package snapshots

import (
	"fmt"

	"github.com/rackspace/gophercloud"
	"github.com/rackspace/gophercloud/pagination"
)

// CreateOptsBuilder allows extensions to add additional parameters to the
// Create request.
type CreateOptsBuilder interface {
	ToSnapshotCreateMap() (map[string]interface{}, error)
}

// CreateOpts contains options for creating a Snapshot. This object is passed to
// the snapshots.Create function. For more information about these parameters,
// see the Snapshot object.
type CreateOpts struct {
	// OPTIONAL
	Description string
	// OPTIONAL
	Force bool
	// OPTIONAL
	Metadata map[string]interface{}
	// OPTIONAL
	Name string
	// REQUIRED
	VolumeID string
}

// ToSnapshotCreateMap assembles a request body based on the contents of a
// CreateOpts.
func (opts CreateOpts) ToSnapshotCreateMap() (map[string]interface{}, error) {
	s := make(map[string]interface{})

	if opts.VolumeID == "" {
		return nil, fmt.Errorf("Required CreateOpts field 'VolumeID' not set.")
	}
	s["volume_id"] = opts.VolumeID

	if opts.Description != "" {
		s["display_description"] = opts.Description
	}
	if opts.Force == true {
		s["force"] = opts.Force
	}
	if opts.Metadata != nil {
		s["metadata"] = opts.Metadata
	}
	if opts.Name != "" {
		s["display_name"] = opts.Name
	}

	return map[string]interface{}{"snapshot": s}, nil
}

// Create will create a new Snapshot based on the values in CreateOpts. To
// extract the Snapshot object from the response, call the Extract method on the
// CreateResult.
func Create(client *gophercloud.ServiceClient, opts CreateOptsBuilder) CreateResult {
	var res CreateResult

	reqBody, err := opts.ToSnapshotCreateMap()
	if err != nil {
		res.Err = err
		return res
	}

	_, res.Err = client.Post(createURL(client), reqBody, &res.Body, &gophercloud.RequestOpts{
		OkCodes: []int{200, 201},
	})
	return res
}

// Delete will delete the existing Snapshot with the provided ID.
func Delete(client *gophercloud.ServiceClient, id string) DeleteResult {
	var res DeleteResult
	_, res.Err = client.Delete(deleteURL(client, id), nil)
	return res
}

// Get retrieves the Snapshot with the provided ID. To extract the Snapshot
// object from the response, call the Extract method on the GetResult.
func Get(client *gophercloud.ServiceClient, id string) GetResult {
	var res GetResult
	_, res.Err = client.Get(getURL(client, id), &res.Body, nil)
	return res
}

// ListOptsBuilder allows extensions to add additional parameters to the List
// request.
type ListOptsBuilder interface {
	ToSnapshotListQuery() (string, error)
}

// ListOpts hold options for listing Snapshots. It is passed to the
// snapshots.List function.
type ListOpts struct {
	Name     string `q:"display_name"`
	Status   string `q:"status"`
	VolumeID string `q:"volume_id"`
}

// ToSnapshotListQuery formats a ListOpts into a query string.
func (opts ListOpts) ToSnapshotListQuery() (string, error) {
	q, err := gophercloud.BuildQueryString(opts)
	if err != nil {
		return "", err
	}
	return q.String(), nil
}

// List returns Snapshots optionally limited by the conditions provided in
// ListOpts.
func List(client *gophercloud.ServiceClient, opts ListOptsBuilder) pagination.Pager {
	url := listURL(client)
	if opts != nil {
		query, err := opts.ToSnapshotListQuery()
		if err != nil {
			return pagination.Pager{Err: err}
		}
		url += query
	}

	createPage := func(r pagination.PageResult) pagination.Page {
		return ListResult{pagination.SinglePageBase(r)}
	}
	return pagination.NewPager(client, url, createPage)
}

// UpdateMetadataOptsBuilder allows extensions to add additional parameters to
// the Update request.
type UpdateMetadataOptsBuilder interface {
	ToSnapshotUpdateMetadataMap() (map[string]interface{}, error)
}

// UpdateMetadataOpts contain options for updating an existing Snapshot. This
// object is passed to the snapshots.Update function. For more information
// about the parameters, see the Snapshot object.
type UpdateMetadataOpts struct {
	Metadata map[string]interface{}
}

// ToSnapshotUpdateMetadataMap assembles a request body based on the contents of
// an UpdateMetadataOpts.
func (opts UpdateMetadataOpts) ToSnapshotUpdateMetadataMap() (map[string]interface{}, error) {
	v := make(map[string]interface{})

	if opts.Metadata != nil {
		v["metadata"] = opts.Metadata
	}

	return v, nil
}

// UpdateMetadata will update the Snapshot with provided information. To
// extract the updated Snapshot from the response, call the ExtractMetadata
// method on the UpdateMetadataResult.
func UpdateMetadata(client *gophercloud.ServiceClient, id string, opts UpdateMetadataOptsBuilder) UpdateMetadataResult {
	var res UpdateMetadataResult

	reqBody, err := opts.ToSnapshotUpdateMetadataMap()
	if err != nil {
		res.Err = err
		return res
	}

	_, res.Err = client.Put(updateMetadataURL(client, id), reqBody, &res.Body, &gophercloud.RequestOpts{
		OkCodes: []int{200},
	})
	return res
}

// IDFromName is a convienience function that returns a snapshot's ID given its name.
func IDFromName(client *gophercloud.ServiceClient, name string) (string, error) {
	snapshotCount := 0
	snapshotID := ""
	if name == "" {
		return "", fmt.Errorf("A snapshot name must be provided.")
	}
	pager := List(client, nil)
	pager.EachPage(func(page pagination.Page) (bool, error) {
		snapshotList, err := ExtractSnapshots(page)
		if err != nil {
			return false, err
		}

		for _, s := range snapshotList {
			if s.Name == name {
				snapshotCount++
				snapshotID = s.ID
			}
		}
		return true, nil
	})

	switch snapshotCount {
	case 0:
		return "", fmt.Errorf("Unable to find snapshot: %s", name)
	case 1:
		return snapshotID, nil
	default:
		return "", fmt.Errorf("Found %d snapshots matching %s", snapshotCount, name)
	}
}