/*
 * Copyright © 2017-2019 AT&T, Bell Canada, Nordix Foundation
 * Modifications Copyright © 2018-2019 IBM.
 * Modifications Copyright © 2019 Huawei.
 *
 * 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 org.onap.ccsdk.cds.blueprintsprocessor.rest.service

import com.fasterxml.jackson.databind.JsonNode
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.withContext
import org.apache.commons.io.IOUtils
import org.apache.http.client.ClientProtocolException
import org.apache.http.client.methods.*
import org.apache.http.entity.StringEntity
import org.apache.http.impl.client.CloseableHttpClient
import org.apache.http.impl.client.HttpClients
import org.apache.http.message.BasicHeader
import org.onap.ccsdk.cds.blueprintsprocessor.rest.RestClientProperties
import org.onap.ccsdk.cds.blueprintsprocessor.rest.RestLibConstants
import org.onap.ccsdk.cds.blueprintsprocessor.rest.utils.WebClientUtils
import org.onap.ccsdk.cds.controllerblueprints.core.BluePrintProcessorException
import org.onap.ccsdk.cds.controllerblueprints.core.BluePrintRetryException
import org.onap.ccsdk.cds.controllerblueprints.core.utils.BluePrintIOUtils
import org.onap.ccsdk.cds.controllerblueprints.core.utils.JacksonUtils
import org.springframework.http.HttpHeaders
import org.springframework.http.HttpMethod
import java.io.IOException
import java.io.InputStream
import java.nio.charset.Charset

interface BlueprintWebClientService {

    fun defaultHeaders(): Map<String, String>

    fun host(uri: String): String

    fun httpClient(): CloseableHttpClient {
        return HttpClients.custom()
            .addInterceptorFirst(WebClientUtils.logRequest())
            .addInterceptorLast(WebClientUtils.logResponse())
            .build()
    }

    /** High performance non blocking Retry function, If execution block [block] throws BluePrintRetryException
     * exception then this will perform wait and retrigger accoring to times [times] with delay [delay]
     */
    suspend fun <T> retry(times: Int = 1, initialDelay: Long = 0, delay: Long = 1000,
                          block: suspend (Int) -> T): T {
        val exceptionBlock = { e: Exception ->
            if (e !is BluePrintRetryException) {
                throw e
            }
        }
        return BluePrintIOUtils.retry(times, initialDelay, delay, block, exceptionBlock)
    }

    fun exchangeResource(methodType: String, path: String, request: String): WebClientResponse<String> {
        return this.exchangeResource(methodType, path, request, defaultHeaders())
    }

    fun exchangeResource(methodType: String, path: String, request: String,
                         headers: Map<String, String>): WebClientResponse<String> {
        /**
         * TODO: Basic headers in the implementations of this client do not get added
         * in blocking version, whereas in NB version defaultHeaders get added.
         * the difference is in convertToBasicHeaders vs basicHeaders
         */
        val convertedHeaders: Array<BasicHeader> = convertToBasicHeaders(headers)
        return when (HttpMethod.resolve(methodType)) {
            HttpMethod.DELETE -> delete(path, convertedHeaders, String::class.java)
            HttpMethod.GET -> get(path, convertedHeaders, String::class.java)
            HttpMethod.POST -> post(path, request, convertedHeaders, String::class.java)
            HttpMethod.PUT -> put(path, request, convertedHeaders, String::class.java)
            HttpMethod.PATCH -> patch(path, request, convertedHeaders, String::class.java)
            else -> throw BluePrintProcessorException(
                "Unsupported methodType($methodType) attempted on path($path)")
        }
    }

