package azblob

import (

	"context"

	"fmt"

	"io"

	"net/url"

	"strconv"

	"github.com/Azure/azure-pipeline-go/pipeline"

)

const (

	// PageBlobPageBytes indicates the number of bytes in a page (512).

	PageBlobPageBytes = 512

	// PageBlobMaxPutPagesBytes indicates the maximum number of bytes that can be sent in a call to PutPage.

	PageBlobMaxUploadPagesBytes = 4 * 1024 * 1024 // 4MB

)

// PageBlobURL defines a set of operations applicable to page blobs.

type PageBlobURL struct {

	BlobURL

	pbClient pageBlobClient

}

// NewPageBlobURL creates a PageBlobURL object using the specified URL and request policy pipeline.

func NewPageBlobURL(url url.URL, p pipeline.Pipeline) PageBlobURL {

	blobClient := newBlobClient(url, p)

	pbClient := newPageBlobClient(url, p)

	return PageBlobURL{BlobURL: BlobURL{blobClient: blobClient}, pbClient: pbClient}

}

// WithPipeline creates a new PageBlobURL object identical to the source but with the specific request policy pipeline.

func (pb PageBlobURL) WithPipeline(p pipeline.Pipeline) PageBlobURL {

	return NewPageBlobURL(pb.blobClient.URL(), p)

}

// WithSnapshot creates a new PageBlobURL object identical to the source but with the specified snapshot timestamp.

// Pass "" to remove the snapshot returning a URL to the base blob.

func (pb PageBlobURL) WithSnapshot(snapshot string) PageBlobURL {

	p := NewBlobURLParts(pb.URL())

	p.Snapshot = snapshot

	return NewPageBlobURL(p.URL(), pb.blobClient.Pipeline())

}

// Create creates a page blob of the specified length. Call PutPage to upload data data to a page blob.

// For more information, see https://docs.microsoft.com/rest/api/storageservices/put-blob.

func (pb PageBlobURL) Create(ctx context.Context, size int64, sequenceNumber int64, h BlobHTTPHeaders, metadata Metadata, ac BlobAccessConditions) (*PageBlobCreateResponse, error) {

	ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag := ac.ModifiedAccessConditions.pointers()

	return pb.pbClient.Create(ctx, 0, size, nil,

		&h.ContentType, &h.ContentEncoding, &h.ContentLanguage, h.ContentMD5, &h.CacheControl,

		metadata, ac.LeaseAccessConditions.pointers(),

		&h.ContentDisposition, ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag, &sequenceNumber, nil)

}

// UploadPages writes 1 or more pages to the page blob. The start offset and the stream size must be a multiple of 512 bytes.

// This method panics if the stream is not at position 0.

// Note that the http client closes the body stream after the request is sent to the service.

// For more information, see https://docs.microsoft.com/rest/api/storageservices/put-page.

func (pb PageBlobURL) UploadPages(ctx context.Context, offset int64, body io.ReadSeeker, ac PageBlobAccessConditions, transactionalMD5 []byte) (*PageBlobUploadPagesResponse, error) {

	count, err := validateSeekableStreamAt0AndGetCount(body)

	if err != nil {

		return nil, err

	}

	ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag := ac.ModifiedAccessConditions.pointers()

	ifSequenceNumberLessThanOrEqual, ifSequenceNumberLessThan, ifSequenceNumberEqual := ac.SequenceNumberAccessConditions.pointers()

	return pb.pbClient.UploadPages(ctx, body, count, transactionalMD5, nil,

		PageRange{Start: offset, End: offset + count - 1}.pointers(),

		ac.LeaseAccessConditions.pointers(),

		ifSequenceNumberLessThanOrEqual, ifSequenceNumberLessThan, ifSequenceNumberEqual,

		ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag, nil)

}

// UploadPagesFromURL copies 1 or more pages from a source URL to the page blob.

// The sourceOffset specifies the start offset of source data to copy from.

// The destOffset specifies the start offset of data in page blob will be written to.

// The count must be a multiple of 512 bytes.

