package server

import (
	"net/http"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"

	"scrabble/backend/internal/payments"
)

// walletSegmentDTO is one chip balance in the wallet view: the funding source, the chip count,
// and whether it can be spent in the current execution context (false for a frozen VK-iOS
// balance or an untrusted platform).
type walletSegmentDTO struct {
	Source    string `json:"source"`
	Chips     int    `json:"chips"`
	Spendable bool   `json:"spendable"`
}

// walletDTO is the user-facing wallet: the context-visible chip segments and the
// context-applicable benefits (the no-ads term or forever flag, and the available hints).
type walletDTO struct {
	Segments     []walletSegmentDTO `json:"segments"`
	AdsForever   bool               `json:"ads_forever"`
	AdsPaidUntil int64              `json:"ads_paid_until_ms"` // unix millis; 0 = no active term
	Hints        int                `json:"hints"`
}

// walletBuyRequest is the POST body of a chip spend: the product to buy with chips.
type walletBuyRequest struct {
	ProductID string `json:"product_id"`
}

// walletDTOFrom projects a payments wallet view into the wire DTO.
func walletDTOFrom(v payments.WalletView) walletDTO {
	out := walletDTO{AdsForever: v.Benefits.AdsForever, Hints: v.Benefits.Hints}
	if v.Benefits.AdsPaidUntil != nil {
		out.AdsPaidUntil = v.Benefits.AdsPaidUntil.UnixMilli()
	}
	out.Segments = make([]walletSegmentDTO, 0, len(v.Segments))
	for _, seg := range v.Segments {
		out.Segments = append(out.Segments, walletSegmentDTO{Source: string(seg.Source), Chips: seg.Chips, Spendable: seg.Spendable})
	}
	return out
}

// handleWallet returns the caller's wallet — the segments and benefits visible in the current
// trusted execution context.
func (s *Server) handleWallet(c *gin.Context) {
	uid, ok := userID(c)
	if !ok {
		return
	}
	ctx := c.Request.Context()
	cxt, present, err := s.walletGate(ctx, uid)
	if err != nil {
		s.abortErr(c, err)
		return
	}
	view, err := s.payments.Wallet(ctx, uid, cxt, present)
	if err != nil {
		s.abortErr(c, err)
		return
	}
	c.JSON(http.StatusOK, walletDTOFrom(view))
}

// handleWalletBuy spends chips on a chip-priced value and returns the updated wallet. It is
// fail-closed: an untrusted or frozen context, or an insufficient balance, is refused.
func (s *Server) handleWalletBuy(c *gin.Context) {
	uid, ok := userID(c)
	if !ok {
		return
	}
	var req walletBuyRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.AbortWithStatusJSON(http.StatusBadRequest, errorResponse{Error: errorBody{Code: "invalid_request", Message: "invalid request body"}})
		return
	}
	productID, err := uuid.Parse(req.ProductID)
	if err != nil {
		c.AbortWithStatusJSON(http.StatusBadRequest, errorResponse{Error: errorBody{Code: "invalid_request", Message: "invalid product id"}})
		return
	}
	ctx := c.Request.Context()
	cxt, present, err := s.walletGate(ctx, uid)
	if err != nil {
		s.abortErr(c, err)
		return
	}
	if err := s.payments.Spend(ctx, uid, cxt, present, productID); err != nil {
		s.abortErr(c, err)
		return
	}
	view, err := s.payments.Wallet(ctx, uid, cxt, present)
	if err != nil {
		s.abortErr(c, err)
		return
	}
	c.JSON(http.StatusOK, walletDTOFrom(view))
}