/*
 * MinIO Cloud Storage, (C) 2020 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 cmd

import (
	"bytes"
	"context"
	"fmt"
	"sync"

	"github.com/minio/minio/pkg/bucket/policy"
)

// BucketMetadataSys captures all bucket metadata for a given cluster.
type BucketMetadataSys struct {
	sync.RWMutex
	metadataMap map[string]BucketMetadata

	// Do fallback to old config when unable to find a bucket config
	fallback bool
}

// Remove bucket metadata from memory.
func (sys *BucketMetadataSys) Remove(bucket string) {
	if globalIsGateway {
		return
	}
	sys.Lock()
	delete(sys.metadataMap, bucket)
	sys.Unlock()
}

// Set - sets a new metadata in-memory.
// Only a shallow copy is saved and fields with references
// cannot be modified without causing a race condition,
// so they should be replaced atomically and not appended to, etc.
// Data is not persisted to disk.
func (sys *BucketMetadataSys) Set(bucket string, meta BucketMetadata) {
	if globalIsGateway {
		return
	}

	if bucket != minioMetaBucket {
		sys.Lock()
		sys.metadataMap[bucket] = meta
		sys.Unlock()
	}
}

// Update update bucket metadata for the specified config file.
// The configData data should not be modified after being sent here.
func (sys *BucketMetadataSys) Update(bucket string, configFile string, configData []byte) error {
	objAPI := newObjectLayerWithoutSafeModeFn()
	if objAPI == nil {
		return errServerNotInitialized
	}

	if globalIsGateway {
		if configFile == bucketPolicyConfig {
			config, err := policy.ParseConfig(bytes.NewReader(configData), bucket)
			if err != nil {
				return err
			}
			return objAPI.SetBucketPolicy(GlobalContext, bucket, config)
		}
		return NotImplemented{}
	}

	if bucket == minioMetaBucket {
		return errInvalidArgument
	}

	defer globalNotificationSys.LoadBucketMetadata(GlobalContext, bucket)

	sys.Lock()
	meta, ok := sys.metadataMap[bucket]
	sys.Unlock()
	if !ok {
		return BucketNotFound{Bucket: bucket}
	}

	switch configFile {
	case bucketPolicyConfig:
		meta.PolicyConfigJSON = configData
	case bucketNotificationConfig:
		meta.NotificationXML = configData
	case bucketLifecycleConfig:
		meta.LifecycleConfigXML = configData
	case bucketSSEConfig:
		meta.EncryptionConfigXML = configData
	case bucketTaggingConfigFile:
		meta.TaggingConfigXML = configData
	case objectLockConfig:
		meta.ObjectLockConfigurationXML = configData
	case bucketQuotaConfigFile:
		meta.QuotaConfigJSON = configData
	default:
		return fmt.Errorf("Unknown bucket %s metadata update requested %s", bucket, configFile)
	}

	if err := meta.Save(GlobalContext, objAPI); err != nil {
		return err
	}

	sys.Lock()
	sys.metadataMap[bucket] = meta
	sys.Unlock()

	return nil
}

// Get metadata for a bucket.
// If no metadata exists errConfigNotFound is returned and a new metadata is returned.
// Only a shallow copy is returned, so referenced data should not be modified,
// but can be replaced atomically.
func (sys *BucketMetadataSys) Get(bucket string) (BucketMetadata, error) {
	if globalIsGateway || bucket == minioMetaBucket {
		return newBucketMetadata(bucket), errConfigNotFound
	}

	sys.RLock()
	defer sys.RUnlock()

	meta, ok := sys.metadataMap[bucket]
	if !ok {
		return newBucketMetadata(bucket), errConfigNotFound
	}

	return meta, nil
}

// GetConfig returns a specific configuration from the bucket metadata.
// The returned data should be copied before being modified.
func (sys *BucketMetadataSys) GetConfig(bucket string, configFile string) ([]byte, error) {
	if globalIsGateway {
		return nil, NotImplemented{}
	}

	if bucket == minioMetaBucket {
		return nil, errInvalidArgument
	}

	sys.RLock()
	defer sys.RUnlock()

	meta, ok := sys.metadataMap[bucket]
	if !ok {
		if !sys.fallback {
			return nil, errConfigNotFound
		}
		objAPI := newObjectLayerWithoutSafeModeFn()
		if objAPI == nil {
			return nil, errServerNotInitialized
		}
		var err error
		meta, err = loadBucketMetadata(GlobalContext, objAPI, bucket)
		if err != nil {
			return nil, err
		}
		sys.metadataMap[bucket] = meta
	}

	var configData []byte
	switch configFile {
	case bucketPolicyConfig:
		configData = meta.PolicyConfigJSON
	case bucketNotificationConfig:
		configData = meta.NotificationXML
	case bucketLifecycleConfig:
		configData = meta.LifecycleConfigXML
	case bucketSSEConfig:
		configData = meta.EncryptionConfigXML
	case bucketTaggingConfigFile:
		configData = meta.TaggingConfigXML
	case objectLockConfig:
		configData = meta.ObjectLockConfigurationXML
	case bucketQuotaConfigFile:
		configData = meta.QuotaConfigJSON
	default:
		return nil, fmt.Errorf("Unknown bucket %s metadata update requested %s", bucket, configFile)
	}

	if len(configData) == 0 {
		return nil, errConfigNotFound
	}

	return configData, nil
}

// Init - initializes bucket metadata system for all buckets.
func (sys *BucketMetadataSys) Init(ctx context.Context, buckets []BucketInfo, objAPI ObjectLayer) error {
	if objAPI == nil {
		return errServerNotInitialized
	}

	// In gateway mode, we don't need to load the policies
	// from the backend.
	if globalIsGateway {
		return nil
	}

	// Load PolicySys once during boot.
	return sys.load(ctx, buckets, objAPI)
}

// Loads bucket metadata for all buckets into BucketMetadataSys.
// When if done successfully fallback will be disabled.
func (sys *BucketMetadataSys) load(ctx context.Context, buckets []BucketInfo, objAPI ObjectLayer) error {
	sys.Lock()
	defer sys.Unlock()

	for _, bucket := range buckets {
		meta, err := loadBucketMetadata(ctx, objAPI, bucket.Name)
		if err != nil {
			return err
		}
		sys.metadataMap[bucket.Name] = meta
	}
	sys.fallback = false
	return nil
}

// NewBucketMetadataSys - creates new policy system.
func NewBucketMetadataSys() *BucketMetadataSys {
	return &BucketMetadataSys{
		metadataMap: make(map[string]BucketMetadata),

		// Do fallback until all buckets have been loaded.
		fallback: true,
	}
}