import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
import { useLocation, useNavigate, useSearchParams } from 'react-router-dom'
import { normalizeLanguageKey } from './localization'
import { setByPath } from './paths'

const DESIGNER_QUERY_KEY = 'design'
const HISTORY_LIMIT = 50

interface UseDesignerStateOptions {
  currentLanguage?: string
  supportedLanguages?: string[]
  /** Tasarim modunun acilabilmesi icin yetki kontrolu. Varsayilan: acik. */
  enabled?: boolean
}

interface LanguageEntry<T> {
  current: T
  /** Sunucudan gelen son icerigin serilestirilmis hali; "kirli mi" karsilastirmasi icin. */
  baseline: string
  past: T[]
  future: T[]
}

function serialize(value: unknown) {
  try {
    return JSON.stringify(value) ?? '__undefined__'
  } catch {
    return '__unserializable__'
  }
}

function clone<T>(value: T): T {
  try {
    return JSON.parse(JSON.stringify(value)) as T
  } catch {
    return value
  }
}

function createEntry<T>(content: T): LanguageEntry<T> {
  return { current: clone(content), baseline: serialize(content), past: [], future: [] }
}

export function useDesignerState<T>(
  pageKey: string,
  initialContent: T | null,
  options?: UseDesignerStateOptions,
) {
  const location = useLocation()
  const navigate = useNavigate()
  const [searchParams, setSearchParams] = useSearchParams()
  const isDesignerRequested =
    searchParams.get(DESIGNER_QUERY_KEY) === '1' || location.pathname.endsWith('/designer')
  const isDesignMode = isDesignerRequested && options?.enabled !== false

  const currentLanguage = normalizeLanguageKey(options?.currentLanguage)
  const supportedLanguages = useMemo(() => {
    const base = (options?.supportedLanguages ?? [currentLanguage]).map(normalizeLanguageKey)

    return Array.from(new Set(base.includes(currentLanguage) ? base : [currentLanguage, ...base]))
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [currentLanguage, serialize(options?.supportedLanguages)])

  const [entries, setEntries] = useState<Record<string, LanguageEntry<T>>>({})
  const [selectedBlockId, setSelectedBlockId] = useState<string | null>(null)
  const entriesRef = useRef(entries)
  entriesRef.current = entries

  const serializedInitial = serialize(initialContent)

  // Sunucu icerigi degistiginde (ilk yukleme veya dil degisimi) o dilin taslagini tohumla.
  // Kullanici o dilde duzenleme yaptiysa taslak korunur, uzerine yazilmaz.
  useEffect(() => {
    if (!initialContent) {
      return
    }

    setEntries((previous) => {
      const entry = previous[currentLanguage]

      if (entry && serialize(entry.current) !== entry.baseline) {
        return previous
      }

      if (entry && entry.baseline === serializedInitial) {
        return previous
      }

      return { ...previous, [currentLanguage]: createEntry(initialContent) }
    })
    // initialContent yerine serilestirilmis hali izlenir: her render'da yeni referans gelse bile
    // efekt yalnizca icerik gercekten degistiginde calisir.
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [currentLanguage, serializedInitial])

  useEffect(() => {
    if (!isDesignMode) {
      setSelectedBlockId(null)
    }
  }, [isDesignMode])

  const entry = entries[currentLanguage]
  const content = entry?.current ?? initialContent ?? null
  const isDirty = Boolean(entry) && serialize(entry.current) !== entry.baseline

  const mutate = useCallback(
    (updater: (current: T) => T | null) => {
      setEntries((previous) => {
        const existing = previous[currentLanguage]

        if (!existing) {
          return previous
        }

        const next = updater(existing.current)

        if (!next || serialize(next) === serialize(existing.current)) {
          return previous
        }

        return {
          ...previous,
          [currentLanguage]: {
            ...existing,
            current: next,
            past: [...existing.past, existing.current].slice(-HISTORY_LIMIT),
            future: [],
          },
        }
      })
    },
    [currentLanguage],
  )

  /** Nokta yolu ile tek bir alani gunceller. */
  const setFieldValue = useCallback(
    (path: string, value: unknown) => {
      mutate((current) => setByPath(current, path, value))
    },
    [mutate],
  )

  const undo = useCallback(() => {
    setEntries((previous) => {
      const existing = previous[currentLanguage]

      if (!existing?.past.length) {
        return previous
      }

      const past = [...existing.past]
      const restored = past.pop() as T

      return {
        ...previous,
        [currentLanguage]: {
          ...existing,
          current: restored,
          past,
          future: [existing.current, ...existing.future].slice(0, HISTORY_LIMIT),
        },
      }
    })
  }, [currentLanguage])

  const redo = useCallback(() => {
    setEntries((previous) => {
      const existing = previous[currentLanguage]

      if (!existing?.future.length) {
        return previous
      }

      const [restored, ...future] = existing.future

      return {
        ...previous,
        [currentLanguage]: {
          ...existing,
          current: restored,
          past: [...existing.past, existing.current].slice(-HISTORY_LIMIT),
          future,
        },
      }
    })
  }, [currentLanguage])

  /** Kaydedilmemis degisiklikleri atip sunucudan gelen son icerige doner. */
  const resetContent = useCallback(() => {
    setEntries((previous) => {
      const existing = previous[currentLanguage]

      if (!existing) {
        return previous
      }

      return {
        ...previous,
        [currentLanguage]: {
          ...existing,
          current: JSON.parse(existing.baseline) as T,
          past: [...existing.past, existing.current].slice(-HISTORY_LIMIT),
          future: [],
        },
      }
    })
  }, [currentLanguage])

  /** Kaydetme basarili olduktan sonra mevcut icerigi yeni referans nokta yapar. */
  const commitContent = useCallback(() => {
    setEntries((previous) => {
      const existing = previous[currentLanguage]

      if (!existing) {
        return previous
      }

      return {
        ...previous,
        [currentLanguage]: { ...existing, baseline: serialize(existing.current) },
      }
    })
  }, [currentLanguage])

  const exitDesignMode = useCallback(() => {
    // Tasarim modu iki sekilde acilabiliyor: `?design=1` veya `/<sayfa>/designer` yolu.
    if (location.pathname.endsWith('/designer')) {
      navigate(location.pathname.replace(/\/designer$/, '') || '/', { replace: true })
      return
    }

    const next = new URLSearchParams(searchParams)
    next.delete(DESIGNER_QUERY_KEY)
    setSearchParams(next, { replace: true })
  }, [location.pathname, navigate, searchParams, setSearchParams])

  // Tasarim modunda sekme kapatilirken kaydedilmemis degisiklikler icin uyari.
  useEffect(() => {
    if (!isDesignMode || !isDirty) {
      return
    }

    const handleBeforeUnload = (event: BeforeUnloadEvent) => {
      event.preventDefault()
      event.returnValue = ''
    }

    window.addEventListener('beforeunload', handleBeforeUnload)

    return () => window.removeEventListener('beforeunload', handleBeforeUnload)
  }, [isDesignMode, isDirty])

  return {
    pageKey,
    content,
    isDesignMode,
    isDirty,
    canUndo: Boolean(entry?.past.length),
    canRedo: Boolean(entry?.future.length),
    selectedBlockId,
    selectedLanguage: currentLanguage,
    supportedLanguages,
    setContent: mutate,
    setFieldValue,
    setSelectedBlockId,
    resetContent,
    commitContent,
    exitDesignMode,
    undo,
    redo,
  }
}