package libraries

import (
	"errors"
	"os"
	"path/filepath"
	"strings"

	"ddc/internal/diskspace"
)

var ErrUnknownDestination = errors.New("destination is not a first level folder of a library root")

type Destination struct {
	Name      string `json:"name"`
	Root      string `json:"root"`
	Path      string `json:"path"`
	FreeBytes int64  `json:"freeBytes"`
}

func Discover(roots []string) []Destination {
	destinations := []Destination{}
	for _, root := range roots {
		entries, err := os.ReadDir(root)
		if err != nil {
			continue
		}
		for _, entry := range entries {
			if !entry.IsDir() || strings.HasPrefix(entry.Name(), ".") {
				continue
			}
			path := filepath.Join(root, entry.Name())
			freeBytes, err := diskspace.Available(path)
			if err != nil {
				freeBytes = -1
			}
			destinations = append(destinations, Destination{
				Name:      entry.Name(),
				Root:      root,
				Path:      path,
				FreeBytes: freeBytes,
			})
		}
	}
	return destinations
}

func Resolve(roots []string, requested string) (Destination, error) {
	cleaned := filepath.Clean(requested)
	name := filepath.Base(cleaned)
	if strings.HasPrefix(name, ".") {
		return Destination{}, ErrUnknownDestination
	}

	for _, root := range roots {
		if filepath.Dir(cleaned) != root {
			continue
		}
		info, err := os.Lstat(cleaned)
		if err != nil || !info.IsDir() {
			return Destination{}, ErrUnknownDestination
		}
		return Destination{Name: name, Root: root, Path: cleaned}, nil
	}
	return Destination{}, ErrUnknownDestination
}