/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package mozilla.components.browser.engine.gecko

import android.util.JsonReader
import android.util.JsonWriter
import mozilla.components.concept.engine.EngineSessionState
import org.json.JSONException
import org.json.JSONObject
import org.mozilla.geckoview.GeckoSession
import java.io.IOException

private const val GECKO_STATE_KEY = "GECKO_STATE"

class GeckoEngineSessionState internal constructor(
    internal val actualState: GeckoSession.SessionState?
) : EngineSessionState {
    override fun writeTo(writer: JsonWriter) {
        with(writer) {
            beginObject()

            name(GECKO_STATE_KEY)
            value(actualState.toString())

            endObject()
            flush()
        }
    }

    companion object {
        fun fromJSON(json: JSONObject): GeckoEngineSessionState = try {
            val state = json.getString(GECKO_STATE_KEY)

            GeckoEngineSessionState(
                GeckoSession.SessionState.fromString(state)
            )
        } catch (e: JSONException) {
            GeckoEngineSessionState(null)
        }

        /**
         * Creates a [GeckoEngineSessionState] from the given [JsonReader].
         */
        fun from(reader: JsonReader): GeckoEngineSessionState = try {
            reader.beginObject()

            val rawState = if (reader.hasNext()) {
                val key = reader.nextName()
                if (key != GECKO_STATE_KEY) {
                    throw AssertionError("Unknown state key: $key")
                }

                reader.nextString()
            } else {
                null
            }

            reader.endObject()

            GeckoEngineSessionState(
                rawState?.let { GeckoSession.SessionState.fromString(it) }
            )
        } catch (e: IOException) {
            GeckoEngineSessionState(null)
        } catch (e: JSONException) {
            // Internally GeckoView uses org.json and currently may throw JSONException in certain cases
            // https://github.com/mozilla-mobile/android-components/issues/9332
            GeckoEngineSessionState(null)
        }
    }
}
