/*
Copyright 2020 The Kubernetes Authors.

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 diskclient

import (
	"context"
	"fmt"
	"net/http"
	"strings"
	"time"

	"github.com/Azure/azure-sdk-for-go/services/compute/mgmt/2020-12-01/compute"
	"github.com/Azure/go-autorest/autorest"
	"github.com/Azure/go-autorest/autorest/azure"
	"github.com/Azure/go-autorest/autorest/to"

	"k8s.io/client-go/util/flowcontrol"
	"k8s.io/klog/v2"

	azclients "sigs.k8s.io/cloud-provider-azure/pkg/azureclients"
	"sigs.k8s.io/cloud-provider-azure/pkg/azureclients/armclient"
	"sigs.k8s.io/cloud-provider-azure/pkg/metrics"
	"sigs.k8s.io/cloud-provider-azure/pkg/retry"
)

var _ Interface = &Client{}

// Client implements Disk client Interface.
type Client struct {
	armClient      armclient.Interface
	subscriptionID string
	cloudName      string

	// Rate limiting configures.
	rateLimiterReader flowcontrol.RateLimiter
	rateLimiterWriter flowcontrol.RateLimiter

	// ARM throttling configures.
	RetryAfterReader time.Time
	RetryAfterWriter time.Time
}

// New creates a new Disk client with ratelimiting.
func New(config *azclients.ClientConfig) *Client {
	baseURI := config.ResourceManagerEndpoint
	authorizer := config.Authorizer
	apiVersion := APIVersion

	if strings.EqualFold(config.CloudName, AzureStackCloudName) && !config.DisableAzureStackCloud {
		apiVersion = AzureStackCloudAPIVersion
	}

	klog.V(2).Infof("Azure DisksClient using API version: %s", apiVersion)
	armClient := armclient.New(authorizer, *config, baseURI, apiVersion)
	rateLimiterReader, rateLimiterWriter := azclients.NewRateLimiter(config.RateLimitConfig)

	if azclients.RateLimitEnabled(config.RateLimitConfig) {
		klog.V(2).Infof("Azure DisksClient (read ops) using rate limit config: QPS=%g, bucket=%d",
			config.RateLimitConfig.CloudProviderRateLimitQPS,
			config.RateLimitConfig.CloudProviderRateLimitBucket)
		klog.V(2).Infof("Azure DisksClient (write ops) using rate limit config: QPS=%g, bucket=%d",
			config.RateLimitConfig.CloudProviderRateLimitQPSWrite,
			config.RateLimitConfig.CloudProviderRateLimitBucketWrite)
	}

	client := &Client{
		armClient:         armClient,
		rateLimiterReader: rateLimiterReader,
		rateLimiterWriter: rateLimiterWriter,
		subscriptionID:    config.SubscriptionID,
		cloudName:         config.CloudName,
	}

	return client
}

// Get gets a Disk.
func (c *Client) Get(ctx context.Context, resourceGroupName string, diskName string) (compute.Disk, *retry.Error) {
	mc := metrics.NewMetricContext("disks", "get", resourceGroupName, c.subscriptionID, "")

	// Report errors if the client is rate limited.
	if !c.rateLimiterReader.TryAccept() {
		mc.RateLimitedCount()
		return compute.Disk{}, retry.GetRateLimitError(false, "GetDisk")
	}

	// Report errors if the client is throttled.
	if c.RetryAfterReader.After(time.Now()) {
		mc.ThrottledCount()
		rerr := retry.GetThrottlingError("GetDisk", "client throttled", c.RetryAfterReader)
		return compute.Disk{}, rerr
	}

	result, rerr := c.getDisk(ctx, resourceGroupName, diskName)
	mc.Observe(rerr)
	if rerr != nil {
		if rerr.IsThrottled() {
			// Update RetryAfterReader so that no more requests would be sent until RetryAfter expires.
			c.RetryAfterReader = rerr.RetryAfter
		}

