// Package handler wires up the public, read-only OpenGoods HTTP API.
//
// The OpenGoods service is a public-good product information API: it only
// collects and serves product facts. It exposes no purchase, checkout, or
// commerce endpoints by design.
package handler

import (
	"encoding/json"
	"net/http"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
)

// APIVersion is the current public API version prefix.
const APIVersion = "v1"

// Router builds the top-level HTTP handler with middleware and routes mounted.
func Router() http.Handler {
	r := chi.NewRouter()
	r.Use(middleware.RequestID)
	r.Use(middleware.RealIP)
	r.Use(middleware.Recoverer)

	r.Get("/healthz", Healthz)

	r.Route("/api/"+APIVersion, func(r chi.Router) {
		r.Route("/products", func(r chi.Router) {
			r.Get("/barcode/{gtin}", notImplemented)
			r.Get("/search", notImplemented)
			r.Get("/{id}", notImplemented)
			r.Get("/{id}/nutriments", notImplemented)
			r.Get("/{id}/msrp", notImplemented)
		})
		r.Get("/brands", notImplemented)
		r.Get("/categories", notImplemented)
		r.Get("/sources/{id}", notImplemented)
	})

	return r
}

// Healthz reports liveness of the service.
func Healthz(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
}

// notImplemented is a placeholder for endpoints scoped to later milestones.
func notImplemented(w http.ResponseWriter, r *http.Request) {
	writeError(w, r, http.StatusNotImplemented, "not_implemented", "endpoint not implemented yet")
}

func writeJSON(w http.ResponseWriter, status int, body any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(body)
}

func writeError(w http.ResponseWriter, r *http.Request, status int, code, message string) {
	writeJSON(w, status, map[string]any{
		"error": map[string]string{
			"code":       code,
			"message":    message,
			"request_id": middleware.GetReqID(r.Context()),
		},
	})
}