import { createElement, useEffect, useMemo, useRef, useState } from 'react'
import { InsertPicker } from '../editors/builtin'
import type { CmsNode, EvaluateContext, ExperimentAnalytics, ExperimentAssignment, ExperimentRule, TypeInfo } from '../api'
import { allowedChildren, connectionsOf, labelKey, sortGroups, typeName } from '../schema'
import type { DropTarget } from '../page/dnd'
import { Icon, TypeIcon } from './Icon'
import { Summary } from './Summary'
import { useCtrl, useEditorState, usePersistentState } from './hooks'
import type { Block, Controller } from '../controller'

/**
 * Left panel: outline + blocks + nodes in one place (no tabs).
 *
 * - Outline is a tree with its slots (e.g. a pdp's `info-section` /
 *   `3d-accessories` connections): drag any row by its grip to reorder, drop
 *   palette blocks and searched nodes onto the gaps between rows or into slots.
 * - Blocks are the new types that fit this page (drag onto the page or the outline).
 * - Nodes finds *existing* nodes (type filter + text) to link into the page.
 */
export function Rail() {
  const ctrl = useCtrl()
  const open = useEditorState((s) => s.rail)
  useEffect(() => {
    if (!open) return
    // Types carry every schema (titles, groups, slots): one request seeds them all.
    void ctrl.api
      .types()
      .then((ts) => {
        ctrl.ingestTypes(ts)
        void ctrl.loadSchemas(ts.map(typeName))
      })
      .catch(() => {})
    void ctrl.fillHandles()
  }, [open, ctrl])
  if (!open) return null
  return (
    <aside className="cms-rail" aria-label="Page panel">
      <header>
        <span className="cms-rail__title">
          <Icon name="outline" size={16} /> Page
        </span>
        <button className="cms-ico" onClick={() => ctrl.setRail(false)} aria-label="Close panel">
          <Icon name="close" />
        </button>
      </header>
      <div className="cms-rail__body">
        <OutlineTree />
        <Palette />
        <NodeSearch />
        <ExperimentsPanel />
      </div>
    </aside>
  )
}

// --- outline -----------------------------------------------------------------

type Gap = { parentId: string; handle?: string; index: number }

function OutlineTree() {
  const ctrl = useCtrl()
  const blocks = useEditorState((s) => s.blocks)
  const selected = useEditorState((s) => s.selected)
  const drag = useEditorState((s) => s.drag)
  useEditorState((s) => s.tick)
  useEditorState((s) => s.schemasVersion)
  useEditorState((s) => s.labelsVersion)
  const [collapsed, setCollapsed] = useState<Set<string>>(new Set())
  const [over, setOver] = useState<Gap | null>(null)
  const dragging = !!drag

  // Our pointerup runs before the page engine's (registered at mount, theirs at
  // drag start): a drop on a gap commits to the outline, anywhere else on the
  // panel just cancels the page ghost.
  useEffect(() => {
    const onUp = (e: PointerEvent) => {
      const d = ctrl.store.get().drag
      if (!d) return
      const path = e.composedPath() as Element[]
      const inRail = path.some((el) => el instanceof Element && el.classList?.contains('cms-rail'))
      if (!inRail) return
      e.stopImmediatePropagation()
      e.preventDefault()
      const gapEl = path.find((el) => el instanceof Element && el.hasAttribute?.('data-ogap'))
      const target: DropTarget | null = gapEl
        ? {
            parentId: gapEl.getAttribute('data-parent') ?? '',
            handle: gapEl.getAttribute('data-handle') || undefined,
            index: Number(gapEl.getAttribute('data-index') ?? 0),
            line: { x: 0, y: 0, w: 0, h: 0 },
          }
        : null
      setOver(null)
      ctrl.cancelDrag()
      if (!target) return
      if (d.source === 'block' && d.id) void ctrl.dropBlock(d.id, target)
      else if (d.source === 'existing' && d.nodeId) void ctrl.dropExisting(target, d.nodeId)
      else if (d.source === 'palette' && d.type && !d.blueprint) void ctrl.dropNew(target, { type: d.type })
      else if (d.source === 'palette' && d.blueprint && !target.handle) void ctrl.dropNew(target, { blueprint: d.blueprint })
      else if (d.source === 'palette' && d.blueprint && target.handle) ctrl.toast('info', 'Blueprints cannot go straight into a slot — drop it on the page first, then move it')
    }
    ctrl.doc.addEventListener('pointerup', onUp, true)
    return () => ctrl.doc.removeEventListener('pointerup', onUp, true)
  }, [ctrl])

