package com.sptmobile.voice

import android.content.Context
import androidx.datastore.preferences.core.edit
import androidx.datastore.preferences.core.stringPreferencesKey
import androidx.datastore.preferences.preferencesDataStore
import java.security.SecureRandom
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.first
import kotlinx.coroutines.flow.map

private val Context.voiceDataStore by preferencesDataStore(name = "voice_settings")

// [impl->REQ-VOICE-PIPE]
/**
 * The webhook auth token (DESIGN.md §Pebble webhook contract: "a locally
 * generated token entered into Pebble's webhook headers"). Generated once
 * with [SecureRandom] on first use, persisted in DataStore; the user copies
 * it into Pebble's `X-Widget-Token` header config. Regenerating revokes the
 * old one (the receiver compares against the current value only).
 */
class VoiceSettings(private val context: Context) {
    private val tokenKey = stringPreferencesKey("webhook_token")

    /** Null until [ensureToken] has run once on this install. */
    val token: Flow<String?> = context.voiceDataStore.data.map { it[tokenKey] }

    /** Generate-if-missing; returns the current token. */
    suspend fun ensureToken(): String {
        context.voiceDataStore.edit { prefs ->
            if (prefs[tokenKey].isNullOrEmpty()) prefs[tokenKey] = newToken()
        }
        return context.voiceDataStore.data.first()[tokenKey]!!
    }

    /** Mint + persist a fresh token, revoking the old one. */
    suspend fun regenerate(): String {
        val fresh = newToken()
        context.voiceDataStore.edit { it[tokenKey] = fresh }
        return fresh
    }

    private fun newToken(): String {
        val bytes = ByteArray(16)
        SecureRandom().nextBytes(bytes)
        return bytes.joinToString("") { "%02x".format(it) }
    }
}