package repository

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

	"github.com/spf13/viper"

	"git.kplus.net.ua/yevhen/resource-scraper/types/resource"
)

// srrdbNormalizedPath turns a search path into a file name. The two characters
// that carry structure in a path are swapped for look-alikes, so the name still
// reads as the query it came from and can be reversed character by character.
func srrdbNormalizedPath(uri string) string {
	return strings.NewReplacer(":", "：", "/", "∕").Replace(uri) + ".json"
}

// srrdbDumpPath is the guard file of a search path inside srrdb.dump_dir.
func srrdbDumpPath(uri string) string {
	return filepath.Join(viper.GetString("srrdb.dump_dir"), srrdbNormalizedPath(uri))
}

// srrdbExists reports whether a dump file is present. Any stat failure other than
// "not found" is returned as an error: treating it as absent would let the run
// overwrite a dump it has no right to read.
func srrdbExists(path string) (bool, error) {
	_, err := os.Stat(path)

	switch {
	case err == nil:
		return true, nil
	case errors.Is(err, fs.ErrNotExist):
		return false, nil
	default:
		return false, fmt.Errorf("stat srrdb dump %q: %w", path, err)
	}
}

// srrdbWriteDump stores the merged answer as indented JSON. It runs only after
// the database is updated, therefore the presence of the file means the whole
// run completed.
//
// The directory is never created here: it holds the cursor of the walk and is made
// once by hand, like the database file.
func srrdbWriteDump(path string, all *resource.SrrdbSearchResponse) error {
	data, err := json.MarshalIndent(all, "", "  ")
	if err != nil {
		return fmt.Errorf("encode srrdb dump %q: %w", path, err)
	}

	if err := os.WriteFile(path, data, 0o644); err != nil {
		return fmt.Errorf("write srrdb dump %q: %w", path, err)
	}

	return nil
}