  useEffect(() => {
    if (!drag) setOver(null)
  }, [drag])

  const roots = useMemo(() => blocks.filter((b) => !b.parentId), [blocks])
  const [open, setOpen] = usePersistentState('cms-onpage.sec.outline', true)
  if (!blocks.length) return null
  return (
    <section aria-label="Outline">
      <h4 className="cms-rail__sec">
        <button className="cms-sectoggle" aria-expanded={open} aria-label="Outline" onClick={() => setOpen((o) => !o)}>
          Outline ({blocks.length})
        </button>
      </h4>
      {open && (
        <>
          <ul className="cms-outline cms-outline--tree">
            {roots.map((b) => (
              <OutlineNode key={b.id} block={b} level={0} collapsed={collapsed} setCollapsed={setCollapsed} over={over} setOver={setOver} dragging={dragging} selected={selected} />
            ))}
          </ul>
          {dragging && <OutlineGap parentId="" index={roots.length} over={over} setOver={setOver} />}
        </>
      )}
    </section>
  )
}

function OutlineGap({ parentId, handle, index, over, setOver }: { parentId: string; handle?: string; index: number; over: Gap | null; setOver: (g: Gap | null) => void }) {
  const ctrl = useCtrl()
  const drag = useEditorState((s) => s.drag)
  if (!drag) return null
  const active = over?.parentId === parentId && (over?.handle ?? '') === (handle ?? '') && over?.index === index
  // Blueprints cannot land in slots; slot gaps refuse them.
  const refused = !!drag.blueprint && !!handle
  // Page drops onto a type the slot does not take are refused too.
  const typeRefused = !!drag.type && !drag.blueprint && parentId !== '' && !ctrl.accepts(parentId, drag.type) && !(handle ? ctrl.acceptsInSlot(parentId, handle, drag.type) : ctrl.handleForDrop(parentId, drag.type))
  return (
    <div
      className={`cms-ogap${active && !refused ? ' is-over' : ''}${refused || typeRefused ? ' is-refused' : ''}`}
      data-ogap=""
      data-parent={parentId}
      data-handle={handle ?? ''}
      data-index={index}
      onPointerEnter={() => (refused ? setOver(null) : setOver({ parentId, handle, index }))}
      onPointerLeave={() => setOver(null)}
    />
  )
}

