package billing

import (
	"context"
	"fmt"
	"net/http"
	"net/url"
	"strconv"
	"strings"
)

// SyncCreditPackResult is one pack after Stripe Product/Price ensure.
type SyncCreditPackResult struct {
	PackID    string `json:"pack_id"`
	ProductID string `json:"product_id"`
	PriceID   string `json:"price_id"`
	Created   bool   `json:"created"`
	Credits   int    `json:"credits"`
	PriceUSD  int    `json:"price_usd"`
}

// SyncCreditPackProducts creates/updates Stripe Products + one-time Prices for
// DefaultCreditPacks. Packs are additional one-time products (Checkout mode=payment),
// not subscription add-ons. Metadata descrybe_pack=<id> identifies each product.
func (s *StripeService) SyncCreditPackProducts(ctx context.Context) ([]SyncCreditPackResult, error) {
	ctx, cfg, err := s.bindCfg(ctx)
	if err != nil {
		return nil, err
	}
	if cfg.MockMode() || strings.TrimSpace(cfg.SecretKey) == "" {
		return nil, ErrStripeNotConfigured
	}

	out := make([]SyncCreditPackResult, 0, len(DefaultCreditPacks()))
	for _, pack := range DefaultCreditPacks() {
		productID, createdProduct, err := s.ensureCreditPackProduct(ctx, pack)
		if err != nil {
			return out, fmt.Errorf("pack %s product: %w", pack.ID, err)
		}
		priceID, createdPrice, err := s.ensureCreditPackPrice(ctx, productID, pack)
		if err != nil {
			return out, fmt.Errorf("pack %s price: %w", pack.ID, err)
		}
		out = append(out, SyncCreditPackResult{
			PackID:    pack.ID,
			ProductID: productID,
			PriceID:   priceID,
			Created:   createdProduct || createdPrice,
			Credits:   pack.Credits,
			PriceUSD:  pack.PriceUSD,
		})
	}
	return out, nil
}

func (s *StripeService) ensureCreditPackProduct(ctx context.Context, pack CreditPack) (productID string, created bool, err error) {
	q := url.QueryEscape(fmt.Sprintf("active:'true' AND metadata['descrybe_pack']:'%s'", pack.ID))
	var search struct {
		Data []struct {
			ID string `json:"id"`
		} `json:"data"`
	}
	if err := s.stripeGET(ctx, "https://api.stripe.com/v1/products/search?query="+q+"&limit=1", &search); err != nil {
		return "", false, err
	}
	if len(search.Data) > 0 && strings.TrimSpace(search.Data[0].ID) != "" {
		return search.Data[0].ID, false, nil
	}

	form := url.Values{}
	form.Set("name", "Descrybe AI credits — "+pack.Name)
	form.Set("description", pack.Description)
	form.Set("metadata[descrybe_pack]", pack.ID)
	form.Set("metadata[credits]", strconv.Itoa(pack.Credits))
	form.Set("metadata[ai_products]", strconv.Itoa(pack.AIProducts))
	form.Set("metadata[price_usd]", strconv.Itoa(pack.PriceUSD))
	var product struct {
		ID string `json:"id"`
	}
	if err := s.stripeForm(ctx, http.MethodPost, "https://api.stripe.com/v1/products", form, &product); err != nil {
		return "", false, err
	}
	if strings.TrimSpace(product.ID) == "" {
		return "", false, fmt.Errorf("stripe product missing id")
	}
	return product.ID, true, nil
}

func (s *StripeService) ensureCreditPackPrice(ctx context.Context, productID string, pack CreditPack) (priceID string, created bool, err error) {
	// Reuse an active one-time price on this product that matches unit amount.
	wantCents := pack.PriceUSD * 100
	var list struct {
		Data []struct {
			ID         string `json:"id"`
			UnitAmount int64  `json:"unit_amount"`
			Currency   string `json:"currency"`
			Type       string `json:"type"`
			Active     bool   `json:"active"`
		} `json:"data"`
	}
	endpoint := "https://api.stripe.com/v1/prices?product=" + url.QueryEscape(productID) + "&active=true&limit=20"
	if err := s.stripeGET(ctx, endpoint, &list); err != nil {
		return "", false, err
	}
	for _, p := range list.Data {
		if p.Active && p.Type == "one_time" && strings.EqualFold(p.Currency, "usd") && int(p.UnitAmount) == wantCents {
			return p.ID, false, nil
		}
	}

	form := url.Values{}
	form.Set("product", productID)
	form.Set("currency", "usd")
	form.Set("unit_amount", strconv.Itoa(wantCents))
	form.Set("metadata[descrybe_pack]", pack.ID)
	form.Set("metadata[credits]", strconv.Itoa(pack.Credits))
	var price struct {
		ID string `json:"id"`
	}
	if err := s.stripeForm(ctx, http.MethodPost, "https://api.stripe.com/v1/prices", form, &price); err != nil {
		return "", false, err
	}
	if strings.TrimSpace(price.ID) == "" {
		return "", false, fmt.Errorf("stripe price missing id")
	}
	return price.ID, true, nil
}