		return result, rerr
	}

	return result, nil
}

// getDisk gets a Disk.
func (c *Client) getDisk(ctx context.Context, resourceGroupName string, diskName string) (compute.Disk, *retry.Error) {
	resourceID := armclient.GetResourceID(
		c.subscriptionID,
		resourceGroupName,
		"Microsoft.Compute/disks",
		diskName,
	)
	result := compute.Disk{}

	response, rerr := c.armClient.GetResource(ctx, resourceID, "")
	defer c.armClient.CloseResponse(ctx, response)
	if rerr != nil {
		klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "disk.get.request", resourceID, rerr.Error())
		return result, rerr
	}

	err := autorest.Respond(
		response,
		azure.WithErrorUnlessStatusCode(http.StatusOK),
		autorest.ByUnmarshallingJSON(&result))
	if err != nil {
		klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "disk.get.respond", resourceID, err)
		return result, retry.GetError(response, err)
	}

	result.Response = autorest.Response{Response: response}
	return result, nil
}

// CreateOrUpdate creates or updates a Disk.
func (c *Client) CreateOrUpdate(ctx context.Context, resourceGroupName string, diskName string, diskParameter compute.Disk) *retry.Error {
	mc := metrics.NewMetricContext("disks", "create_or_update", resourceGroupName, c.subscriptionID, "")

	// Report errors if the client is rate limited.
	if !c.rateLimiterWriter.TryAccept() {
		mc.RateLimitedCount()
		return retry.GetRateLimitError(true, "DiskCreateOrUpdate")
	}

	// Report errors if the client is throttled.
	if c.RetryAfterWriter.After(time.Now()) {
		mc.ThrottledCount()
		rerr := retry.GetThrottlingError("DiskCreateOrUpdate", "client throttled", c.RetryAfterWriter)
		return rerr
	}

	rerr := c.createOrUpdateDisk(ctx, resourceGroupName, diskName, diskParameter)
	mc.Observe(rerr)
	if rerr != nil {
		if rerr.IsThrottled() {
			// Update RetryAfterReader so that no more requests would be sent until RetryAfter expires.
			c.RetryAfterWriter = rerr.RetryAfter
		}

		return rerr
	}

	return nil
}

// createOrUpdateDisk creates or updates a Disk.
func (c *Client) createOrUpdateDisk(ctx context.Context, resourceGroupName string, diskName string, diskParameter compute.Disk) *retry.Error {
	resourceID := armclient.GetResourceID(
		c.subscriptionID,
		resourceGroupName,
		"Microsoft.Compute/disks",
		diskName,
	)

	response, rerr := c.armClient.PutResource(ctx, resourceID, diskParameter)
	defer c.armClient.CloseResponse(ctx, response)
	if rerr != nil {
		klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "disk.put.request", resourceID, rerr.Error())
		return rerr
	}

	if response != nil && response.StatusCode != http.StatusNoContent {
		_, rerr = c.createOrUpdateResponder(response)
		if rerr != nil {
			klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "disk.put.respond", resourceID, rerr.Error())
			return rerr
		}
	}

	return nil
}

func (c *Client) createOrUpdateResponder(resp *http.Response) (*compute.Disk, *retry.Error) {
	result := &compute.Disk{}
	err := autorest.Respond(
		resp,
		azure.WithErrorUnlessStatusCode(http.StatusOK, http.StatusCreated),
		autorest.ByUnmarshallingJSON(&result))
	result.Response = autorest.Response{Response: resp}
	return result, retry.GetError(resp, err)
}

// Update creates or updates a Disk.
func (c *Client) Update(ctx context.Context, resourceGroupName string, diskName string, diskParameter compute.DiskUpdate) *retry.Error {
	mc := metrics.NewMetricContext("disks", "update", resourceGroupName, c.subscriptionID, "")

	// Report errors if the client is rate limited.
	if !c.rateLimiterWriter.TryAccept() {
		mc.RateLimitedCount()
		return retry.GetRateLimitError(true, "DiskUpdate")
	}