function OutlineNode({ block: b, level, collapsed, setCollapsed, over, setOver, dragging, selected }: {
  block: Block
  level: number
  collapsed: Set<string>
  setCollapsed: (f: (s: Set<string>) => Set<string>) => void
  over: Gap | null
  setOver: (g: Gap | null) => void
  dragging: boolean
  selected: string | null
}) {
  const ctrl = useCtrl()
  const kids = useEditorState((s) => s.blocks.filter((x) => (x.parentId ?? '') === b.id && !ctrl.handleOf(x.id)))
  const slots = useMemo(() => ctrl.slotsFor(b.id), [ctrl, b.id, b.schema, kids.length])
  useEditorState((s) => s.tick)
  const isCollapsed = collapsed.has(b.id)
  const isSel = b.id === selected
  const toggle = () => setCollapsed((s) => {
    const n = new Set(s)
    if (n.has(b.id)) n.delete(b.id)
    else n.add(b.id)
    return n
  })
  const title = ctrl.labelFor(b.id)
  const hasKids = kids.length > 0 || slots.some((sl) => ctrl.slotChildren(b.id, sl.name).length > 0)
  return (
    <li>
      <div className={`cms-orow${isSel ? ' is-sel' : ''}`} style={{ paddingLeft: 4 + level * 14 }}>
        {(b.container || slots.length > 0) && hasKids ? (
          <button className="cms-ico cms-orow__chev" onClick={toggle} aria-label={isCollapsed ? 'Expand' : 'Collapse'} title={isCollapsed ? 'Expand' : 'Collapse'}>
            <span className={`cms-chev${isCollapsed ? '' : ' is-open'}`} style={{ display: 'inline-flex' }}>
              <Icon name="chevron" size={14} />
            </span>
          </button>
        ) : (
          <span className="cms-orow__spacer" />
        )}
        <span
          className="cms-orow__grip"
          title="Drag to reorder"
          aria-label={`Drag ${title ?? b.type} to reorder`}
          onPointerDown={(e) => {
            if (e.button !== 0) return
            e.stopPropagation()
            const x0 = e.clientX
            const y0 = e.clientY
            const doc = e.currentTarget.ownerDocument
            const move = (m: PointerEvent) => {
              if (Math.hypot(m.clientX - x0, m.clientY - y0) < 5) return
              doc.removeEventListener('pointermove', move, true)
              doc.removeEventListener('pointerup', stop, true)
              ctrl.setMode('edit')
              ctrl.beginDrag(b.id)
            }
            const stop = () => {
              doc.removeEventListener('pointermove', move, true)
              doc.removeEventListener('pointerup', stop, true)
            }
            doc.addEventListener('pointermove', move, true)
            doc.addEventListener('pointerup', stop, true)
          }}
        >
          <Icon name="grip" size={14} />
        </span>
        <button
          className="cms-orow__main"
          onMouseEnter={() => ctrl.store.set({ hovered: b.id })}
          onMouseLeave={() => ctrl.store.set({ hovered: null })}
          onClick={() => {
            ctrl.setMode('edit')
            ctrl.select(b.id, { scroll: true })
          }}
          title={`${b.type}${ctrl.handleOf(b.id) ? ` · in slot ${ctrl.handleOf(b.id)}` : ''}`}
        >
          <TypeIcon type={b.type} size={15} />
          {title ? (
            <>
              <span className="cms-outline__type">{title}</span>
              <span className="cms-outline__text">{b.type}</span>
            </>
          ) : (
            <>
              <span className="cms-outline__type">{b.type || '?'}</span>
              <span className="cms-outline__text">{(b.el.textContent ?? '').trim().slice(0, 40)}</span>
            </>
          )}
          {ctrl.handleOf(b.id) && <em className="cms-oslot-tag">{ctrl.handleOf(b.id)}</em>}
        </button>
      </div>
      {!isCollapsed && (
        <ul className="cms-outline cms-outline--nested">
          {dragging && <OutlineGap parentId={b.id} index={0} over={over} setOver={setOver} />}
          {kids.map((k, i) => (
            <OutlineNodeInner key={`${k.id}-${i}`} block={k} index={i} level={level + 1} collapsed={collapsed} setCollapsed={setCollapsed} over={over} setOver={setOver} dragging={dragging} selected={selected} />
          ))}
          {dragging && kids.length > 0 && <OutlineGap parentId={b.id} index={kids.length} over={over} setOver={setOver} />}
          {slots.map((sl) => (
            <SlotGroup key={sl.name} parentId={b.id} level={level + 1} slot={sl} over={over} setOver={setOver} dragging={dragging} collapsed={collapsed} setCollapsed={setCollapsed} selected={selected} />
          ))}
        </ul>
      )}
    </li>
  )
}

/** A plain (non-slot) child: its own row, followed by the gap after it. */
function OutlineNodeInner(props: { block: Block; index: number; level: number } & Omit<Parameters<typeof OutlineNode>[0], 'block' | 'level'>) {
  const { block, index, level, ...rest } = props
  return (
    <>
      <OutlineNode block={block} level={level} {...rest} />
      {rest.dragging && <OutlineGap parentId={block.parentId ?? ''} index={index + 1} over={rest.over} setOver={rest.setOver} />}
    </>
  )
}

