package rate

import (
	"fmt"
	"regexp"
	"strconv"
	"strings"

	"ops-assistant/internal/core/command"
)

type Module struct{}

func New() *Module { return &Module{} }

var re = regexp.MustCompile(`(?i)^/rate\s+([0-9]+(?:\.[0-9]+)?)\s*([a-z]{3})\s*(?:(?:to)\s*|->\s*|/\s*)([a-z]{3})\s*$`)

func (m *Module) Handle(_ int64, cmd *command.ParsedCommand) (string, error) {
	text := strings.TrimSpace(cmd.Raw)
	if strings.EqualFold(text, "/rate") || strings.HasPrefix(strings.ToLower(text), "/rate help") {
		return help(), nil
	}
	hit := re.FindStringSubmatch(text)
	if hit == nil {
		return help(), nil
	}
	amount, err := strconv.ParseFloat(hit[1], 64)
	if err != nil || amount <= 0 {
		return "❌ 金额无效", nil
	}
	base := strings.ToUpper(hit[2])
	quote := strings.ToUpper(hit[3])
	if base == quote {
		return fmt.Sprintf("💱 %s → %s\n\n%s %s = %s %s", base, quote, hit[1], base, hit[1], quote), nil
	}
	return query(amount, base, quote)
}

func help() string {
	return "💱 汇率转换\n\n用法：/rate 138 sgd to cny\n\n也支持：\n/rate 138sgd to cny\n/rate 100 usd to cny\n/rate 50 eur -> sgd\n/rate 1000 php/cny\n\n数据源：Google Finance、Visa、Mastercard。Visa/万事达为官方结算汇率；Google 为市场参考价。"
}