// SPDX-FileCopyrightText: 2026 Echolot contributors
// SPDX-License-Identifier: GPL-3.0-or-later

package adminui

import (
	"encoding/json"
	"html/template"
	"log/slog"
	"net/http"
	"net/url"
	"sort"
	"strings"
	"time"

	"echo-lot.app/server/internal/adminauth"
	"echo-lot.app/server/internal/runs"
	"echo-lot.app/server/internal/store"
)

// visibleDevices returns the devices a session may see: everything for an administrator, and for
// anyone else the devices linked to their own account.
//
// Every page goes through this rather than filtering for itself. Scoping applied per-page is
// scoping that will be missing from the next page someone adds, and the failure is silent — a
// listing that quietly shows other people's uploads looks exactly like one that does not.
func (s *Server) visibleDevices(sess *adminauth.Session) []store.Device {
	all := s.Store.Devices()
	if sess.Admin {
		return all
	}
	owned := make(map[string]bool)
	for _, id := range s.Store.DeviceIDsForAccount(sess.Subject) {
		owned[id] = true
	}
	out := make([]store.Device, 0, len(owned))
	for _, d := range all {
		if owned[d.ID] {
			out = append(out, d)
		}
	}
	return out
}

// mayTouchRun reports whether this session may read or delete a given run.
//
// Checked against the device list rather than against the run's own metadata, so an unlinked or
// revoked device stops granting access the moment the link is gone.
func (s *Server) mayTouchRun(sess *adminauth.Session, device string) bool {
	if sess.Admin {
		return true
	}
	for _, d := range s.visibleDevices(sess) {
		if d.ID == device {
			return true
		}
	}
	return false
}

func (s *Server) loginForm(w http.ResponseWriter, r *http.Request) {
	if s.session(r) != nil {
		http.Redirect(w, r, "/", http.StatusSeeOther)
		return
	}
	s.render(w, r, "login", map[string]any{
		"OIDC":      s.oidcAvailable(),
		"LocalSet":  s.Store.LocalAdmin() != nil,
		"AdminUser": s.AdminUser,
	})
}

func (s *Server) dashboard(w http.ResponseWriter, r *http.Request, sess *adminauth.Session) {
	devices := s.visibleDevices(sess)
	linked := 0
	for _, d := range devices {
		if d.LinkedToAccount() {
			linked++
		}
	}
	var selftest any
	// The self-test describes the server's own health, which is an operator's concern; a user
	// looking at their uploads has no use for it and no ability to act on it.
	if s.SelfTest != nil && sess.Admin {
		selftest = s.SelfTest()
	}
	s.render(w, r, "dashboard", map[string]any{
		"Session":  sess,
		"CSRF":     s.csrfToken(sess),
		"Devices":  len(devices),
		"Linked":   linked,
		"Runs":     s.totalRuns(devices),
		"SelfTest": selftest,
		"Version":  s.Version,
		"Admin":    sess.Admin,
	})
}

func (s *Server) totalRuns(devices []store.Device) int {
	if s.Runs == nil {
		return 0
	}
	n := 0
	for _, d := range devices {
		n += len(s.Runs.List(d.ID))
	}
	return n
}

func (s *Server) devices(w http.ResponseWriter, r *http.Request, sess *adminauth.Session) {
	devices := s.visibleDevices(sess)
	// Newest first: the device someone is looking for is almost always the one just enrolled.
	sort.Slice(devices, func(i, j int) bool { return devices[i].Enrolled.After(devices[j].Enrolled) })

	type row struct {
		store.Device
		Runs int
	}
	rows := make([]row, 0, len(devices))
	for _, d := range devices {
		n := 0
		if s.Runs != nil {
			n = len(s.Runs.List(d.ID))
		}
		rows = append(rows, row{Device: d, Runs: n})
	}
	// html/template rewrites an href whose scheme it does not recognise to "#ZgotmplZ", so the
	// enrollment link rendered as a dead anchor that did nothing when tapped — silently, since the
	// markup looks fine and only the sanitised attribute gives it away.
	//
	// Marking it template.URL opts out of that sanitising, which is only safe because the shape is
	// checked first: this value arrives in a query parameter, so without the check a crafted
	// /devices?link=javascript:… would put a script URL straight into the page.
	link := r.URL.Query().Get("link")
	var href template.URL
	if strings.HasPrefix(link, "echolot://enroll?") {
		href = template.URL(link)
	}
	s.render(w, r, "devices", map[string]any{
		"Session": sess, "CSRF": s.csrfToken(sess), "Rows": rows,
		// Rendered from the same validated value as the href, so a rejected link produces neither.
		"Link": link, "LinkHref": href, "LinkQR": qrSVG(string(href)), "Admin": sess.Admin,
	})
}

