FacebookGraphUtil.kt

object FacebookGraphUtil {

    @Throws(RuntimeException::class)
    fun getFacebookPageList(accessToken: AccessToken, doOnSuccess: (List<FacebookPage>) -> Unit) {
        GraphRequest.newGraphPathRequest(
            accessToken,
            "/me/accounts"
        ) { response: GraphResponse ->
     
            parsePageListJson(response.jsonObject)
                .also(doOnSuccess)

        }.executeAsync()
    }
    
    @Throws(RuntimeException::class)
    private fun parsePageListJson(jsonObject: JSONObject?): List<FacebookPage> {
        jsonObject
            ?: throw RuntimeException("Failed to get Facebook business pages you have access to. Please check you have access to a business page.")
        val pagesList = ArrayList<FacebookPage>()

        try {
            jsonObject.getJSONArray(KEY_DATA)
                .also { jsonArray ->

                    for (i in 0 until jsonArray.length())
                        jsonArray.getJSONObject(i).let { page ->
                            FacebookPage(
                                page.getString(KEY_PAGE_ID),
                                page.getString(KEY_PAGE_NAME),
                                page.getString(KEY_ACCESS_TOKEN)
                            )
                        }.also(pagesList::add)
                }

        } catch (e: JSONException) {
            throw RuntimeException("Failed to parse Facebook pages list: ${e.localizedMessage}")
        }

        return pagesList
    }

    private const val KEY_DATA = "data"
    private const val KEY_PAGE_ID = "id"
    private const val KEY_PAGE_NAME = "name"
    private const val KEY_ACCESS_TOKEN = "access_token"
    
}

data class FacebookPage(
    val id: String,
    val name: String,
    val accessToken: String
)