import { useEffect, useRef, useState, type PointerEvent as ReactPointerEvent, type ReactNode } from 'react'
import { NavMenu } from './components/NavMenu'
import { FilterBar } from './components/FilterBar'
import {
  LogTimeline,
  TIME_RANGE_PRESETS,
  computeBucketMs,
  computePresetRange,
  loadLogSortSettings,
  saveLogSortSettings,
  type LogSortSettings,
  type TimeRange,
  type TimeRangePresetId,
} from './components/LogTimeline'
import { LogPreview } from './components/LogPreview'
import { Params } from './components/Params'
import { Metrics } from './components/Metrics'
import { Dashboards } from './components/Dashboards'
import { Alerts } from './components/Alerts'
import { CollapseToggle, PopOutButton, type PopOutSectionId, useSectionCollapsed } from './components/CollapsibleSection'
import {
  fetchLogs,
  fetchParamDeclarations,
  fetchStats,
  fetchTimeline,
  type LogEntry,
  type ParamDeclaration,
  type Stats,
  type TimelineBucket,
} from './lib/api'
import { DocsNavProvider } from './lib/docsNav'
import { useSettingsPanel } from './lib/useSettingsPanel'
import { POLL_MS } from './lib/polling'

// Height (px) the log viewer had before it became resizable — kept as the default so existing
// layouts don't jump on first load after this change.
const DEFAULT_LOG_VIEWER_HEIGHT_PX = 352
const MIN_LOG_VIEWER_HEIGHT_PX = 200
// Leaves room below the log viewer for the drag handle and at least a sliver of the next
// section, so a drag can never grow it to swallow the whole viewport.
const LOG_VIEWER_HEIGHT_VIEWPORT_MARGIN_PX = 160

// Namespaced under `ottyl.` per the app's existing localStorage convention (see
// CollapsibleSection.tsx's COLLAPSED_SECTIONS_STORAGE_KEY, LogPreview.tsx's
// VISIBLE_PARAM_COLUMNS_STORAGE_KEY).
const LOG_VIEWER_HEIGHT_STORAGE_KEY = 'ottyl.logViewerHeightPx'

function clampLogViewerHeight(px: number): number {
  const max = Math.max(MIN_LOG_VIEWER_HEIGHT_PX, window.innerHeight - LOG_VIEWER_HEIGHT_VIEWPORT_MARGIN_PX)
  return Math.min(max, Math.max(MIN_LOG_VIEWER_HEIGHT_PX, px))
}

function loadLogViewerHeight(): number {
  try {
    const raw = localStorage.getItem(LOG_VIEWER_HEIGHT_STORAGE_KEY)
    if (!raw) return DEFAULT_LOG_VIEWER_HEIGHT_PX
    const parsed = Number(raw)
    return Number.isFinite(parsed) ? clampLogViewerHeight(parsed) : DEFAULT_LOG_VIEWER_HEIGHT_PX
  } catch {
    return DEFAULT_LOG_VIEWER_HEIGHT_PX
  }
}

function saveLogViewerHeight(px: number) {
  try {
    localStorage.setItem(LOG_VIEWER_HEIGHT_STORAGE_KEY, String(px))
  } catch {
    // best-effort — private browsing or full storage just means the size won't persist across reloads
  }
}

// Ticket 074: a sort helper index's one-time full-scan build (`build_sort_helper_index`) runs
// inline in the engine actor, so a `sort_by` poll can occasionally take much longer than the usual
// sub-poll-interval round trip — without this, that stall looks exactly like "sorting is broken"
// rather than "still indexing". Only flips `setBuilding(true)` if the fetch is still in flight after
// `thresholdMs`, so an ordinary fast poll (helper index already built/incrementally maintained)
// never flashes the indicator.
const SORT_BUILDING_INDICATOR_THRESHOLD_MS = 400

function trackSlowSortedFetch<T>(sortBy: string | null, setBuilding: (building: boolean) => void, promise: Promise<T>): Promise<T> {
  if (!sortBy) return promise
  const timer = setTimeout(() => setBuilding(true), SORT_BUILDING_INDICATOR_THRESHOLD_MS)
  return promise.finally(() => {
    clearTimeout(timer)
    setBuilding(false)
  })
}

