vorteil/vorteil

package vdisk

/**
 * SPDX-License-Identifier: Apache-2.0
 * Copyright 2020 vorteil.io Pty Ltd
 */

import (
    "fmt"
    "sort"

    "github.com/vorteil/vorteil/pkg/elog"
    "github.com/vorteil/vorteil/pkg/ext"
    "github.com/vorteil/vorteil/pkg/vimg"
    "github.com/vorteil/vorteil/pkg/vio"
)

func init() {

    if len(FilesystemCompilers()) != 0 {
        return
    }

    fn := func(log elog.Logger, tree vio.FileTree, args interface{}) (vimg.FSCompiler, error) {
        return ext.NewCompiler(&ext.CompilerArgs{
            Logger:   log,
            FileTree: tree,
        }), nil
    }

    err := RegisterFilesystemCompiler("", fn)
    if err != nil {
        panic(err)
    }

    err = RegisterFilesystemCompiler("ext", fn)
    if err != nil {
        panic(err)
    }

    err = RegisterFilesystemCompiler("ext2", fn)
    if err != nil {
        panic(err)
    }

}

// FSCompilerInstantiator is a function that returns a new file-system compiler
// when provided with common arguments (any uncommon arguments can be passed
// through 'args').
type FSCompilerInstantiator func(log elog.Logger, tree vio.FileTree, args interface{}) (vimg.FSCompiler, error)

var registeredFSCompilers map[string]FSCompilerInstantiator

// RegisterFilesystemCompiler registers a FSCompilerInstantiator with a given
// name.
func RegisterFilesystemCompiler(name string, fn FSCompilerInstantiator) error {

    if registeredFSCompilers == nil {
        registeredFSCompilers = make(map[string]FSCompilerInstantiator)
    }

    if _, exists := registeredFSCompilers[name]; exists {
        return fmt.Errorf("refusing to register file-system compiler '%s': already registered", name)
    }

    registeredFSCompilers[name] = fn
    return nil

}

// FilesystemCompilers returns an alphabetised list of all registered
// file-system compilers. Note that a single compiler may appear multiple times
// in the list under different names.
func FilesystemCompilers() []string {

    var names = []string{}

    if registeredFSCompilers == nil {
        return names
    }

    for k := range registeredFSCompilers {
        names = append(names, k)
    }

    sort.Strings(names)
    return names

}

// DeregisterFilesystemCompiler deregisters a FSCompilerInstantiator for the
// given name.
func DeregisterFilesystemCompiler(name string) error {

    if registeredFSCompilers != nil {
        if _, exists := registeredFSCompilers[name]; exists {
            delete(registeredFSCompilers, name)
            return nil
        }
    }

    return fmt.Errorf("file-system compiler '%s' not found", name)

}

// NewFilesystemCompiler returns a vimg.FSCompiler object that can be used to
// start a Vorteil image build, if the named file-system compiler has been
// registered.
func NewFilesystemCompiler(name string, log elog.Logger, tree vio.FileTree, args interface{}) (vimg.FSCompiler, error) {

    fn, exists := registeredFSCompilers[name]
    if !exists {
        return nil, fmt.Errorf("file-system compiler '%s' not found", name)
    }

    return fn(log, tree, args)

}