// Package mcp is the MCP edge for the cart's promotion engine: a Model Context
// Protocol server exposing the promotion Store and evaluator as tools so an
// agent can list, create, update, status-toggle and delete the promotions the
// cart actually applies (e.g. Volymrabatt), plus preview the discount a cart
// total would receive.
//
// Transport/dispatch and the schema/result helpers live in platform/mcp; this
// package defines the promotion tools (full set via New, read-only via NewPublic)
// and the admin tools (AdminTools) that backoffice merges into the CMS MCP.
package mcp

import (
	"net/http"

	"git.k6n.net/mats/go-cart-actor/pkg/promotions"
	pmcp "git.k6n.net/mats/platform/mcp"
)

const (
	serverName    = "cart-promotions"
	serverVersion = "0.1.0"
)

// Server is the MCP edge over the shared promotion Store and evaluator.
type Server struct {
	store *promotions.Store
	eval  *promotions.PromotionService
	mcp   *pmcp.Server
}

// New builds an MCP server exposing the full promotion tool set.
func New(store *promotions.Store, eval *promotions.PromotionService) *Server {
	if eval == nil {
		eval = promotions.NewPromotionService(nil)
	}
	s := &Server{store: store, eval: eval}
	s.mcp = pmcp.NewServer(pmcp.Info{Name: serverName, Version: serverVersion}, s.buildTools()...)
	return s
}

// Handler returns the streamable-HTTP handler to mount (e.g. at /mcp).
func (s *Server) Handler() http.Handler { return s.mcp.Handler() }