package config

import (
	"fmt"
	"time"

	"github.com/kelseyhightower/envconfig"
)

// Config holds all application configuration
type Config struct {
	// Database configuration
	DatabaseURL string `envconfig:"DATABASE_URL" required:"true"`

	// Server configuration
	Port int `envconfig:"PORT" default:"8080"`

	// Location configuration
	LocationLat  float64 `envconfig:"LOCATION_LAT" default:"37.7749"`
	LocationLon  float64 `envconfig:"LOCATION_LON" default:"-122.4194"`
	LocationName string  `envconfig:"LOCATION_NAME" default:"San Francisco"`

	// Timezone configuration
	Timezone string `envconfig:"TIMEZONE" default:"America/Los_Angeles"`

	// Weather fetcher configuration
	FetchInterval time.Duration `envconfig:"FETCH_INTERVAL" default:"15m"`

	// Cache configuration
	CacheTTL time.Duration `envconfig:"CACHE_TTL" default:"10m"`
}

// Load reads configuration from environment variables
func Load() (*Config, error) {
	var cfg Config
	if err := envconfig.Process("", &cfg); err != nil {
		return nil, fmt.Errorf("failed to process environment config: %w", err)
	}

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

	return &cfg, nil
}

// validate checks that configuration values are valid
func (c *Config) validate() error {
	if c.Port < 1 || c.Port > 65535 {
		return fmt.Errorf("port must be between 1 and 65535, got %d", c.Port)
	}

	if c.LocationLat < -90 || c.LocationLat > 90 {
		return fmt.Errorf("location latitude must be between -90 and 90, got %f", c.LocationLat)
	}

	if c.LocationLon < -180 || c.LocationLon > 180 {
		return fmt.Errorf("location longitude must be between -180 and 180, got %f", c.LocationLon)
	}

	if c.FetchInterval < time.Minute {
		return fmt.Errorf("fetch interval must be at least 1 minute, got %s", c.FetchInterval)
	}

	if c.CacheTTL < time.Second {
		return fmt.Errorf("cache TTL must be at least 1 second, got %s", c.CacheTTL)
	}

	return nil
}

// Addr returns the server address in host:port format
func (c *Config) Addr() string {
	return fmt.Sprintf(":%d", c.Port)
}