package sdlc

import (
	"path/filepath"
	"regexp"
)

const (
	// SDLCDir is the root directory name for SDLC state.
	SDLCDir = ".sdlc"

	// StateFile is the filename for global state.
	StateFile = "state.yaml"

	// ConfigFile is the filename for project config.
	ConfigFile = "config.yaml"

	// FeaturesDir holds per-feature subdirectories.
	FeaturesDir = "features"

	// PatternsDir holds pattern definitions.
	PatternsDir = "patterns"

	// AuditsDir holds audit reports.
	AuditsDir = "audits"

	// BranchesDir holds branch tracking files.
	BranchesDir = "branches"

	// ArchivesDir holds archived (released) features.
	ArchivesDir = "archives"

	// RoadmapDir holds roadmap documents.
	RoadmapDir = "roadmap"

	// ManifestFile is the per-feature metadata file.
	ManifestFile = "manifest.yaml"
)

var slugPattern = regexp.MustCompile(`^[a-z][a-z0-9-]*$`)

// ValidateSlug returns nil if the slug is valid, ErrInvalidSlug otherwise.
func ValidateSlug(slug string) error {
	if slug == "" || len(slug) > 64 || !slugPattern.MatchString(slug) {
		return ErrInvalidSlug
	}
	return nil
}

// SDLCRoot returns the .sdlc directory path within a project root.
func SDLCRoot(root string) string {
	return filepath.Join(root, SDLCDir)
}

// StatePath returns the path to state.yaml.
func StatePath(root string) string {
	return filepath.Join(root, SDLCDir, StateFile)
}

// ConfigPath returns the path to config.yaml.
func ConfigPath(root string) string {
	return filepath.Join(root, SDLCDir, ConfigFile)
}

// FeaturesDirPath returns the features/ directory path.
func FeaturesDirPath(root string) string {
	return filepath.Join(root, SDLCDir, FeaturesDir)
}

// FeatureDir returns the directory for a specific feature.
func FeatureDir(root, slug string) string {
	return filepath.Join(root, SDLCDir, FeaturesDir, slug)
}

// ManifestPath returns the manifest.yaml path for a feature.
func ManifestPath(root, slug string) string {
	return filepath.Join(root, SDLCDir, FeaturesDir, slug, ManifestFile)
}

// ArtifactPath returns the file path for a feature artifact.
func ArtifactPath(root, slug string, artifactType ArtifactType) string {
	filename := ArtifactFilename(artifactType)
	if filename == "" {
		return ""
	}
	return filepath.Join(root, SDLCDir, FeaturesDir, slug, filename)
}

// SubDirs returns all subdirectories that sdlc init creates.
func SubDirs() []string {
	return []string{
		FeaturesDir,
		PatternsDir,
		AuditsDir,
		BranchesDir,
		ArchivesDir,
		RoadmapDir,
	}
}