package environment

import (
	"bytes"
	"context"
	"io"
	"io/fs"
	"os"

	"github.com/tkw1536/goprogram/stream"
)

// ExecCommandError is returned by Exec when a command could not be executed.
// This typically hints that the executable cannot be found, but may have other causes.
const ExecCommandError = 127

// ExecCommandErrorFunc always returns ExecCommandError.
func ExecCommandErrorFunc() int {
	return ExecCommandError
}

// DefaultFilePerm is the default mode to use for files
const DefaultFilePerm fs.FileMode = 0666

// DefaultDirPerm is the default mode to use for directories
const DefaultDirPerm fs.FileMode = fs.ModeDir | fs.ModePerm

// IsExist checks if the provided error represents a 'does not exist' errror
func IsExist(err error) bool {
	return os.IsExist(err)
}

// IsNotExist checks if the provided error represents a 'does exist' error
func IsNotExist(err error) bool {
	return os.IsNotExist(err)
}

// WriteFile is like [os.WriteFile].
func WriteFile(env Environment, path string, data []byte, mode fs.FileMode) error {
	handle, err := env.Create(path, mode)
	if err != nil {
		return err
	}
	defer handle.Close()

	if _, err := handle.Write(data); err != nil {
		return err
	}

	return nil
}

// ReadFile is like [os.ReadFile]
func ReadFile(env Environment, path string) ([]byte, error) {
	// open the file!
	file, err := env.Open(path)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	// copy everything into a buffer!
	var buffer bytes.Buffer
	if _, err := io.Copy(&buffer, file); err != nil {
		return nil, err
	}

	// return the buffer contents!
	return buffer.Bytes(), nil
}

// MustExec is like Exec, except that it returns true if the command exited successfully, and else false.
func MustExec(ctx context.Context, env Environment, io stream.IOStream, workdir string, exe string, argv ...string) bool {
	return env.Exec(ctx, io, workdir, exe, argv...)() == 0
}