import { EMPTY_OBJ, NO, hasOwn, isArray, isFunction } from '@vue/shared'
import { type Block, type BlockFn, insert, setScopeId } from './block'
import { rawPropsProxyHandlers, resolveFunctionSource } from './componentProps'
import {
  type GenericComponentInstance,
  currentInstance,
  isAsyncWrapper,
  isRef,
} from '@vue/runtime-dom'
import type { LooseRawProps, VaporComponentInstance } from './component'
import { renderEffect } from './renderEffect'
import {
  insertionAnchor,
  insertionParent,
  isLastInsertion,
  resetInsertionState,
} from './insertionState'
import {
  advanceHydrationNode,
  isHydrating,
  locateHydrationNode,
} from './dom/hydration'
import {
  type DynamicFragment,
  SlotFragment,
  type VaporFragment,
} from './fragment'
import { createElement } from './dom/node'
import { setDynamicProps } from './dom/prop'
import { isInteropEnabled } from './vdomInteropState'

/**
 * Flag to indicate if we are executing a once slot.
 * When true, renderEffect should skip creating reactive effect.
 */
export let inOnceSlot = false

/**
 * Current slot scopeIds for vdom interop
 */
export let currentSlotScopeIds: string[] | null = null

function setCurrentSlotScopeIds(scopeIds: string[] | null): string[] | null {
  try {
    return currentSlotScopeIds
  } finally {
    currentSlotScopeIds = scopeIds
  }
}

export type RawSlots = Record<string, VaporSlot> & {
  $?: DynamicSlotSource[]
}

export type StaticSlots = Record<string, VaporSlot>

export type VaporSlot = BlockFn
export type DynamicSlot = { name: string; fn: VaporSlot }
export type DynamicSlotFn = () => DynamicSlot | DynamicSlot[]
export type DynamicSlotSource = StaticSlots | DynamicSlotFn

export const dynamicSlotsProxyHandlers: ProxyHandler<RawSlots> = {
  get: getSlot,
  has: (target, key: string) => !!getSlot(target, key),
  getOwnPropertyDescriptor(target, key: string) {
    const slot = getSlot(target, key)
    if (slot) {
      return {
        configurable: true,
        enumerable: true,
        value: slot,
      }
    }
  },
  ownKeys(target) {
    let keys = Object.keys(target)
    const dynamicSources = target.$
    if (dynamicSources) {
      keys = keys.filter(k => k !== '$')
      for (const source of dynamicSources) {
        if (isFunction(source)) {
          const slot = resolveFunctionSource(source)
          if (slot) {
            if (isArray(slot)) {
              for (const s of slot) keys.push(String(s.name))
            } else {
              keys.push(String(slot.name))
            }
          }
        } else {
          keys.push(...Object.keys(source))
        }
      }
    }
    return keys
  },
  set: NO,
  deleteProperty: NO,
}

export function getSlot(
  target: RawSlots,
  key: string,
):
  | (VaporSlot & { _boundMap?: WeakMap<DynamicFragment, VaporSlot> })
  | undefined {
  if (key === '$') return
  const dynamicSources = target.$
  if (dynamicSources) {
    let i = dynamicSources.length
    let source
    while (i--) {
      source = dynamicSources[i]
      if (isFunction(source)) {
        const slot = resolveFunctionSource(source)
        if (slot) {
          if (isArray(slot)) {
            for (const s of slot) {
              if (String(s.name) === key) return s.fn
            }
          } else if (String(slot.name) === key) {
            return slot.fn
          }
        }
      } else if (hasOwn(source, key)) {
        return source[key]
      }
    }
  }
  if (hasOwn(target, key)) {
    return target[key]
  }
}

/**
 * Tracks the slot owner (the component that defines the slot content).
 * This is used for:
 * 1. Getting the correct rawSlots in forwarded slots (via createSlot)
 * 2. Inheriting the slot owner's scopeId
 */
export let currentSlotOwner: VaporComponentInstance | null = null

export function setCurrentSlotOwner(
  owner: VaporComponentInstance | null,
): VaporComponentInstance | null {
  try {
    return currentSlotOwner
  } finally {
    currentSlotOwner = owner
  }
}

/**
 * Get the effective slot instance for accessing rawSlots and scopeId.
 * Prefers currentSlotOwner (if inside a slot), falls back to currentInstance.
 */
export function getScopeOwner(): VaporComponentInstance | null {
  return (currentSlotOwner || currentInstance) as VaporComponentInstance | null
}

