iptvnator/docs/architecture/stalker-epg.md

Stalker Portal EPG Architecture

This document describes the current EPG implementation for Stalker/Ministra ITV channels in IPTVnator.

Related architecture docs:

• Stalker Portal Architecture
• Remote Control Architecture

Overview

Stalker now uses two EPG paths with different purposes:

• The active channel EPG panel uses get_epg_info as a bulk endpoint, fetches a 7-day window once per playlist session, caches programs by channel id, and renders the selected channel through the shared app-epg-timeline component.
• Channel rows read the bulk cache first. The bulk EPG load is triggered eagerly when a category's channels first render (a constructor effect in StalkerLiveStreamLayoutComponent calls ensureBulkItvEpg(168) once ITV channels are present) — not only after the first channel is played — so the row "now playing" previews and the EPG panel populate immediately. Rows derive their current program and progress bar from the cached bulk map; rows the settled bulk guide cannot answer fall back to throttled per-channel get_short_epg through StalkerEpgPreviewQueue (see "Channel row preview flow").
  • Effect ordering matters: the eager-EPG effect is registered after the playlist-change effect that calls clearBulkItvEpgCache(). On a portal switch the cache is cleared first and then refilled; if the order is reversed the clear clobbers the just-loaded bulk EPG on initial render.
  • ensureBulkItvEpg de-duplicates (via isLoadingBulkItvEpg / bulkItvEpgLoaded + matching playlist/period), so the eager trigger and the play-time loadEpgForChannel path never double-fetch.
• If a portal does not return usable bulk data for the selected channel, the active panel falls back to get_short_epg.

This keeps the live list cheap while giving the active panel the same date-navigator UI used in the M3U/Xtream flows.

Architecture

┌────────────────────────────────────────────────────────────────────────────┐
│                 StalkerLiveStreamLayoutComponent                          │
│  libs/portal/stalker/feature/src/lib/stalker-live-stream-layout/         │
│                                                                            │
│  sidebar rows                    active channel panel                      │
│  ────────────                    ───────────────────                      │
│  row preview map                 playChannel()                             │
│  from bulk cache                 │                                          │
│         │                        ▼                                          │
│         │                  ensureBulkItvEpg(168)                           │
│         │                  selectedItvEpgPrograms()                        │
│         ▼                        │                                          │
│  current program preview         ├── bulk hit → app-epg-timeline               │
│  after first bulk load           └── empty/unsupported → short fallback    │
└────────────────────────────────────────────────────────────────────────────┘
                   │                                │
                   ▼                                ▼
┌────────────────────────────────────────────────────────────────────────────┐
│                           with-stalker-epg.feature                         │
│                                                                            │
│  bulkItvEpgByChannel: Record<string, EpgProgram[]>                         │
│  bulkItvEpgPlaylistId / bulkItvEpgPeriodHours / bulkItvEpgLoaded           │
│  ensureBulkItvEpg()  selectedItvEpgPrograms()                              │
└────────────────────────────────────────────────────────────────────────────┘
                   │                                │
                   ▼                                ▼
┌────────────────────────────────────────────────────────────────────────────┐
│                            Stalker Portal API                              │
│                                                                            │
│  action=create_link      action=get_short_epg      action=get_epg_info     │
└────────────────────────────────────────────────────────────────────────────┘

Stalker EPG API

get_short_epg (active-panel and row-preview fallback)

Request

GET load.php?type=itv&action=get_short_epg&ch_id={channel_id}&size={n}&JsHttpRequest=1-xml

Current usage

• Active panel fallback path: size=10
• Row-preview fallback queue: size=3 (EPG_PREVIEW_FETCH_SIZE)

Response

{
    "js": {
        "data": [
            {
                "id": "123",
                "ch_id": "45",
                "name": "Program Title",
                "descr": "Program description",
                "time": "2025-01-15 14:00:00",
                "time_to": "2025-01-15 14:30:00",
                "duration": "1800",
                "start_timestamp": "1736949600",
                "stop_timestamp": "1736951400"
            }
        ]
    }
}

Notes

• The response is normalized into shared EpgItem[]
• Two fallback consumers use this path and map the result into controlled EpgProgram[]: the active-panel fallback and the throttled row-preview queue (both only when the bulk guide cannot answer "what's on now")

get_epg_info (bulk row-preview and active-panel source)

Request

GET load.php?type=itv&action=get_epg_info&period={hours}&JsHttpRequest=1-xml

Current usage

• Fetched once with period=168
• Scoped to the current playlist session
• Not refetched on active-channel change

