package configuration

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

var errCfg = errors.New("configuration")

// Config is a configuration controlling structure.
type Config struct {
	RSS     *RSS     `json:"rss"`
	Outputs *Outputs `json:"outputs"`
}

// New creates new configuration controller.
func New(path string) (*Config, error) {
	cfg := &Config{}

	// Get configuration file real path.
	userHomeDir, err := os.UserHomeDir()
	if err != nil {
		return nil, fmt.Errorf("%w: parse configuration file: get real path: get user home dir: %w", errCfg, err)
	}

	path = strings.Replace(path, "~", userHomeDir, 1)

	absPath, err := filepath.Abs(path)
	if err != nil {
		return nil, fmt.Errorf("%w: parse configuration file: get real path: get absolute path: %w", errCfg, err)
	}

	cfgFileData, err := os.ReadFile(absPath)
	if err != nil {
		return nil, fmt.Errorf("%w: parse configuration file: read file: %w", errCfg, err)
	}

	if err := json.Unmarshal(cfgFileData, cfg); err != nil {
		return nil, fmt.Errorf("%w: parse configuration file: %w", errCfg, err)
	}

	// Validate configuration.
	if err := cfg.Validate(); err != nil {
		return nil, fmt.Errorf("%w: %w", errCfg, err)
	}

	return cfg, nil
}

// Validate validates app configuration.
func (c *Config) Validate() error {
	if err := c.RSS.Validate(); err != nil {
		return fmt.Errorf("validate configuration: %w", err)
	}

	return nil
}