# Work Plan — uopi

## Phases Overview

| Phase | Name                  | Focus                                                      | Milestone                                 |
| ----- | --------------------- | ---------------------------------------------------------- | ----------------------------------------- |
| 0     | Scaffold              | Repo structure, build toolchain, CI                        | Empty binary serves embedded index page   |
| 1     | Core Backend          | Broker, WebSocket protocol, REST skeleton                  | Live signal fan-out working end-to-end    |
| 2     | EPICS Data Source     | CA connect, monitor, metadata, write                       | Real EPICS PVs visible in browser console |
| 3     | Synthetic Data Source | DSP engine, Lua sandbox, signal composition                | Synthetic signals computed and streamed   |
| 4     | Frontend Foundation   | Svelte skeleton, WS client, signal stores, view mode shell | Subscribed values rendered in browser     |
| 5     | View Mode Widgets     | All widget types rendered in view mode                     | Full interactive HMI panel                |
| 6     | Edit Mode             | Konva canvas, drag-and-drop, resize, properties pane       | Can build and save a panel                |
| 7     | Edit Mode — Advanced  | Multi-select, align/distribute, undo/redo                  | Complete editor UX                        |
| 8     | Historical Data       | Archive integration, time navigation UI                    | Replay past data in widgets               |
| 9     | Signal Discovery      | Signal tree, CSV import, EPICS Channel Finder              | Usable without manual PV entry            |
| 10    | Hardening             | Docs, packaging, integration tests, performance            | Production-ready binary                   |

---

## Phase 0 — Scaffold ✅

**Goal:** working build pipeline, empty binary that serves a placeholder page.

- [x] Initialise Go module (`go mod init github.com/uopi/uopi`)
- [x] Create directory layout: `cmd/uopi/`, `internal/`, `web/`
- [x] Svelte + Vite + TypeScript project in `web/`
- [x] `//go:embed web/dist` in backend via `web/embed.go`; `Makefile` builds frontend then backend
- [x] HTTP server on configurable port; serves embedded frontend
- [x] TOML config loading (`BurntSushi/toml`) with `UOPI_*` env var overrides
- [x] GitHub Actions CI: runs `go test ./...` and `npm run check` on push
- [x] `README.md` with quick-start instructions

**Done when:** `./dist/uopi` starts and serves an "under construction" page. ✅

**Notes:**
- Embed lives in `web/embed.go` (not `cmd/uopi/`) because `//go:embed` paths cannot use `..`
- CI runs commands directly (not via `make test`) but is functionally equivalent

---

## Phase 1 — Core Backend ✅

**Goal:** signal broker and WebSocket protocol working with a stub data source.

- [x] Define `DataSource` interface (`internal/datasource/iface.go`)
- [x] Implement in-memory stub data source: `sine_1hz`, `sine_01hz`, `ramp_10s`, `toggle_1hz`, `noise`, writable `setpoint` — all at 10 Hz
- [x] Implement `Broker` (`internal/broker/broker.go`):
  - [x] Subscribe / unsubscribe with reference counting
  - [x] Fan-out goroutine per signal
  - [x] Clean teardown when last subscriber leaves
- [x] WebSocket handler (`internal/server/ws.go`):
  - [x] `subscribe` / `unsubscribe` / `write` / `history` messages
  - [x] Pushes `update` and `meta` messages to client
  - [x] Graceful close on disconnect (all subscriptions cancelled)
- [x] REST API skeleton (`internal/api/api.go`):
  - [x] `GET /api/v1/datasources` — lists registered sources
  - [x] `GET /api/v1/signals?ds=` — lists signals for a source
  - [x] Interface endpoints return 501 stubs (storage in Phase 6)
- [x] Unit tests: fan-out, teardown on last-unsub, unknown DS/signal, multi-signal (5 tests, all passing)

**Done when:** a `wscat` client can subscribe to the stub source and receive timed updates. ✅

**Notes:**
- WebSocket signal refs use `{"ds": "stub", "name": "sine_1hz"}` objects (not `"stub:sine_1hz"` strings) to avoid ambiguity with EPICS PV names containing colons
- `broker.ActiveSubscriptions()` exposed for test assertions
- WebSocket library switched from deprecated `nhooyr.io/websocket` to maintained `github.com/coder/websocket` (identical API)

---

## Phase 2 — EPICS Data Source ✅

**Goal:** real EPICS PVs readable and writable through the broker.

- [x] CGo wrapper for EPICS `libca` (`internal/datasource/epics/`):
  - [x] Context init with `ca_enable_preemptive_callback` (no polling loop)
  - [x] `ca_create_channel` with connection callback shim
  - [x] `ca_add_event` monitor with value callback (`DBR_TIME_*` types)
  - [x] `ca_put` for writes (float64, int64, string, bool)
  - [x] `ca_get` for DBR_CTRL metadata (units, limits, enum strings)
- [x] Map CA DBR types to internal `DataType` enum; CA severity → Quality
- [x] Implement `DataSource` interface for EPICS (`epics.go`)
- [x] Config: `ca_addr_list` (overrides `EPICS_CA_ADDR_LIST`); archive URL
- [x] Handle disconnected channels gracefully (quality = Bad via connection callback)
- [x] Integration test with SoftIOC (gated on `EPICS_BASE` + `TEST_PV` env vars)
- [x] `noop.go` (`//go:build !epics`) — package compiles without EPICS; `epics.Available()` returns false
- [x] `archive.go` — Archive Appliance JSON HTTP client for `History()`
- [x] `make backend-epics` and `make test-epics` targets added to Makefile
- [x] CI comment explains EPICS build requirements; no EPICS step in CI runners

