package server

import (
	"context"
	"errors"
	"fmt"
	"strconv"
	"strings"

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

	"scrabble/backend/internal/adminconsole"
	"scrabble/backend/internal/payments"
)

// catalogBack is the product-list path the catalog console actions return to.
const catalogBack = "/_gm/catalog"

// atomField pairs a form field with its atom type; priceField pairs a form field with the payment
// method + currency it prices, following the one-currency-per-rail mapping (direct→RUB, vk→VOTE,
// telegram→XTR) plus the value's CHIP price (no method).
var atomFields = []struct{ field, atom string }{
	{"chips", "chips"}, {"hints", "hints"}, {"noads", "noads_days"}, {"tournament", "tournament"},
}
var priceFields = []struct {
	field, method string
	currency      payments.Currency
}{
	{"price_rub", "direct", payments.CurrencyRUB},
	{"price_vote", "vk", payments.CurrencyVote},
	{"price_star", "telegram", payments.CurrencyStar},
	{"price_chip", "", payments.CurrencyChip},
}

// consoleCatalog lists every product (active and archived) with its composition, prices, transacted
// flag, and the inline create form.
func (s *Server) consoleCatalog(c *gin.Context) {
	products, err := s.payments.AdminCatalog(c.Request.Context())
	if err != nil {
		s.consoleError(c, err)
		return
	}
	var view adminconsole.CatalogView
	for _, p := range products {
		view.Products = append(view.Products, catalogRow(p))
	}
	s.renderConsole(c, "catalog", "catalog", "Catalog", view)
}

// catalogRow projects a product into its list row.
func catalogRow(p payments.AdminProduct) adminconsole.ProductRow {
	row := adminconsole.ProductRow{ID: p.ID.String(), Title: p.Title, Active: p.Active, Transacted: p.Transacted}
	for _, a := range p.Atoms {
		row.Atoms = append(row.Atoms, adminconsole.AtomRow{Atom: a.Atom, Quantity: a.Quantity})
	}
	for _, pr := range p.Prices {
		row.Prices = append(row.Prices, adminconsole.PriceRow{Method: pr.Method, Currency: string(pr.Currency), Amount: pr.Amount})
	}
	return row
}

// consoleCatalogDetail renders one product's edit form, pre-filled from its current composition.
func (s *Server) consoleCatalogDetail(c *gin.Context) {
	id, ok := s.consoleUUID(c, catalogBack)
	if !ok {
		return
	}
	products, err := s.payments.AdminCatalog(c.Request.Context())
	if err != nil {
		s.consoleError(c, err)
		return
	}
	for _, p := range products {
		if p.ID == id {
			s.renderConsole(c, "product_detail", "catalog", p.Title, productForm(p))
			return
		}
	}
	s.renderConsoleMessage(c, "Not found", "no such product", catalogBack)
}

// productForm builds the pre-filled edit form for a product.
func productForm(p payments.AdminProduct) adminconsole.ProductFormView {
	fv := adminconsole.ProductFormView{ID: p.ID.String(), Title: p.Title, Active: p.Active, Transacted: p.Transacted}
	for _, a := range p.Atoms {
		switch a.Atom {
		case "chips":
			fv.Chips = a.Quantity
		case "hints":
			fv.Hints = a.Quantity
		case "noads_days":
			fv.NoAds = a.Quantity
		case "tournament":
			fv.Tournament = a.Quantity
		}
	}
	for _, pr := range p.Prices {
		switch pr.Currency {
		case payments.CurrencyRUB:
			fv.PriceRUB = pr.Amount
		case payments.CurrencyVote:
			fv.PriceVote = pr.Amount
		case payments.CurrencyStar:
			fv.PriceStar = pr.Amount
		case payments.CurrencyChip:
			fv.PriceChip = pr.Amount
		}
	}
	return fv
}

// parseProductForm reads a product's title, atoms, prices and active flag from the submitted form.
func parseProductForm(c *gin.Context) (payments.ProductInput, bool) {
	in := payments.ProductInput{Title: strings.TrimSpace(c.PostForm("title"))}
	for _, a := range atomFields {
		if q, err := strconv.Atoi(strings.TrimSpace(c.PostForm(a.field))); err == nil && q > 0 {
			in.Atoms = append(in.Atoms, payments.AtomLine{Atom: a.atom, Quantity: q})
		}
	}
	for _, p := range priceFields {
		if amt, err := strconv.ParseInt(strings.TrimSpace(c.PostForm(p.field)), 10, 64); err == nil && amt > 0 {
			in.Prices = append(in.Prices, payments.PriceLine{Method: p.method, Currency: p.currency, Amount: amt})
		}
	}
	return in, c.PostForm("active") != ""
}

// consoleCreateProduct validates and inserts a new product from the create form.
func (s *Server) consoleCreateProduct(c *gin.Context) {
	in, active := parseProductForm(c)
	if _, err := s.payments.CreateProduct(c.Request.Context(), in, active); err != nil {
		s.renderConsoleMessage(c, "Invalid product", err.Error(), catalogBack)
		return
	}
	s.renderConsoleMessage(c, "Created", "the product was created", catalogBack)
}

