package stripe

import (
	"errors"
	"log"
	"strconv"
	"time"

	"git.nixc.us/a250/ss-atlas/internal/config"
	"git.nixc.us/a250/ss-atlas/internal/pricing"
	stripego "github.com/stripe/stripe-go/v84"
	portalsession "github.com/stripe/stripe-go/v84/billingportal/session"
	checkoutsession "github.com/stripe/stripe-go/v84/checkout/session"
	"github.com/stripe/stripe-go/v84/subscription"
)

var ErrNoPriceForTier = errors.New("no Stripe price configured for this tier")

type SubscriptionStatus struct {
	Label    string // "Active", "Cancels soon", etc.
	Badge    string // "badge-active", "badge-inactive", etc.
	CancelAt string // empty or formatted date
}

type Client struct {
	cfg *config.Config
}

func New(cfg *config.Config) *Client {
	stripego.Key = cfg.StripeSecretKey
	return &Client{cfg: cfg}
}

func (c *Client) priceForTier(t pricing.Tier) string {
	switch t {
	case pricing.TierFree:
		if c.cfg.StripePriceIDFree != "" {
			return c.cfg.StripePriceIDFree
		}
	case pricing.TierYear:
		if c.cfg.StripePriceIDYear != "" {
			return c.cfg.StripePriceIDYear
		}
	case pricing.TierPremium:
		if c.cfg.StripePriceIDMonth200 != "" {
			return c.cfg.StripePriceIDMonth200
		}
		if c.cfg.StripePriceIDMonth100 != "" {
			return c.cfg.StripePriceIDMonth100
		}
	}
	return c.cfg.StripePriceID
}

func (c *Client) CreateCheckoutSession(email, customerDomain, customerPhone string, customerCount int) (*stripego.CheckoutSession, error) {
	t := pricing.ForCustomer(customerCount, c.cfg.FreeTierLimit, c.cfg.YearTierLimit)
	priceID := c.priceForTier(t)
	if priceID == "" {
		log.Printf("stripe: no price for tier %d (count=%d freeLimit=%d yearLimit=%d); set STRIPE_PRICE_ID or tier-specific price",
			t, customerCount, c.cfg.FreeTierLimit, c.cfg.YearTierLimit)
		return nil, ErrNoPriceForTier
	}

	params := &stripego.CheckoutSessionParams{
		Mode: stripego.String(string(stripego.CheckoutSessionModeSubscription)),
		LineItems: []*stripego.CheckoutSessionLineItemParams{
			{Price: stripego.String(priceID), Quantity: stripego.Int64(1)},
		},
		CustomerEmail: stripego.String(email),
		SuccessURL:    stripego.String(c.cfg.AppURL + "/success?session_id={CHECKOUT_SESSION_ID}"),
		CancelURL:     stripego.String(c.cfg.AppURL + "/"),
	}
	if customerDomain != "" {
		params.AddMetadata("customer_domain", customerDomain)
	}
	if customerPhone != "" {
		params.AddMetadata("customer_phone", customerPhone)
	}
	params.AddMetadata("pricing_tier", strconv.Itoa(int(t)))
	return checkoutsession.New(params)
}

// CreateCheckoutForCustomer creates a new subscription checkout for an existing
// Stripe customer (e.g. resubscribe after expiry). Uses current tier by customer count.
func (c *Client) CreateCheckoutForCustomer(customerID string, customerCount int) (*stripego.CheckoutSession, error) {
	t := pricing.ForCustomer(customerCount, c.cfg.FreeTierLimit, c.cfg.YearTierLimit)
	priceID := c.priceForTier(t)
	if priceID == "" {
		log.Printf("stripe: no price for tier %d (count=%d); set STRIPE_PRICE_ID or tier-specific price", t, customerCount)
		return nil, ErrNoPriceForTier
	}

	params := &stripego.CheckoutSessionParams{
		Mode: stripego.String(string(stripego.CheckoutSessionModeSubscription)),
		LineItems: []*stripego.CheckoutSessionLineItemParams{
			{Price: stripego.String(priceID), Quantity: stripego.Int64(1)},
		},
		Customer:   stripego.String(customerID),
		SuccessURL: stripego.String(c.cfg.AppURL + "/success?session_id={CHECKOUT_SESSION_ID}"),
		CancelURL:  stripego.String(c.cfg.AppURL + "/dashboard"),
	}
	return checkoutsession.New(params)
}

func (c *Client) CreatePortalSession(customerID string) (*stripego.BillingPortalSession, error) {
	params := &stripego.BillingPortalSessionParams{
		Customer:  stripego.String(customerID),
		ReturnURL: stripego.String(c.cfg.AppURL + "/dashboard"),
	}
	return portalsession.New(params)
}

func (c *Client) GetCheckoutSession(sessionID string) (*stripego.CheckoutSession, error) {
	params := &stripego.CheckoutSessionParams{}
	params.AddExpand("customer")
	params.AddExpand("subscription")
	return checkoutsession.Get(sessionID, params)
}

func (c *Client) GetSubscription(subID string) (*stripego.Subscription, error) {
	return subscription.Get(subID, nil)
}

// ScheduleSubscriptionCancelAt sets the subscription to cancel at the given unix timestamp.
// Used for free-tier subs that should auto-cancel after 3 months.
func (c *Client) ScheduleSubscriptionCancelAt(subID string, cancelAt int64) error {
	_, err := subscription.Update(subID, &stripego.SubscriptionParams{
		CancelAt: stripego.Int64(cancelAt),
	})
	return err
}

func (c *Client) IsFreeTierPrice(priceID string) bool {
	return c.cfg.StripePriceIDFree != "" && priceID == c.cfg.StripePriceIDFree
}

func (c *Client) IsYearTierPrice(priceID string) bool {
	return c.cfg.StripePriceIDYear != "" && priceID == c.cfg.StripePriceIDYear
}

func (c *Client) GetCustomerSubscriptionStatus(customerID string) *SubscriptionStatus {
	if customerID == "" {
		return &SubscriptionStatus{Label: "Active", Badge: "badge-active"}
	}
	params := &stripego.SubscriptionListParams{
		Customer: stripego.String(customerID),
		Status:   stripego.String(string(stripego.SubscriptionStatusActive)),
	}
	iter := subscription.List(params)
	if iter.Next() {
		sub := iter.Subscription()
		log.Printf("stripe: customer=%s sub=%s cancel_at_period_end=%v cancel_at=%d",
			customerID, sub.ID, sub.CancelAtPeriodEnd, sub.CancelAt)
		if sub.CancelAtPeriodEnd || sub.CancelAt > 0 {
			// Prefer explicit cancel_at; fall back to current_period_end from the first item
			endTs := sub.CancelAt
			if endTs == 0 && sub.Items != nil && len(sub.Items.Data) > 0 {
				endTs = sub.Items.Data[0].CurrentPeriodEnd
			}
			var cancelAt string
			if endTs > 0 {
				cancelAt = time.Unix(endTs, 0).Format("Jan 2, 2006")
			}
			return &SubscriptionStatus{
				Label:    "Expiring",
				Badge:    "badge-inactive",
				CancelAt: cancelAt,
			}
		}
		return &SubscriptionStatus{Label: "Active", Badge: "badge-active"}
	}
	log.Printf("stripe: no active subscription found for customer=%s", customerID)
	// No active subscription; user was a customer so subscription has expired
	return &SubscriptionStatus{Label: "Expired", Badge: "badge-inactive"}
}

func (c *Client) WebhookSecret() string {
	return c.cfg.StripeWebhookSecret
}