function SlotGroup({ parentId, level, slot, over, setOver, dragging, collapsed, setCollapsed, selected }: {
  parentId: string
  level: number
  slot: { name: string; def: { to: string[]; kind: string; description?: string }; count: number; accepts: (t: string) => boolean }
  over: Gap | null
  setOver: (g: Gap | null) => void
  dragging: boolean
  collapsed: Set<string>
  setCollapsed: (f: (s: Set<string>) => Set<string>) => void
  selected: string | null
}) {
  const ctrl = useCtrl()
  const kids = useEditorState((s) => s.blocks.filter((x) => (x.parentId ?? '') === parentId && ctrl.handleOf(x.id) === slot.name))
  const add = () => {
    let key = 0
    key = ctrl.openDialog({ id: `insert:${parentId}:${slot.name}`, title: `Add to ${slot.name}`, size: 'sm', content: createElement(InsertPicker, { parentId, handle: slot.name, ctrl, close: () => ctrl.closeDialog(key) }) })
  }
  return (
    <li className="cms-oslot" style={{ marginLeft: level * 14 }}>
      <div className="cms-oslot__head" title={slot.def.description ?? `Slot: ${slot.name}`}>
        <Icon name="shape" size={13} />
        <span>{slot.name}</span>
        <span className="cms-muted">{slot.def.to.length ? slot.def.to.join(', ') : 'any'}</span>
        <button className="cms-ico" onClick={add} title={`Add to ${slot.name}`} aria-label={`Add to ${slot.name}`}>
          <Icon name="add" size={14} />
        </button>
      </div>
      <ul className="cms-outline cms-outline--nested">
        {dragging && <OutlineGap parentId={parentId} handle={slot.name} index={0} over={over} setOver={setOver} />}
        {kids.map((k, i) => (
          <OutlineNodeInner key={`${k.id}-${i}`} block={k} index={i} level={level + 1} collapsed={collapsed} setCollapsed={setCollapsed} over={over} setOver={setOver} dragging={dragging} selected={selected} />
        ))}
        {dragging && kids.length > 0 && <OutlineGap parentId={parentId} handle={slot.name} index={kids.length} over={over} setOver={setOver} />}
      </ul>
    </li>
  )
}

// --- palette (new blocks) -------------------------------------------------------

const DRAG_THRESHOLD = 5

type Item = { key: string; label: string; sub?: string; type?: string; blueprint?: string; group: string; description?: string }

function Palette() {
  const ctrl = useCtrl()
  const [types, setTypes] = useState<TypeInfo[] | null>(null)
  const [blueprints, setBlueprints] = useState<import('../api').Blueprint[]>([])
  const [q, setQ] = useState('')
  const { selected, blocks } = useEditorState((s) => ({ selected: s.selected, blocks: s.blocks }))
  const schemasVersion = useEditorState((s) => s.schemasVersion)
  const suppressClick = useRef(false)

  useEffect(() => {
    void ctrl.api
      .types()
      .then((ts) => {
        ctrl.ingestTypes(ts) // /api/types includes every schema: titles + groups with no further requests
        setTypes(ts)
        void ctrl.loadSchemas(ts.map(typeName)) // only for entries that arrived without a schema
      })
      .catch(() => setTypes([]))
    void ctrl.api.blueprints().then(setBlueprints).catch(() => {})
  }, [ctrl])

  // Types some container on the page (or the page itself) can hold - the rest would only ever be refused.
  const items = useMemo<Item[]>(() => {
    if (!types) return []
    const all = types.map(typeName).filter(Boolean)
    const allowed = new Set<string>()
    for (const b of blocks) if (b.container) allowedChildren(b.schema, all).forEach((t) => allowed.add(t))
    // Slots accept more than plain children (e.g. a pdp's info-section): include slot types too.
    for (const b of blocks) for (const h of Object.keys(connectionsOf(b.schema))) for (const t of connectionsOf(b.schema)[h]?.to ?? []) allowed.add(t)
    const rootAllowed = !allowed.size // schemas not loaded yet: show everything rather than nothing
    return [
      ...types
        .map((t) => ({ t, name: typeName(t) }))
        .filter(({ name }) => name && !ctrl.isStaticRoot(name) && (rootAllowed || allowed.has(name)))
        .map(({ name }) => {
          const title = ctrl.typeTitle(name)
          return { key: `t:${name}`, label: title, sub: title !== name ? name : undefined, type: name, group: ctrl.groupOfType(name), description: ctrl.schemaOf(name)?.description as string | undefined }
        }),
      ...blueprints.map((b) => ({ key: `b:${b.id}`, label: b.name ?? b.id, blueprint: b.id, group: 'Blueprints', description: b.description })),
    ]
  }, [types, blueprints, blocks, ctrl, schemasVersion])

