package web

import (
	"log"
	"net/http"
	"strconv"

	"bookmarkmanager/backend/internal/store"
)

// adminView is the shared shell data for an administrative page and the roster
// fragment returned after a Reader action.
type adminView struct {
	Page    string
	Readers []store.ReaderSummary
	// OwnerID travels with the roster so it can tell the owner's own row from
	// the Readers they may act on.
	OwnerID int64
	Lanes   lanesView
}

// adminRoute pairs a route pattern with its handler so the route list and the
// gate cannot drift apart.
type adminRoute struct {
	pattern string
	handler http.HandlerFunc
}

// adminRoutes is every route that reaches past the acting Reader. Register
// wraps each one in requireOwner, so a new administrative route is gated by
// being listed here rather than by remembering to write a check inside it.
func (h *Handler) adminRoutes() []adminRoute {
	return []adminRoute{
		{"GET /admin", h.admin},
		{"GET /admin/lanes", h.adminLanes},
		{"GET /admin/readers", h.adminReaders},
		{"GET /admin/series", h.adminSeries},
		{"GET /ui/admin/lanes", h.uiLanes},
		{"POST /readers/{id}/revoke", h.revokeReaderSessions},
		{"POST /readers/{id}/clear-marks", h.clearReaderMarks},
	}
}

// AdminPatterns names every administrative route, so one test can prove the
// owner gate covers all of them rather than one test per route. The receiver is
// nil because only the patterns are read; the bound handlers are never called.
func AdminPatterns() []string {
	routes := (*Handler)(nil).adminRoutes()
	out := make([]string, 0, len(routes))
	for _, rt := range routes {
		out = append(out, rt.pattern)
	}
	return out
}

// requireOwner is the owner test, in one place, layered on the session gate: no
// session is still 401, and a signed-in Reader who is not the owner gets 404
// rather than 403 — a refusal that confirms the address exists is a refusal
// that helps whoever is probing for it.
func (h *Handler) requireOwner(next http.HandlerFunc) http.HandlerFunc {
	return h.requireSession(func(w http.ResponseWriter, r *http.Request) {
		if readerOf(r) != h.store.OwnerID() {
			http.NotFound(w, r)
			return
		}
		next(w, r)
	})
}

// admin renders the Overview shell. Its data arrives in later admin tickets.
func (h *Handler) admin(w http.ResponseWriter, r *http.Request) {
	h.renderAdmin(w, adminView{Page: "overview"})
}

// adminReaders renders the Reader roster on its own bookmarkable page.
func (h *Handler) adminReaders(w http.ResponseWriter, r *http.Request) {
	readers, err := h.store.Readers()
	if err != nil {
		log.Printf("admin readers: %v", err)
		http.Error(w, "internal error", http.StatusInternalServerError)
		return
	}
	h.renderAdmin(w, adminView{Page: "readers", Readers: readers, OwnerID: h.store.OwnerID()})
}

// adminSeries renders the Series shell. Its data arrives in a later admin
// ticket.
func (h *Handler) adminSeries(w http.ResponseWriter, r *http.Request) {
	h.renderAdmin(w, adminView{Page: "series"})
}

func (h *Handler) renderAdmin(w http.ResponseWriter, view adminView) {
	h.render(w, http.StatusOK, "admin", view)
}

// revokeReaderSessions logs one Reader out of every browser they are signed in
// on. The owner gate is the route's, not this handler's.
func (h *Handler) revokeReaderSessions(w http.ResponseWriter, r *http.Request) {
	target, ok := readerPathID(w, r)
	if !ok {
		return
	}
	// The owner is not one of the Readers this endpoint reaches: revoking
	// themselves would sign out the browser making the request, which is what
	// logout is for. The roster hides the button; this refuses the hand-rolled
	// POST behind it.
	if target == h.store.OwnerID() {
		http.NotFound(w, r)
		return
	}
	if err := h.store.DeleteReaderSessions(target); err != nil {
		log.Printf("revoke sessions: %v", err)
		http.Error(w, "internal error", http.StatusInternalServerError)
		return
	}
	h.renderRoster(w, "revoke sessions")
}

// clearReaderMarks zeroes one Reader's Sighting counters. The guard those
// counters feed has one known false positive — a Site changing its page shape
// makes a correct adapter read a wrong high number and marks every honest
// Reader of that Site at once (issue #103) — and this is its remedy. It
// restores a privilege rather than destroying anything, so the control is
// confirmed but never wears the destruction accent.
func (h *Handler) clearReaderMarks(w http.ResponseWriter, r *http.Request) {
	target, ok := readerPathID(w, r)
	if !ok {
		return
	}
	if err := h.store.ClearReaderMarks(target); err != nil {
		log.Printf("clear marks: %v", err)
		http.Error(w, "internal error", http.StatusInternalServerError)
		return
	}
	h.renderRoster(w, "clear marks")
}

// readerPathID reads the Reader a route names, answering the request itself
// when there is nobody to act on.
func readerPathID(w http.ResponseWriter, r *http.Request) (int64, bool) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.Error(w, "bad reader id", http.StatusBadRequest)
		return 0, false
	}
	return id, true
}

// renderRoster answers an action with the whole roster, so the counts and marks
// it shows cannot describe the state before the tap.
func (h *Handler) renderRoster(w http.ResponseWriter, what string) {
	readers, err := h.store.Readers()
	if err != nil {
		log.Printf("%s: %v", what, err)
		http.Error(w, "internal error", http.StatusInternalServerError)
		return
	}
	h.render(w, http.StatusOK, "readers", adminView{Readers: readers, OwnerID: h.store.OwnerID()})
}