//
// Copyright 2024 CloudWeGo 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 obj

import (
    `fmt`
    `io`
    `os`
)

// Format represents the saved binary file format.
type Format int

const (
    // ELF indicates it should be saved as an ELF binary.
    ELF Format = iota

    // MachO indicates it should be saved as a Mach-O binary.
    MachO
)

var formatTab = [...]func(w io.Writer, code []byte, base uint64, entry uint64) error {
    ELF   : nil,
    MachO : assembleMachO,
}

var formatNames = map[Format]string {
    ELF   : "ELF",
    MachO : "Mach-O",
}

// String returns the name of a specified format.
func (self Format) String() string {
    if v, ok := formatNames[self]; ok {
        return v
    } else {
        return fmt.Sprintf("Format(%d)", self)
    }
}

// Write assembles a binary executable.
func (self Format) Write(w io.Writer, code []byte, base uint64, entry uint64) error {
    if self >= 0 && int(self) < len(formatTab) && formatTab[self] != nil {
        return formatTab[self](w, code, base, entry)
    } else {
        return fmt.Errorf("unsupported format: %s", self)
    }
}

// Generate generates a binary executable file from the specified code.
func (self Format) Generate(name string, code []byte, base uint64, entry uint64) error {
    var fp *os.File
    var err error

    /* create the output file */
    if fp, err = os.Create(name); err != nil {
        return err
    }

    /* generate the code */
    if err = self.Write(fp, code, base, entry); err != nil {
        _ = fp.Close()
        _ = os.Remove(name)
        return err
    }

    /* close the file and make it executable */
    _ = fp.Close()
    _ = os.Chmod(name, 0755)
    return nil
}