nix-amer/internal/instruction/set.go

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package instruction
import (
"fmt"
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"github.com/xdrm-brackets/nix-amer/internal/cnf"
"os"
"strings"
)
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// ErrCannotSet is raised when there is an error trying to update
// a field
var ErrCannotSet = fmt.Errorf("cannot set the field")
type set struct {
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raw string
// File is the path to the file
File string
// Path is the configuration field path
Path string
// Value if the value to add or update
Value string
// Format is the configuration format in use
Format *cnf.ConfigurationFormat
}
func (d *set) Raw() string { return strings.Join([]string{"set", d.raw}, " ") }
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func (d *set) Build(_args string) error {
// 1. extract action (sub command)
split := strings.Fields(_args)
// 2. check path
if len(split) < 2 {
return fmt.Errorf("missing configuration path")
}
path := split[0]
value := strings.Join(split[1:], "")
// 3. check path separator
splitPath := strings.Split(path, "@")
if len(splitPath) > 2 {
return fmt.Errorf("invalid path (additional '@'?)")
}
d.File = splitPath[0]
if len(splitPath) > 1 { // add field path only if set
d.Path = splitPath[1]
}
// add value
d.Value = value
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d.raw = _args
return nil
}
func (d set) Exec(ctx ExecutionContext) ([]byte, error) {
// 1. get file / alias
path := d.File
if !strings.Contains(path, "/") {
if p, exists := ctx.Alias[path]; exists {
path = p
}
}
// 2. fail if file not found
if _, err := os.Stat(path); os.IsNotExist(err) {
return nil, fmt.Errorf("cannot find file '%s'", path)
}
// 3. try to load format
format, err := cnf.Load(path)
if err != nil {
return nil, err
}
// 4. try to update value
if !format.Set(d.Path, d.Value) {
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return nil, ErrCannotSet
}
// 5. Update file
file, err := os.OpenFile(path, os.O_WRONLY, 0)
if err != nil {
return nil, err
}
defer file.Close()
if _, err = format.WriteTo(file); err != nil {
return nil, err
}
return nil, nil
}