/*
 * MinIO Cloud Storage, (C) 2019 MinIO, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package lifecycle

import (
	"bytes"
	"encoding/xml"

	"github.com/google/uuid"
)

// Status represents lifecycle configuration status
type Status string

// Supported status types
const (
	Enabled  Status = "Enabled"
	Disabled Status = "Disabled"
)

// Rule - a rule for lifecycle configuration.
type Rule struct {
	XMLName    xml.Name   `xml:"Rule"`
	ID         string     `xml:"ID,omitempty"`
	Status     Status     `xml:"Status"`
	Filter     Filter     `xml:"Filter,omitempty"`
	Expiration Expiration `xml:"Expiration,omitempty"`
	Transition Transition `xml:"Transition,omitempty"`
	// FIXME: add a type to catch unsupported AbortIncompleteMultipartUpload AbortIncompleteMultipartUpload `xml:"AbortIncompleteMultipartUpload,omitempty"`
	NoncurrentVersionExpiration NoncurrentVersionExpiration `xml:"NoncurrentVersionExpiration,omitempty"`
	NoncurrentVersionTransition NoncurrentVersionTransition `xml:"NoncurrentVersionTransition,omitempty"`
}

var (
	errInvalidRuleID     = Errorf("ID length is limited to 255 characters")
	errEmptyRuleStatus   = Errorf("Status should not be empty")
	errInvalidRuleStatus = Errorf("Status must be set to either Enabled or Disabled")
)

// generates random UUID
func getNewUUID() (string, error) {
	u, err := uuid.NewRandom()
	if err != nil {
		return "", err
	}

	return u.String(), nil
}

// validateID - checks if ID is valid or not.
func (r Rule) validateID() error {
	IDLen := len(string(r.ID))
	// generate new ID when not provided
	// cannot be longer than 255 characters
	if IDLen == 0 {
		if newID, err := getNewUUID(); err == nil {
			r.ID = newID
		} else {
			return err
		}
	} else if IDLen > 255 {
		return errInvalidRuleID
	}
	return nil
}

// validateStatus - checks if status is valid or not.
func (r Rule) validateStatus() error {
	// Status can't be empty
	if len(r.Status) == 0 {
		return errEmptyRuleStatus
	}

	// Status must be one of Enabled or Disabled
	if r.Status != Enabled && r.Status != Disabled {
		return errInvalidRuleStatus
	}
	return nil
}

func (r Rule) validateAction() error {
	return r.Expiration.Validate()
}

func (r Rule) validateFilter() error {
	return r.Filter.Validate()
}

func (r Rule) validateTransition() error {
	return r.Transition.Validate()
}

// Prefix - a rule can either have prefix under <filter></filter> or under
// <filter><and></and></filter>. This method returns the prefix from the
// location where it is available
func (r Rule) Prefix() string {
	if r.Filter.Prefix != "" {
		return r.Filter.Prefix
	}
	if r.Filter.And.Prefix != "" {
		return r.Filter.And.Prefix
	}
	return ""
}

// Tags - a rule can either have tag under <filter></filter> or under
// <filter><and></and></filter>. This method returns all the tags from the
// rule in the format tag1=value1&tag2=value2
func (r Rule) Tags() string {
	if !r.Filter.Tag.IsEmpty() {
		return r.Filter.Tag.String()
	}
	if len(r.Filter.And.Tags) != 0 {
		var buf bytes.Buffer
		for _, t := range r.Filter.And.Tags {
			if buf.Len() > 0 {
				buf.WriteString("&")
			}
			buf.WriteString(t.String())
		}
		return buf.String()
	}
	return ""
}

// Validate - validates the rule element
func (r Rule) Validate() error {
	if err := r.validateID(); err != nil {
		return err
	}
	if err := r.validateStatus(); err != nil {
		return err
	}
	if err := r.validateAction(); err != nil {
		return err
	}
	if err := r.validateFilter(); err != nil {
		return err
	}
	if err := r.validateTransition(); err != nil {
		return err
	}
	return nil
}