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package ec2test
import (
"fmt"
"net/url"
"strings"
)
// filter holds an ec2 filter. A filter maps an attribute to a set of
// possible values for that attribute. For an item to pass through the
// filter, every attribute of the item mentioned in the filter must match
// at least one of its given values.
type filter map[string][]string
// newFilter creates a new filter from the Filter fields in the url form.
//
// The filtering is specified through a map of name=>values, where the
// name is a well-defined key identifying the data to be matched,
// and the list of values holds the possible values the filtered
// item can take for the key to be included in the
// result set. For example:
//
// Filter.1.Name=instance-type
// Filter.1.Value.1=m1.small
// Filter.1.Value.2=m1.large
//
func newFilter(form url.Values) filter {
// TODO return an error if the fields are not well formed?
names := make(map[int]string)
values := make(map[int][]string)
maxId := 0
for name, fvalues := range form {
var rest string
var id int
if x, _ := fmt.Sscanf(name, "Filter.%d.%s", &id, &rest); x != 2 {
continue
}
if id > maxId {
maxId = id
}
if rest == "Name" {
names[id] = fvalues[0]
continue
}
if !strings.HasPrefix(rest, "Value.") {
continue
}
values[id] = append(values[id], fvalues[0])
}
f := make(filter)
for id, name := range names {
f[name] = values[id]
}
return f
}
func notDigit(r rune) bool {
return r < '0' || r > '9'
}
// filterable represents an object that can be passed through a filter.
type filterable interface {
// matchAttr returns true if given attribute of the
// object matches value. It returns an error if the
// attribute is not recognised or the value is malformed.
matchAttr(attr, value string) (bool, error)
}
// ok returns true if x passes through the filter.
func (f filter) ok(x filterable) (bool, error) {
next:
for a, vs := range f {
for _, v := range vs {
if ok, err := x.matchAttr(a, v); ok {
continue next
} else if err != nil {
return false, fmt.Errorf("bad attribute or value %q=%q for type %T: %v", a, v, x, err)
}
}
return false, nil
}
return true, nil
}
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