/// Thin drag handle between the log viewer and the sections below it. Reports each pointer-move
/// delta via `onResize` (letting the caller clamp/apply it) and fires `onResizeEnd` on release so
/// the final size can be persisted once, not on every pixel of movement.
function ResizeHandle({ onResize, onResizeEnd }: { onResize: (deltaY: number) => void; onResizeEnd: () => void }) {
  const draggingRef = useRef(false)

  function handlePointerDown(e: ReactPointerEvent) {
    e.preventDefault()
    draggingRef.current = true
    let lastY = e.clientY

    function handlePointerMove(ev: PointerEvent) {
      if (!draggingRef.current) return
      onResize(ev.clientY - lastY)
      lastY = ev.clientY
    }

    function handlePointerUp() {
      draggingRef.current = false
      window.removeEventListener('pointermove', handlePointerMove)
      window.removeEventListener('pointerup', handlePointerUp)
      onResizeEnd()
    }

    window.addEventListener('pointermove', handlePointerMove)
    window.addEventListener('pointerup', handlePointerUp)
  }

  return (
    <div
      role="separator"
      aria-orientation="horizontal"
      aria-label="Resize log viewer"
      title="Drag to resize"
      onPointerDown={handlePointerDown}
      className="group relative h-1.5 shrink-0 cursor-ns-resize touch-none"
    >
      <div className="absolute inset-x-0 top-1/2 h-px -translate-y-1/2 bg-border-soft group-hover:bg-border-strong" />
    </div>
  )
}

/// Reads the routing params `PopOutButton` writes: `section` picks which primary section to render full-page. `preset` carries over which rolling preset (e.g. `5m`) was active, so the popped-out tab can resolve and keep re-resolving its own independent window of the same size instead of freezing whatever absolute bounds happened to be active at click time. `startMs`/`endMs` carry over a fixed/dragged (non-preset) range as absolute bounds, same as before.
function parsePopOutQuery(): { section: PopOutSectionId | null; presetId: TimeRangePresetId | null; fixedRange: TimeRange | null } {
  const query = new URLSearchParams(window.location.search)
  const section = query.get('section') as PopOutSectionId | null
  const presetParam = query.get('preset')
  const presetId = TIME_RANGE_PRESETS.some((p) => p.id === presetParam) ? (presetParam as TimeRangePresetId) : null
  const startMs = Number(query.get('startMs'))
  const endMs = Number(query.get('endMs'))
  const fixedRange = query.has('startMs') && query.has('endMs') && Number.isFinite(startMs) && Number.isFinite(endMs)
    ? { startMs, endMs }
    : null
  return { section, presetId, fixedRange }
}

// Popped-out routes render outside NavMenu, which is otherwise the only place that calls `useSettingsPanel()` and applies the
// colour scheme / custom theme CSS as a side effect. Calling it here (state unused) keeps standalone tabs themed the same as
// the main window, including staying live if settings change while the tab is open.
function StandalonePage({ children }: { children: ReactNode }) {
  useSettingsPanel()

  return (
    <DocsNavProvider>
      <div className="h-screen w-screen overflow-auto">{children}</div>
    </DocsNavProvider>
  )
}

/// Popped out on its own, Params has no lifted-state sibling to share `params`/`loadParams` with, so it owns a minimal fetch here instead.
function StandaloneParams() {
  const [params, setParams] = useState<ParamDeclaration[]>([])

  async function loadParams() {
    try {
      setParams(await fetchParamDeclarations())
    } catch {
      // engine not reachable yet; leave the previous list in place
    }
  }

  useEffect(() => {
    loadParams()
  }, [])

  return (
    <StandalonePage>
      <Params params={params} onDeclared={loadParams} />
    </StandalonePage>
  )
}

