package web

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

	"gitea.dooplex.hu/admin/felhom-controller/internal/stacks"
)

// AFTER-START FIELDS (v0.315.0, D2 = A) — a value the household can only give once the app RUNS.
//
// Plex was the first: its claim code is minted on plex.tv and handed to the server that is already
// up, so the install wizard cannot ask for it (R-1028/R-1060). The catalog marks such a field
// `after_start: true`, the wizard skips it, and the app page's „Beallitasok" tab grows a card for it.
//
// WHAT THE CATALOG MAY SAY, AND WHAT IT MAY NOT. The catalog declares THAT a field is asked after the
// start, and its label, description and placeholder. It does NOT declare what happens to the value.
// The action is Go code in the registry below, keyed by slug and env var, and that is the whole point
// of the decision: the household's text is an ARGUMENT to a function this repository wrote, never a
// fragment of a command, a URL or a container name a template chose. A catalog file cannot make the
// box run anything, and adding a template cannot add an action.
//
// AN UNREGISTERED FIELD IS INERT AND SAID SO. A template that declares `after_start` for an app with
// no entry here renders no card and POSTs 404 — and the render logs one WARN naming the slug and the
// env var KEY, because a field that silently does nothing is exactly the kind of absence nobody
// notices. The VALUE is never logged (it is a credential: Plex's code claims a server).
//
// Pinned by TestAfterStart_PlexThroughRouter (the production router, the real registry, a fake Plex)
// and TestAfterStart_NoActionNoCard (the inert case, with a fake that must record zero calls).

// afterStartError is an action's refusal, carrying the HTTP status and the locale key the page shows
// inline. An action returns one of these so the route stays copy-free: the sentence the household
// reads belongs to the app, not to the plumbing.
type afterStartError struct {
	Status int
	MsgKey string
}

func (e *afterStartError) Error() string { return e.MsgKey }

// afterStartAction is one registered field: when to ask, and what to do with the answer.
type afterStartAction struct {
	// Needed reports whether the household still has to give this value. False hides the card.
	Needed func(st *stacks.Stack) bool
	// Apply does the app-specific thing with the value. It must never log the value.
	Apply func(s *Server, r *http.Request, st *stacks.Stack, value string) error
}

// afterStartRegistry maps `<slug>/<ENV_VAR>` to its action. Adding an app means adding Go here.
var afterStartRegistry = map[string]afterStartAction{
	"plex/PLEX_CLAIM": {
		// Today's condition, unchanged: the card stands while the setup gate does (v0.280.0 decision 46).
		Needed: func(st *stacks.Stack) bool {
			return st != nil && st.Deployed && st.AppConfig != nil && st.AppConfig.SetupGate.Closed()
		},
		Apply: func(s *Server, _ *http.Request, _ *stacks.Stack, value string) error {
			return s.applyPlexClaim(value)
		},
	},
}

// afterStartKey is the registry key for one app's field.
func afterStartKey(slug, envVar string) string { return slug + "/" + envVar }

// afterStartFields returns the after-start fields of this app that have a registered action AND
// currently need an answer — the cards the settings tab renders, in catalog order.
//
// It logs one WARN per render for a declared field with no action (the inert case above). Per
// render and not once at load: the catalog is re-synced every fifteen minutes, so there is no
// "load" to hang the warning on, and a page nobody opens needs no warning.
func (s *Server) afterStartFields(st *stacks.Stack) []stacks.DeployField {
	if st == nil || !st.Deployed {
		return nil
	}
	var out []stacks.DeployField
	for _, f := range st.Meta.DeployFields {
		if !f.AfterStart {
			continue
		}
		act, ok := afterStartRegistry[afterStartKey(st.Meta.Slug, f.EnvVar)]
		if !ok {
			// KEY only — never the value, and never the household's text.
			s.logger.Printf("[WARN] [web] after-start field %s declared for app %q has no registered action: no card is shown and nothing runs", f.EnvVar, st.Meta.Slug)
			continue
		}
		if !act.Needed(st) {
			continue
		}
		out = append(out, f)
	}
	return out
}

// appAfterStartHandler is POST /apps/{slug}/after-start/{ENV}: the household's answer, routed to the
// registered action. An unknown app, an unknown field or an unregistered one is a 404 and nothing
// runs. JSON in, JSON out, like the press handlers beside it.
func (s *Server) appAfterStartHandler(w http.ResponseWriter, r *http.Request, slug, envVar string) {
	st := s.stackBySlug(slug)
	if st == nil {
		http.NotFound(w, r)
		return
	}
	// The field must be DECLARED by the catalog as well as registered here — one of the two alone is
	// not an invitation to run anything.
	declared := false
	for _, f := range st.Meta.DeployFields {
		if f.AfterStart && f.EnvVar == envVar {
			declared = true
			break
		}
	}
	act, ok := afterStartRegistry[afterStartKey(slug, envVar)]
	if !declared || !ok {
		s.logger.Printf("[WARN] [web] after-start POST refused for app %q field %s (declared=%v registered=%v)", slug, envVar, declared, ok)
		http.NotFound(w, r)
		return
	}

	value := strings.TrimSpace(afterStartValueFrom(r))
	if err := act.Apply(s, r, st, value); err != nil {
		var ae *afterStartError
		if errors.As(err, &ae) {
			escrowJSON(w, ae.Status, nil, s.msg(r, ae.MsgKey))
			return
		}
		s.logger.Printf("[WARN] [web] after-start %s/%s failed: %v", slug, envVar, err)
		escrowJSON(w, http.StatusConflict, nil, s.msg(r, "err.after_start.failed"))
		return
	}
	escrowJSON(w, http.StatusOK, map[string]any{"ok": true}, "")
}

// afterStartValueFrom reads the single `value` field the card's script POSTs. A body that is not
// JSON, or carries no value, yields the empty string — which every action then refuses on its own
// terms, so a malformed request cannot reach an action as if it were a valid blank.
func afterStartValueFrom(r *http.Request) string {
	if r == nil || r.Body == nil {
		return ""
	}
	var req struct {
		Value string `json:"value"`
	}
	_ = json.NewDecoder(r.Body).Decode(&req)
	return req.Value
}

// stackNameForSlug maps an app's slug to its stack NAME — the identity the /stacks/ POST routes and
// the backup engine use. The two are equal for every app in the catalog today, and that is exactly
// why it is resolved rather than assumed: a redirect built on the assumption would 404 the first time
// they differ, on a page nobody tests. Empty when no stack carries the slug.
func (s *Server) stackNameForSlug(slug string) string {
	if st := s.stackBySlug(slug); st != nil {
		return st.Name
	}
	return ""
}

// slugForStackName is stackNameForSlug the other way round: it turns the name in an old
// /stacks/{name}/… URL into the slug the new app page is keyed by. Empty when unknown.
func (s *Server) slugForStackName(name string) string {
	if name == "" || s.stackMgr == nil {
		return ""
	}
	if st, ok := s.stackMgr.GetStack(name); ok && st != nil {
		return st.Meta.Slug
	}
	return ""
}