// Copyright © 2017 Aqua Security Software Ltd. <info@aquasec.com>
//
// 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 check

import (
	"fmt"
	"os"
	"regexp"
	"strconv"
	"strings"
)

// test:
// flag: OPTION
// set: (true|false)
// compare:
//   op: (eq|gt|gte|lt|lte|has)
//   value: val

type binOp string

const (
	and binOp = "and"
	or        = "or"
)

type testItem struct {
	Flag    string
	Value   string
	Set     bool
	Compare compare
}

type compare struct {
	Op    string
	Value string
}

func (t *testItem) execute(s string) (result bool) {
	result = false
	match := strings.Contains(s, t.Flag)

	if t.Set {
		var flagVal string
		isset := match

		if isset && t.Compare.Op != "" {
			pttn := t.Flag + `=(\S*) *`
			flagRe := regexp.MustCompile(pttn)
			vals := flagRe.FindStringSubmatch(s)

			if len(vals) > 0 {
				flagVal = vals[1]
			} else {
				fmt.Fprintf(os.Stderr, "expected value for %s but none found\n", t.Flag)
				os.Exit(1)
			}

			switch t.Compare.Op {
			case "eq":
				result = flagVal == t.Compare.Value

			case "noteq":
				result = !(flagVal == t.Compare.Value)

			case "gt":
				a, b := toNumeric(flagVal, t.Compare.Value)
				result = a > b

			case "gte":
				a, b := toNumeric(flagVal, t.Compare.Value)
				result = a >= b

			case "lt":
				a, b := toNumeric(flagVal, t.Compare.Value)
				result = a < b

			case "lte":
				a, b := toNumeric(flagVal, t.Compare.Value)
				result = a <= b

			case "has":
				result = strings.Contains(flagVal, t.Compare.Value)

			case "nothave":
				result = !strings.Contains(flagVal, t.Compare.Value)
			}
		} else {
			result = isset
		}

	} else {
		notset := !match
		result = notset
	}

	return
}

type tests struct {
	TestItems []*testItem `yaml:"test_items"`
	BinOp     binOp       `yaml:"bin_op"`
}

func (ts *tests) execute(s string) (result bool) {
	res := make([]bool, len(ts.TestItems))

	for i, t := range ts.TestItems {
		res[i] = t.execute(s)
	}

	// If no binary operation is specified, default to AND
	switch ts.BinOp {
	default:
		fmt.Fprintf(os.Stderr, "unknown binary operator for tests %s\n", ts.BinOp)
		os.Exit(1)
	case and, "":
		result = true
		for i := range res {
			result = result && res[i]
		}
	case or:
		result = false
		for i := range res {
			result = result || res[i]
		}
	}

	return
}

func toNumeric(a, b string) (c, d int) {
	var err error
	c, err = strconv.Atoi(a)
	if err != nil {
		fmt.Fprintf(os.Stderr, "error converting %s: %s\n", a, err)
		os.Exit(1)
	}
	d, err = strconv.Atoi(b)
	if err != nil {
		fmt.Fprintf(os.Stderr, "error converting %s: %s\n", b, err)
		os.Exit(1)
	}

	return c, d
}