  const needle = q.toLowerCase()
  const shown = items.filter((i) => i.label.toLowerCase().includes(needle) || (i.type ?? '').toLowerCase().includes(needle))
  const groups = sortGroups(shown.map((i) => i.group).filter((g) => g !== 'Blueprints'))
  if (shown.some((i) => i.group === 'Blueprints')) groups.push('Blueprints')

  const addToSelection = async (item: Item) => {
    const sel = ctrl.block(selected)
    try {
      let parent: string
      let index: number | undefined
      let handle: string | undefined
      if (sel && sel.container && (!item.type || ctrl.accepts(sel.id, item.type) || (handle = ctrl.handleForDrop(sel.id, item.type)))) parent = sel.id
      else if (sel) {
        parent = await ctrl.parentIdOf(sel.id)
        handle = ctrl.handleOf(sel.id)
        index = (await ctrl.position(sel.id)).index + 1
      } else parent = await ctrl.pageRoot()
      if (item.blueprint) await ctrl.insertBlueprint(parent, item.blueprint, index)
      else if (item.type) await ctrl.insert(parent, item.type, { ...(index !== undefined ? { index } : {}), ...(handle ? { handle } : {}) })
    } catch (e) {
      ctrl.toast('error', (e as Error).message)
    }
  }

  const onPointerDown = (e: React.PointerEvent, item: Item) => {
    if (e.button !== 0) return
    const x0 = e.clientX
    const y0 = e.clientY
    const doc = e.currentTarget.ownerDocument
    const move = (m: PointerEvent) => {
      if (Math.hypot(m.clientX - x0, m.clientY - y0) < DRAG_THRESHOLD) return
      stop()
      suppressClick.current = true
      ctrl.setMode('edit')
      ctrl.beginPaletteDrag({ type: item.type, blueprint: item.blueprint, label: item.label })
    }
    const stop = () => {
      doc.removeEventListener('pointermove', move, true)
      doc.removeEventListener('pointerup', stop, true)
    }
    doc.addEventListener('pointermove', move, true)
    doc.addEventListener('pointerup', stop, true)
  }

  const [open, setOpen] = usePersistentState('cms-onpage.sec.blocks', true)
  return (
    <section aria-label="Blocks">
      <h4 className="cms-rail__sec">
        <button className="cms-sectoggle" aria-expanded={open} aria-label="Blocks" onClick={() => setOpen((o) => !o)}>
          Blocks
        </button>
      </h4>
      {open && (
      <>
      <div className="cms-pad">
        <input className="cms-input" placeholder="Search blocks…" aria-label="Search blocks" value={q} onChange={(e) => setQ(e.target.value)} />
        <p className="cms-muted cms-hint">Drag onto the page or the outline, or click to add to the selection.</p>
      </div>
      {!types && <p className="cms-muted cms-pad">Loading…</p>}
      {groups.map((g) => (
        <details key={g} className="cms-group-sec" open>
          <Summary>
            {g} <span className="cms-muted">{shown.filter((i) => i.group === g).length}</span>
          </Summary>
          <div className="cms-palette__grid">
            {shown
              .filter((i) => i.group === g)
              .map((i) => (
                <button
                  key={i.key}
                  className="cms-block"
                  data-type={i.type}
                  title={i.description ?? `Add ${i.label}`}
                  onPointerDown={(e) => onPointerDown(e, i)}
                  onClick={() => {
                    if (suppressClick.current) return void (suppressClick.current = false)
                    void addToSelection(i)
                  }}
                >
                  <TypeIcon type={i.type ?? i.label} size={22} />
                  <span>{i.label}</span>
                  {i.sub && <small>{i.sub}</small>}
                </button>
              ))}
          </div>
        </details>
      ))}
      {types && !shown.length && <p className="cms-muted cms-pad">Nothing matches.</p>}
      </>
      )}
    </section>
  )
}

