/*
 * Minio Cloud Storage, (C) 2018 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 (
	"context"
	"encoding/json"
	"fmt"
	"time"
)

// Captures configurable parameters of usage check.
type usageConfig struct {
	UsageCheckInterval time.Duration
}

// MarshalJSON - encodes to JSON data.
func (u usageConfig) MarshalJSON() ([]byte, error) {
	type _usageConfig struct {
		UsageCheckInterval string `json:"interval"`
	}
	return json.Marshal(_usageConfig{u.UsageCheckInterval.String()})
}

// parseDuration - parse duration string
func parseDuration(dStr string) (time.Duration, error) {
	d, err := time.ParseDuration(dStr)
	if err != nil {
		return d, err
	}
	if d < globalMinimumUsageCheckInterval {
		return d, fmt.Errorf("interval %s is not allowed, minimum required value is %s",
			d, globalMinimumUsageCheckInterval)
	}
	return d, nil
}

// UnmarshalJSON - decodes JSON data.
func (u *usageConfig) UnmarshalJSON(data []byte) error {
	type _usageConfig struct {
		UsageCheckInterval string `json:"interval"`
	}
	var u1 = _usageConfig{}
	if err := json.Unmarshal(data, &u1); err != nil {
		return err
	}
	if !globalIsEnvUsageCheck {
		d, err := parseDuration(u1.UsageCheckInterval)
		if err != nil {
			return err
		}
		u.UsageCheckInterval = d
	}
	return nil
}

// getDiskUsage walks the file tree rooted at root, calling usageFn
// for each file or directory in the tree, including root.
func getDiskUsage(ctx context.Context, root string, usageFn usageFunc) error {
	return walk(ctx, root+slashSeparator, usageFn)
}

type usageFunc func(ctx context.Context, entry string) error

// walk recursively descends path, calling walkFn.
func walk(ctx context.Context, path string, usageFn usageFunc) error {
	if err := usageFn(ctx, path); err != nil {
		return err
	}

	if !hasSuffix(path, slashSeparator) {
		return nil
	}

	entries, err := readDir(path)
	if err != nil {
		return usageFn(ctx, path)
	}

	for _, entry := range entries {
		fname := pathJoin(path, entry)
		if err = walk(ctx, fname, usageFn); err != nil {
			return err
		}
	}

	return nil
}