	// Report errors if the client is throttled.
	if c.RetryAfterWriter.After(time.Now()) {
		mc.ThrottledCount()
		rerr := retry.GetThrottlingError("DiskUpdate", "client throttled", c.RetryAfterWriter)
		return rerr
	}

	rerr := c.updateDisk(ctx, resourceGroupName, diskName, diskParameter)
	mc.Observe(rerr)
	if rerr != nil {
		if rerr.IsThrottled() {
			// Update RetryAfterReader so that no more requests would be sent until RetryAfter expires.
			c.RetryAfterWriter = rerr.RetryAfter
		}

		return rerr
	}

	return nil
}

// updateDisk updates a Disk.
func (c *Client) updateDisk(ctx context.Context, resourceGroupName string, diskName string, diskParameter compute.DiskUpdate) *retry.Error {
	resourceID := armclient.GetResourceID(
		c.subscriptionID,
		resourceGroupName,
		"Microsoft.Compute/disks",
		diskName,
	)

	response, rerr := c.armClient.PatchResource(ctx, resourceID, diskParameter)
	defer c.armClient.CloseResponse(ctx, response)
	if rerr != nil {
		klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "disk.put.request", resourceID, rerr.Error())
		return rerr
	}

	if response != nil && response.StatusCode != http.StatusNoContent {
		_, rerr = c.updateResponder(response)
		if rerr != nil {
			klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "disk.put.respond", resourceID, rerr.Error())
			return rerr
		}
	}

	return nil
}

func (c *Client) updateResponder(resp *http.Response) (*compute.Disk, *retry.Error) {
	result := &compute.Disk{}
	err := autorest.Respond(
		resp,
		azure.WithErrorUnlessStatusCode(http.StatusOK, http.StatusCreated),
		autorest.ByUnmarshallingJSON(&result))
	result.Response = autorest.Response{Response: resp}
	return result, retry.GetError(resp, err)
}

// Delete deletes a Disk by name.
func (c *Client) Delete(ctx context.Context, resourceGroupName string, diskName string) *retry.Error {
	mc := metrics.NewMetricContext("disks", "delete", resourceGroupName, c.subscriptionID, "")

	// Report errors if the client is rate limited.
	if !c.rateLimiterWriter.TryAccept() {
		mc.RateLimitedCount()
		return retry.GetRateLimitError(true, "DiskDelete")
	}

	// Report errors if the client is throttled.
	if c.RetryAfterWriter.After(time.Now()) {
		mc.ThrottledCount()
		rerr := retry.GetThrottlingError("DiskDelete", "client throttled", c.RetryAfterWriter)
		return rerr
	}

	rerr := c.deleteDisk(ctx, resourceGroupName, diskName)
	mc.Observe(rerr)
	if rerr != nil {
		if rerr.IsThrottled() {
			// Update RetryAfterReader so that no more requests would be sent until RetryAfter expires.
			c.RetryAfterWriter = rerr.RetryAfter
		}

		return rerr
	}

	return nil
}

// deleteDisk deletes a PublicIPAddress by name.
func (c *Client) deleteDisk(ctx context.Context, resourceGroupName string, diskName string) *retry.Error {
	resourceID := armclient.GetResourceID(
		c.subscriptionID,
		resourceGroupName,
		"Microsoft.Compute/disks",
		diskName,
	)

	return c.armClient.DeleteResource(ctx, resourceID, "")
}

// ListByResourceGroup lists all the disks under a resource group.
func (c *Client) ListByResourceGroup(ctx context.Context, resourceGroupName string) ([]compute.Disk, *retry.Error) {
	resourceID := fmt.Sprintf("/subscriptions/%s/resourceGroups/%s/providers/Microsoft.Compute/disks",
		autorest.Encode("path", c.subscriptionID),
		autorest.Encode("path", resourceGroupName))

	result := make([]compute.Disk, 0)
	page := &DiskListPage{}
	page.fn = c.listNextResults

	resp, rerr := c.armClient.GetResource(ctx, resourceID, "")
	defer c.armClient.CloseResponse(ctx, resp)
	if rerr != nil {
		klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "disk.list.request", resourceID, rerr.Error())
		return result, rerr
	}

	var err error
	page.dl, err = c.listResponder(resp)
	if err != nil {
		klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "disk.list.respond", resourceID, err)
		return result, retry.GetError(resp, err)
	}

	for {
		result = append(result, page.Values()...)

