package project

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

// Store manages project directories under DataDir/projects.
type Store interface {
	List() ([]Project, error)
	Ensure(id string) error
	Delete(id string) error
}

// DirStore discovers projects as subdirectories of dataDir/projects.
type DirStore struct {
	dataDir string
}

// NewDirStore creates a project store rooted at dataDir.
func NewDirStore(dataDir string) *DirStore {
	return &DirStore{dataDir: dataDir}
}

func (s *DirStore) projectsRoot() string {
	return filepath.Join(s.dataDir, "projects")
}

// List returns all project directories, sorted by name.
func (s *DirStore) List() ([]Project, error) {
	root := s.projectsRoot()
	entries, err := os.ReadDir(root)
	if err != nil {
		if os.IsNotExist(err) {
			return []Project{}, nil
		}
		return nil, fmt.Errorf("list projects: %w", err)
	}

	var projects []Project
	for _, e := range entries {
		if !e.IsDir() {
			continue
		}
		name := e.Name()
		projects = append(projects, Project{ID: name, Name: name})
	}
	sort.Slice(projects, func(i, j int) bool {
		return projects[i].Name < projects[j].Name
	})
	return projects, nil
}

// Ensure creates the project directory if it does not exist.
func (s *DirStore) Ensure(id string) error {
	if id == "" {
		return fmt.Errorf("project id is required")
	}
	dir := filepath.Join(s.projectsRoot(), id)
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return fmt.Errorf("create project %s: %w", id, err)
	}
	return nil
}

// Delete removes the project directory and all of its files.
func (s *DirStore) Delete(id string) error {
	if id == "" {
		return fmt.Errorf("project id is required")
	}
	dir := filepath.Join(s.projectsRoot(), id)
	st, err := os.Stat(dir)
	if err != nil {
		if os.IsNotExist(err) {
			return fmt.Errorf("project %s: not found", id)
		}
		return fmt.Errorf("stat project %s: %w", id, err)
	}
	if !st.IsDir() {
		return fmt.Errorf("project %s: not a directory", id)
	}
	if err := os.RemoveAll(dir); err != nil {
		return fmt.Errorf("delete project %s: %w", id, err)
	}
	return nil
}