package loader

import (
	"errors"
	"fmt"
	"galaxy/connector"
	"galaxy/util"
)

func (l *loader) checkAndDownloadPluginVersion() error {
	versions, err := l.connector.CheckVersion()
	if err != nil {
		return err
	} else if latest, ok, err := latestVersion(versions); err != nil {
		return err
	} else if ok {
		return l.preparePluginVersion(latest)
	} else {
		return errors.New("Server did not respond with a suitable client version")
	}
}

// preparePluginVersion fetches and stores given version of plugin artifact, if newer to the current known version.
func (l *loader) preparePluginVersion(v connector.VersionInfo) error {
	s, exists, err := l.loadCurrentState()
	if err != nil {
		return err
	}
	version, err := util.ParseSemver(v.Version)
	if err != nil {
		return err
	}
	if exists {
		currentVersion, err := util.ParseSemver(s.ClientCurrentVersion)
		if err != nil {
			return err
		}
		if util.CompareSemver(currentVersion, version) > 0 {
			return nil
		}
	}
	err = l.downloadPlugin(v.URL, v.Version, v.Checksum)
	if err != nil {
		return err
	}
	return nil
}

// downloadPlugin downloads and stores at the App's local storage with a pre-defined name with semver suffix.
func (l *loader) downloadPlugin(url, version string, checksum [32]byte) error {
	data, err := l.connector.DownloadVersion(url)
	if err != nil {
		return fmt.Errorf("Plugin v%s download error: %w", version, err)
	}
	dataChecksum := SumSHA256(data)
	if !EqualSHA256(checksum, dataChecksum) {
		return errors.New("Downloaded pligin checksum incorrect")
	}
	versionFileName := resolvePluginFile(version)
	versionFileExists, _, err := l.storage.FileExists(versionFileName)
	if err != nil {
		return fmt.Errorf("Check plugin v%s exists error: %w", version, err)
	}
	if versionFileExists {
		storedData, err := l.storage.ReadFile(versionFileName)
		if err != nil {
			return err
		}
		if EqualSHA256(dataChecksum, SumSHA256(storedData)) {
			return nil
		}
		if err := l.storage.DeleteFile(versionFileName); err != nil {
			return fmt.Errorf("Plugin v%s delete error: %w", version, err)
		}
	}
	err = l.storage.WriteFile(versionFileName, data)
	if err != nil {
		return fmt.Errorf("Plugin file write error: %w", err)
	}
	if err := l.setNextVersion(&version); err != nil {
		return err
	}
	return nil
}