func (s *Server) revokeDevice(w http.ResponseWriter, r *http.Request, sess *adminauth.Session) {
	id := r.PathValue("id")
	if err := s.Store.DeleteDevice(id); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	// Worth a log line: revoking a device is destructive, immediate, and someone will eventually
	// want to know who did it and when.
	slog.Info("device revoked", "device", id, "by", sess.Subject)
	http.Redirect(w, r, "/devices", http.StatusSeeOther)
}

func (s *Server) mintToken(w http.ResponseWriter, r *http.Request, sess *adminauth.Session) {
	tok, err := s.Store.NewEnrollToken(24*time.Hour, "admin-ui")
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	slog.Info("enrolment token minted", "by", sess.Subject)
	// The whole link, not the bare token: it carries the URL and the pin as well, and assembling
	// those by hand is where an operator gets a pin wrong by one character.
	http.Redirect(w, r, "/devices?link="+url.QueryEscape(s.EnrollLink(tok)), http.StatusSeeOther)
}

// enrollTokensAPI is POST /admin/enroll-tokens, the endpoint the spec's §2.1 example names.
// Content-negotiated: Accept: application/json gets the spec shape {token, expires_in_s,
// enroll_uri}; anything else (a browser) gets the same redirect-to-QR flow as the form above,
// so the one path serves both audiences.
func (s *Server) enrollTokensAPI(w http.ResponseWriter, r *http.Request) {
	subject, ok := s.apiAdmin(w, r)
	if !ok {
		return
	}
	note := r.URL.Query().Get("note")
	if note == "" {
		note = "admin-api"
	}
	const ttl = 24 * time.Hour
	tok, err := s.Store.NewEnrollToken(ttl, note)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	slog.Info("enrolment token minted", "by", subject, "note", note)
	if !strings.Contains(r.Header.Get("Accept"), "application/json") {
		http.Redirect(w, r, "/devices?link="+url.QueryEscape(s.EnrollLink(tok)), http.StatusSeeOther)
		return
	}
	w.Header().Set("Content-Type", "application/json")
	// The whole link, not the bare token (§2.1): the server is the only party holding URL, pin
	// and token at once, and a hand-assembled pin wrong by one character fails as an inscrutable
	// TLS error later rather than loudly here.
	_ = json.NewEncoder(w).Encode(map[string]any{
		"token":        tok,
		"expires_in_s": int(ttl.Seconds()),
		"enroll_uri":   s.EnrollLink(tok),
	})
}

// EnrollLink is supplied by the caller so this package does not need the control server's pin.
var _ = 0

func (s *Server) runsList(w http.ResponseWriter, r *http.Request, sess *adminauth.Session) {
	type row struct {
		runs.Meta
		DeviceName string
	}
	var rows []row
	for _, d := range s.visibleDevices(sess) {
		if s.Runs == nil {
			break
		}
		name := d.Name
		if name == "" {
			name = d.ID
		}
		for _, m := range s.Runs.List(d.ID) {
			rows = append(rows, row{Meta: m, DeviceName: name})
		}
	}
	sort.Slice(rows, func(i, j int) bool { return rows[i].UploadedAt.After(rows[j].UploadedAt) })
	if len(rows) > 200 {
		rows = rows[:200] // a page, not the archive; the count is on the dashboard
	}
	s.render(w, r, "runs", map[string]any{
		"Session": sess, "CSRF": s.csrfToken(sess), "Rows": rows, "Admin": sess.Admin,
	})
}

func (s *Server) runView(w http.ResponseWriter, r *http.Request, sess *adminauth.Session) {
	// 404 rather than 403 for someone else's run: a distinguishable "you may not see this" tells
	// an unauthorised caller that the run exists, which is itself something they should not learn.
	if !s.mayTouchRun(sess, r.PathValue("device")) {
		http.NotFound(w, r)
		return
	}
	body, err := s.Runs.Get(r.PathValue("device"), r.PathValue("id"))
	if err != nil {
		http.NotFound(w, r)
		return
	}
	// Re-indented for reading, but otherwise exactly what was stored. An admin sees the document
	// at the privacy level its uploader chose — there is nothing here that can un-redact it.
	var pretty json.RawMessage = body
	out, err := json.MarshalIndent(json.RawMessage(pretty), "", "  ")
	if err != nil {
		out = body
	}
	s.render(w, r, "run", map[string]any{
		"Session": sess, "CSRF": s.csrfToken(sess), "Admin": sess.Admin,
		"Device": r.PathValue("device"), "ID": r.PathValue("id"),
		"JSON": string(out),
	})
}

func (s *Server) runDelete(w http.ResponseWriter, r *http.Request, sess *adminauth.Session) {
	device, id := r.PathValue("device"), r.PathValue("id")
	if !s.mayTouchRun(sess, device) {
		http.NotFound(w, r)
		return
	}
	if err := s.Runs.Delete(device, id); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	slog.Info("run deleted", "device", device, "run", id, "by", sess.Subject)
	http.Redirect(w, r, "/runs", http.StatusSeeOther)
}