    //TODO: convert to multi-map
    fun convertToBasicHeaders(headers: Map<String, String>): Array<BasicHeader> {
        return headers.map { BasicHeader(it.key, it.value) }.toTypedArray()
    }

    fun <T> delete(path: String, headers: Array<BasicHeader>, responseType: Class<T>): WebClientResponse<T> {
        val httpDelete = HttpDelete(host(path))
        httpDelete.setHeaders(headers)
        return performCallAndExtractTypedWebClientResponse(httpDelete, responseType)
    }

    fun <T> get(path: String, headers: Array<BasicHeader>, responseType: Class<T>): WebClientResponse<T> {
        val httpGet = HttpGet(host(path))
        httpGet.setHeaders(headers)
        return performCallAndExtractTypedWebClientResponse(httpGet, responseType)
    }

    fun <T> post(path: String, request: Any, headers: Array<BasicHeader>, responseType: Class<T>): WebClientResponse<T> {
        val httpPost = HttpPost(host(path))
        val entity = StringEntity(strRequest(request))
        httpPost.entity = entity
        httpPost.setHeaders(headers)
        return performCallAndExtractTypedWebClientResponse(httpPost, responseType)
    }

    fun <T> put(path: String, request: Any, headers: Array<BasicHeader>, responseType: Class<T>): WebClientResponse<T> {
        val httpPut = HttpPut(host(path))
        val entity = StringEntity(strRequest(request))
        httpPut.entity = entity
        httpPut.setHeaders(headers)
        return performCallAndExtractTypedWebClientResponse(httpPut, responseType)
    }

    fun <T> patch(path: String, request: Any, headers: Array<BasicHeader>, responseType: Class<T>): WebClientResponse<T> {
        val httpPatch = HttpPatch(host(path))
        val entity = StringEntity(strRequest(request))
        httpPatch.entity = entity
        httpPatch.setHeaders(headers)
        return performCallAndExtractTypedWebClientResponse(httpPatch, responseType)
    }

    /**
     * Perform the HTTP call and return HTTP status code and body.
     * @param httpUriRequest {@link HttpUriRequest} object
     * @return {@link WebClientResponse} object
     * http client may throw IOException and ClientProtocolException on error
     */

    @Throws(IOException::class, ClientProtocolException::class)
    private fun <T> performCallAndExtractTypedWebClientResponse(
        httpUriRequest: HttpUriRequest, responseType: Class<T>):
        WebClientResponse<T> {
        val httpResponse = httpClient().execute(httpUriRequest)
        val statusCode = httpResponse.statusLine.statusCode
        httpResponse.entity.content.use {
            val body = getResponse(it, responseType)
            return WebClientResponse(statusCode, body)
        }
    }

    suspend fun getNB(path: String): WebClientResponse<String> {
        return getNB(path, null, String::class.java)
    }

    suspend fun getNB(path: String, additionalHeaders: Array<BasicHeader>?): WebClientResponse<String> {
        return getNB(path, additionalHeaders, String::class.java)
    }

    suspend fun <T> getNB(path: String, additionalHeaders: Array<BasicHeader>?, responseType: Class<T>):
        WebClientResponse<T> = withContext(Dispatchers.IO) {
        get(path, additionalHeaders!!, responseType)
    }

    suspend fun postNB(path: String, request: Any): WebClientResponse<String> {
        return postNB(path, request, null, String::class.java)
    }

    suspend fun postNB(path: String, request: Any, additionalHeaders: Array<BasicHeader>?): WebClientResponse<String> {
        return postNB(path, request, additionalHeaders, String::class.java)
    }

    suspend fun <T> postNB(path: String, request: Any, additionalHeaders: Array<BasicHeader>?,
                           responseType: Class<T>): WebClientResponse<T> = withContext(Dispatchers.IO) {
        post(path, request, additionalHeaders!!, responseType)
    }

    suspend fun putNB(path: String, request: Any): WebClientResponse<String> {
        return putNB(path, request, null, String::class.java)
    }

    suspend fun putNB(path: String, request: Any,
                      additionalHeaders: Array<BasicHeader>?): WebClientResponse<String> {
        return putNB(path, request, additionalHeaders, String::class.java)
    }

    suspend fun <T> putNB(path: String, request: Any,
                          additionalHeaders: Array<BasicHeader>?,
                          responseType: Class<T>): WebClientResponse<T> = withContext(Dispatchers.IO) {
        put(path, request, additionalHeaders!!, responseType)
    }

    suspend fun <T> deleteNB(path: String): WebClientResponse<String> {
        return deleteNB(path, null, String::class.java)
    }

    suspend fun <T> deleteNB(path: String, additionalHeaders: Array<BasicHeader>?):
        WebClientResponse<String> {
        return deleteNB(path, additionalHeaders, String::class.java)
    }