Expected response

{
    "js": {
        "data": {
            "45": [
                {
                    "id": "1",
                    "name": "Program Title",
                    "descr": "Program description",
                    "time": "2025-01-15 14:00:00",
                    "time_to": "2025-01-15 16:00:00",
                    "start_timestamp": "1736949600",
                    "stop_timestamp": "1736956800"
                }
            ]
        }
    }
}

Notes

• The store supports the channel-keyed bulk shape above as the primary contract
• For weak or mock-style portals that still return array-style data, the store treats the result as compatibility input and leaves the short-EPG fallback path available

Data Mapping

Fallback data (get_short_epg) → EpgItem

The short EPG path serves the two fallback flows: the active panel and the throttled row-preview queue.

Key mapped fields:

Stalker field	EpgItem field
id	id
ch_id	channel_id
name	title
descr	description
time	start
time_to	end, stop
start_timestamp	start_timestamp
stop_timestamp	stop_timestamp

Active panel data (get_epg_info / fallback) → EpgProgram

The active panel uses controlled EpgProgram[] because app-epg-timeline filters and groups by day.

Normalization rules:

• start / end are converted to ISO strings
• startTimestamp / stopTimestamp are always populated
• Programs are sorted by start time per channel
• selectedItvId is used to project cached bulk data to the active channel

Implementation Details

Key files

File	Purpose
libs/portal/stalker/data-access/src/lib/stores/features/with-stalker-epg.feature.ts	bulk cache and fallback handling
libs/portal/stalker/feature/src/lib/stalker-live-stream-layout/stalker-live-stream-layout.component.ts	active-channel EPG loading and controlled app-epg-timeline wiring
libs/portal/stalker/feature/src/lib/stalker-live-stream-layout/stalker-live-stream-layout.component.html	active panel template
libs/ui/epg/src/lib/epg-timeline/epg-timeline.component.ts	shared controlled EPG timeline with date navigator

Store API

The Stalker EPG feature exposes one bulk method plus the short-EPG fallback:

fetchChannelEpg(channelId: number | string, size?: number): Promise<EpgItem[]>
ensureBulkItvEpg(periodHours = 168): Promise<void>

It also exposes:

• selectedItvEpgPrograms
• clearBulkItvEpgCache()

Bulk state is keyed by playlist so cached results do not leak between Stalker playlists.

Active panel flow

1. User activates a live channel
2. The component ensures playback link resolution as before
3. The component ensures ensureBulkItvEpg(168) has run; the eager row effect normally started the same de-duplicated request before playback
4. selectedItvEpgPrograms() merged with the short-EPG fallback feeds app-epg-timeline (mergeEpgProgramLists; bulk wins an exact start-time collision)
5. The component falls back to get_short_epg whenever the bulk list cannot answer "what's on now" — because it is empty or because it only carries future programmes (some portals' get_epg_info omits the currently airing one). The fallback fills the gap; the bulk data keeps providing the days ahead.

The active panel no longer uses local EPG pagination or a "Load more" button. When Stalker live TV is playing through an internal player, the active panel is wrapped in the shared collapsible live EPG panel. The collapsed/expanded state uses the shared live-epg-panel-state preference and is only applied after a stream URL has been resolved; external playback keeps the full EPG-only panel.

Channel row preview flow

Once non-radio ITV channels render, the post-reset component effect calls ensureBulkItvEpg(168). It starts eagerly before playback and is de-duplicated against the active-channel path. As soon as the bulk request completes, visible row previews derive locally from bulkItvEpgByChannel:

• pick the current program for the channel, if one exists
• compute progress from the cached program timestamps

