package com.hyperling.weather

import android.content.Context

/**
 * SharedPreferences-based local storage manager for location entries (Android).
 */
class AndroidStorageBackend(private val context: Context) : StorageBackend {

    private companion object {
        const val PREFS_NAME = "nomadic_weather_prefs"
        const val KEY_LOCATIONS = "locations_json"
    }

    private val prefs by lazy {
        context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)
    }

    override fun load(): List<LocationEntry> {
        val jsonStr = prefs.getString(KEY_LOCATIONS, null) ?: return emptyList()
        if (jsonStr.isEmpty()) return emptyList()
        return try {
            LocationSerializer.jsonToLocations(jsonStr)
        } catch (e: Exception) {
            emptyList()
        }
    }

    override fun save(locations: List<LocationEntry>) {
        prefs.edit().putString(KEY_LOCATIONS, LocationSerializer.locationsToJson(locations)).apply()
    }

    override fun saveOne(location: LocationEntry) {
        val existing = load().toMutableList()
        val idx = existing.indexOfFirst { it == location }
        if (idx >= 0) existing[idx] = location
        else {
            if (existing.size >= 8) existing.removeAt(0)
            existing.add(location)
        }
        save(existing)
    }

    override fun delete(id: Long) {
        save(load().filter { it.id != id })
    }
}

actual fun LocationStorage.getStorage(): StorageBackend =
    throw UnsupportedOperationException("getStorage requires AndroidContext - this is a desktop build")