// The List blueprint, as data. Lifted verbatim from the blueprint-ontology
// `list` README: signature, behaviors, invariants, failure modes, performance.
// The generic Viewer renders this; ListSpecimen supplies the bespoke visual.

import type { Blueprint } from "./blueprint"
import { LOADSTATE_MACHINE } from "./loadStateMachine"

export const list: Blueprint = {
  slug: "list",
  name: "List<Item>",
  tagline: "A scrollable, ordered set of items.",
  role: "feature",
  extendsName: "Set<Item>",
  composesCount: 5,

  sig: {
    header: "List<Item> + Async + Paginated + Pullable + Selectable + Filterable",
    fields: [
      { name: "items", type: "seq Item", note: "List: ordered, loaded subset" },
      { name: "loadState", type: "LoadState", note: "Async · Paginated · Pullable" },
      { name: "totalCount", type: "Int", note: "Paginated" },
      { name: "selectionMode", type: "SelectionMode", note: "Selectable" },
      { name: "selected", type: "set Item", note: "Selectable" },
      { name: "visible", type: "set Item", note: "Filterable" },
    ],
    types: [
      "LoadState     = Idle | Loading | Refreshing | LoadingMore | Error",
      "SelectionMode = None | Single | Multi",
    ],
  },

  functions: [
    {
      id: "display",
      name: "Display",
      fig: "01",
      caps: ["List", "Async"],
      verb: "Render items in order; render skeleton placeholders during initial load; handle empty, loading, and error states distinctly.",
      state: [
        ["items", "seq Item"],
        ["loadState", "LoadState"],
      ],
      behaviors: [],
      invariants: ["#1  items = ∅ is a valid state (empty list, not an error)"],
      failures: [
        "empty vs error conflation — network returns 0 items with 4xx; empty state treated as error, user sees wrong UI",
        "skeleton / content mismatch — skeleton row dimensions differ from real item; layout shift on Loading → Idle",
      ],
      perf: [
        "skeleton placeholders render within 100 ms of navigation",
        "real items replace the skeleton within 300 ms",
        "skeleton dimensions must match real items to prevent layout shift",
      ],
      notes: [],
    },
    {
      id: "scroll",
      name: "Scroll",
      fig: "02",
      caps: ["List"],
      verb: "Allow the user to navigate the full item sequence; virtualize off-screen items.",
      state: [["items", "seq Item"]],
      behaviors: [],
      invariants: ["items form a well-formed sequence (no duplicate indices) — l.items.isSeq"],
      failures: [],
      perf: [
        "60 fps minimum — off-screen items must not be rendered (virtualization required)",
        "items outside the render window must release their view references (memory)",
      ],
      notes: [
        "Scroll is navigation, not a mutating behavior — it moves the render window over items, it does not change them.",
      ],
    },
    {
      id: "load",
      name: "Load",
      fig: "03",
      caps: ["Async", "Paginated", "Pullable"],
      verb: "Fetch the initial page; support refresh (restart) and pagination (append).",
      state: [
        ["loadState", "LoadState"],
        ["totalCount", "Int"],
      ],
      behaviors: [
        {
          sig: "refresh()",
          pre: "loadState = idle",
          eff: "loadState ← refreshing, reload items from page 1, selected ← ∅",
        },
        {
          sig: "loadMore()",
          pre: "#items < totalCount, loadState = idle",
          eff: "loadState ← loadingMore, append next page to items",
        },
      ],
      invariants: ["#6  #items ≤ totalCount", "#7  loadState = loadingMore → #items < totalCount"],
      failures: [
        "duplicate load — loadMore() called while loadState = loadingMore; duplicate items appended, items loses uniqueness",
        "unknown total — streaming source, totalCount never known; use CursorPaginated with a hasMore sentinel instead",
      ],
      perf: ["loadMore appends new items without layout shift or scroll-position jump"],
      notes: [],
    },
    {
      id: "filter",
      name: "Filter",
      fig: "04",
      caps: ["Filterable"],
      verb: "Restrict the visible set without mutating the underlying sequence.",
      state: [["visible", "set Item"]],
      behaviors: [{ sig: "filter(pred)", pre: "—", eff: "visible ← { x ∈ items | pred(x) }" }],
      invariants: ["#8  visible ⊆ items — filter never introduces new items"],
      failures: [
        "filter after reload — predicate references old item shape; visible silently empties without error",
      ],
      perf: ["result updates within one frame (≤ 16 ms) for in-memory data"],
      notes: [
        "Ephemeral: derives visible from items but does not mutate the sequence. Persisting a filter is a consumer concern.",
      ],
    },
    {
      id: "sort",
      name: "Sort",
      fig: "05",
      caps: ["Sortable"],
      verb: "Reorder the sequence by a comparator without changing identity.",
      state: [["items", "seq Item"]],
      behaviors: [{ sig: "sort(cmp)", pre: "—", eff: "reorder items by comparator" }],
      invariants: ["identity is preserved — sorting changes order, never membership"],
      failures: [
        "sort invalidates cursor (CursorPaginated) — cursor is stale; must reset to NoCursor and reload from page 1",
      ],
      perf: [],
      notes: [
        "Ephemeral alongside filter: reorders the displayed sequence without persisting the change.",
      ],
    },
    {
      id: "select",
      name: "Select",
      fig: "06",
      caps: ["Selectable"],
      verb: "Track user intent over a subset of items (none / single / multi).",
      state: [
        ["selectionMode", "SelectionMode"],
        ["selected", "set Item"],
      ],
      behaviors: [
        {
          sig: "select(x)",
          pre: "x ∈ visible, selectionMode ≠ none",
          eff: "selected ← selected ∪ {x}",
        },
        { sig: "deselect(x)", pre: "x ∈ selected", eff: "selected ← selected \\ {x}" },
        { sig: "selectAll()", pre: "selectionMode = multi", eff: "selected ← visible" },
        { sig: "clearSelection()", pre: "—", eff: "selected ← ∅" },
      ],
      invariants: [
        "#3  selected ⊆ items",
        "#4  selectionMode = none → selected = ∅",
        "#5  selectionMode = single → #selected ≤ 1",
      ],
      failures: [
        "stale selection — refresh() clears items but not selected; selected ⊄ items, invariant #3 violated",
      ],
      perf: [],
      notes: [],
    },
    {
      id: "act",
      name: "Act",
      fig: "07",
      caps: ["Swipeable", "Reorderable"],
      verb: "Expose per-item contextual actions (swipe, long-press) to the consumer.",
      state: [],
      behaviors: [
        {
          sig: "swipeAction(x, dir)",
          pre: "x ∈ visible",
          eff: "trigger consumer-defined contextual action",
        },
        {
          sig: "reorder(from, to)",
          pre: "capability: reorderable = true",
          eff: "swap positions in items",
        },
      ],
      invariants: [],
      failures: [
        "reorder on filtered view — reorder operates on visible, not items; position mismatch between displayed and stored order",
      ],
      perf: [],
      notes: ["Open question: swipe direction — left | right only, or also up | down?"],
    },
  ],