// For more information, see https://docs.microsoft.com/rest/api/storageservices/put-page-from-url.

func (pb PageBlobURL) UploadPagesFromURL(ctx context.Context, sourceURL url.URL, sourceOffset int64, destOffset int64, count int64, transactionalMD5 []byte, destinationAccessConditions PageBlobAccessConditions, sourceAccessConditions ModifiedAccessConditions) (*PageBlobUploadPagesFromURLResponse, error) {

	ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag := destinationAccessConditions.ModifiedAccessConditions.pointers()

	sourceIfModifiedSince, sourceIfUnmodifiedSince, sourceIfMatchETag, sourceIfNoneMatchETag := sourceAccessConditions.pointers()

	ifSequenceNumberLessThanOrEqual, ifSequenceNumberLessThan, ifSequenceNumberEqual := destinationAccessConditions.SequenceNumberAccessConditions.pointers()

	return pb.pbClient.UploadPagesFromURL(ctx, sourceURL.String(), *PageRange{Start: sourceOffset, End: sourceOffset + count - 1}.pointers(), 0,

		*PageRange{Start: destOffset, End: destOffset + count - 1}.pointers(), transactionalMD5, nil, destinationAccessConditions.LeaseAccessConditions.pointers(),

		ifSequenceNumberLessThanOrEqual, ifSequenceNumberLessThan, ifSequenceNumberEqual,

		ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag, sourceIfModifiedSince, sourceIfUnmodifiedSince, sourceIfMatchETag, sourceIfNoneMatchETag, nil)

}

// ClearPages frees the specified pages from the page blob.

// For more information, see https://docs.microsoft.com/rest/api/storageservices/put-page.

func (pb PageBlobURL) ClearPages(ctx context.Context, offset int64, count int64, ac PageBlobAccessConditions) (*PageBlobClearPagesResponse, error) {

	ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag := ac.ModifiedAccessConditions.pointers()

	ifSequenceNumberLessThanOrEqual, ifSequenceNumberLessThan, ifSequenceNumberEqual := ac.SequenceNumberAccessConditions.pointers()

	return pb.pbClient.ClearPages(ctx, 0, nil,

		PageRange{Start: offset, End: offset + count - 1}.pointers(),

		ac.LeaseAccessConditions.pointers(),

		ifSequenceNumberLessThanOrEqual, ifSequenceNumberLessThan,

		ifSequenceNumberEqual, ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag, nil)

}

// GetPageRanges returns the list of valid page ranges for a page blob or snapshot of a page blob.

// For more information, see https://docs.microsoft.com/rest/api/storageservices/get-page-ranges.

func (pb PageBlobURL) GetPageRanges(ctx context.Context, offset int64, count int64, ac BlobAccessConditions) (*PageList, error) {

	ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag := ac.ModifiedAccessConditions.pointers()

	return pb.pbClient.GetPageRanges(ctx, nil, nil,

		httpRange{offset: offset, count: count}.pointers(),

		ac.LeaseAccessConditions.pointers(),

		ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag, nil)

}

// GetPageRangesDiff gets the collection of page ranges that differ between a specified snapshot and this page blob.

// For more information, see https://docs.microsoft.com/rest/api/storageservices/get-page-ranges.

func (pb PageBlobURL) GetPageRangesDiff(ctx context.Context, offset int64, count int64, prevSnapshot string, ac BlobAccessConditions) (*PageList, error) {

	ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag := ac.ModifiedAccessConditions.pointers()

	return pb.pbClient.GetPageRangesDiff(ctx, nil, nil, &prevSnapshot,

		httpRange{offset: offset, count: count}.pointers(),

		ac.LeaseAccessConditions.pointers(),

		ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag,

		nil)

}

// Resize resizes the page blob to the specified size (which must be a multiple of 512).

// For more information, see https://docs.microsoft.com/rest/api/storageservices/set-blob-properties.

func (pb PageBlobURL) Resize(ctx context.Context, size int64, ac BlobAccessConditions) (*PageBlobResizeResponse, error) {

	ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag := ac.ModifiedAccessConditions.pointers()

	return pb.pbClient.Resize(ctx, size, nil, ac.LeaseAccessConditions.pointers(),

		ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag, nil)

}

// SetSequenceNumber sets the page blob's sequence number.

func (pb PageBlobURL) UpdateSequenceNumber(ctx context.Context, action SequenceNumberActionType, sequenceNumber int64,

	ac BlobAccessConditions) (*PageBlobUpdateSequenceNumberResponse, error) {

	sn := &sequenceNumber

	if action == SequenceNumberActionIncrement {

		sn = nil

	}

	ifModifiedSince, ifUnmodifiedSince, ifMatch, ifNoneMatch := ac.ModifiedAccessConditions.pointers()

	return pb.pbClient.UpdateSequenceNumber(ctx, action, nil,

		ac.LeaseAccessConditions.pointers(), ifModifiedSince, ifUnmodifiedSince, ifMatch, ifNoneMatch,

		sn, nil)

}

// StartIncrementalCopy begins an operation to start an incremental copy from one page blob's snapshot to this page blob.