Rows the bulk guide cannot answer fall back to per-channel get_short_epg through StalkerEpgPreviewQueue (stalker-live-stream-layout/stalker-live-epg-preview.ts), mirroring the Xtream EpgQueueService: the queue only starts after the bulk request has settled (so it never races the answer it is a fallback for), fetches the currently rendered channels with bounded concurrency and inter-request spacing, caches results — including empty ones — for five minutes, and is reset on playlist switch because channel ids are only unique per portal. Each sync's backlog is additionally capped (30 channels, top of the list first) and the sidebar's scroll handler re-syncs (throttled) to fill the next gaps, so request count tracks how far the user actually scrolls rather than how many rows are rendered. Channels with a manual XMLTV mapping are excluded from the fallback entirely — their bulk record holds the mapped schedule, and the portal short EPG must not stand in for the data the mapping deliberately replaces. Because a fetch can be enqueued before the mapping lookup resolves, the queue's completion callback revalidates ownership: a row claimed in the meantime by a mapping override or by bulk data is never overwritten by the late portal response. Mapping ownership is a fact of the saved mapping row, independent of whether the mapped guide currently has programs — an empty mapped guide still keeps the portal EPG out. Ownership changes are published reactively (applyMappedItvEpg re-patches the bulk record even when the mapped guide contributed nothing), so a fallback row rendered before the mapping lookup finished is removed by the rerun sync. The backlog is superseded whenever the rendered list empties (a legacy-paged category switch) or the view leaves ITV (radio), so abandoned rows stop consuming portal request capacity.

Cache Lifecycle

• Bulk EPG is fetched once per playlist session
• Channel switches only read from bulkItvEpgByChannel
• The cache is cleared when the Stalker playlist changes
• Committed XMLTV source reconciliation also clears mapping overrides, checked IDs and bulk data, reloads the guide and selected mapping, and fences pending mapping/bulk replies. Saved mappings remain authoritative even when removal leaves their guide empty; portal EPG is not mixed into that empty override.
• This implementation does not add TTL-based refresh or background polling

Authentication

EPG requests follow the standard Stalker request path:

Portal type	Auth path
Full Stalker portal	StalkerSessionService.makeAuthenticatedRequest()
Simple Stalker portal	generic IPC request path via Electron

No EPG-specific backend transport was needed; the Electron Stalker request handler forwards portal params directly.

Fallback Behavior

Some providers do not implement get_epg_info consistently. The active panel therefore falls back to get_short_epg when:

• the bulk request fails
• the bulk response is empty
• the selected channel has no currently airing program in the cached bulk map — a bulk list of future-only programmes is treated as incomplete, not as an answer

The fallback is merged with the bulk list rather than replacing it, so the panel shows "now" from the short EPG and the days ahead from the bulk guide.

The fallback is keyed to the selected channel, not to the category: a category switch in the sidebar leaves the channel playing and keeps its fallback (and a fallback load still in flight) intact. It is dropped when the selection moves to another channel or when the view leaves ITV for radio, where the route session clears the selection. The stored fallback is tagged with the channel it was fetched for and the merge only applies while that channel is still selected — a channel switch moves the selection synchronously, while the old fallback is replaced only after the new channel's EPG load runs, so an unscoped merge would leak the previous channel's programmes into the new panel during (or after a failed) playback resolution. Row previews use the same per-channel fallback through the throttled StalkerEpgPreviewQueue once the bulk request has settled (see "Channel row preview flow").

Manually mapped channels never take the portal fallback, on either path: the component resolves the channel's mapping before falling back (applyMappedItvEpg for the one id, then hasItvEpgMappingOverride) and keeps mapped channels on their mapped schedule even when it has no currently airing entry — the mapping exists to replace the portal EPG, so portal data must not be merged back in.

Manual EPG Mapping

Stalker channels carry no XMLTV identifier, so when the portal's own EPG is missing or wrong the only uploaded-EPG entry point is a manual mapping: right-click a channel in the ITV sidebar (or in global favorites) and pick "Map EPG channel" to attach it to a channel from an uploaded XMLTV guide.

• Mappings are stored in the shared epg_channel_mappings table under the playlist-scoped key stalker:{playlistId}:{channelId} (buildStalkerEpgMappingKey in libs/shared/interfaces/src/lib/epg-mapping-key.util.ts).
• withStalkerEpg().applyMappedItvEpg(channelIds) batch-resolves mappings (one getEpgMappingsBatch IPC per new id set) and overlays the mapped XMLTV programs onto bulkItvEpgByChannel, so both the active panel and the row previews pick them up with no template changes. Overrides are re-merged whenever ensureBulkItvEpg replaces the bulk record and are re-checked after the mapping dialog closes with a change.
• The collection views (global favorites/recent) resolve the same keys in StreamResolverService (loadStalkerEpgItems for the detail panel, loadStalkerEpgBatch + prefetchEpgMappings for row previews).
• Everything is gated behind supportsEpgMapping, so the PWA never shows the menu entry.

Future Enhancements

• add cache refresh / invalidation for long-running live sessions
• add Stalker catch-up support to app-epg-timeline once the playback flow exists
• optionally add category-level prefetch timing metrics for bulk EPG