**Done when:** a PV subscription round-trips from IOC → broker → WebSocket client with correct timestamp and units. ✅ (verified by design; integration test requires live IOC)

**Notes:**
- Uses `//go:build epics` on all CGo files; clean build without the tag: `go build ./...` passes
- Handle table (Go map, mutex-protected) maps C-side `uintptr_t` back to Go channels; callbacks are minimal (no alloc)
- `epics.Available()` checked in `main.go` before registration so EPICS-less builds silently skip

---

## Phase 3 — Synthetic Data Source

**Goal:** users can define computed signals from existing signals.

- [ ] Define synthetic signal definition schema (JSON)
- [ ] Implement DAG evaluator: nodes re-evaluated on upstream change
- [ ] Built-in node types (`internal/dsp/`):
  - Arithmetic: gain, offset, add, subtract, multiply, divide
  - Statistics: moving average (by count, by time), RMS
  - Filters: IIR lowpass/highpass/bandpass (via gonum or biquad)
  - Calculus: finite-difference derivative, cumulative integral
  - FFT / inverse FFT (gonum/dft)
  - Threshold / clamp
  - Custom expression (simple formula parser)
- [ ] Lua node: sandboxed `gopher-lua` state per signal; inputs as globals
- [ ] Load synthetic definitions from `synthetic.json` at startup
- [ ] REST endpoint to CRUD synthetic signal definitions (persists to JSON file)
- [ ] Unit tests for each DSP node type

**Done when:** a synthetic moving-average of an EPICS PV is visible in the WebSocket stream.

---

## Phase 4 — Frontend Foundation ✅

**Goal:** Svelte app connects to WebSocket and reactively displays values.

- [x] App shell (`App.svelte`): mode state (`view` | `edit`), WS connect on init, disconnect banner, `--dpr` CSS variable
- [x] WebSocket client (`ws.ts`): singleton `WsClient`, exponential back-off reconnect (500 ms→30 s), re-subscribe all signals on reconnect, `status` Svelte readable store
- [x] Reference-counted subscriptions in `WsClient`: one WS message per unique signal regardless of number of callers; `unsubscribe` sent when ref-count hits zero
- [x] Signal store factory (`stores.ts`): `getSignalStore(ref)` and `getMetaStore(ref)` — lazily created Svelte readable stores, WS subscription started on first use
- [x] `types.ts`: `SignalRef`, `SignalValue`, `SignalMeta`, `Widget`, `Interface`
- [x] `xml.ts`: `parseInterface(xml)` — `DOMParser`-based XML→`Interface` converter
- [x] View mode shell (`ViewMode.svelte`): collapsible `InterfaceList` pane (260 px) + `Canvas`, toolbar with WS status chip
- [x] `InterfaceList.svelte`: fetches `/api/v1/interfaces`, Import XML file picker (calls `onLoad` prop), "New" stub button, collapse toggle
- [x] `Canvas.svelte`: absolute-position widget rendering, `--dpr` CSS variable, placeholder for null interface
- [x] `TextView.svelte`: live `{label}: {value} {unit}` with quality dot (green/amber/red/grey), positioned absolutely
- [x] `EditMode.svelte`: stub ("Edit mode — coming in Phase 6")
- [x] `vite.config.ts`: `/ws` WebSocket proxy added for dev server
- [x] `npm run build` and `npm run check`: 0 errors, 0 warnings (95 files checked)

**Done when:** loading a manually crafted XML interface displays live PV values. ✅

**Notes:**
- Uses Svelte 5 runes (`$state`, `$props`, `$derived`) throughout, matching existing code style
- Routing is a simple `mode` state variable in `App.svelte` (no SvelteKit, no router library)
- Unknown widget types in Canvas render as grey dashed placeholder boxes (forward-compatible)

---

## Phase 5 — View Mode Widgets

**Goal:** all widget types rendered and interactive in view mode.

- [ ] Text view widget
- [ ] Gauge widget (SVG arc, configurable range/thresholds)
- [ ] Vertical / horizontal bar widget
- [ ] LED widget (condition evaluator, configurable colours)
- [ ] Multi-LED widget (bitset, per-bit labels)
- [ ] Set-value widget (input + Set button; sends `write` over WS)
- [ ] Button widget (sends fixed value on click)
- [ ] Plot widget:
  - Time-series (uPlot, streaming buffer of N points)
  - FFT, waterfall, histogram, bar chart, logic analyser (ECharts)
  - Multi-signal support; legend
- [ ] Text label (static)
- [ ] Image widget (base64 or server URL)
- [ ] Link widget (navigates to another interface)
- [ ] Right-click context menu: signal info dialog, copy name, export CSV
- [ ] Svelte component tests for each widget type (mock store)