// The snapshot is copied such that only the differential changes between the previously copied snapshot are transferred to the destination.

// The copied snapshots are complete copies of the original snapshot and can be read or copied from as usual.

// For more information, see https://docs.microsoft.com/rest/api/storageservices/incremental-copy-blob and

// https://docs.microsoft.com/en-us/azure/virtual-machines/windows/incremental-snapshots.

func (pb PageBlobURL) StartCopyIncremental(ctx context.Context, source url.URL, snapshot string, ac BlobAccessConditions) (*PageBlobCopyIncrementalResponse, error) {

	ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag := ac.ModifiedAccessConditions.pointers()

	qp := source.Query()

	qp.Set("snapshot", snapshot)

	source.RawQuery = qp.Encode()

	return pb.pbClient.CopyIncremental(ctx, source.String(), nil,

		ifModifiedSince, ifUnmodifiedSince, ifMatchETag, ifNoneMatchETag, nil)

}

func (pr PageRange) pointers() *string {

	endOffset := strconv.FormatInt(int64(pr.End), 10)

	asString := fmt.Sprintf("bytes=%v-%s", pr.Start, endOffset)

	return &asString

}

type PageBlobAccessConditions struct {

	ModifiedAccessConditions

	LeaseAccessConditions

	SequenceNumberAccessConditions

}

// SequenceNumberAccessConditions identifies page blob-specific access conditions which you optionally set.

type SequenceNumberAccessConditions struct {

	// IfSequenceNumberLessThan ensures that the page blob operation succeeds

	// only if the blob's sequence number is less than a value.

	// IfSequenceNumberLessThan=0 means no 'IfSequenceNumberLessThan' header specified.

	// IfSequenceNumberLessThan>0 means 'IfSequenceNumberLessThan' header specified with its value

	// IfSequenceNumberLessThan==-1 means 'IfSequenceNumberLessThan' header specified with a value of 0

	IfSequenceNumberLessThan int64

	// IfSequenceNumberLessThanOrEqual ensures that the page blob operation succeeds

	// only if the blob's sequence number is less than or equal to a value.

	// IfSequenceNumberLessThanOrEqual=0 means no 'IfSequenceNumberLessThanOrEqual' header specified.

	// IfSequenceNumberLessThanOrEqual>0 means 'IfSequenceNumberLessThanOrEqual' header specified with its value

	// IfSequenceNumberLessThanOrEqual=-1 means 'IfSequenceNumberLessThanOrEqual' header specified with a value of 0

	IfSequenceNumberLessThanOrEqual int64

	// IfSequenceNumberEqual ensures that the page blob operation succeeds

	// only if the blob's sequence number is equal to a value.

	// IfSequenceNumberEqual=0 means no 'IfSequenceNumberEqual' header specified.

	// IfSequenceNumberEqual>0 means 'IfSequenceNumberEqual' header specified with its value

	// IfSequenceNumberEqual=-1 means 'IfSequenceNumberEqual' header specified with a value of 0

	IfSequenceNumberEqual int64

}

// pointers is for internal infrastructure. It returns the fields as pointers.

func (ac SequenceNumberAccessConditions) pointers() (snltoe *int64, snlt *int64, sne *int64) {

	var zero int64 // Defaults to 0

	switch ac.IfSequenceNumberLessThan {

	case -1:

		snlt = &zero

	case 0:

		snlt = nil

	default:

		snlt = &ac.IfSequenceNumberLessThan

	}

	switch ac.IfSequenceNumberLessThanOrEqual {

	case -1:

		snltoe = &zero

	case 0:

		snltoe = nil

	default:

		snltoe = &ac.IfSequenceNumberLessThanOrEqual

	}

	switch ac.IfSequenceNumberEqual {

	case -1:

		sne = &zero

	case 0:

		sne = nil

	default:

		sne = &ac.IfSequenceNumberEqual

	}

	return

}