// setup_handler.go — public landing page for the user-setup link
// emitted by the admin's "+ Add user" / "Regenerate setup link" flow.
//
// Routes (wired in server.go):
//
//	GET  /setup   → handleUISetupGet
//	POST /setup   → handleUISetupPost  (lands in Task D2)
//
// The token in the querystring (`?token=<raw>`) is the credential.
// Auth middleware does not run on these routes.
package http

import (
	"crypto/sha256"
	"encoding/hex"
	"log/slog"
	stdhttp "net/http"
	"time"

	"gitea.dcglab.co.uk/steve/restic-manager/internal/server/ui"
)

type setupPage struct {
	Username string
	Token    string // round-tripped to the POST form
	Error    string // displayed when password validation fails or token is invalid
}

// hashSetupToken is the canonical hashing for setup tokens. Must
// match what the admin handler uses when SetSetupToken is called,
// so the digest at rest matches what GET /setup hashes.
func hashSetupToken(raw string) string {
	h := sha256.Sum256([]byte(raw))
	return hex.EncodeToString(h[:])
}

func (s *Server) handleUISetupGet(w stdhttp.ResponseWriter, r *stdhttp.Request) {
	raw := r.URL.Query().Get("token")
	if raw == "" {
		s.renderSetupExpired(w, r)
		return
	}
	tok, err := s.deps.Store.LookupSetupToken(r.Context(), hashSetupToken(raw))
	if err != nil {
		s.renderSetupExpired(w, r)
		return
	}
	if tok.ExpiresAt.Before(time.Now().UTC()) {
		s.renderSetupExpired(w, r)
		return
	}
	u, err := s.deps.Store.GetUserByID(r.Context(), tok.UserID)
	if err != nil {
		s.renderSetupExpired(w, r)
		return
	}
	view := s.baseView(r, nil)
	view.Title = "Set your password · restic-manager"
	view.Page = setupPage{Username: u.Username, Token: raw}
	if err := s.deps.UI.Render(w, "setup", view); err != nil {
		slog.Error("ui setup: render", "err", err)
	}
}

func (s *Server) renderSetupExpired(w stdhttp.ResponseWriter, r *stdhttp.Request) {
	w.WriteHeader(stdhttp.StatusGone)
	view := s.baseView(r, nil)
	view.Title = "Link expired · restic-manager"
	view.Page = setupPage{Error: "expired"}
	_ = s.deps.UI.Render(w, "setup", view)
	_ = ui.User{} // keep ui import alive
}

// handleUISetupPost is a stub — full implementation lands in Task D2.
func (s *Server) handleUISetupPost(w stdhttp.ResponseWriter, r *stdhttp.Request) {
	stdhttp.Error(w, "not implemented", stdhttp.StatusNotImplemented)
}