/// Metrics/Dashboards own their own data fetching — they only need the range. Unlike the log viewer's standalone page, there's no pre-existing per-section timeline to seed buckets from, so this owns its own minimal timeline poll purely to drive `LogTimeline`'s picker UI (preset buttons + drag-to-select) and, when a preset was carried over, to keep independently re-resolving that rolling window on its own cadence — it never tracks or freezes to whatever the source tab's window does after this tab was opened.
function StandaloneRanged({
  section,
  initialPresetId,
  initialFixedRange,
}: {
  section: 'metrics' | 'dashboards'
  initialPresetId: TimeRangePresetId | null
  initialFixedRange: TimeRange | null
}) {
  const [buckets, setBuckets] = useState<TimelineBucket[]>([])
  const [range, setRange] = useState<TimeRange | null>(
    initialPresetId ? computePresetRange(initialPresetId) : initialFixedRange,
  )
  // No preset and no fixed range means the popout was opened with nothing carried over (e.g. a bare URL) — default to 'all', matching FullApp's own default.
  const [activePreset, setActivePreset] = useState<TimeRangePresetId | null>(
    initialPresetId ?? (initialFixedRange ? null : 'all'),
  )

  const rangeRef = useRef(range)
  useEffect(() => {
    rangeRef.current = range
  }, [range])

  function selectPreset(id: TimeRangePresetId) {
    setActivePreset(id)
    setRange(computePresetRange(id))
  }

  function handleManualRangeSelect(next: TimeRange | null) {
    if (next === null) {
      selectPreset('all')
    } else {
      setActivePreset(null)
      setRange(next)
    }
  }

  useEffect(() => {
    let cancelled = false

    async function poll() {
      // Rolling presets re-resolve on this same polling cadence instead of freezing the window at selection time — this is what makes a carried-over preset independently slide rather than track the source tab.
      const effectiveRange =
        activePreset && activePreset !== 'all' ? computePresetRange(activePreset) : rangeRef.current
      if (activePreset && activePreset !== 'all') {
        setRange((current) =>
          current && effectiveRange && current.startMs === effectiveRange.startMs && current.endMs === effectiveRange.endMs
            ? current
            : effectiveRange,
        )
      }
      try {
        const nextBuckets = await fetchTimeline({
          startMs: effectiveRange?.startMs,
          endMs: effectiveRange?.endMs,
          bucketMs: effectiveRange ? computeBucketMs(effectiveRange.endMs - effectiveRange.startMs) : undefined,
        })
        if (!cancelled) setBuckets(nextBuckets)
      } catch {
        // engine not reachable yet; leave the previous buckets in place
      }
    }

    poll()
    const id = setInterval(poll, POLL_MS)
    return () => {
      cancelled = true
      clearInterval(id)
    }
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [activePreset])

  return (
    <StandalonePage>
      <div className="flex h-full min-h-0 flex-col overflow-y-auto">
        <LogTimeline
          buckets={buckets}
          range={range}
          onSelectRange={handleManualRangeSelect}
          activePreset={activePreset}
          onSelectPreset={selectPreset}
        />
        {section === 'metrics' ? (
          <Metrics range={range} activePreset={activePreset} />
        ) : (
          <Dashboards range={range} activePreset={activePreset} />
        )}
      </div>
    </StandalonePage>
  )
}

/// Ticket 058: only replaces `params` state when the declaration list actually changed, so a param
/// list refetched on every poll tick doesn't force `Params.tsx` to re-render when nothing changed.
function updateParamsIfChanged(
  setParams: (updater: (current: ParamDeclaration[]) => ParamDeclaration[]) => void,
  next: ParamDeclaration[],
) {
  setParams((current) => (JSON.stringify(current) === JSON.stringify(next) ? current : next))
}

