// Mgmt
// Copyright (C) James Shubin and the project contributors
// Written by James Shubin <james@shubin.ca> and the project contributors
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//
// Additional permission under GNU GPL version 3 section 7
//
// If you modify this program, or any covered work, by linking or combining it
// with embedded mcl code and modules (and that the embedded mcl code and
// modules which link with this program, contain a copy of their source code in
// the authoritative form) containing parts covered by the terms of any other
// license, the licensors of this program grant you additional permission to
// convey the resulting work. Furthermore, the licensors of this program grant
// the original author, James Shubin, additional permission to update this
// additional permission if he deems it necessary to achieve the goals of this
// additional permission.

package coresys

import (
	"context"
	"os"
	"strings"

	"github.com/purpleidea/mgmt/lang/funcs/simple"
	"github.com/purpleidea/mgmt/lang/types"
)

func init() {
	simple.ModuleRegister(ModuleName, "getenv", &simple.Scaffold{
		I: &simple.Info{
			Pure: false,
			Memo: false,
			Fast: true,
			Spec: false,
		},
		T: types.NewType("func(str) str"),
		F: GetEnv,
	})
	simple.ModuleRegister(ModuleName, "defaultenv", &simple.Scaffold{
		I: &simple.Info{
			Pure: false,
			Memo: false,
			Fast: true,
			Spec: false,
		},
		T: types.NewType("func(str, str) str"),
		F: DefaultEnv,
	})
	simple.ModuleRegister(ModuleName, "hasenv", &simple.Scaffold{
		I: &simple.Info{
			Pure: false,
			Memo: false,
			Fast: true,
			Spec: false,
		},
		T: types.NewType("func(str) bool"),
		F: HasEnv,
	})
	simple.ModuleRegister(ModuleName, "env", &simple.Scaffold{
		I: &simple.Info{
			Pure: false,
			Memo: false,
			Fast: true,
			Spec: false,
		},
		T: types.NewType("func() map{str: str}"),
		F: Env,
	})
}

// GetEnv gets environment variable by name or returns empty string if non
// existing.
func GetEnv(ctx context.Context, input []types.Value) (types.Value, error) {
	return &types.StrValue{
		V: os.Getenv(input[0].Str()),
	}, nil
}

// DefaultEnv gets environment variable by name or returns default if non
// existing.
func DefaultEnv(ctx context.Context, input []types.Value) (types.Value, error) {
	value, exists := os.LookupEnv(input[0].Str())
	if !exists {
		value = input[1].Str()
	}
	return &types.StrValue{
		V: value,
	}, nil
}

// HasEnv returns true if environment variable exists.
func HasEnv(ctx context.Context, input []types.Value) (types.Value, error) {
	_, exists := os.LookupEnv(input[0].Str())
	return &types.BoolValue{
		V: exists,
	}, nil
}

// Env returns a map of all keys and their values.
func Env(ctx context.Context, input []types.Value) (types.Value, error) {
	m := types.NewType("map{str: str}").New().(*types.MapValue)

	for _, keyval := range os.Environ() {
		i := strings.IndexRune(keyval, '=')
		if i == -1 {
			continue
		}

		k := &types.StrValue{V: keyval[:i]}
		v := &types.StrValue{V: keyval[i+1:]}

		if err := m.Set(k, v); err != nil {
			return nil, err
		}
	}

	return m, nil
}
