// Copyright 2013 Prometheus Team
// 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 rules

import (
	"fmt"
	"net/url"
	"strings"

	clientmodel "github.com/prometheus/client_golang/model"

	"github.com/prometheus/prometheus/rules/ast"
	"github.com/prometheus/prometheus/utility"
)

func CreateRecordingRule(name string, labels clientmodel.LabelSet, expr ast.Node, permanent bool) (*RecordingRule, error) {
	if _, ok := expr.(ast.VectorNode); !ok {
		return nil, fmt.Errorf("Recording rule expression %v does not evaluate to vector type", expr)
	}
	return NewRecordingRule(name, labels, expr.(ast.VectorNode), permanent), nil
}

func CreateAlertingRule(name string, expr ast.Node, holdDurationStr string, labels clientmodel.LabelSet, summary string, description string) (*AlertingRule, error) {
	if _, ok := expr.(ast.VectorNode); !ok {
		return nil, fmt.Errorf("Alert rule expression %v does not evaluate to vector type", expr)
	}
	holdDuration, err := utility.StringToDuration(holdDurationStr)
	if err != nil {
		return nil, err
	}
	return NewAlertingRule(name, expr.(ast.VectorNode), holdDuration, labels, summary, description), nil
}

func NewFunctionCall(name string, args []ast.Node) (ast.Node, error) {
	function, err := ast.GetFunction(name)
	if err != nil {
		return nil, fmt.Errorf("Unknown function \"%v\"", name)
	}
	functionCall, err := ast.NewFunctionCall(function, args)
	if err != nil {
		return nil, fmt.Errorf(err.Error())
	}
	return functionCall, nil
}

func NewVectorAggregation(aggrTypeStr string, vector ast.Node, groupBy clientmodel.LabelNames, keepExtraLabels bool) (*ast.VectorAggregation, error) {
	if _, ok := vector.(ast.VectorNode); !ok {
		return nil, fmt.Errorf("Operand of %v aggregation must be of vector type", aggrTypeStr)
	}
	var aggrTypes = map[string]ast.AggrType{
		"SUM":   ast.SUM,
		"MAX":   ast.MAX,
		"MIN":   ast.MIN,
		"AVG":   ast.AVG,
		"COUNT": ast.COUNT,
	}
	aggrType, ok := aggrTypes[aggrTypeStr]
	if !ok {
		return nil, fmt.Errorf("Unknown aggregation type '%v'", aggrTypeStr)
	}
	return ast.NewVectorAggregation(aggrType, vector.(ast.VectorNode), groupBy, keepExtraLabels), nil
}

func NewArithExpr(opTypeStr string, lhs ast.Node, rhs ast.Node) (ast.Node, error) {
	var opTypes = map[string]ast.BinOpType{
		"+":   ast.ADD,
		"-":   ast.SUB,
		"*":   ast.MUL,
		"/":   ast.DIV,
		"%":   ast.MOD,
		">":   ast.GT,
		"<":   ast.LT,
		"==":  ast.EQ,
		"!=":  ast.NE,
		">=":  ast.GE,
		"<=":  ast.LE,
		"AND": ast.AND,
		"OR":  ast.OR,
	}
	opType, ok := opTypes[opTypeStr]
	if !ok {
		return nil, fmt.Errorf("Invalid binary operator \"%v\"", opTypeStr)
	}
	expr, err := ast.NewArithExpr(opType, lhs, rhs)
	if err != nil {
		return nil, fmt.Errorf(err.Error())
	}
	return expr, nil
}

func NewMatrixSelector(vector ast.Node, intervalStr string) (ast.MatrixNode, error) {
	switch vector.(type) {
	case *ast.VectorSelector:
		{
			break
		}
	default:
		return nil, fmt.Errorf("Intervals are currently only supported for vector selectors.")
	}
	interval, err := utility.StringToDuration(intervalStr)
	if err != nil {
		return nil, err
	}
	vectorSelector := vector.(*ast.VectorSelector)
	return ast.NewMatrixSelector(vectorSelector, interval), nil
}

func ConsoleLinkForExpression(expr string) string {
	// url.QueryEscape percent-escapes everything except spaces, for which it
	// uses "+". However, in the non-query part of a URI, only percent-escaped
	// spaces are legal, so we need to manually replace "+" with "%20" after
	// query-escaping the string.
	//
	// See also:
	// http://stackoverflow.com/questions/1634271/url-encoding-the-space-character-or-20.
	urlData := url.QueryEscape(fmt.Sprintf(`[{"expr":%q,"tab":1}]`, expr))
	return fmt.Sprintf("/graph#%s", strings.Replace(urlData, "+", "%20", -1))
}