/**
 * Wrap a slot function to track the slot owner.
 *
 * This ensures:
 * 1. createSlot gets rawSlots from the correct instance (slot owner)
 * 2. elements inherit the slot owner's scopeId
 */
export function withVaporCtx(fn: Function): BlockFn {
  const owner = getScopeOwner()
  return (...args: any[]) => {
    const prevOwner = setCurrentSlotOwner(owner)
    try {
      return fn(...args)
    } finally {
      setCurrentSlotOwner(prevOwner)
    }
  }
}

export function createSlot(
  name: string | (() => string),
  rawProps?: LooseRawProps | null,
  fallback?: VaporSlot,
  noSlotted?: boolean,
  once?: boolean,
): Block {
  const _insertionParent = insertionParent
  const _insertionAnchor = insertionAnchor
  const _isLastInsertion = isLastInsertion
  if (!isHydrating) resetInsertionState()

  const instance = getScopeOwner()!
  const rawSlots = instance.rawSlots
  const slotProps = rawProps
    ? new Proxy(rawProps, rawPropsProxyHandlers)
    : EMPTY_OBJ

  let fragment: SlotFragment
  if (isRef(rawSlots._) && isInteropEnabled) {
    if (isHydrating) locateHydrationNode()
    fragment = instance.appContext.vapor!.vdomSlot(
      rawSlots._,
      name,
      slotProps,
      instance,
      fallback,
    )
  } else {
    fragment = new SlotFragment()
    // mark the slot as forwarded
    fragment.forwarded =
      currentSlotOwner != null && currentSlotOwner !== currentInstance
    const isDynamicName = isFunction(name)

    // Calculate slotScopeIds once (for vdom interop)
    const slotScopeIds: string[] = []
    if (!noSlotted) {
      const scopeId = instance.type.__scopeId
      if (scopeId) {
        slotScopeIds.push(`${scopeId}-s`)
      }
    }

    const renderSlot = () => {
      const slotName = isFunction(name) ? name() : name

      // in custom element mode, render <slot/> as actual slot outlets
      // because in shadowRoot: false mode the slot element gets
      // replaced by injected content
      if (
        (instance as GenericComponentInstance).ce ||
        (instance.parent &&
          isAsyncWrapper(instance.parent) &&
          instance.parent.ce)
      ) {
        const el = createElement('slot')
        renderEffect(() => {
          setDynamicProps(el, [
            slotProps,
            slotName !== 'default' ? { name: slotName } : {},
          ])
        })
        if (fallback) insert(fallback(), el)
        fragment.nodes = el
        return
      }

      const slot = getSlot(rawSlots, slotName)
      if (slot) {
        // Create and cache bound slot to keep it stable and avoid unnecessary
        // updates when it resolves to the same slot. Cache per-fragment
        // (v-for creates multiple fragments) so each fragment keeps its own
        // slotProps without cross-talk.
        const boundMap = slot._boundMap || (slot._boundMap = new WeakMap())
        let bound = boundMap.get(fragment)
        if (!bound) {
          bound = () => {
            const prevSlotScopeIds = setCurrentSlotScopeIds(
              slotScopeIds.length > 0 ? slotScopeIds : null,
            )
            const prev = inOnceSlot
            try {
              if (once) inOnceSlot = true
              return slot(slotProps)
            } finally {
              inOnceSlot = prev
              setCurrentSlotScopeIds(prevSlotScopeIds)
            }
          }
          boundMap.set(fragment, bound)
        }
        fragment.updateSlot(bound, fallback)
      } else {
        fragment.updateSlot(undefined, fallback)
      }
    }

    // dynamic slot name or has dynamicSlots
    if (!once && (isDynamicName || rawSlots.$)) {
      renderEffect(renderSlot)
    } else {
      renderSlot()
    }
  }

  if (!isHydrating) {
    if (!noSlotted) {
      const scopeId = instance.type.__scopeId
      if (scopeId) {
        setScopeId(fragment, [`${scopeId}-s`])
      }
    }

    if (_insertionParent) insert(fragment, _insertionParent, _insertionAnchor)
  } else {
    if (fragment.insert) {
      ;(fragment as VaporFragment).hydrate!()
    }
    if (_isLastInsertion) {
      advanceHydrationNode(_insertionParent!)
    }
  }

  return fragment
}