package main

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

// AgentConfig holds user-editable settings for the agent.
type AgentConfig struct {
	Server           string `json:"server"`
	HeadscaleURL     string `json:"headscale_url"`
	HeadscaleAuthKey string `json:"headscale_auth_key"`
	NodeID           string `json:"node_id"`
	DataDir          string `json:"data_dir"`
}

const configFileName = "studioE5-config.json"

// defaultConfig returns sensible defaults for a first run.
func defaultConfig(dataDir string) *AgentConfig {
	return &AgentConfig{
		Server:           "ws://localhost:3001",
		HeadscaleURL:     "",
		HeadscaleAuthKey: "",
		NodeID:           defaultNodeID(),
		DataDir:          dataDir,
	}
}

// configPath returns the absolute path to the config file.
func configPath(dataDir string) string {
	return filepath.Join(dataDir, configFileName)
}

// loadOrCreateConfig loads the config file. If it does not exist, it creates
// one with default values and returns it (the caller can then open the settings UI).
func loadOrCreateConfig(dataDir string) (*AgentConfig, bool, error) {
	cp := configPath(dataDir)

	if _, err := os.Stat(cp); err == nil {
		data, err := os.ReadFile(cp)
		if err != nil {
			return nil, false, err
		}
		var cfg AgentConfig
		if err := json.Unmarshal(data, &cfg); err != nil {
			return nil, false, err
		}
		return &cfg, false, nil
	}

	cfg := defaultConfig(dataDir)
	if err := saveConfig(dataDir, cfg); err != nil {
		return nil, true, err
	}
	return cfg, true, nil
}

// saveConfig writes the config file to disk.
func saveConfig(dataDir string, cfg *AgentConfig) error {
	cp := configPath(dataDir)
	data, err := json.MarshalIndent(cfg, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(cp, data, 0644)
}