/// Ticket 066: text shown under the filter bar when the user hasn't typed a manual filter, so an active preset/sort order is still visible somewhere near the filter input instead of leaving it looking empty/stale.
function describeActiveState(activePreset: TimeRangePresetId | null, sortSettings: LogSortSettings): string | null {
  const parts: string[] = []
  if (activePreset && activePreset !== 'all') {
    const preset = TIME_RANGE_PRESETS.find((p) => p.id === activePreset)
    parts.push(`last ${preset?.label ?? activePreset}`)
  }
  if (sortSettings.sortBy) {
    parts.push(`sorted by ${sortSettings.sortBy}`)
  }
  return parts.length > 0 ? parts.join(', ') : null
}

/// The log viewer has its own `LogTimeline`, so it needs its own copy of App's log/timeline polling state instead of a carried-over range.
function StandaloneLog() {
  const [logs, setLogs] = useState<LogEntry[]>([])
  const [params, setParams] = useState<ParamDeclaration[]>([])
  const [buckets, setBuckets] = useState<TimelineBucket[]>([])
  const [range, setRange] = useState<TimeRange | null>(null)
  const [activePreset, setActivePreset] = useState<TimeRangePresetId | null>('all')
  const [filter, setFilter] = useState('')
  const [filterError, setFilterError] = useState<string | null>(null)
  const [sortSettings, setSortSettings] = useState<LogSortSettings>(loadLogSortSettings)
  const [sortIndexBuilding, setSortIndexBuilding] = useState(false)

  function handleSortSettingsChange(next: LogSortSettings) {
    setSortSettings(next)
    saveLogSortSettings(next)
  }

  const rangeRef = useRef(range)
  useEffect(() => {
    rangeRef.current = range
  }, [range])

  useEffect(() => {
    fetchParamDeclarations()
      .then(setParams)
      .catch(() => {
        // engine not reachable yet; leave the previous list in place
      })
  }, [])

  function selectPreset(id: TimeRangePresetId) {
    setActivePreset(id)
    setRange(computePresetRange(id))
  }

  function handleManualRangeSelect(next: TimeRange | null) {
    if (next === null) {
      selectPreset('all')
    } else {
      setActivePreset(null)
      setRange(next)
    }
  }

  useEffect(() => {
    let cancelled = false

    async function poll() {
      const effectiveRange =
        activePreset && activePreset !== 'all' ? computePresetRange(activePreset) : rangeRef.current
      if (activePreset && activePreset !== 'all') {
        setRange((current) =>
          current && effectiveRange && current.startMs === effectiveRange.startMs && current.endMs === effectiveRange.endMs
            ? current
            : effectiveRange,
        )
      }
      try {
        const [nextBuckets, nextLogs, nextParams] = await Promise.all([
          fetchTimeline({
            startMs: effectiveRange?.startMs,
            endMs: effectiveRange?.endMs,
            // Only meaningful for a fixed window — 'all' has no span to derive a resolution from, so it keeps the server's default bucketing.
            bucketMs: effectiveRange ? computeBucketMs(effectiveRange.endMs - effectiveRange.startMs) : undefined,
            filter: filter || undefined,
          }),
          trackSlowSortedFetch(
            sortSettings.sortBy,
            setSortIndexBuilding,
            fetchLogs({
              startMs: effectiveRange?.startMs,
              endMs: effectiveRange?.endMs,
              limit: 1000,
              filter: filter || undefined,
              sortBy: sortSettings.sortBy ?? undefined,
              sortMissingFallback: sortSettings.sortBy ? sortSettings.sortMissingFallback : undefined,
            }),
          ),
          // Ticket 058: params can get auto-declared from freshly ingested lines mid-run, not just from a user's own edit.
          fetchParamDeclarations(),
        ])
        if (!cancelled) {
          setBuckets(nextBuckets)
          setLogs(nextLogs)
          updateParamsIfChanged(setParams, nextParams)
          setFilterError(null)
        }
      } catch (err) {
        if (!cancelled) {
          setFilterError(err instanceof Error ? err.message : String(err))
        }
      }
    }

