package state

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
)

// State represents the local ship configuration
type State struct {
	DefaultHost string           `json:"default_host,omitempty"`
	Hosts       map[string]*Host `json:"hosts"`
}

// Host represents configuration for a single VPS
type Host struct {
	BaseDomain string `json:"base_domain,omitempty"`
	GitSetup   bool   `json:"git_setup,omitempty"`
}

var validName = regexp.MustCompile(`^[a-z][a-z0-9-]{0,62}$`)

// ValidateName checks that a name is safe for use in shell commands,
// file paths, systemd units, and DNS labels.
func ValidateName(name string) error {
	if !validName.MatchString(name) {
		return fmt.Errorf("invalid name %q: must start with a lowercase letter, contain only lowercase letters, digits, and hyphens, and be 1-63 characters", name)
	}
	return nil
}

// Load reads state from ~/.config/ship/state.json
func Load() (*State, error) {
	path := statePath()

	if _, err := os.Stat(path); os.IsNotExist(err) {
		return &State{
			Hosts: make(map[string]*Host),
		}, nil
	}

	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("failed to read state file: %w", err)
	}

	var state State
	if err := json.Unmarshal(data, &state); err != nil {
		return nil, fmt.Errorf("failed to parse state file: %w", err)
	}

	if state.Hosts == nil {
		state.Hosts = make(map[string]*Host)
	}

	return &state, nil
}

// Save writes state to ~/.config/ship/state.json
func (s *State) Save() error {
	path := statePath()

	dir := filepath.Dir(path)
	if err := os.MkdirAll(dir, 0755); err != nil {
		return fmt.Errorf("failed to create config directory: %w", err)
	}

	data, err := json.MarshalIndent(s, "", "  ")
	if err != nil {
		return fmt.Errorf("failed to marshal state: %w", err)
	}

	if err := os.WriteFile(path, data, 0600); err != nil {
		return fmt.Errorf("failed to write state file: %w", err)
	}

	return nil
}

// GetHost returns the host config, creating it if it doesn't exist
func (s *State) GetHost(host string) *Host {
	if s.Hosts[host] == nil {
		s.Hosts[host] = &Host{}
	}
	return s.Hosts[host]
}

// GetDefaultHost returns the default host, or empty string if not set
func (s *State) GetDefaultHost() string {
	return s.DefaultHost
}

// SetDefaultHost sets the default host
func (s *State) SetDefaultHost(host string) {
	s.DefaultHost = host
}

func statePath() string {
	home, err := os.UserHomeDir()
	if err != nil {
		return ".ship-state.json"
	}
	return filepath.Join(home, ".config", "ship", "state.json")
}