package main

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

type Project struct {
	Name        string
	Path        string
	Description string
	HasReadme   bool
}

// ListProjects returns a sorted list of projects from the given directory.
// Only directories are considered projects. Hidden directories (starting with .)
// are excluded.
func ListProjects(projectsPath string) ([]Project, error) {
	entries, err := os.ReadDir(projectsPath)
	if err != nil {
		return nil, err
	}

	var projects []Project
	for _, e := range entries {
		if !e.IsDir() {
			continue
		}
		name := e.Name()
		if strings.HasPrefix(name, ".") {
			continue
		}

		p := Project{
			Name: name,
			Path: filepath.Join(projectsPath, name),
		}

		// Try to read description from README.md first line
		readmePath := filepath.Join(p.Path, "README.md")
		if data, err := os.ReadFile(readmePath); err == nil {
			p.HasReadme = true
			lines := strings.SplitN(string(data), "\n", 3)
			for _, line := range lines {
				line = strings.TrimSpace(line)
				line = strings.TrimLeft(line, "# ")
				if line != "" {
					p.Description = line
					break
				}
			}
		}

		projects = append(projects, p)
	}

	sort.Slice(projects, func(i, j int) bool {
		return projects[i].Name < projects[j].Name
	})

	return projects, nil
}

var validProjectName = regexp.MustCompile(`^[a-zA-Z0-9][a-zA-Z0-9_-]*$`)

// CreateProject creates a new empty project directory.
// Name must contain only alphanumeric characters, hyphens, and underscores.
func CreateProject(projectsPath, name string) error {
	if name == "" {
		return fmt.Errorf("ime projekta ne može biti prazno")
	}

	if !validProjectName.MatchString(name) {
		return fmt.Errorf("ime projekta može sadržati samo slova, brojeve, '-' i '_'")
	}

	path := filepath.Join(projectsPath, name)

	if _, err := os.Stat(path); err == nil {
		return fmt.Errorf("projekat '%s' već postoji", name)
	}

	return os.MkdirAll(path, 0755)
}