// Package api holds the SEO plugin's JSON endpoints under /_seo/api/v1.
package api

import (
	"errors"
	"net/http"

	"git.golem15.com/golem15/sm-seo-plugin/classes"
	"git.golem15.com/golem15/summercms/modules/diary"
	"git.golem15.com/golem15/summercms/modules/wire"
)

var log = diary.For("seo")

// Resolve serves GET /_seo/api/v1/resolve?url=<path or absolute URL>: the
// redirect decision and the effective SEO of a public URL for the
// frontend (D-20a, D-103). It answers 200 with the resolve answer: action
// redirect with status (301 or 302) and an absolute location, reached in
// one hop through normalisation, redirects and strict URLs; gone with 410;
// ok with the page's SEO; or not_found with 404, the status the page
// should answer with. It answers 422 when url is missing or not a path or
// an http(s) URL. Absolute URLs come from the configured site URL, never
// from the request's Host. The frontend enforces the decision (Phase 33).
func Resolve(service func() *classes.Service) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		svc := service()
		if svc == nil {
			wire.WriteJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "SEO is not available"})
			return
		}
		res, err := svc.Resolver().Resolve(r.Context(), r.URL.Query().Get("url"))
		if errors.Is(err, classes.ErrBadURL) {
			wire.WriteJSON(w, http.StatusUnprocessableEntity, map[string]string{"error": err.Error()})
			return
		}
		if err != nil {
			log.Error("golem15.seo: resolve", "error", err)
			wire.WriteJSON(w, http.StatusInternalServerError, map[string]string{"error": "Internal Server Error"})
			return
		}
		w.Header().Set("X-Robots-Tag", "noindex")
		wire.WriteJSON(w, http.StatusOK, res)
	}
}