// --- node search (existing nodes) -----------------------------------------------

function nodeTitle(ctrl: Controller, n: CmsNode): string | undefined {
  const key = labelKey(ctrl.schemaOf(n.dataType))
  const v = key ? (n.data as Record<string, unknown>)?.[key] : undefined
  const text = typeof v === 'string' || typeof v === 'number' ? String(v).replace(/\s+/g, ' ').trim() : ''
  if (text) return text.length > 40 ? `${text.slice(0, 39)}…` : text
  const first = Object.values(n.data ?? {}).find((x) => typeof x === 'string' && x.trim())
  const fb = typeof first === 'string' ? first.trim().slice(0, 40) : ''
  return fb || undefined
}

function NodeSearch() {
  const ctrl = useCtrl()
  const [typeNames, setTypeNames] = useState<string[]>([])
  const [type, setType] = useState('')
  const [q, setQ] = useState('')
  const [results, setResults] = useState<CmsNode[] | null>(null)
  const [total, setTotal] = useState(0)
  const [busy, setBusy] = useState(false)
  const selected = useEditorState((s) => s.selected)
  useEditorState((s) => s.schemasVersion)

  useEffect(() => {
    void ctrl.api
      .types()
      .then((ts) => {
        ctrl.ingestTypes(ts)
        setTypeNames(ts.map(typeName).filter(Boolean).sort())
      })
      .catch(() => {})
  }, [ctrl])

  useEffect(() => {
    const t = setTimeout(() => {
      setBusy(true)
      void ctrl.api
        .searchNodes({ type: type || undefined, q: q || undefined, limit: 20 })
        .then((r) => {
          setResults(r.items)
          setTotal(r.total)
          void ctrl.loadSchemas([...new Set(r.items.map((n) => n.dataType))])
        })
        .catch(() => setResults([]))
        .finally(() => setBusy(false))
    }, q ? 250 : 0)
    return () => clearTimeout(t)
  }, [q, type, ctrl])

  const linkToSelection = async (node: CmsNode) => {
    const sel = ctrl.block(selected)
    try {
      if (sel && sel.container && (ctrl.accepts(sel.id, node.dataType) || ctrl.handleForDrop(sel.id, node.dataType))) {
        await ctrl.linkExisting(sel.id, node.id, { handle: ctrl.handleForDrop(sel.id, node.dataType) })
      } else if (sel) {
        const parent = await ctrl.parentIdOf(sel.id)
        const { index } = await ctrl.position(sel.id)
        await ctrl.linkExisting(parent, node.id, { handle: ctrl.handleOf(sel.id), index: index + 1 })
      } else {
        await ctrl.linkExisting(await ctrl.pageRoot(), node.id, {})
      }
    } catch (e) {
      ctrl.toast('error', (e as Error).message)
    }
  }

  const onPointerDown = (e: React.PointerEvent, node: CmsNode) => {
    if (e.button !== 0) return
    const x0 = e.clientX
    const y0 = e.clientY
    const doc = e.currentTarget.ownerDocument
    const move = (m: PointerEvent) => {
      if (Math.hypot(m.clientX - x0, m.clientY - y0) < DRAG_THRESHOLD) return
      stop()
      ctrl.setMode('edit')
      ctrl.beginExistingDrag({ id: node.id, type: node.dataType, label: nodeTitle(ctrl, node) ?? node.dataType })
    }
    const stop = () => {
      doc.removeEventListener('pointermove', move, true)
      doc.removeEventListener('pointerup', stop, true)
    }
    doc.addEventListener('pointermove', move, true)
    doc.addEventListener('pointerup', stop, true)
  }

