package approle

import (
	"context"
	"fmt"
	"sync/atomic"
	"time"

	"github.com/hashicorp/errwrap"
	"github.com/hashicorp/go-multierror"
	"github.com/hashicorp/vault/logical"
	"github.com/hashicorp/vault/logical/framework"
)

func pathTidySecretID(b *backend) *framework.Path {
	return &framework.Path{
		Pattern: "tidy/secret-id$",

		Callbacks: map[logical.Operation]framework.OperationFunc{
			logical.UpdateOperation: b.pathTidySecretIDUpdate,
		},

		HelpSynopsis:    pathTidySecretIDSyn,
		HelpDescription: pathTidySecretIDDesc,
	}
}

// tidySecretID is used to delete entries in the whitelist that are expired.
func (b *backend) tidySecretID(ctx context.Context, s logical.Storage) error {
	grabbed := atomic.CompareAndSwapUint32(&b.tidySecretIDCASGuard, 0, 1)
	if grabbed {
		defer atomic.StoreUint32(&b.tidySecretIDCASGuard, 0)
	} else {
		return fmt.Errorf("SecretID tidy operation already running")
	}

	var result error

	tidyFunc := func(secretIDPrefixToUse, accessorIDPrefixToUse string) error {
		roleNameHMACs, err := s.List(ctx, secretIDPrefixToUse)
		if err != nil {
			return err
		}

		// List all the accessors and add them all to a map
		accessorHashes, err := s.List(ctx, accessorIDPrefixToUse)
		if err != nil {
			return err
		}
		accessorMap := make(map[string]bool, len(accessorHashes))
		for _, accessorHash := range accessorHashes {
			accessorMap[accessorHash] = true
		}

		for _, roleNameHMAC := range roleNameHMACs {
			// roleNameHMAC will already have a '/' suffix. Don't append another one.
			secretIDHMACs, err := s.List(ctx, fmt.Sprintf("%s%s", secretIDPrefixToUse, roleNameHMAC))
			if err != nil {
				return err
			}
			for _, secretIDHMAC := range secretIDHMACs {
				// In order to avoid lock swapping in case there is need to delete,
				// grab the write lock.
				lock := b.secretIDLock(secretIDHMAC)
				lock.Lock()
				// roleNameHMAC will already have a '/' suffix. Don't append another one.
				entryIndex := fmt.Sprintf("%s%s%s", secretIDPrefixToUse, roleNameHMAC, secretIDHMAC)
				secretIDEntry, err := s.Get(ctx, entryIndex)
				if err != nil {
					lock.Unlock()
					return errwrap.Wrapf(fmt.Sprintf("error fetching SecretID %q: {{err}}", secretIDHMAC), err)
				}

				if secretIDEntry == nil {
					result = multierror.Append(result, fmt.Errorf("entry for SecretID %q is nil", secretIDHMAC))
					lock.Unlock()
					continue
				}

				if secretIDEntry.Value == nil || len(secretIDEntry.Value) == 0 {
					lock.Unlock()
					return fmt.Errorf("found entry for SecretID %q but actual SecretID is empty", secretIDHMAC)
				}

				var result secretIDStorageEntry
				if err := secretIDEntry.DecodeJSON(&result); err != nil {
					lock.Unlock()
					return err
				}

				// ExpirationTime not being set indicates non-expiring SecretIDs
				if !result.ExpirationTime.IsZero() && time.Now().After(result.ExpirationTime) {
					// Clean up the accessor of the secret ID first
					err = b.deleteSecretIDAccessorEntry(ctx, s, result.SecretIDAccessor, secretIDPrefixToUse)
					if err != nil {
						lock.Unlock()
						return err
					}

					if err := s.Delete(ctx, entryIndex); err != nil {
						lock.Unlock()
						return errwrap.Wrapf(fmt.Sprintf("error deleting SecretID %q from storage: {{err}}", secretIDHMAC), err)
					}
				}

				// At this point, the secret ID is not expired and is valid. Delete
				// the corresponding accessor from the accessorMap. This will leave
				// only the dangling accessors in the map which can then be cleaned
				// up later.
				salt, err := b.Salt(ctx)
				if err != nil {
					lock.Unlock()
					return err
				}
				delete(accessorMap, salt.SaltID(result.SecretIDAccessor))

				lock.Unlock()
			}
		}

		// Accessor indexes were not getting cleaned up until 0.9.3. This is a fix
		// to clean up the dangling accessor entries.
		for accessorHash, _ := range accessorMap {
			// Ideally, locking should be performed here. But for that, accessors
			// are required in plaintext, which are not available. Hence performing
			// a racy cleanup.
			err = s.Delete(ctx, secretIDAccessorPrefix+accessorHash)
			if err != nil {
				return err
			}
		}

		return nil
	}

	err := tidyFunc(secretIDPrefix, secretIDAccessorPrefix)
	if err != nil {
		return err
	}
	err = tidyFunc(secretIDLocalPrefix, secretIDAccessorLocalPrefix)
	if err != nil {
		return err
	}

	return result
}

// pathTidySecretIDUpdate is used to delete the expired SecretID entries
func (b *backend) pathTidySecretIDUpdate(ctx context.Context, req *logical.Request, data *framework.FieldData) (*logical.Response, error) {
	return nil, b.tidySecretID(ctx, req.Storage)
}

const pathTidySecretIDSyn = "Trigger the clean-up of expired SecretID entries."
const pathTidySecretIDDesc = `SecretIDs will have expiration time attached to them. The periodic function
of the backend will look for expired entries and delete them. This happens once in a minute. Invoking
this endpoint will trigger the clean-up action, without waiting for the backend's periodic function.`