package payout

import (
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"net"
	"net/http"
	"regexp"

	"go.uber.org/fx"

	"payouts/internal/config"
	"payouts/internal/models"
	"payouts/internal/service/cache"
	"payouts/internal/service/database"
	"payouts/internal/service/database/orm"
	"payouts/internal/service/yookassa"
	yookassaConf "payouts/internal/service/yookassa/config"
)

const (
	BaseRoute     = "/payout"
	CreateRoute   = "/create"
	CallbackRoute = "/callback"
	BanksRoute    = "/sbp/banks"
)

var authHeaderRe = regexp.MustCompile(`^Bearer\s+(.*)$`)

type payoutHandler struct {
	dbService    database.Service
	cacheService cache.Service
	yooKassa     yookassa.Service
	yookassaConf yookassaConf.YooKassa
}

// Params represents the module input params
type Params struct {
	fx.In

	AppConfig    *config.App
	DbService    database.Service
	YooKassa     yookassa.Service
	CacheService cache.Service
}

func NewPayoutHandler(p Params) (Handler, error) {
	return &payoutHandler{
		dbService:    p.DbService,
		cacheService: p.CacheService,
		yooKassa:     p.YooKassa,
		yookassaConf: p.YooKassa.GetConfig(),
	}, nil
}

func (p *payoutHandler) getSession(r *http.Request) (*orm.User, error) {
	authHeaderValue := r.Header.Get("Authorization")
	if len(authHeaderValue) == 0 {
		return nil, errors.New("no valid auth header")
	}

	matches := authHeaderRe.FindStringSubmatch(authHeaderValue)
	if matches == nil {
		return nil, errors.New("no valid auth header")
	}

	sessionId := matches[1]
	userSession, err := p.cacheService.GetSession(sessionId)
	if err != nil {
		return nil, errors.New("session not found")
	}
	return &userSession, nil

}

func (p *payoutHandler) checkAllowedIpCallback(ipStr string) bool {
	ipWithoutPort, _, _ := net.SplitHostPort(ipStr)

	ip := net.ParseIP(ipWithoutPort)
	if ip == nil {
		slog.Error(fmt.Sprintf("Invalid IP: %s", ipStr))
		return false
	}
	for _, subnetStr := range p.yookassaConf.AllowedCallbackSubnets {
		_, ipNet, err := net.ParseCIDR(subnetStr)
		if err != nil {
			slog.Error(fmt.Sprintf("Invalid subnet CIDR: %v", err))
			continue
		}
		if ipNet.Contains(ip) {
			return true
		}
	}
	return false
}

// GetSbpBanks implements [Handler].
func (p *payoutHandler) GetSbpBanks(w http.ResponseWriter, r *http.Request) {
	panic("unimplemented")
}

// PaymentCreate implements [Handler].
func (p *payoutHandler) PayoutCreate(w http.ResponseWriter, r *http.Request) {
	errResponse := func(message string, err error, status int) {
		http.Error(w, errors.Join(errors.New(message), err).Error(), status)
	}

	userSession, err := p.getSession(r)
	if err != nil {
		errResponse("unauthorized", err, http.StatusUnauthorized)
		return
	}

	payoutReq := models.PayoutReq{
		PayoutType: models.TypeSBP,
	}
	decoder := json.NewDecoder(r.Body)
	err = decoder.Decode(&payoutReq)
	if err != nil {
		slog.Error("Failed to decode request body", slog.String("error", err.Error()))
		errResponse("failed to decode request body", err, http.StatusBadRequest)
		return
	}

	slog.Debug(fmt.Sprintf("Received create payload request: %v from user %v", payoutReq, userSession))
	err = p.yooKassa.CreatePayout(payoutReq, userSession)
	if err != nil {
		slog.Error("Failed to create payout request", slog.String("error", err.Error()))
		errResponse("failed to create payout request", err, http.StatusBadRequest)
		return
	}
}

// PaymentCallback implements [Handler].
func (p *payoutHandler) PayoutCallback(w http.ResponseWriter, r *http.Request) {
	inData := map[string]any{}
	decoder := json.NewDecoder(r.Body)
	decoder.Decode(&inData)

	// todo: check also the X-real-ip and/or X-Forwarded-For
	if !p.checkAllowedIpCallback(r.RemoteAddr) {
		slog.Error(fmt.Sprintf("Callback came from unallowed ip: %s", r.RemoteAddr))
		http.Error(w, "unallowed", http.StatusForbidden)
		return
	}

	slog.Info(fmt.Sprintf("Received callback from %s with object %v with headers %v", r.RemoteAddr, inData, r.Header))
}