package space.luminic.finance.api


import kotlinx.serialization.json.Json
import kotlinx.serialization.json.JsonBuilder
import org.slf4j.LoggerFactory
import org.springframework.beans.factory.annotation.Value
import org.springframework.security.core.context.SecurityContextHolder
import org.springframework.web.bind.annotation.*
import space.luminic.finance.dtos.UserDTO
import space.luminic.finance.dtos.UserDTO.AuthUserDTO
import space.luminic.finance.dtos.UserDTO.RegisterUserDTO
import space.luminic.finance.mappers.UserMapper.toDto
import space.luminic.finance.mappers.UserMapper.toTelegramMap
import space.luminic.finance.services.AuthService
import java.net.URLDecoder
import java.security.MessageDigest
import java.time.Instant
import javax.crypto.Mac
import javax.crypto.spec.SecretKeySpec

@RestController
@RequestMapping("/auth")
class AuthController(
    private val authService: AuthService,
    @Value("\${telegram.bot.token}") private val botToken: String
) {

    private val logger = LoggerFactory.getLogger(javaClass)

    fun verifyTelegramAuth(
        loginData: Map<String, String>? = null,       // from login widget
        webAppInitData: String? = null
    ): Boolean {

        // --- LOGIN WIDGET CHECK ---
        if (loginData != null) {
            val hash = loginData["hash"]
            if (hash != null) {
                val dataCheckString = loginData
                    .filterKeys { it != "hash" }
                    .toSortedMap()
                    .map { "${it.key}=${it.value}" }
                    .joinToString("\n")

                val secretKey = MessageDigest.getInstance("SHA-256")
                    .digest(botToken.toByteArray())

                val hmac = Mac.getInstance("HmacSHA256").apply {
                    init(SecretKeySpec(secretKey, "HmacSHA256"))
                }.doFinal(dataCheckString.toByteArray())
                    .joinToString("") { "%02x".format(it) }

                val authDate = loginData["auth_date"]?.toLongOrNull() ?: return false
                if (Instant.now().epochSecond - authDate > 3600) return false

                if (hmac == hash) return true
            }
        }

        // --- WEBAPP CHECK ---
        // --- WEBAPP CHECK ---
        if (webAppInitData != null) {
            // Разбираем query string корректно (учитывая '=' внутри значения)
            val pairs: Map<String, String> = webAppInitData.split("&")
                .mapNotNull { part ->
                    val idx = part.indexOf('=')
                    if (idx <= 0) return@mapNotNull null
                    val k = part.substring(0, idx)
                    val v = part.substring(idx + 1)
                    k to URLDecoder.decode(v, Charsets.UTF_8.name())
                }.toMap()

            val receivedHash = pairs["hash"] ?: return false

            // Строка для подписи: все поля КРОМЕ hash, отсортированные по ключу, в формате key=value с \n
            val dataCheckString = pairs
                .filterKeys { it != "hash" }
                .toSortedMap()
                .entries
                .joinToString("\n") { (k, v) -> "$k=$v" }

            // ВАЖНО: secret_key = HMAC_SHA256(message=botToken, key="WebAppData")
            val secretKeyBytes = Mac.getInstance("HmacSHA256").apply {
                init(SecretKeySpec("WebAppData".toByteArray(Charsets.UTF_8), "HmacSHA256"))
            }.doFinal(botToken.toByteArray(Charsets.UTF_8))

            // hash = HMAC_SHA256(message=data_check_string, key=secret_key)
            val calcHashHex = Mac.getInstance("HmacSHA256").apply {
                init(SecretKeySpec(secretKeyBytes, "HmacSHA256"))
            }.doFinal(dataCheckString.toByteArray(Charsets.UTF_8))
                .joinToString("") { "%02x".format(it) }

            // опциональная проверка свежести
            val authDate = pairs["auth_date"]?.toLongOrNull() ?: return false
            val now = Instant.now().epochSecond
            val ttl = 6 * 3600L // например, 6 часов для WebApp
            val skew = 300L     // допускаем до 5 минут будущего/прошлого
            val diff = now - authDate
            if (diff > ttl || diff < -skew) return false

            if (calcHashHex == receivedHash) return true
        }

        return false

        return false
    }

    private fun sha256(input: String): ByteArray =
        MessageDigest.getInstance("SHA-256").digest(input.toByteArray())

    private fun hmacSha256(secret: ByteArray, message: String): String {
        val key = SecretKeySpec(secret, "HmacSHA256")
        val mac = Mac.getInstance("HmacSHA256")
        mac.init(key)
        val hashBytes = mac.doFinal(message.toByteArray())
        return hashBytes.joinToString("") { "%02x".format(it) }
    }


    @GetMapping("/test")
    fun test(): String {
        val authentication = SecurityContextHolder.getContext().authentication
        logger.info("SecurityContext in controller: $authentication")
        return "Hello, ${authentication.name}"
    }

    @PostMapping("/login")
    fun login(@RequestBody request: AuthUserDTO): Map<String, String> {
        val token = authService.login(request.username.lowercase(), request.password)
        return mapOf("token" to token)
    }

    @PostMapping("/register")
    fun register(@RequestBody request: RegisterUserDTO): UserDTO {
        return authService.register(request.username, request.password, request.firstName).toDto()
    }

    private val json = Json { ignoreUnknownKeys = true }


    @PostMapping("/tg-login")
    fun tgLogin(@RequestBody tgUser: UserDTO.TelegramAuthDTO): Map<String, String> {
//        println(tgUser.hash)
//        println(botToken)
        if (tgUser.initData == null) {
            if (verifyTelegramAuth(
                    loginData = tgUser.toTelegramMap(),
                )
            ) {
                return mapOf("token" to authService.tgAuth(tgUser))
            } else throw IllegalArgumentException("Invalid Telegram login")
        } else {
            if (verifyTelegramAuth(webAppInitData = tgUser.initData)) {
                val params = tgUser.initData.split("&").associate {
                    val (k, v) = it.split("=", limit = 2)
                    k to URLDecoder.decode(v, "UTF-8")
                }

                val userJson = params["user"] ?: error("No user data")
                val jsonUser = json.decodeFromString<UserDTO.TelegramUserData>(userJson)
                val newUser = UserDTO.TelegramAuthDTO(
                    jsonUser.id,
                    jsonUser.first_name,
                    jsonUser.last_name,
                    jsonUser.username,
                    jsonUser.photo_url,
                   null,
                    hash = tgUser.hash,
                    initData = null,
                )
                return mapOf("token" to authService.tgAuth(newUser))
            } else throw IllegalArgumentException("Invalid Telegram login")
        }
    }


    @GetMapping("/me")
    fun getMe(): UserDTO {
        logger.info("Get Me")
        authService.getSecurityUser()

        return authService.getSecurityUser().toDto()
    }
}