  const [open, setOpen] = usePersistentState('cms-onpage.sec.nodes', true)
  return (
    <section aria-label="Nodes">
      <h4 className="cms-rail__sec">
        <button className="cms-sectoggle" aria-expanded={open} aria-label="Nodes" onClick={() => setOpen((o) => !o)}>
          Nodes
        </button>
      </h4>
      {open && (
      <>
      <div className="cms-pad cms-nodefind">
        <input className="cms-input" placeholder="Search existing nodes…" aria-label="Search nodes" value={q} onChange={(e) => setQ(e.target.value)} />
        <select className="cms-input" aria-label="Filter by type" value={type} onChange={(e) => setType(e.target.value)}>
          <option value="">All types</option>
          {typeNames.map((t) => (
            <option key={t} value={t}>
              {ctrl.typeTitle(t)}
            </option>
          ))}
        </select>
        <p className="cms-muted cms-hint">Link a shared block into the page — drag it onto the outline, or click + to add to the selection.</p>
      </div>
      {busy && !results && <p className="cms-muted cms-pad">Searching…</p>}
      {results && !results.length && <p className="cms-muted cms-pad">No nodes match.</p>}
      {!!results?.length && (
        <ul className="cms-nodelist">
          {results.map((n) => (
            <li key={n.id} className="cms-noderow" onPointerDown={(e) => onPointerDown(e, n)} title={`${n.dataType} · ${n.id}`}>
              <TypeIcon type={n.dataType} size={15} />
              <span className="cms-noderow__main">
                <span className="cms-outline__type">{nodeTitle(ctrl, n) ?? n.dataType}</span>
                <span className="cms-outline__text">
                  {n.dataType} · {n.id.slice(0, 8)}
                </span>
              </span>
              <button
                className="cms-ico"
                aria-label={`Link ${nodeTitle(ctrl, n) ?? n.id}`}
                title="Link into the page"
                onClick={(e) => {
                  e.stopPropagation()
                  void linkToSelection(n)
                }}
                onPointerDown={(e) => e.stopPropagation()}
              >
                <Icon name="add" size={15} />
              </button>
            </li>
          ))}
        </ul>
      )}
      {!!results?.length && total > results.length && <p className="cms-muted cms-pad">Showing {results.length} of {total} — refine the search.</p>}
      </>
      )}
    </section>
  )
}

// --- experiments: QA + eligibility on the page (plan-onpage-experiments-personalisation.md P0) ---------

const expCookie = (name: string): string | null => {
  const m = document.cookie.match(new RegExp(`(?:^|; )${name}=([^;]*)`))
  return m ? decodeURIComponent(m[1]) : null
}
const setExpCookie = (name: string, value: string | null) => {
  document.cookie = value === null ? `${name}=; expires=Thu, 01 Jan 1970 00:00:00 GMT; path=/` : `${name}=${encodeURIComponent(value)}; path=/; SameSite=Lax`
}
const targetingSummary = (rules?: ExperimentRule['targeting']): string =>
  !rules?.length ? 'everyone' : rules.map((r) => `${r.field} ${r.op} ${r.value ?? (r.values ?? []).join('|')}`).join(' · ')
const armNames = (rule: ExperimentRule): string[] => Object.keys(rule.variant_weights ?? {})

function ExperimentsPanel() {
  const ctrl = useCtrl()
  const [rules, setRules] = useState<ExperimentRule[] | null>(null)
  const [adminDenied, setAdminDenied] = useState(false)
  const [assign, setAssign] = useState<Record<string, ExperimentAssignment>>({})
  const [stats, setStats] = useState<Record<string, ExperimentAnalytics>>({})
  const [confirmOff, setConfirmOff] = useState<string | null>(null)
  const [tick, setTick] = useState(0) // re-read override cookies after set/clear
  const [open, setOpen] = usePersistentState('cms-onpage.sec.experiments', false)

  useEffect(() => {
    if (!open) return
    let live = true
    const ctx: EvaluateContext = { pagePath: location.pathname, referrer: document.referrer || undefined, language: navigator.language || undefined }
    void ctrl.api
      .trackingConfig()
      .then((cfg) => {
        if (!live) return
        const rs = cfg.experiment_rules ?? []
        setRules(rs)
        if (!rs.length) return
        void ctrl.api.evaluateExperiments(rs.map((r) => r.experiment_id), ctx).then(
          (res) => live && setAssign(Object.fromEntries((res.assignments ?? []).map((a) => [a.experimentId, a]))),
          () => {}, // evaluate is public; a failure just leaves assignments blank
        )
        void ctrl.api.experimentAnalytics().then(
          (rows) => live && setStats(Object.fromEntries((rows ?? []).map((s) => [s.experiment_id, s]))),
          () => live && setAdminDenied(true), // admin-gated: eligibility still works, stats hide
        )
      })
      .catch(() => live && (setRules([]), setAdminDenied(true)))
    return () => void (live = false)
  }, [open, ctrl])

