package discovery

import (
	"crypto/sha256"
	"io"
	"os"
)

// PluginMeta is metadata about a plugin, useful for launching the plugin
// and for understanding which plugins are available.
type PluginMeta struct {
	// Name is the name of the plugin, e.g. as inferred from the plugin
	// binary's filename, or by explicit configuration.
	Name string

	// Version is the semver version of the plugin, expressed as a string
	// that might not be semver-valid.
	Version VersionStr

	// Path is the absolute path of the executable that can be launched
	// to provide the RPC server for this plugin.
	Path string
}

// SHA256 returns a SHA256 hash of the content of the referenced executable
// file, or an error if the file's contents cannot be read.
func (m PluginMeta) SHA256() ([]byte, error) {
	f, err := os.Open(m.Path)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	h := sha256.New()
	_, err = io.Copy(h, f)
	if err != nil {
		return nil, err
	}

	return h.Sum(nil), nil
}