This will:
     * 1. Return cached OK status if within cache window
     * 2. Try to verify existing token
     * 3. Register new device if no token exists
     *
     * @return LicenseResult.Success if license is valid, LicenseResult.Error otherwise
     */
    @JvmStatic
    suspend fun checkLicense(userInfo: LicenseUserInfo? = null): LicenseResult = withContext(Dispatchers.IO) {
        ensureInitialized()

        // Check cached status
        val cachedStatus = store.status
        val cachedTime = store.statusTime
        if (cachedStatus == STATUS_OK && System.currentTimeMillis() - cachedTime < config.cacheWindowMs) {
            return@withContext LicenseResult.Success("Cached")
        }

        val deviceId = getOrCreateDeviceId()
        val token = store.token

        try {
            if (token != null) {
                // Try to verify existing token
                val result = apiService.verify(
                    VerifyRequest(
                        companyId = config.appKey,
                        deviceId = deviceId,
                        token = token,
                        userInfo = userInfo,
                    )
                )

                if (result.data?.valid == true) {
                    persistStatus(STATUS_OK)
                    return@withContext LicenseResult.Success("Verified")
                }

                // Token invalid, clear and will try register below
                store.token = null
            }

            // No token or token invalid, register new device
            val result = apiService.register(
                RegisterRequest(
                    companyId = config.appKey,
                    deviceId = deviceId,
                    deviceName = config.deviceName,
                    deviceModel = DeviceInfoProvider.getDeviceModel(),
                    deviceVendor = DeviceInfoProvider.getDeviceVendor(),
                    osVersion = DeviceInfoProvider.getOsVersion(),
                    userInfo = userInfo,
                )
            )

            if (result.data?.success == true && result.data.token != null) {
                store.token = result.data.token
                persistStatus(STATUS_OK)
                return@withContext LicenseResult.Success("Registered")
            }

            persistStatus(STATUS_DENIED)
            return@withContext LicenseResult.Error(result.data?.message ?: "Registration denied")
        } catch (e: Exception) {
            // Network error: use cached status if available
            if (cachedStatus == STATUS_OK) {
                return@withContext LicenseResult.Success("Offline - using cached status")
            }
            return@withContext LicenseResult.Error(e.message ?: "Network error")
        }
    }

    /**
     * Force re-register the device (e.g., after token revocation).
     */
    suspend fun reRegister(userInfo: LicenseUserInfo? = null): LicenseResult = withContext(Dispatchers.IO) {
        requireInit()
        store.token = null
        store.status = null
        store.statusTime = 0
        checkLicense(userInfo)
    }

    /**
     * Get current license status without network call.
     */
    fun getStatus(): LicenseStatus {
        if (!initialized && !tryAutoInitialize()) return LicenseStatus.UNKNOWN
        return when (store.status) {
            STATUS_OK -> LicenseStatus.OK
            STATUS_DENIED -> LicenseStatus.DENIED
            else -> LicenseStatus.UNKNOWN
        }
    }

    /**
     * Get the stable device ID used for registration.
     */
    fun getDeviceId(): String? {
        if (!initialized && !tryAutoInitialize()) return null
        return store.deviceId
    }

    /**
     * Clear all license data (token, device ID, status).
     */
    fun clear() {
        if (::store.isInitialized) {
            store.clear()
        }
    }

    private fun requireInit() {
        check(initialized) { "LicenseSDK not initialized. Call LicenseSDK.initialize() first." }
    }

    private fun getOrCreateDeviceId(): String {
        store.deviceId?.let { return it }
        val newId = DeviceInfoProvider.getDeviceId(appContext)
        store.deviceId = newId
        return newId
    }

    private fun persistStatus(status: String) {
        store.status = status
        store.statusTime = System.currentTimeMillis()
    }

    private fun ensureInitialized() {
        if (!initialized) {
            tryAutoInitialize()
        }
        requireInit()
    }

    private fun tryAutoInitialize(): Boolean {
        synchronized(this) {
            if (initialized) return true
            val ctx = LicenseContextHolder.appContext ?: return false
            val licenseFile = LicenseFileReader.read(ctx) ?: return false
            val appKey = licenseFile.appKey.takeIf { it.isNotBlank() } ?: return false
            appContext = ctx
            store = LicenseStore(ctx)
            if (store.appKey != null && store.appKey != appKey) {
                store.clear()
            }
            store.appKey = appKey
            config = LicenseConfig(
                appKey = appKey,
                baseUrl = normalizeBaseUrl(licenseFile.baseUrl ?: DEFAULT_BASE_URL),
                deviceName = DeviceInfoProvider.getDeviceName(),
            )
            apiService = LicenseHttpClient.create(LicenseApiService::class.java, config.baseUrl)
            initialized = true
            return true
        }
    }

    private fun normalizeBaseUrl(value: String): String {
        val trimmed = value.trim().ifBlank { DEFAULT_BASE_URL }
        return if (trimmed.endsWith("/")) trimmed else "$trimmed/"
    }
}