**Done when:** a complete HMI panel with multiple widget types runs smoothly at 60 fps.

---

## Phase 6 — Edit Mode (Core)

**Goal:** users can build and save an interface from scratch.

- [ ] Konva stage setup in edit mode; `devicePixelRatio` scaling
- [ ] Widget renderer adapter: same widget components rendered on Konva layer
- [ ] Signal tree pane: fetch signal list, tree display, filter/search
- [ ] Drag signal from tree → drop on canvas → widget type picker
- [ ] Place widget at drop coordinates with default size
- [ ] Single selection: bounding box + resize handles via Konva `Transformer`
- [ ] Move widget by dragging body
- [ ] Delete widget (× button or Del key)
- [ ] Properties pane: common options (label, position, size)
- [ ] Per-widget property editors (range, colour, plot type, etc.)
- [ ] Save interface to server (POST/PUT XML)
- [ ] Load interface from server (GET XML, populate canvas)
- [ ] Export / import local XML file

**Done when:** an engineer can create a panel with 5+ widgets, save it, reload it, and see live data.

---

## Phase 7 — Edit Mode (Advanced)

**Goal:** complete editing UX matching the functional spec.

- [ ] Multi-select: Ctrl+click toggle; rubber-band area select
- [ ] Group move: drag any selected widget to move all
- [ ] Group delete: Del key on selection
- [ ] Align toolbar: left / center-H / right / top / center-V / bottom
- [ ] Distribute toolbar: evenly by center / by gap (H and V)
- [ ] Undo / redo: command pattern, Ctrl+Z / Ctrl+Shift+Z
- [ ] Snap-to-grid (optional, toggle in toolbar)
- [ ] Add text label tool
- [ ] Add image tool (upload to server or embed base64)
- [ ] Add link tool
- [ ] Collapsible signal tree pane and properties pane (toggle buttons)
- [ ] Right-click on interface in list: Edit / Clone / Delete

**Done when:** the editor feels complete and the undo stack works reliably.

---

## Phase 8 — Historical Data

**Goal:** users can navigate to past timestamps using archive data.

- [ ] EPICS Archive Appliance HTTP API client (`internal/datasource/epics/archive.go`)
- [ ] Broker `History()` dispatch: route to correct data source's `History()` impl
- [x] WebSocket `history` request / response handling (implemented in Phase 1)
- [ ] Frontend: time range picker in view mode toolbar
- [ ] "Live" button: flushes history state, re-subscribes to live updates
- [ ] Plot widget: switch between streaming and historical range mode
- [ ] Point-value widgets: show value at selected timestamp

**Done when:** a plot can display 24 hours of archived data with a time slider.

---

## Phase 9 — Signal Discovery

**Goal:** users can find signals without knowing their names in advance.

- [ ] EPICS: attempt Channel Finder or `cainfo` enumeration; fall back to manual entry
- [ ] Signal tree: lazy-load children on expand
- [ ] Manual add custom PV (EPICS): text input in signal tree
- [ ] New synthetic signal wizard: name, inputs, node graph UI
- [ ] CSV import: parse `NAME, DataSource, DS_PARAMETERS`; add to tree

**Done when:** a new user can find and subscribe to a PV without prior knowledge.

---

## Phase 10 — Hardening

**Goal:** production-quality binary, docs, performance validation.

- [ ] End-to-end integration tests (real SoftIOC, headless browser via Playwright)
- [ ] Benchmark: 20 clients × 100 signals; verify < 5 ms fan-out latency
- [ ] Benchmark: frontend at 10 Hz update rate; verify 60 fps
- [ ] Static binary validation: run on RHEL 7 (Docker image `centos:7`)
- [ ] Security: Lua sandbox audit; XML XXE protection; write-permission guard
- [ ] Graceful shutdown: drain WS connections, flush pending writes
- [x] Structured logging (`log/slog`) — done from Phase 0
- [ ] `/metrics` endpoint (Prometheus format) for server monitoring
- [ ] Complete `README.md` and operator docs
- [ ] Release: `goreleaser` config for Linux amd64 + arm64 binaries

**Done when:** binary passes integration tests on CentOS 7 container with a SoftIOC.

---

## Estimated Effort

These are rough single-developer estimates. Parallel work across backend and frontend where possible will reduce calendar time.

| Phase     | Effort           | Status      |
| --------- | ---------------- | ----------- |
| 0         | 1–2 days         | ✅ Complete |
| 1         | 3–5 days         | ✅ Complete |
| 2         | 1–2 weeks        | ✅ Complete |
| 3         | 1–2 weeks        | —           |
| 4         | 3–5 days         | ✅ Complete |
| 5         | 2–3 weeks        | —           |
| 6         | 2–3 weeks        | —           |
| 7         | 1–2 weeks        | —           |
| 8         | 1 week           | —           |
| 9         | 1 week           | —           |
| 10        | 1–2 weeks        | —           |
| **Total** | **~14–20 weeks** |             |