// Copyright © 2016 Abcum Ltd
//
// 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 db

import (
	"errors"
	"runtime"
)

type method int

const (
	_SELECT method = iota
	_CREATE
	_UPDATE
	_DELETE
)

const (
	docKeyId  = "id"
	docKeyOne = "0"
	docKeyAll = "*"
)

const (
	ctxKeyId    = "id"
	ctxKeyNs    = "ns"
	ctxKeyDb    = "db"
	ctxKeyVars  = "vars"
	ctxKeySubs  = "subs"
	ctxKeySpec  = "spec"
	ctxKeyKeep  = "keep"
	ctxKeyAuth  = "auth"
	ctxKeyKind  = "kind"
	ctxKeyScope = "scope"
)

const (
	varKeyId     = "id"
	varKeyIp     = "ip"
	varKeyAuth   = "auth"
	varKeyKeep   = "keep"
	varKeyThis   = "this"
	varKeyScope  = "scope"
	varKeyValue  = "value"
	varKeyAfter  = "after"
	varKeyBefore = "before"
	varKeyMethod = "method"
	varKeyParent = "parent"
	varKeyOrigin = "origin"
)

var (
	// workerCount specifies how many workers should be used
	// to process each query statement concurrently.
	workerCount = runtime.NumCPU() * 2

	// queryIdentFailed occurs when a permission query asks
	// for a field, meaning a document has to be fetched.
	queryIdentFailed = errors.New("Found ident but no doc available")

	// errQueryNotExecuted occurs when a transaction has
	// failed, and the following queries are not executed.
	errQueryNotExecuted = errors.New("Query not executed")

	// errRaceCondition occurs when a record which is locked
	// for editing, is updated from within a subquery.
	errRaceCondition = errors.New("Failed to update the same document recursively")

	// errRecursiveOverload occurs when too many subqueries
	// are executed within one other, causing an endless loop.
	errRecursiveOverload = errors.New("Infinite loop when running recursive subqueries")

	// errFeatureNotImplemented occurs when a feature which
	// has not yet been implemented, has been used in a query.
	errFeatureNotImplemented = errors.New("Feature is not yet implemented")

	// paramSearchKeys specifies the order in which context
	// variables should be checked for any specified value.
	paramSearchKeys = []string{ctxKeySpec, ctxKeySubs, ctxKeyVars, ctxKeyKeep}
)