    suspend fun <T> deleteNB(path: String, additionalHeaders: Array<BasicHeader>?, responseType: Class<T>):
        WebClientResponse<T> = withContext(Dispatchers.IO) {
        delete(path, additionalHeaders!!, responseType)
    }

    suspend fun <T> patchNB(path: String, request: Any, additionalHeaders: Array<BasicHeader>?, responseType: Class<T>):
        WebClientResponse<T> = withContext(Dispatchers.IO) {
        patch(path, request, additionalHeaders!!, responseType)
    }

    suspend fun exchangeNB(methodType: String, path: String, request: Any): WebClientResponse<String> {
        return exchangeNB(methodType, path, request, hashMapOf(),
            String::class.java)
    }

    suspend fun exchangeNB(methodType: String, path: String, request: Any, additionalHeaders: Map<String, String>?):
        WebClientResponse<String> {
        return exchangeNB(methodType, path, request, additionalHeaders, String::class.java)
    }

    suspend fun <T> exchangeNB(methodType: String, path: String, request: Any,
                               additionalHeaders: Map<String, String>?,
                               responseType: Class<T>): WebClientResponse<T> {

        //TODO: possible inconsistency
        //NOTE: this basic headers function is different from non-blocking
        val convertedHeaders: Array<BasicHeader> = basicHeaders(additionalHeaders!!)
        return when (HttpMethod.resolve(methodType)) {
            HttpMethod.GET -> getNB(path, convertedHeaders, responseType)
            HttpMethod.POST -> postNB(path, request, convertedHeaders, responseType)
            HttpMethod.DELETE -> deleteNB(path, convertedHeaders, responseType)
            HttpMethod.PUT -> putNB(path, request, convertedHeaders, responseType)
            HttpMethod.PATCH -> patchNB(path, request, convertedHeaders, responseType)
            else -> throw BluePrintProcessorException("Unsupported methodType($methodType)")
        }
    }

    private fun strRequest(request: Any): String {
        return when (request) {
            is String -> request.toString()
            is JsonNode -> request.toString()
            else -> JacksonUtils.getJson(request)
        }
    }

    private fun <T> getResponse(it: InputStream, responseType: Class<T>): T {
        return if (responseType == String::class.java) {
            IOUtils.toString(it, Charset.defaultCharset()) as T
        } else {
            JacksonUtils.readValue(it, responseType)!!
        }
    }

    private fun basicHeaders(headers: Map<String, String>?):
        Array<BasicHeader> {
        val basicHeaders = mutableListOf<BasicHeader>()
        defaultHeaders().forEach { (name, value) ->
            basicHeaders.add(BasicHeader(name, value))
        }
        headers?.forEach { name, value ->
            basicHeaders.add(BasicHeader(name, value))
        }
        return basicHeaders.toTypedArray()
    }

    // Non Blocking Rest Implementation
    suspend fun httpClientNB(): CloseableHttpClient {
        return HttpClients.custom()
            .addInterceptorFirst(WebClientUtils.logRequest())
            .addInterceptorLast(WebClientUtils.logResponse())
            .build()
    }

    //TODO maybe there could be cases where we care about return headers?
    data class WebClientResponse<T>(val status: Int, val body: T)

    fun verifyAdditionalHeaders(restClientProperties: RestClientProperties): Map<String, String> {
        val customHeaders: MutableMap<String, String> = mutableMapOf()
        //Extract additionalHeaders from the requestProperties and
        //throw an error if HttpHeaders.AUTHORIZATION key (headers are case-insensitive)
        restClientProperties.additionalHeaders?.let {
            if (it.keys.map { k -> k.toLowerCase().trim() }.contains(HttpHeaders.AUTHORIZATION.toLowerCase())) {
                val errMsg = "Error in definition of endpoint ${restClientProperties.url}." +
                    " User-supplied \"additionalHeaders\" cannot contain AUTHORIZATION header with" +
                    " auth-type \"${RestLibConstants.TYPE_BASIC_AUTH}\""
                WebClientUtils.log.error(errMsg)
                throw BluePrintProcessorException(errMsg)
            } else {
                customHeaders.putAll(it)
            }
        }
        return customHeaders
    }
}