// Package shares manages the persistent multi-share configuration stored in shares.json.
// Shares are additive to the existing single-dir ShareDir mechanism.
package shares

import (
	"encoding/json"
	"os"
	"path/filepath"
	"sync"
)

// Share describes one shared directory entry.
type Share struct {
	Path     string   `json:"path"`
	Networks []string `json:"networks"` // ["*"] = global (all networks); otherwise list of network IDs
}

// Store manages the shares.json file.
type Store struct {
	mu     sync.RWMutex
	path   string
	shares []Share
}

// Load reads shares.json from dataDir. Returns an empty store if the file doesn't exist.
func Load(dataDir string) (*Store, error) {
	s := &Store{path: filepath.Join(dataDir, "shares.json")}
	data, err := os.ReadFile(s.path)
	if os.IsNotExist(err) {
		return s, nil
	}
	if err != nil {
		return nil, err
	}
	if err := json.Unmarshal(data, &s.shares); err != nil {
		return nil, err
	}
	return s, nil
}

func (s *Store) save() error {
	data, err := json.MarshalIndent(s.shares, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(s.path, data, 0600)
}

// All returns a copy of all shares.
func (s *Store) All() []Share {
	s.mu.RLock()
	defer s.mu.RUnlock()
	out := make([]Share, len(s.shares))
	copy(out, s.shares)
	return out
}

// ForNetwork returns all shares visible on networkID (global + network-specific).
func (s *Store) ForNetwork(networkID string) []Share {
	s.mu.RLock()
	defer s.mu.RUnlock()
	var out []Share
	for _, sh := range s.shares {
		for _, n := range sh.Networks {
			if n == "*" || n == networkID {
				out = append(out, sh)
				break
			}
		}
	}
	return out
}

// Add adds a share (no-op if path already present). Persists immediately.
func (s *Store) Add(sh Share) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	for i, existing := range s.shares {
		if existing.Path == sh.Path {
			s.shares[i].Networks = sh.Networks
			return s.save()
		}
	}
	s.shares = append(s.shares, sh)
	return s.save()
}

// Remove removes the share with the given path. Persists immediately.
func (s *Store) Remove(path string) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	for i, sh := range s.shares {
		if sh.Path == path {
			s.shares = append(s.shares[:i], s.shares[i+1:]...)
			return s.save()
		}
	}
	return nil
}