// loads environment-based configuration.
package config

import (
	"fmt"
	"os"
	"strconv"
	"strings"
)

const (
	defaultPort                = 3001
	defaultDBPort              = 5432
	defaultPollIntervalMS      = 60000
	minPollIntervalMS          = 1000
	defaultDigestIntervalHours = 24
)

type Config struct {
	Port                       int
	APIBasePath                string
	DatabaseURL                string
	DBHost                     string
	DBPort                     int
	DBUser                     string
	DBPassword                 string
	DBName                     string
	FirebaseProjectID          string
	EthRPCURL                  string
	PollIntervalMS             int
	NodeEnv                    string
	ResendAPIKey               string
	EmailFrom                  string
	SupportInboxEmail          string
	DigestIntervalHours        int
	StripeSecretKey            string
	StripeWebhookSecret        string
	StripePriceIDPremium       string
	StripePriceIDPro           string
	StripePriceIDPremiumAnnual string
	StripePriceIDProAnnual     string
	StripePublishableKey       string
	FrontendURL                string
}

// Load reads configuration from environment variables and returns a Config.
func Load() (*Config, error) {
	cfg := &Config{
		Port:                       getEnvInt("PORT", defaultPort),
		APIBasePath:                getEnv("API_BASE_PATH", "/v1"),
		DatabaseURL:                os.Getenv("DATABASE_URL"),
		DBHost:                     getEnv("DB_HOST", "localhost"),
		DBPort:                     getEnvInt("DB_PORT", defaultDBPort),
		DBUser:                     os.Getenv("DB_USER"),
		DBPassword:                 os.Getenv("DB_PASSWORD"),
		DBName:                     os.Getenv("DB_NAME"),
		FirebaseProjectID:          os.Getenv("FIREBASE_PROJECT_ID"),
		EthRPCURL:                  os.Getenv("ETH_RPC_URL"),
		PollIntervalMS:             getEnvInt("POLL_INTERVAL_MS", defaultPollIntervalMS),
		NodeEnv:                    getEnv("NODE_ENV", "development"),
		ResendAPIKey:               os.Getenv("RESEND_API_KEY"),
		EmailFrom:                  getEnv("EMAIL_FROM", "Koin Ping <alerts@koinping.com>"),
		SupportInboxEmail:          getEnv("SUPPORT_INBOX_EMAIL", "sj@sjdev.co"),
		DigestIntervalHours:        getEnvInt("DIGEST_INTERVAL_HOURS", defaultDigestIntervalHours),
		StripeSecretKey:            os.Getenv("STRIPE_SECRET_KEY"),
		StripeWebhookSecret:        os.Getenv("STRIPE_WEBHOOK_SECRET"),
		StripePriceIDPremium:       os.Getenv("STRIPE_PRICE_ID_PREMIUM"),
		StripePriceIDPro:           os.Getenv("STRIPE_PRICE_ID_PRO"),
		StripePriceIDPremiumAnnual: os.Getenv("STRIPE_PRICE_ID_PREMIUM_ANNUAL"),
		StripePriceIDProAnnual:     os.Getenv("STRIPE_PRICE_ID_PRO_ANNUAL"),
		StripePublishableKey:       os.Getenv("STRIPE_PUBLISHABLE_KEY"),
		FrontendURL:                getEnv("FRONTEND_URL", "http://localhost:3000"),
	}

	if cfg.PollIntervalMS < minPollIntervalMS {
		return nil, fmt.Errorf("POLL_INTERVAL_MS must be >= 1000, got %d", cfg.PollIntervalMS) //nolint:err113
	}

	return cfg, nil
}

func (c *Config) DSN() string {
	if c.DatabaseURL != "" {
		// Append sslmode=disable if not already specified.
		if !strings.Contains(c.DatabaseURL, "sslmode=") {
			sep := "?"
			if strings.Contains(c.DatabaseURL, "?") {
				sep = "&"
			}

			return c.DatabaseURL + sep + "sslmode=disable"
		}

		return c.DatabaseURL
	}

	return fmt.Sprintf(
		"host=%s port=%d user=%s password=%s dbname=%s sslmode=disable",
		c.DBHost, c.DBPort, c.DBUser, c.DBPassword, c.DBName,
	)
}

// TierForPriceID maps a Stripe price ID back to the corresponding
// subscription tier. Returns empty string if the price is unrecognised.
func (c *Config) TierForPriceID(priceID string) string {
	if priceID == "" {
		return ""
	}
	switch priceID {
	case c.StripePriceIDPremium, c.StripePriceIDPremiumAnnual:
		return "premium"
	case c.StripePriceIDPro, c.StripePriceIDProAnnual:
		return "pro"
	default:
		return ""
	}
}

func getEnv(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}

	return fallback
}

func getEnvInt(key string, fallback int) int {
	if v := os.Getenv(key); v != "" {
		if n, err := strconv.Atoi(v); err == nil {
			return n
		}
	}

	return fallback
}