template.go

package accountserver

import (
	"context"
	"errors"
	"fmt"
	"math/rand"
	"path/filepath"
	"strings"
	"time"
)

// Templating, in this context, means filling up derived attributes in a resource.
//
// Derived attributes are always enforced (i.e. we don't check if the
// attribute already has a value), but currently this is only done at
// resource creation time. The plan is to extend this to cover any
// Update call as well.
type templateContext struct {
	shards  shardBackend
	webroot string
}

func (c *templateContext) pickShard(ctx context.Context, r *Resource) (string, error) {
	avail := c.shards.GetAvailableShards(ctx, r.Type)
	if len(avail) == 0 {
		return "", fmt.Errorf("no available shards for resource type %s", r.Type)
	}
	return avail[rand.Intn(len(avail))], nil
}

func (c *templateContext) setResourceShard(ctx context.Context, r *Resource, ref *Resource) error {
	if r.Shard == "" {
		if ref != nil {
			r.Shard = ref.Shard
		} else {
			s, err := c.pickShard(ctx, r)
			if err != nil {
				return err
			}
			r.Shard = s
		}
	}
	if r.OriginalShard == "" {
		r.OriginalShard = r.Shard
	}
	return nil
}

func (c *templateContext) setResourceStatus(r *Resource) {
	if r.Status == "" {
		r.Status = ResourceStatusActive
	}
}

func (c *templateContext) setCommonResourceAttrs(ctx context.Context, r *Resource, ref *Resource, user *User) error {
	// If we reference another resource, ensure it has been templated.
	if ref != nil {
		if err := c.applyTemplate(ctx, ref, user); err != nil {
			return err
		}
	}

	r.CreatedAt = time.Now().UTC().Format("2006-01-02")

	c.setResourceStatus(r)
	return c.setResourceShard(ctx, r, ref)
}

// Apply default values to an Email resource.
func (c *templateContext) emailResourceTemplate(ctx context.Context, r *Resource, _ *User) error {
	// Force the email address to lowercase.
	r.Name = strings.ToLower(r.Name)

	if r.Email == nil {
		r.Email = new(Email)
	}

	addrParts := strings.Split(r.Name, "@")
	if len(addrParts) != 2 {
		return errors.New("malformed name")
	}
	r.Email.Maildir = fmt.Sprintf("%s/%s", addrParts[1], addrParts[0])
	r.Email.QuotaLimit = 4096
	return c.setCommonResourceAttrs(ctx, r, nil, nil)
}

// Apply default values to a Website or Domain resource.
func (c *templateContext) websiteResourceTemplate(ctx context.Context, r *Resource, user *User) error {
	if user == nil {
		return errors.New("website resource needs owner")
	}

	// Force the website address to lowercase.
	r.Name = strings.ToLower(r.Name)

	if r.Website == nil {
		r.Website = new(Website)
	}

	// If the client did not specify a DocumentRoot, find a DAV resource
	// and associate the website with it.
	if r.Website.DocumentRoot == "" {
		dav := user.GetSingleResourceByType(ResourceTypeDAV)
		if dav == nil {
			return errors.New("user has no DAV accounts")
		}

		// The DAV resource may not have been templatized yet.
		if dav.DAV == nil || dav.DAV.Homedir == "" {
			if err := c.davResourceTemplate(ctx, dav, user); err != nil {
				return err
			}
		}
		r.Website.DocumentRoot = filepath.Join(dav.DAV.Homedir, "html-"+r.Name)
	}
	r.Website.DocumentRoot = filepath.Clean(r.Website.DocumentRoot)

	if len(r.Website.Options) == 0 {
		r.Website.Options = []string{"nomail"}
	}

	r.Website.UID = user.UID

	dav := findMatchingDAVAccount(user, r)
	if dav == nil {
		return fmt.Errorf("no DAV resources matching website %s", r.String())
	}
	return c.setCommonResourceAttrs(ctx, r, dav, user)
}

// Apply default values to a DAV resource.
func (c *templateContext) davResourceTemplate(ctx context.Context, r *Resource, user *User) error {
	if user == nil {
		return errors.New("dav resource needs owner")
	}

	// Force the account name to lowercase.
	r.Name = strings.ToLower(r.Name)

	if r.DAV == nil {
		r.DAV = new(WebDAV)
	}
	if r.DAV.Homedir == "" {
		r.DAV.Homedir = filepath.Join(c.webroot, r.Name)
	}
	r.DAV.Homedir = filepath.Clean(r.DAV.Homedir)
	r.DAV.UID = user.UID

	return c.setCommonResourceAttrs(ctx, r, nil, user)
}

// Apply default values to a Database resource.
func (c *templateContext) databaseResourceTemplate(ctx context.Context, r *Resource, user *User) error {
	if user == nil {
		return errors.New("database resource needs owner")
	}

	// Force the database name to lowercase.
	r.Name = strings.ToLower(r.Name)

	if r.Database == nil {
		r.Database = new(Database)
	}
	if r.Database.DBUser == "" {
		r.Database.DBUser = r.Name
	}

	return c.setCommonResourceAttrs(ctx, r, user.GetResourceByID(r.ParentID), user)
}

// Apply default values to a MailingList resource.
func (c *templateContext) listResourceTemplate(ctx context.Context, r *Resource, user *User) error {
	// Force the list address to lowercase.
	r.Name = strings.ToLower(r.Name)

	if r.List == nil {
		r.List = new(MailingList)
	}

	// As a convenience, if a user is passed in the context, we add it to
	// the list admins.
	if user != nil && len(r.List.Admins) == 0 {
		r.List.Admins = []string{user.Name}
	}

	return c.setCommonResourceAttrs(ctx, r, nil, nil)
}

// Apply default values to a Newsletter resource.
func (c *templateContext) newsletterResourceTemplate(ctx context.Context, r *Resource, user *User) error {
	// Force the list address to lowercase.
	r.Name = strings.ToLower(r.Name)

	if r.Newsletter == nil {
		r.Newsletter = new(Newsletter)
	}

	// As a convenience, if a user is passed in the context, we add it to
	// the list admins.
	if user != nil && len(r.Newsletter.Admins) == 0 {
		r.Newsletter.Admins = []string{user.Name}
	}

	return c.setCommonResourceAttrs(ctx, r, nil, nil)
}

// Apply default values to a resource.
func (c *templateContext) applyTemplate(ctx context.Context, r *Resource, user *User) error {
	switch r.Type {
	case ResourceTypeEmail:
		return c.emailResourceTemplate(ctx, r, user)
	case ResourceTypeWebsite, ResourceTypeDomain:
		return c.websiteResourceTemplate(ctx, r, user)
	case ResourceTypeDAV:
		return c.davResourceTemplate(ctx, r, user)
	case ResourceTypeDatabase:
		return c.databaseResourceTemplate(ctx, r, user)
	case ResourceTypeMailingList:
		return c.listResourceTemplate(ctx, r, user)
	case ResourceTypeNewsletter:
		return c.newsletterResourceTemplate(ctx, r, user)
	}
	return nil
}