// consoleUpdateProduct validates and replaces a product's title, atoms and prices.
func (s *Server) consoleUpdateProduct(c *gin.Context) {
	id, ok := s.consoleUUID(c, catalogBack)
	if !ok {
		return
	}
	in, _ := parseProductForm(c)
	back := catalogBack + "/" + id.String()
	if err := s.payments.UpdateProduct(c.Request.Context(), id, in); err != nil {
		s.renderConsoleMessage(c, "Invalid product", err.Error(), back)
		return
	}
	s.renderConsoleMessage(c, "Saved", "the product was updated", back)
}

// consoleArchiveProduct archives or unarchives a product (the desired state rides in the form);
// unarchiving revalidates the sellable shape.
func (s *Server) consoleArchiveProduct(c *gin.Context) {
	id, ok := s.consoleUUID(c, catalogBack)
	if !ok {
		return
	}
	active := c.PostForm("active") == "true"
	if err := s.payments.SetProductActive(c.Request.Context(), id, active); err != nil {
		s.renderConsoleMessage(c, "Cannot change status", err.Error(), catalogBack)
		return
	}
	s.renderConsoleMessage(c, "Updated", "the product status was changed", catalogBack)
}

// consoleDeleteProductAction hard-deletes a never-transacted product; a transacted one is refused
// with a hint to archive instead.
func (s *Server) consoleDeleteProductAction(c *gin.Context) {
	id, ok := s.consoleUUID(c, catalogBack)
	if !ok {
		return
	}
	err := s.payments.DeleteProduct(c.Request.Context(), id)
	if errors.Is(err, payments.ErrProductTransacted) {
		s.renderConsoleMessage(c, "Cannot delete", "this product has transactions; archive it instead", catalogBack)
		return
	}
	if err != nil {
		s.consoleError(c, err)
		return
	}
	s.renderConsoleMessage(c, "Deleted", "the product was deleted", catalogBack)
}

// consoleGrant grants raw benefit atoms (hints / no-ads days / forever) to a chosen origin — a
// zero-price admin sale.
func (s *Server) consoleGrant(c *gin.Context) {
	id, ok := s.consoleUUID(c, "/_gm/users")
	if !ok {
		return
	}
	back := "/_gm/users/" + id.String()
	if s.payments == nil {
		s.renderConsoleMessage(c, "Unavailable", "payments are not enabled", back)
		return
	}
	origin := payments.Source(c.PostForm("origin"))
	hints, _ := strconv.Atoi(strings.TrimSpace(c.PostForm("hints")))
	noads, _ := strconv.Atoi(strings.TrimSpace(c.PostForm("noads")))
	forever := c.PostForm("forever") != ""
	if err := s.payments.Grant(c.Request.Context(), id, origin, hints, noads, forever); err != nil {
		s.renderConsoleMessage(c, "Grant failed", err.Error(), back)
		return
	}
	s.publishBannerChange(id)
	s.renderConsoleMessage(c, "Granted", "the benefit was granted", back)
}

// consoleGrantProduct grants a value product's atoms (a reward bundle, possibly archived) to a
// chosen origin. It refuses a product carrying chips or the tournament atom (payments enforces it).
func (s *Server) consoleGrantProduct(c *gin.Context) {
	id, ok := s.consoleUUID(c, "/_gm/users")
	if !ok {
		return
	}
	back := "/_gm/users/" + id.String()
	if s.payments == nil {
		s.renderConsoleMessage(c, "Unavailable", "payments are not enabled", back)
		return
	}
	origin := payments.Source(c.PostForm("origin"))
	productID, err := uuid.Parse(strings.TrimSpace(c.PostForm("product_id")))
	if err != nil {
		s.renderConsoleMessage(c, "Grant failed", "choose a product", back)
		return
	}
	if err := s.payments.GrantProduct(c.Request.Context(), id, origin, productID); err != nil {
		s.renderConsoleMessage(c, "Grant failed", err.Error(), back)
		return
	}
	s.publishBannerChange(id)
	s.renderConsoleMessage(c, "Granted", "the product was granted", back)
}

// grantForm builds the admin-grant panel: the origin picker and the grantable products (value
// bundles, including archived ones — chips and tournament products are excluded).
func (s *Server) grantForm(ctx context.Context) adminconsole.GrantFormView {
	fv := adminconsole.GrantFormView{Present: true, Origins: []string{"direct", "vk", "telegram"}}
	products, err := s.payments.AdminCatalog(ctx)
	if err != nil {
		return fv
	}
	for _, p := range products {
		if grantableProduct(p) {
			fv.Products = append(fv.Products, adminconsole.GrantProductOption{
				ID: p.ID.String(), Title: p.Title, Summary: atomSummary(p.Atoms), Archived: !p.Active,
			})
		}
	}
	return fv
}

// grantableProduct reports whether a product can be admin-granted: it carries at least one benefit
// atom (hints / no-ads days) and no chips or tournament atom.
func grantableProduct(p payments.AdminProduct) bool {
	benefit := false
	for _, a := range p.Atoms {
		switch a.Atom {
		case "chips", "tournament":
			return false
		case "hints", "noads_days":
			benefit = true
		}
	}
	return benefit
}

// atomSummary renders a product's atoms as "hints×5, noads_days×30".
func atomSummary(atoms []payments.AtomLine) string {
	parts := make([]string, 0, len(atoms))
	for _, a := range atoms {
		parts = append(parts, fmt.Sprintf("%s×%d", a.Atom, a.Quantity))
	}
	return strings.Join(parts, ", ")
}