// Fetch returns a list of images for the specified cloud matching the constraint.
// The base URL locations are as specified - the first location which has a file is the one used.
// Signed data is preferred, but if there is no signed data available and onlySigned is false,
// then unsigned data is used.
func Fetch(
	sources []simplestreams.DataSource, cons *ImageConstraint,
) ([]*ImageMetadata, *simplestreams.ResolveInfo, error) {

	params := simplestreams.GetMetadataParams{
		StreamsVersion:   currentStreamsVersion,
		LookupConstraint: cons,
		ValueParams: simplestreams.ValueParams{
			DataType:      ImageIds,
			FilterFunc:    appendMatchingImages,
			ValueTemplate: ImageMetadata{},
		},
	}
	items, resolveInfo, err := simplestreams.GetMetadata(sources, params)
	if err != nil {
		return nil, resolveInfo, err
	}
	metadata := make([]*ImageMetadata, len(items))
	for i, md := range items {
		metadata[i] = md.(*ImageMetadata)
	}
	// Sorting the metadata is not strictly necessary, but it ensures consistent ordering for
	// all compilers, and it just makes it easier to look at the data.
	Sort(metadata)
	return metadata, resolveInfo, nil
}

// Fetch returns a list of tools for the specified cloud matching the constraint.
// The base URL locations are as specified - the first location which has a file is the one used.
// Signed data is preferred, but if there is no signed data available and onlySigned is false,
// then unsigned data is used.
func Fetch(
	sources []simplestreams.DataSource, cons *ToolsConstraint,
	onlySigned bool) ([]*ToolsMetadata, *simplestreams.ResolveInfo, error) {

	params := simplestreams.GetMetadataParams{
		StreamsVersion:   currentStreamsVersion,
		OnlySigned:       onlySigned,
		LookupConstraint: cons,
		ValueParams: simplestreams.ValueParams{
			DataType:        ContentDownload,
			FilterFunc:      appendMatchingTools,
			MirrorContentId: ToolsContentId(cons.Stream),
			ValueTemplate:   ToolsMetadata{},
			PublicKey:       simplestreamsToolsPublicKey,
		},
	}
	items, resolveInfo, err := simplestreams.GetMetadata(sources, params)
	if err != nil {
		return nil, nil, err
	}
	metadata := make([]*ToolsMetadata, len(items))
	for i, md := range items {
		metadata[i] = md.(*ToolsMetadata)
	}
	// Sorting the metadata is not strictly necessary, but it ensures consistent ordering for
	// all compilers, and it just makes it easier to look at the data.
	Sort(metadata)
	return metadata, resolveInfo, nil
}

// FetchMetadata fetches and returns Juju GUI metadata from simplestreams,
// sorted by version descending.
func FetchMetadata(stream string, sources ...simplestreams.DataSource) ([]*Metadata, error) {
	params := simplestreams.GetMetadataParams{
		StreamsVersion: streamsVersion,
		LookupConstraint: &constraint{
			LookupParams: simplestreams.LookupParams{Stream: stream},
			majorVersion: jujuversion.Current.Major,
		},
		ValueParams: simplestreams.ValueParams{
			DataType:        downloadType,
			MirrorContentId: contentId(stream),
			FilterFunc:      appendArchives,
			ValueTemplate:   Metadata{},
		},
	}
	items, _, err := simplestreams.GetMetadata(sources, params)
	if err != nil {
		return nil, errors.Annotate(err, "error fetching simplestreams metadata")
	}
	allMeta := make([]*Metadata, len(items))
	for i, item := range items {
		allMeta[i] = item.(*Metadata)
	}
	sort.Sort(byVersion(allMeta))
	return allMeta, nil
}

func (s *simplestreamsSuite) TestGetMetadataNoMatching(c *gc.C) {
	source := &countingSource{
		DataSource: simplestreams.NewURLDataSource(
			"test", "test:/daily", utils.VerifySSLHostnames,
		),
	}
	sources := []simplestreams.DataSource{source, source, source}
	constraint := sstesting.NewTestConstraint(simplestreams.LookupParams{
		CloudSpec: simplestreams.CloudSpec{
			Region:   "us-east-1",
			Endpoint: "https://ec2.us-east-1.amazonaws.com",
		},
		Series: []string{"precise"},
		Arches: []string{"not-a-real-arch"}, // never matches
	})
	params := simplestreams.GetMetadataParams{
		StreamsVersion:   s.StreamsVersion,
		LookupConstraint: constraint,
		ValueParams:      simplestreams.ValueParams{DataType: "image-ids"},
	}

	items, resolveInfo, err := simplestreams.GetMetadata(sources, params)
	c.Assert(err, jc.ErrorIsNil)
	c.Assert(items, gc.HasLen, 0)
	c.Assert(resolveInfo, gc.DeepEquals, &simplestreams.ResolveInfo{
		Source:    "test",
		Signed:    false,
		IndexURL:  "test:/daily/streams/v1/index.json",
		MirrorURL: "",
	})

	// There should be 4 calls to each data-source:
	// one for .sjson, one for .json, repeated for legacy vs new index files.
	c.Assert(source.count, gc.Equals, 4*len(sources))
}

func imageMetadataFetch(sources []simplestreams.DataSource, cons *imagemetadata.ImageConstraint) ([]*OvaFileMetadata, error) {
	params := simplestreams.GetMetadataParams{
		StreamsVersion:   imagemetadata.StreamsVersionV1,
		LookupConstraint: cons,
		ValueParams: simplestreams.ValueParams{
			DataType:      "image-downloads",
			FilterFunc:    appendMatchingFunc,
			ValueTemplate: OvaFileMetadata{},
		},
	}
	items, _, err := simplestreams.GetMetadata(sources, params)
	if err != nil {
		return nil, errors.Trace(err)
	}
	metadata := make([]*OvaFileMetadata, len(items))
	for i, md := range items {
		metadata[i] = md.(*OvaFileMetadata)
	}
	return metadata, nil
}