		// Abort the loop when there's no nextLink in the response.
		if to.String(page.Response().NextLink) == "" {
			break
		}

		if err = page.NextWithContext(ctx); err != nil {
			klog.V(5).Infof("Received error in %s: resourceID: %s, error: %s", "disk.list.next", resourceID, err)
			return result, retry.GetError(page.Response().Response.Response, err)
		}
	}

	return result, nil
}

// listNextResults retrieves the next set of results, if any.
func (c *Client) listNextResults(ctx context.Context, lastResults compute.DiskList) (result compute.DiskList, err error) {
	req, err := c.diskListPreparer(ctx, lastResults)
	if err != nil {
		return result, autorest.NewErrorWithError(err, "diskclient", "listNextResults", nil, "Failure preparing next results request")
	}
	if req == nil {
		return
	}

	resp, rerr := c.armClient.Send(ctx, req)
	defer c.armClient.CloseResponse(ctx, resp)
	if rerr != nil {
		result.Response = autorest.Response{Response: resp}
		return result, autorest.NewErrorWithError(rerr.Error(), "diskclient", "listNextResults", resp, "Failure sending next results request")
	}

	result, err = c.listResponder(resp)
	if err != nil {
		err = autorest.NewErrorWithError(err, "diskclient", "listNextResults", resp, "Failure responding to next results request")
	}
	return
}

// listResponder handles the response to the List request. The method always
// closes the http.Response Body.
func (c *Client) listResponder(resp *http.Response) (result compute.DiskList, err error) {
	err = autorest.Respond(
		resp,
		azure.WithErrorUnlessStatusCode(http.StatusOK),
		autorest.ByUnmarshallingJSON(&result),
		autorest.ByClosing())
	result.Response = autorest.Response{Response: resp}
	return
}

func (c *Client) diskListPreparer(ctx context.Context, lr compute.DiskList) (*http.Request, error) {
	if lr.NextLink == nil || len(to.String(lr.NextLink)) < 1 {
		return nil, nil
	}
	return autorest.Prepare((&http.Request{}).WithContext(ctx),
		autorest.AsJSON(),
		autorest.AsGet(),
		autorest.WithBaseURL(to.String(lr.NextLink)))
}

// DiskListPage contains a page of Disk values.
type DiskListPage struct {
	fn func(context.Context, compute.DiskList) (compute.DiskList, error)
	dl compute.DiskList
}

// NextWithContext advances to the next page of values.  If there was an error making
// the request the page does not advance and the error is returned.
func (page *DiskListPage) NextWithContext(ctx context.Context) (err error) {
	next, err := page.fn(ctx, page.dl)
	if err != nil {
		return err
	}
	page.dl = next
	return nil
}

// Next advances to the next page of values.  If there was an error making
// the request the page does not advance and the error is returned.
// Deprecated: Use NextWithContext() instead.
func (page *DiskListPage) Next() error {
	return page.NextWithContext(context.Background())
}

// NotDone returns true if the page enumeration should be started or is not yet complete.
func (page DiskListPage) NotDone() bool {
	return !page.dl.IsEmpty()
}

// Response returns the raw server response from the last page request.
func (page DiskListPage) Response() compute.DiskList {
	return page.dl
}

// Values returns the slice of values for the current page or nil if there are no values.
func (page DiskListPage) Values() []compute.Disk {
	if page.dl.IsEmpty() {
		return nil
	}
	return *page.dl.Value
}
