package controllers

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"log"
	"net/mail"
	"strings"
	"time"

	"github.com/gofiber/fiber/v3"
	"gorm.io/gorm"
)

type SubscribeController struct {
	DB                 *gorm.DB
	IsUniqueConstraint func(error) bool
}

type subscribeRequest struct {
	Email       string         `json:"email"`
	BrowserData map[string]any `json:"browserData"`
}

const subscriptionCookieName = "bag_exchange_subscribed"

func (s *SubscribeController) Subscribe(c fiber.Ctx) error {
	var req subscribeRequest
	if err := json.Unmarshal(c.Body(), &req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(map[string]string{"error": "invalid payload"})
	}

	email := strings.ToLower(strings.TrimSpace(req.Email))
	if _, err := mail.ParseAddress(email); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(map[string]string{"error": "invalid email"})
	}

	emailHash := hashEmail(email)
	if c.Cookies(subscriptionCookieName) == emailHash {
		return c.Status(fiber.StatusConflict).JSON(map[string]string{"status": "already_submitted"})
	}

	browserData := "{}"
	if len(req.BrowserData) > 0 {
		payload, err := json.Marshal(req.BrowserData)
		if err != nil {
			return c.Status(fiber.StatusBadRequest).JSON(map[string]string{"error": "invalid browser data"})
		}
		browserData = string(payload)
	}

	err := s.DB.Table("subscribers").Create(map[string]any{
		"email":           email,
		"ip_address":      c.IP(),
		"user_agent":      c.Get("User-Agent"),
		"accept_language": c.Get("Accept-Language"),
		"browser_data":    browserData,
	}).Error
	if err != nil {
		if s.IsUniqueConstraint != nil && s.IsUniqueConstraint(err) {
			setSubscriptionCookie(c, emailHash)
			return c.Status(fiber.StatusConflict).JSON(map[string]string{"status": "already_submitted"})
		}
		log.Printf("unable to insert subscriber: %v", err)
		return c.Status(fiber.StatusInternalServerError).JSON(map[string]string{"error": "unable to save subscription"})
	}

	setSubscriptionCookie(c, emailHash)
	return c.Status(fiber.StatusCreated).JSON(map[string]string{"status": "subscribed"})
}

func hashEmail(email string) string {
	sum := sha256.Sum256([]byte(strings.ToLower(strings.TrimSpace(email))))
	return hex.EncodeToString(sum[:])
}

func setSubscriptionCookie(c fiber.Ctx, value string) {
	c.Cookie(&fiber.Cookie{
		Name:     subscriptionCookieName,
		Value:    value,
		Path:     "/",
		HTTPOnly: false,
		Secure:   false,
		Expires:  time.Now().AddDate(1, 0, 0),
		MaxAge:   60 * 60 * 24 * 365,
	})
}