package config

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

type Config struct {
	Port                  int
	AWConnStr             string
	WWIConnStr            string
	PostgresDSN           string
	OtelCollectorEndpoint string
	OtelServiceName       string
	OtelServiceNamespace  string
	DefaultTopN           int
	ForecastHorizonDays   int
	DefaultHistoryDays    int
}

func Load() Config {
	port, _ := strconv.Atoi(getEnv("PORT", "8080"))
	topN, _ := strconv.Atoi(getEnv("DEFAULT_TOP_N", "10"))
	forecastDays, _ := strconv.Atoi(getEnv("FORECAST_HORIZON_DAYS", "30"))
	historyDays, _ := strconv.Atoi(getEnv("DEFAULT_HISTORY_DAYS", "365"))
	return Config{
		Port:                  port,
		AWConnStr:             mustEnv("AW_MSSQL_DSN"),
		WWIConnStr:            mustEnv("WWI_MSSQL_DSN"),
		PostgresDSN:           mustEnv("POSTGRES_DSN"),
		OtelCollectorEndpoint: getEnv("OTEL_COLLECTOR_ENDPOINT", "http://localhost:4318"),
		OtelServiceName:       getEnv("OTEL_SERVICE_NAME", "otel-bi-analytics"),
		OtelServiceNamespace:  getEnv("OTEL_SERVICE_NAMESPACE", "final-thesis"),
		DefaultTopN:           topN,
		ForecastHorizonDays:   forecastDays,
		DefaultHistoryDays:    historyDays,
	}
}

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

func mustEnv(key string) string {
	v := os.Getenv(key)
	if v == "" {
		panic(fmt.Sprintf("required environment variable %s is not set", key))
	}
	return v
}