/*
Copyright 2021 The Kubernetes Authors.

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 process

import (
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

const (
	// EnvAssetsPath is the environment variable that stores the global test
	// binary location override.
	EnvAssetsPath = "KUBEBUILDER_ASSETS"
	// EnvAssetOverridePrefix is the environment variable prefix for per-binary
	// location overrides.
	EnvAssetOverridePrefix = "TEST_ASSET_"
	// AssetsDefaultPath is the default location to look for test binaries in,
	// if no override was provided.
	AssetsDefaultPath = "/usr/local/kubebuilder/bin"
)

// BinPathFinder finds the path to the given named binary, using the following locations
// in order of precedence (highest first).  Notice that the various env vars only need
// to be set -- the asset is not checked for existence on the filesystem.
//
// 1. TEST_ASSET_{tr/a-z-/A-Z_/} (if set; asset overrides -- EnvAssetOverridePrefix)
// 1. KUBEBUILDER_ASSETS (if set; global asset path -- EnvAssetsPath)
// 3. assetDirectory (if set; per-config asset directory)
// 4. /usr/local/kubebuilder/bin (AssetsDefaultPath).
func BinPathFinder(symbolicName, assetDirectory string) (binPath string) {
	punctuationPattern := regexp.MustCompile("[^A-Z0-9]+")
	sanitizedName := punctuationPattern.ReplaceAllString(strings.ToUpper(symbolicName), "_")
	leadingNumberPattern := regexp.MustCompile("^[0-9]+")
	sanitizedName = leadingNumberPattern.ReplaceAllString(sanitizedName, "")
	envVar := EnvAssetOverridePrefix + sanitizedName

	// TEST_ASSET_XYZ
	if val, ok := os.LookupEnv(envVar); ok {
		return val
	}

	// KUBEBUILDER_ASSETS
	if val, ok := os.LookupEnv(EnvAssetsPath); ok {
		return filepath.Join(val, symbolicName)
	}

	// assetDirectory
	if assetDirectory != "" {
		return filepath.Join(assetDirectory, symbolicName)
	}

	// default path
	return filepath.Join(AssetsDefaultPath, symbolicName)
}