package mock

import (
	"os"
	"strings"
)

// Env mocking

// MockEnvValue will store old env value, set new val. will restore old value on end.
func MockEnvValue(key, val string, fn func(nv string)) {
	old := os.Getenv(key)
	err := os.Setenv(key, val)
	if err != nil {
		panic(err)
	}

	fn(os.Getenv(key))

	// if old is empty, unset key.
	if old == "" {
		err = os.Unsetenv(key)
	} else {
		err = os.Setenv(key, old)
	}
	if err != nil {
		panic(err)
	}
}

// MockEnvValues will store old env value, set new val. will restore old value on end.
func MockEnvValues(kvMap map[string]string, fn func()) {
	backups := make(map[string]string, len(kvMap))

	for key, val := range kvMap {
		backups[key] = os.Getenv(key)
		_ = os.Setenv(key, val)
	}

	fn()

	for key := range kvMap {
		if old := backups[key]; old == "" {
			_ = os.Unsetenv(key)
		} else {
			_ = os.Setenv(key, old)
		}
	}
}

// MockOsEnvByText by env text string.
// will clear all old ENV data, use given data map.
// will recover old ENV after fn run.
func MockOsEnvByText(envText string, fn func()) {
	ss := strings.Split(envText, "\n")
	mp := make(map[string]string, len(ss))

	for _, line := range ss {
		if line = strings.TrimSpace(line); line == "" {
			continue
		}
		nodes := strings.SplitN(line, "=", 2)
		envKey := strings.TrimSpace(nodes[0])

		if len(nodes) < 2 {
			mp[envKey] = ""
		} else {
			mp[envKey] = strings.TrimSpace(nodes[1])
		}
	}

	MockCleanOsEnv(mp, fn)
}

// MockOsEnv by env map data. alias of MockCleanOsEnv
func MockOsEnv(mp map[string]string, fn func()) {
	MockCleanOsEnv(mp, fn)
}

// backup os ENV
var envBak = os.Environ()

// ClearOSEnv info.
//
// Usage:
//
//	testutil.ClearOSEnv()
//	defer testutil.RevertOSEnv()
//	// do something ...
func ClearOSEnv() { os.Clearenv() }

// RevertOSEnv info
func RevertOSEnv() {
	os.Clearenv()
	for _, str := range envBak {
		nodes := strings.SplitN(str, "=", 2)
		_ = os.Setenv(nodes[0], nodes[1])
	}
}

// MockCleanOsEnv by env map data.
//
// will clear all old ENV data, use given data map.
// will recover old ENV after fn run.
func MockCleanOsEnv(mp map[string]string, fn func()) {
	os.Clearenv()
	for key, val := range mp {
		_ = os.Setenv(key, val)
	}

	fn()

	os.Clearenv()
	for _, str := range envBak {
		nodes := strings.SplitN(str, "=", 2)
		_ = os.Setenv(nodes[0], nodes[1])
	}
}