package main

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

type config struct {
	ServerAddr           string
	FrontendOrigin       string
	ZarinHubEndpoint     string
	ZarinHubAuthEndpoint string
	ZarinHubUsername     string
	ZarinHubPassword     string
	ZarinHubTimeout      time.Duration
	ZarinHubRetries      int
	DatabasePath         string
}

func loadConfig() (config, error) {
	return readConfig(os.Getenv)
}

func readConfig(getenv func(string) string) (config, error) {
	username := strings.TrimSpace(getenv("ZARINHUB_API_USERNAME"))
	if username == "" {
		return config{}, fmt.Errorf("ZARINHUB_API_USERNAME is required")
	}

	password := strings.TrimSpace(getenv("ZARINHUB_API_PASSWORD"))
	if password == "" {
		return config{}, fmt.Errorf("ZARINHUB_API_PASSWORD is required")
	}

	timeoutText := valueOrDefault(
		getenv("ZARINHUB_TIMEOUT"),
		"5s",
	)
	timeout, err := time.ParseDuration(timeoutText)
	if err != nil || timeout <= 0 {
		return config{}, fmt.Errorf(
			"ZARINHUB_TIMEOUT must be a positive duration",
		)
	}

	retriesText := valueOrDefault(
		getenv("ZARINHUB_RETRIES"),
		"2",
	)

	retries, err := strconv.Atoi(retriesText)
	if err != nil || retries < 0 {
		return config{}, fmt.Errorf(
			"ZARINHUB_RETRIES must be a non-negative integer",
		)
	}

	return config{
		ServerAddr: valueOrDefault(
			getenv("SERVER_ADDR"),
			"127.0.0.1:8080",
		),
		FrontendOrigin: valueOrDefault(
			getenv("FRONTEND_ORIGIN"),
			"http://127.0.0.1:3000",
		),
		ZarinHubEndpoint: valueOrDefault(
			getenv("ZARINHUB_ENDPOINT"),
			"https://zarin-hub.com/api/v5/KYC/CardToIban",
		),
		ZarinHubAuthEndpoint: valueOrDefault(
			getenv("ZARINHUB_AUTH_ENDPOINT"),
			"https://zarin-hub.com/api/v5/Authentication/GetToken",
		),
		ZarinHubUsername: username,
		ZarinHubPassword: password,
		ZarinHubTimeout:  timeout,
		ZarinHubRetries: retries,
		DatabasePath: valueOrDefault(
			getenv("DATABASE_PATH"),
			"./card-to-iban.db",
		),
	}, nil
}

func valueOrDefault(value string, fallback string) string {
	if strings.TrimSpace(value) == "" {
		return fallback
	}

	return strings.TrimSpace(value)
}