/*
Copyright 2026 The Flux 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 plugin

const (
	SkipReasonManual   = "manually installed"
	SkipReasonUpToDate = "already up to date"
)

// UpdateResult represents the outcome of updating a single plugin.
// When an update is available, Manifest, Version and Platform are
// populated so the caller can install without re-fetching or re-resolving.
type UpdateResult struct {
	Name        string
	FromVersion string
	ToVersion   string
	Skipped     bool
	SkipReason  string
	Manifest    *PluginManifest
	Version     *PluginVersion
	Platform    *PluginPlatform
	Err         error
}

// CheckUpdate compares the installed version against the latest in the catalog.
// Returns an UpdateResult describing what should happen. When an update is
// available, Manifest is populated so the caller can install without re-fetching.
func CheckUpdate(pluginDir string, name string, catalog *CatalogClient, goos, goarch string) UpdateResult {
	receipt := ReadReceipt(pluginDir, name)
	if receipt == nil {
		return UpdateResult{
			Name:       name,
			Skipped:    true,
			SkipReason: SkipReasonManual,
		}
	}

	manifest, err := catalog.FetchManifest(name)
	if err != nil {
		return UpdateResult{Name: name, Err: err}
	}

	latest, err := ResolveVersion(manifest, "")
	if err != nil {
		return UpdateResult{Name: name, Err: err}
	}

	if receipt.Version == latest.Version {
		return UpdateResult{
			Name:        name,
			FromVersion: receipt.Version,
			ToVersion:   latest.Version,
			Skipped:     true,
			SkipReason:  SkipReasonUpToDate,
		}
	}

	plat, err := ResolvePlatform(latest, goos, goarch)
	if err != nil {
		return UpdateResult{Name: name, Err: err}
	}

	return UpdateResult{
		Name:        name,
		FromVersion: receipt.Version,
		ToVersion:   latest.Version,
		Manifest:    manifest,
		Version:     latest,
		Platform:    plat,
	}
}