  coreInvariants: [
    "items = ∅ is a valid state (empty list, not an error)",
    "items are identity-unique — no duplicates by key",
    "elems[items] = members — ordered form stays in sync with the set",
  ],

  composition: {
    caps: [
      { id: "core", label: "List : Set", sub: "items : seq Item", core: true },
      { id: "async", label: "Async", sub: "loadState" },
      { id: "paginated", label: "Paginated", sub: "totalCount" },
      { id: "pullable", label: "Pullable", sub: "refresh" },
      { id: "filterable", label: "Filterable", sub: "visible" },
      { id: "selectable", label: "Selectable", sub: "selected" },
      { id: "sortable", label: "Sortable", sub: "cmp" },
      { id: "swipeable", label: "Swipeable", sub: "+ Reorderable" },
    ],
    funcs: ["Display", "Scroll", "Load", "Filter", "Sort", "Select", "Act"],
    links: [
      ["core", "Display"],
      ["core", "Scroll"],
      ["async", "Display"],
      ["async", "Load"],
      ["paginated", "Load"],
      ["pullable", "Load"],
      ["filterable", "Filter"],
      ["selectable", "Select"],
      ["sortable", "Sort"],
      ["swipeable", "Act"],
    ],
  },

  stateMachines: [LOADSTATE_MACHINE],
}