    poll()
    const id = setInterval(poll, POLL_MS)
    return () => {
      cancelled = true
      clearInterval(id)
    }
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [filter, activePreset, sortSettings])

  return (
    <StandalonePage>
      <div className="flex h-full min-h-0 flex-col">
        <FilterBar
          value={filter}
          onChange={setFilter}
          error={filterError}
          activeSummary={describeActiveState(activePreset, sortSettings)}
        />
        <div className="flex min-h-0 flex-1 flex-col">
          <LogTimeline
            buckets={buckets}
            range={range}
            onSelectRange={handleManualRangeSelect}
            activePreset={activePreset}
            onSelectPreset={selectPreset}
            paramNames={params.map((p) => p.name)}
            sortSettings={sortSettings}
            onSortSettingsChange={handleSortSettingsChange}
            sortIndexBuilding={sortIndexBuilding}
          />
          <LogPreview logs={logs} params={params} />
        </div>
      </div>
    </StandalonePage>
  )
}

export default function App() {
  const { section, presetId, fixedRange } = parsePopOutQuery()
  if (section === 'log') return <StandaloneLog />
  if (section === 'params') return <StandaloneParams />
  if (section === 'metrics' || section === 'dashboards')
    return <StandaloneRanged section={section} initialPresetId={presetId} initialFixedRange={fixedRange} />

  return <FullApp />
}

function FullApp() {
  const [stats, setStats] = useState<Stats | null>(null)
  const [logs, setLogs] = useState<LogEntry[]>([])
  const [params, setParams] = useState<ParamDeclaration[]>([])
  const [buckets, setBuckets] = useState<TimelineBucket[]>([])
  const [range, setRange] = useState<TimeRange | null>(null)
  const [activePreset, setActivePreset] = useState<TimeRangePresetId | null>('all')
  const [filter, setFilter] = useState('')
  const [filterError, setFilterError] = useState<string | null>(null)
  const [logViewerCollapsed, setLogViewerCollapsed] = useSectionCollapsed('log-viewer')
  const [logViewerHeight, setLogViewerHeight] = useState(() => loadLogViewerHeight())
  const [sortSettings, setSortSettings] = useState<LogSortSettings>(loadLogSortSettings)
  const [sortIndexBuilding, setSortIndexBuilding] = useState(false)

  function handleSortSettingsChange(next: LogSortSettings) {
    setSortSettings(next)
    saveLogSortSettings(next)
  }

  function handleLogViewerResize(deltaY: number) {
    setLogViewerHeight((current) => clampLogViewerHeight(current + deltaY))
  }

  function handleLogViewerResizeEnd() {
    setLogViewerHeight((current) => {
      saveLogViewerHeight(current)
      return current
    })
  }

  // Read via ref inside the poll loop instead of depending on `range` directly, which would restart the interval every rolling-preset tick.
  const rangeRef = useRef(range)
  useEffect(() => {
    rangeRef.current = range
  }, [range])

  async function loadParams() {
    try {
      setParams(await fetchParamDeclarations())
    } catch {
      // engine not reachable yet; leave the previous list in place
    }
  }

  useEffect(() => {
    loadParams()
  }, [])

  function selectPreset(id: TimeRangePresetId) {
    setActivePreset(id)
    setRange(computePresetRange(id))
  }

