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/*
 * Copyright (C) 2018 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.squareup.moshi

import com.google.auto.common.MoreTypes
import com.squareup.kotlinpoet.AnnotationSpec
import com.squareup.kotlinpoet.AnnotationSpec.UseSiteTarget.FIELD
import com.squareup.kotlinpoet.ClassName
import com.squareup.kotlinpoet.CodeBlock
import com.squareup.kotlinpoet.KModifier
import com.squareup.kotlinpoet.NameAllocator
import com.squareup.kotlinpoet.ParameterSpec
import com.squareup.kotlinpoet.ParameterizedTypeName
import com.squareup.kotlinpoet.PropertySpec
import com.squareup.kotlinpoet.TypeName
import com.squareup.kotlinpoet.TypeVariableName
import com.squareup.kotlinpoet.WildcardTypeName
import com.squareup.kotlinpoet.asTypeName
import java.lang.annotation.ElementType
import java.lang.annotation.RetentionPolicy
import javax.annotation.processing.Messager
import javax.lang.model.element.AnnotationMirror
import javax.tools.Diagnostic.Kind.ERROR

/** A JsonAdapter that can be used to encode and decode a particular field. */
internal data class DelegateKey(
  private val type: TypeName,
  private val jsonQualifiers: Set
) {
  val nullable get() = type.nullable

  /** Returns an adapter to use when encoding and decoding this property. */
  fun generateProperty(
    nameAllocator: NameAllocator,
    typeRenderer: TypeRenderer,
    moshiParameter: ParameterSpec,
    messager: Messager): PropertySpec {
    fun AnnotationMirror.validate(): AnnotationMirror {
      // Check java types since that covers both java and kotlin annotations
      val annotationElement = MoreTypes.asTypeElement(annotationType)
      annotationElement.getAnnotation(java.lang.annotation.Retention::class.java)?.let {
        if (it.value != RetentionPolicy.RUNTIME) {
          messager.printMessage(ERROR, "JsonQualifier @${MoreTypes.asTypeElement(annotationType).simpleName} must have RUNTIME retention")
        }
      }
      annotationElement.getAnnotation(java.lang.annotation.Target::class.java)?.let {
        if (ElementType.FIELD !in it.value) {
          messager.printMessage(ERROR, "JsonQualifier @${MoreTypes.asTypeElement(annotationType).simpleName} must support FIELD target")
        }
      }
      return this
    }
    jsonQualifiers.forEach { it.validate() }
    val qualifierNames = jsonQualifiers.joinToString("") {
      "At${it.annotationType.asElement().simpleName}"
    }
    val adapterName = nameAllocator.newName(
        "${type.toVariableName().decapitalize()}${qualifierNames}Adapter", this)

    val adapterTypeName = ParameterizedTypeName.get(
        JsonAdapter::class.asTypeName(), type)
    val qualifiers = jsonQualifiers
    val standardArgs = arrayOf(moshiParameter,
        if (type is ClassName && qualifiers.isEmpty()) {
          ""
        } else {
          CodeBlock.of("<%T>", type)
        },
        typeRenderer.render(type))
    val standardArgsSize = standardArgs.size + 1
    val (initializerString, args) = when {
      qualifiers.isEmpty() -> "" to emptyArray()
      else -> {
        ", %${standardArgsSize}T.getFieldJsonQualifierAnnotations(javaClass, %${standardArgsSize + 1}S)" to arrayOf(
            Types::class.asTypeName(),
            adapterName)
      }
    }
    val finalArgs = arrayOf(*standardArgs, *args)

    val nullModifier = if (nullable) ".nullSafe()" else ".nonNull()"

    return PropertySpec.builder(adapterName, adapterTypeName, KModifier.PRIVATE)
        .addAnnotations(qualifiers.map { AnnotationSpec.get(it).toBuilder().useSiteTarget(FIELD).build() })
        .initializer("%1N.adapter%2L(%3L$initializerString)$nullModifier", *finalArgs)
        .build()
  }
}

/**
 * Returns a suggested variable name derived from a list of type names. This just concatenates,
 * yielding types like MapOfStringLong.
 */
private fun List.toVariableNames(): String {
  return joinToString("") { it.toVariableName() }
}

/** Returns a suggested variable name derived from a type name, like nullableListOfString. */
private fun TypeName.toVariableName(): String {
  val base = when (this) {
    is ClassName -> simpleName()
    is ParameterizedTypeName -> rawType.simpleName() + "Of" + typeArguments.toVariableNames()
    is WildcardTypeName -> (lowerBounds + upperBounds).toVariableNames()
    is TypeVariableName -> name + bounds.toVariableNames()
    else -> throw IllegalArgumentException("Unrecognized type! $this")
  }

  return if (nullable) {
    "Nullable$base"
  } else {
    base
  }
}