package config

import (
	"encoding/json"
	"fmt"
	"os"
)

// Config is the application configuration loaded from JSON.
type Config struct {
	Host      string `json:"host"`
	APIPort   int    `json:"api_port"`
	AdminPort int    `json:"admin_port"`

	// Port is deprecated; mapped to APIPort when api_port is unset.
	Port int `json:"port"`
}

// Default returns sensible defaults when no config file is used.
func Default() *Config {
	return &Config{
		Host:      "127.0.0.1",
		APIPort:   8080,
		AdminPort: 8081,
	}
}

// Load reads and parses a JSON config file from path.
func Load(path string) (*Config, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read config: %w", err)
	}

	cfg := Default()
	if err := json.Unmarshal(data, cfg); err != nil {
		return nil, fmt.Errorf("parse config: %w", err)
	}

	cfg.applyLegacyPort()
	return cfg, nil
}

func (c *Config) applyLegacyPort() {
	if c.Port != 0 && c.APIPort == 8080 {
		c.APIPort = c.Port
	}
}

func (c *Config) APIAddr() string {
	return fmt.Sprintf("%s:%d", c.Host, c.APIPort)
}

func (c *Config) AdminAddr() string {
	return fmt.Sprintf("%s:%d", c.Host, c.AdminPort)
}