package config

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

	"gopkg.in/yaml.v3"
)

// Config represents the root configuration of the proxy.
type Config struct {
	HTTP HTTPConfig `yaml:"http" json:"http"`
	TCP  TCPConfig  `yaml:"tcp" json:"tcp"`
	UDP  UDPConfig  `yaml:"udp" json:"udp"`
}

type UDPConfig struct {
	Port    int    `yaml:"port" json:"port"`
	Backend string `yaml:"backend" json:"backend"`
}

type HTTPConfig struct {
	Port    int           `yaml:"port" json:"port"`
	TLS     TLSConfig     `yaml:"tls" json:"tls"`
	Routers []RouterRoute `yaml:"routers" json:"routers"`
}

type TLSConfig struct {
	Enabled  bool   `yaml:"enabled" json:"enabled"`
	Port     int    `yaml:"port" json:"port"`
	CertFile string `yaml:"cert_file" json:"cert_file"`
	KeyFile  string `yaml:"key_file" json:"key_file"`
}

type TCPConfig struct {
	Port    int    `yaml:"port" json:"port"`
	Backend string `yaml:"backend" json:"backend"`
}

type RouterRoute struct {
	Path        string   `yaml:"path" json:"path"`
	Host        string   `yaml:"host" json:"host"`
	Backends    []string `yaml:"backends" json:"backends"`       // Used for Load Balancing
	BackendURL  string   `yaml:"backend_url" json:"backend_url"` // Legacy / Single backend
	StripPrefix bool     `yaml:"strip_prefix" json:"strip_prefix"`
}

// LoadConfig reads a configuration file (YAML or JSON) and parses it into the Config struct.
func LoadConfig(path string) (*Config, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, fmt.Errorf("failed to open config file: %w", err)
	}
	defer file.Close()

	var cfg Config
	ext := filepath.Ext(path)
	
	switch ext {
	case ".yaml", ".yml":
		decoder := yaml.NewDecoder(file)
		if err := decoder.Decode(&cfg); err != nil {
			return nil, fmt.Errorf("failed to parse yaml config: %w", err)
		}
	case ".json":
		decoder := json.NewDecoder(file)
		if err := decoder.Decode(&cfg); err != nil {
			return nil, fmt.Errorf("failed to parse json config: %w", err)
		}
	default:
		return nil, fmt.Errorf("unsupported config format: %s", ext)
	}

	return &cfg, nil
}