// Package config loads and saves hamlet's JSON config file.
package config

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

type Config struct {
	Listen       string `json:"listen"`
	PasswordHash string `json:"password_hash"`

	path string
}

func Default(path string) *Config {
	return &Config{Listen: "127.0.0.1:8100", path: path}
}

// Load reads the config at path. A missing file yields the defaults.
func Load(path string) (*Config, error) {
	c := Default(path)
	b, err := os.ReadFile(path)
	if errors.Is(err, os.ErrNotExist) {
		return c, nil
	}
	if err != nil {
		return nil, err
	}
	if err := json.Unmarshal(b, c); err != nil {
		return nil, fmt.Errorf("parse %s: %w", path, err)
	}
	return c, nil
}

func (c *Config) Path() string    { return c.path }
func (c *Config) DataDir() string { return filepath.Dir(c.path) }

func (c *Config) Save() error {
	if err := os.MkdirAll(c.DataDir(), 0o700); err != nil {
		return err
	}
	b, err := json.MarshalIndent(c, "", "  ")
	if err != nil {
		return err
	}
	tmp := c.path + ".tmp"
	if err := os.WriteFile(tmp, append(b, '\n'), 0o600); err != nil {
		return err
	}
	return os.Rename(tmp, c.path)
}