/*
 * Copyright 2017-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
 */

package kotlinx.serialization.json

import kotlinx.serialization.*
import kotlinx.serialization.builtins.*
import kotlinx.serialization.descriptors.*
import kotlinx.serialization.encoding.*
import kotlin.test.*

class MapLikeSerializerTest : JsonTestBase() {

    @Serializable
    data class StringPair(val a: String, val b: String)

    object StringPairSerializer : KSerializer<StringPair> {

        override val descriptor: SerialDescriptor = buildSerialDescriptor("package.StringPair", StructureKind.MAP) {
            element<String>("a")
            element<String>("b")
        }

        override fun serialize(encoder: Encoder, value: StringPair) {
            val structuredEncoder = encoder.beginStructure(descriptor)
            structuredEncoder.encodeSerializableElement(descriptor, 0, String.serializer(), value.a)
            structuredEncoder.encodeSerializableElement(descriptor, 1, String.serializer(), value.b)
            structuredEncoder.endStructure(descriptor)
        }

        override fun deserialize(decoder: Decoder): StringPair {
            val composite = decoder.beginStructure(descriptor)
            if (composite.decodeSequentially()) {
                val key = composite.decodeSerializableElement(descriptor, 0, String.serializer())
                val value = composite.decodeSerializableElement(descriptor, 1, String.serializer())
                return StringPair(key, value)
            }

            var key: String? = null
            var value: String? = null
            mainLoop@ while (true) {
                when (val idx = composite.decodeElementIndex(descriptor)) {
                    CompositeDecoder.DECODE_DONE -> {
                        break@mainLoop
                    }
                    0 -> {
                        key = composite.decodeSerializableElement(descriptor, 0, String.serializer())
                    }
                    1 -> {
                        value = composite.decodeSerializableElement(descriptor, 1, String.serializer())
                    }
                    else -> throw SerializationException("Invalid index: $idx")
                }
            }
            composite.endStructure(descriptor)
            if (key == null) throw SerializationException("Element 'a' is missing")
            if (value == null) throw SerializationException("Element 'b' is missing")
            @Suppress("UNCHECKED_CAST")
            return StringPair(key, value)
        }
    }

    @Test
    fun testStringPair() = assertJsonFormAndRestored(StringPairSerializer, StringPair("a", "b"), """{"a":"b"}""")
}