  const toggleDisabled = async (rule: ExperimentRule) => {
    if (confirmOff !== rule.experiment_id) return void setConfirmOff(rule.experiment_id)
    setConfirmOff(null)
    try {
      const res = await ctrl.api.setExperimentDisabled(rule.experiment_id, !rule.disabled)
      setRules((rs) => rs?.map((r) => (r.experiment_id === rule.experiment_id ? { ...r, disabled: res.disabled } : r)) ?? rs)
      ctrl.toast('info', `${rule.experiment_id} ${res.disabled ? 'paused' : 'resumed'}`)
    } catch (e) {
      ctrl.toast('error', (e as Error).message)
    }
  }

  return (
    <section aria-label="Experiments panel">
      <h4 className="cms-rail__sec">
        <button className="cms-sectoggle" aria-expanded={open} aria-label="Experiments" onClick={() => setOpen((o) => !o)}>
          Experiments{rules ? ` (${rules.length})` : ''}
        </button>
      </h4>
      {open && (
        <div className="cms-pad">
          {rules === null && <p className="cms-muted">Loading experiments…</p>}
          {rules !== null && !rules.length && <p className="cms-muted">No experiments configured in tracking.</p>}
          {adminDenied && !!rules?.length && <p className="cms-muted cms-hint">Tracking admin refused — eligibility still works; stats and pause need an admin credential.</p>}
          {!!rules?.length && (
            <ul className="cms-explist">
              {rules.map((rule) => {
                const a = assign[rule.experiment_id]
                const s = stats[rule.experiment_id]
                const arms = armNames(rule)
                const cookie = expCookie(a?.cookieName ?? `exp_${rule.experiment_id}`)
                void tick
                return (
                  <li key={rule.experiment_id} className="cms-exp">
                    <div className="cms-exp__head">
                      <strong>{rule.experiment_id}</strong>
                      <span className={`cms-pill${rule.disabled ? ' is-off' : ''}`}>{rule.disabled ? 'paused' : 'live'}</span>
                    </div>
                    <div className="cms-muted cms-exp__meta">
                      traffic {Math.round((rule.traffic_fraction ?? 1) * 100)}% · arms {arms.length ? arms.join(' / ') : 'a / b'} · {targetingSummary(rule.targeting)}
                    </div>
                    <div className="cms-exp__assign">
                      {a ? (a.eligible ? <>you: <b>{a.variant || '—'}</b></> : 'you: not eligible') : 'you: …'}
                      {cookie && cookie !== a?.variant && <span className="cms-muted"> (override: {cookie})</span>}
                    </div>
                    {s && (
                      <div className="cms-muted cms-exp__meta">
                        {s.total_sessions} sessions · winner <b>{s.winner || '—'}</b>
                        {s.winner ? ` (${Math.round((s.winner_probability ?? 0) * 100)}%)` : ''}
                        {s.significant ? ' · significant' : ''} — {s.conclusion || 'collecting data'}
                      </div>
                    )}
                    <div className="cms-exp__actions">
                      <label className="cms-muted">
                        QA arm{' '}
                        <select
                          className="cms-input"
                          aria-label={`Force variant for ${rule.experiment_id}`}
                          value={cookie ?? ''}
                          onChange={(e) => {
                            setExpCookie(a?.cookieName ?? `exp_${rule.experiment_id}`, e.target.value || null)
                            setTick((t) => t + 1)
                          }}
                        >
                          <option value="">session default</option>
                          {arms.map((v) => (
                            <option key={v} value={v}>
                              {v}
                            </option>
                          ))}
                        </select>
                      </label>
                      <button
                        className={`cms-ico${confirmOff === rule.experiment_id ? ' is-on' : ''}`}
                        aria-label={rule.disabled ? `Resume ${rule.experiment_id}` : `Pause ${rule.experiment_id}`}
                        title={rule.disabled ? 'Resume (re-buckets new sessions)' : 'Pause (kill-switch: new sessions see control)'}
                        onClick={() => void toggleDisabled(rule)}
                      >
                        <Icon name={confirmOff === rule.experiment_id ? 'check' : rule.disabled ? 'play' : 'pause'} size={15} />
                        {confirmOff === rule.experiment_id && <span>confirm</span>}
                      </button>
                    </div>
                  </li>
                )
              })}
            </ul>
          )}
          <p className="cms-muted cms-hint">Overrides set the storefront variant cookie — reload the page to preview the arm.</p>
        </div>
      )}
    </section>
  )
}