import {
  createEffect,
  createMemo,
  createSignal,
  onCleanup,
  onMount,
} from 'solid-js'
import { Header, HeaderLogo, MainPanel } from '@tanstack/devtools-ui'
import { useStyles } from '../styles/use-styles'
import { usePacerDevtoolsState } from '../PacerContextProvider'
import { UTIL_GROUPS } from './util-groups'
import { UtilList } from './UtilList'
import { DetailsPanel } from './DetailsPanel'
import type { StateKey } from './util-groups'

function readResizeObserverBlockSize(entry: ResizeObserverEntry): number {
  const [box] = entry.borderBoxSize
  if (box !== undefined) return box.blockSize
  return entry.contentRect.height
}

/** Outer plugin slot from TanStack Devtools (not the inner React mount div, which can report a tiny height). */
function resolvePluginHost(el: HTMLElement): HTMLElement | null {
  const byId = el.closest<HTMLElement>('[id^="plugin-container-"]')
  if (byId) return byId
  return (
    el.parentElement?.parentElement?.parentElement ??
    el.parentElement?.parentElement ??
    el.parentElement
  )
}

export function Shell() {
  const styles = useStyles()
  const state = usePacerDevtoolsState()
  const utilState = () => state
  const [selectedKey, setSelectedKey] = createSignal<string | null>(null)
  const [leftPanelWidth, setLeftPanelWidth] = createSignal(300)
  const [isDragging, setIsDragging] = createSignal(false)
  const [shellRootEl, setShellRootEl] = createSignal<HTMLDivElement | null>(
    null,
  )
  const [slotHeightPx, setSlotHeightPx] = createSignal<number | undefined>(
    undefined,
  )

  const selectedInstance = createMemo(() => {
    const key = selectedKey()
    if (!key) return null
    for (const group of UTIL_GROUPS) {
      const instance = (utilState() as unknown as Record<StateKey, Array<any>>)[
        group.key
      ].find((inst) => inst.key === key)
      if (instance) return { instance, type: group.displayName }
    }
    return null
  })

  let dragStartX = 0
  let dragStartWidth = 0

  const handleMouseDown = (e: MouseEvent) => {
    e.preventDefault()
    e.stopPropagation()
    setIsDragging(true)
    document.body.style.cursor = 'col-resize'
    document.body.style.userSelect = 'none'
    dragStartX = e.clientX
    dragStartWidth = leftPanelWidth()
  }

  const handleMouseMove = (e: MouseEvent) => {
    if (!isDragging()) return

    e.preventDefault()
    const deltaX = e.clientX - dragStartX
    const newWidth = Math.max(150, Math.min(800, dragStartWidth + deltaX))
    setLeftPanelWidth(newWidth)
  }

  const handleMouseUp = () => {
    setIsDragging(false)
    document.body.style.cursor = ''
    document.body.style.userSelect = ''
  }

  onMount(() => {
    document.addEventListener('mousemove', handleMouseMove)
    document.addEventListener('mouseup', handleMouseUp)
  })

  onCleanup(() => {
    document.removeEventListener('mousemove', handleMouseMove)
    document.removeEventListener('mouseup', handleMouseUp)
  })

  /**
   * TanStack Devtools plugin slots use height: 100% without min-height: 0 on flex
   * ancestors, so percentage height often never constrains our tree. Observing the
   * outer `plugin-container-*` host (not the immediate React mount wrapper) and
   * setting an explicit pixel height makes inner overflow-y regions scroll without
   * capping to the mount div’s collapsed height.
   */
  createEffect(() => {
    const el = shellRootEl()
    if (!el || typeof ResizeObserver === 'undefined') return
    const pluginSlot = resolvePluginHost(el)
    if (!pluginSlot) return

    const ro = new ResizeObserver((entries) => {
      const entry = entries[0]
      if (!entry) return
      const target = entry.target as HTMLElement
      const h =
        target.clientHeight > 0
          ? target.clientHeight
          : readResizeObserverBlockSize(entry)
      if (h > 0) setSlotHeightPx(Math.round(h))
    })
    ro.observe(pluginSlot)
    onCleanup(() => ro.disconnect())
  })

  return (
    <div
      ref={setShellRootEl}
      class={styles().shellRoot}
      style={{
        ...(slotHeightPx() !== undefined
          ? {
              height: `${slotHeightPx()}px`,
              'max-height': `${slotHeightPx()}px`,
            }
          : {}),
      }}
    >
      <MainPanel class={styles().mainPanelShell}>
        <Header>
          <HeaderLogo flavor={{ light: '#84cc16', dark: '#84cc16' }}>
            TanStack Pacer
          </HeaderLogo>
        </Header>

        <div class={styles().mainContainer}>
          <div
            class={styles().leftPanel}
            style={{
              width: `${leftPanelWidth()}px`,
              'min-width': '150px',
              'max-width': '800px',
            }}
          >
            <UtilList
              selectedKey={selectedKey}
              setSelectedKey={setSelectedKey}
              utilState={utilState}
            />
          </div>

          <div
            class={`${styles().dragHandle} ${isDragging() ? 'dragging' : ''}`}
            onMouseDown={handleMouseDown}
          />

          <div class={styles().rightPanel} style={{ flex: 1 }}>
            <div class={styles().panelHeader}>Details</div>
            <DetailsPanel
              selectedInstance={selectedInstance}
              utilState={utilState}
            />
          </div>
        </div>
      </MainPanel>
    </div>
  )
}