package library

import (
	"fmt"
	"os"
	"path/filepath"

	"github.com/arnef/toni-sync/internal/tonieapi"
)

// ScaffoldClient is the subset of tonieapi.Client needed to scaffold a library folder tree.
type ScaffoldClient interface {
	GetHouseholds() ([]tonieapi.Household, error)
	GetCreativeTonies(householdID string) ([]tonieapi.CreativeTonie, error)
}

// ScaffoldResult reports what Scaffold did for a single tonie.
type ScaffoldResult struct {
	HouseholdID string
	TonieID     string
	Name        string
	Folder      string
	Created     bool // false if a matching folder already existed and was left untouched
}

// Scaffold creates the "<root>/<household_id>/<name> [id=<tonie_id>]" folder
// structure for every household and Kreativ-Tonie on the account. Existing
// tonie folders (matched by id, regardless of the current display name) are
// left untouched so local audio files are never affected.
func Scaffold(client ScaffoldClient, root string) ([]ScaffoldResult, error) {
	households, err := client.GetHouseholds()
	if err != nil {
		return nil, err
	}

	var results []ScaffoldResult
	for _, h := range households {
		householdPath := filepath.Join(root, h.ID)
		if err := os.MkdirAll(householdPath, 0o755); err != nil {
			return nil, fmt.Errorf("creating household folder %s: %w", householdPath, err)
		}

		existingByID, err := existingTonieFoldersByID(householdPath)
		if err != nil {
			return nil, err
		}

		tonies, err := client.GetCreativeTonies(h.ID)
		if err != nil {
			return nil, err
		}

		for _, t := range tonies {
			if existingDir, ok := existingByID[t.ID]; ok {
				results = append(results, ScaffoldResult{
					HouseholdID: h.ID,
					TonieID:     t.ID,
					Name:        t.Name,
					Folder:      filepath.Join(householdPath, existingDir),
					Created:     false,
				})
				continue
			}

			dirName := DirName(t.Name, t.ID)
			tonieFolder := filepath.Join(householdPath, dirName)
			if err := os.MkdirAll(tonieFolder, 0o755); err != nil {
				return nil, fmt.Errorf("creating tonie folder %s: %w", tonieFolder, err)
			}
			results = append(results, ScaffoldResult{
				HouseholdID: h.ID,
				TonieID:     t.ID,
				Name:        t.Name,
				Folder:      tonieFolder,
				Created:     true,
			})
		}
	}
	return results, nil
}

// existingTonieFoldersByID maps tonie id -> existing folder name within a household folder.
func existingTonieFoldersByID(householdPath string) (map[string]string, error) {
	entries, err := os.ReadDir(householdPath)
	if err != nil {
		return nil, fmt.Errorf("reading household folder %s: %w", householdPath, err)
	}
	byID := make(map[string]string)
	for _, e := range entries {
		if !e.IsDir() {
			continue
		}
		if _, id, ok := ParseTonieDir(e.Name()); ok {
			byID[id] = e.Name()
		}
	}
	return byID, nil
}