package file

// Contract: Be a service layer for data storage and retrieval
// see validation.go for details on json.

import (
	"encoding/json"
	"fmt"
	"io/fs"
	"os"
	"path"
	"strings"

	rulesengine "edge-infra.dev/pkg/sds/emergencyaccess/rules"

	"github.com/go-logr/logr"
)

const (
	defaultRolesName = "default"
)

type Dataset struct {
	rootDir       string
	log           logr.Logger
	bannerRoleMap map[string]map[string][]string
	rulesengine.Dataset
}

// New generates a new dataset struct by loading all json files under the input directory and stores it as a map in memory.
func New(log logr.Logger, dir string) (Dataset, error) {
	ds := Dataset{
		rootDir:       dir,
		log:           log,
		bannerRoleMap: map[string]map[string][]string{},
	}
	// loadfiles checks if rootdir is correct and no duplicate bannerids exist
	return ds, ds.loadFiles()
}

func (ds *Dataset) loadFiles() error {
	dirEntries, err := os.ReadDir(ds.rootDir)
	if err != nil {
		return err
	}
	for _, dirEntry := range dirEntries {
		var vals jsonData
		if dirEntry.IsDir() {
			continue
		}
		if !strings.HasSuffix(dirEntry.Name(), ".json") {
			continue
		}
		err := ds.parseJSONFile(dirEntry, &vals)
		if err != nil {
			ds.log.Error(err, "error when parsing file", "file", dirEntry.Name())
			continue
		}

		if _, exists := ds.bannerRoleMap[vals.BannerID]; exists {
			// continuing with load here would result in unpredictable behaviour depending on what order the file are loaded in
			return fmt.Errorf("cannot overwrite unique id %s", vals.BannerID)
		}
		ds.bannerRoleMap[vals.BannerID] = vals.Roles
	}
	return nil
}

func (ds Dataset) parseJSONFile(dirEntry fs.DirEntry, vals *jsonData) error {
	file, err := os.ReadFile(path.Join(ds.rootDir, dirEntry.Name()))
	if err != nil {
		return err
	}
	return json.Unmarshal(file, vals)
}