  // A drag always yields a fixed (non-rolling) range, overriding any active preset.
  function handleManualRangeSelect(next: TimeRange | null) {
    if (next === null) {
      selectPreset('all')
    } else {
      setActivePreset(null)
      setRange(next)
    }
  }

  useEffect(() => {
    let cancelled = false

    async function poll() {
      // Rolling presets re-resolve on this same polling cadence instead of freezing the window at selection time.
      const effectiveRange =
        activePreset && activePreset !== 'all' ? computePresetRange(activePreset) : rangeRef.current
      if (activePreset && activePreset !== 'all') {
        setRange((current) =>
          current && effectiveRange && current.startMs === effectiveRange.startMs && current.endMs === effectiveRange.endMs
            ? current
            : effectiveRange,
        )
      }
      try {
        const [nextStats, nextBuckets, nextLogs, nextParams] = await Promise.all([
          fetchStats(),
          fetchTimeline({
            startMs: effectiveRange?.startMs,
            endMs: effectiveRange?.endMs,
            // Only meaningful for a fixed window — 'all' has no span to derive a resolution from, so it keeps the server's default bucketing.
            bucketMs: effectiveRange ? computeBucketMs(effectiveRange.endMs - effectiveRange.startMs) : undefined,
            filter: filter || undefined,
          }),
          trackSlowSortedFetch(
            sortSettings.sortBy,
            setSortIndexBuilding,
            fetchLogs({
              startMs: effectiveRange?.startMs,
              endMs: effectiveRange?.endMs,
              limit: 1000,
              filter: filter || undefined,
              sortBy: sortSettings.sortBy ?? undefined,
              sortMissingFallback: sortSettings.sortBy ? sortSettings.sortMissingFallback : undefined,
            }),
          ),
          // Ticket 058: params can get auto-declared from freshly ingested lines mid-run, not just from a user's own edit.
          fetchParamDeclarations(),
        ])
        if (!cancelled) {
          setStats(nextStats)
          setBuckets(nextBuckets)
          setLogs(nextLogs)
          updateParamsIfChanged(setParams, nextParams)
          setFilterError(null)
        }
      } catch (err) {
        if (!cancelled) {
          setFilterError(err instanceof Error ? err.message : String(err))
        }
      }
    }

    poll()
    const id = setInterval(poll, POLL_MS)
    return () => {
      cancelled = true
      clearInterval(id)
    }
    // Intentionally excludes `range` to avoid restarting this interval on every rolling-preset tick.
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [filter, activePreset, sortSettings])

  return (
    <DocsNavProvider>
      <div className="flex h-screen w-screen overflow-hidden">
        <NavMenu stats={stats} />
        <div className="flex min-w-0 flex-1 flex-col overflow-y-auto">
          <FilterBar
            value={filter}
            onChange={setFilter}
            error={filterError}
            activeSummary={describeActiveState(activePreset, sortSettings)}
            collapseToggle={
              <>
                <CollapseToggle collapsed={logViewerCollapsed} onToggle={() => setLogViewerCollapsed(!logViewerCollapsed)} />
                <PopOutButton section="log" />
              </>
            }
          />
          {/* An explicit height (user-resizable via the handle below, persisted to localStorage) keeps this
              from being squeezed by the sections below it in the shared scroll container, and bounds
              LogPreview's own internal `flex-1 overflow-auto` scroll area. */}
          <div
            className="flex shrink-0 flex-col overflow-hidden"
            style={{ height: logViewerHeight }}
            hidden={logViewerCollapsed}
          >
            <LogTimeline
              buckets={buckets}
              range={range}
              onSelectRange={handleManualRangeSelect}
              activePreset={activePreset}
              onSelectPreset={selectPreset}
              paramNames={params.map((p) => p.name)}
              sortSettings={sortSettings}
              onSortSettingsChange={handleSortSettingsChange}
              sortIndexBuilding={sortIndexBuilding}
            />
            <LogPreview logs={logs} params={params} />
          </div>
          {!logViewerCollapsed && <ResizeHandle onResize={handleLogViewerResize} onResizeEnd={handleLogViewerResizeEnd} />}
          <Params params={params} onDeclared={loadParams} />
          <Metrics range={range} activePreset={activePreset} />
          <Dashboards range={range} activePreset={activePreset} />
          <Alerts />
        </div>
      </div>
    </DocsNavProvider>
  )
}