package downloader

import (
	"os"
	"strconv"
	"time"
)

// Config holds downloader configuration, loaded from environment variables.
type Config struct {
	// DataDir is the directory for storing dataset files and temporary GRIB data.
	DataDir string

	// Parallel is the maximum number of concurrent GRIB downloads.
	Parallel int

	// UpdateInterval is how often the scheduler checks for new forecast data.
	UpdateInterval time.Duration

	// DatasetTTL is how long a dataset is considered fresh before a new one is needed.
	DatasetTTL time.Duration
}

// DefaultConfig returns the default configuration.
func DefaultConfig() *Config {
	return &Config{
		DataDir:        "/tmp/predictor-data",
		Parallel:       8,
		UpdateInterval: 6 * time.Hour,
		DatasetTTL:     48 * time.Hour,
	}
}

// LoadConfig loads configuration from environment variables, falling back to defaults.
func LoadConfig() *Config {
	cfg := DefaultConfig()

	if v := os.Getenv("PREDICTOR_DATA_DIR"); v != "" {
		cfg.DataDir = v
	}
	if v := os.Getenv("PREDICTOR_DOWNLOAD_PARALLEL"); v != "" {
		if n, err := strconv.Atoi(v); err == nil && n > 0 {
			cfg.Parallel = n
		}
	}
	if v := os.Getenv("PREDICTOR_UPDATE_INTERVAL"); v != "" {
		if d, err := time.ParseDuration(v); err == nil {
			cfg.UpdateInterval = d
		}
	}
	if v := os.Getenv("PREDICTOR_DATASET_TTL"); v != "" {
		if d, err := time.ParseDuration(v); err == nil {
			cfg.DatasetTTL = d
		}
	}

	return cfg
}