import { memo, useCallback, useEffect, useMemo, useRef, useState } from 'react'
import { isEqual } from 'es-toolkit'
import { useStoreWithEqualityFn } from 'zustand/traditional'
import { Badge } from '@/components/emcn'
import { Combobox, type ComboboxOption } from '@/components/emcn/components'
import { generateId } from '@/lib/core/utils/uuid'
import { buildCanonicalIndex, resolveDependencyValue } from '@/lib/workflows/subblocks/visibility'
import { useSubBlockValue } from '@/app/workspace/[workspaceId]/w/[workflowId]/components/panel/components/editor/components/sub-block/hooks/use-sub-block-value'
import { getBlock } from '@/blocks/registry'
import type { SubBlockConfig } from '@/blocks/types'
import { getDependsOnFields } from '@/blocks/utils'
import { ResponseBlockHandler } from '@/executor/handlers/response/response-handler'
import { useWorkflowRegistry } from '@/stores/workflows/registry/store'
import { useSubBlockStore } from '@/stores/workflows/subblock/store'
import { useWorkflowStore } from '@/stores/workflows/workflow/store'

/**
 * Dropdown option type - can be a simple string or an object with label, id, and optional icon.
 * Options with `hidden: true` are excluded from the picker but still resolve for label display,
 * so existing workflows that reference them continue to work.
 */
type DropdownOption =
  | string
  | {
      label: string
      id: string
      icon?: React.ComponentType<{ className?: string }>
      hidden?: boolean
    }

/**
 * Props for the Dropdown component
 */
interface DropdownProps {
  /** Static options array or function that returns options */
  options: DropdownOption[] | (() => DropdownOption[])
  /** Default value to select when no value is set */
  defaultValue?: string
  /** Unique identifier for the block */
  blockId: string
  /** Unique identifier for the sub-block */
  subBlockId: string
  /** Current value(s) - string for single select, array for multi-select */
  value?: string | string[]
  /** Whether component is in preview mode */
  isPreview?: boolean
  /** Value to display in preview mode */
  previewValue?: string | string[] | null
  /** Whether the dropdown is disabled */
  disabled?: boolean
  /** Placeholder text when no value is selected */
  placeholder?: string
  /** Enable multi-select mode */
  multiSelect?: boolean
  /** Async function to fetch options dynamically */
  fetchOptions?: (blockId: string) => Promise<Array<{ label: string; id: string }>>
  /** Async function to fetch a single option's label by ID (for hydration) */
  fetchOptionById?: (
    blockId: string,
    optionId: string
  ) => Promise<{ label: string; id: string } | null>
  /** Field dependencies that trigger option refetch when changed */
  dependsOn?: SubBlockConfig['dependsOn']
  /** Enable search input in dropdown */
  searchable?: boolean
}

/**
 * Dropdown component with support for single/multi-select, async options, and data mode conversion
 *
 * @remarks
 * - Supports both static and dynamic (fetched) options
 * - Can operate in single-select or multi-select mode
 * - Special handling for dataMode subblock to convert between JSON and structured formats
 * - Integrates with the workflow state management system
 */
export const Dropdown = memo(function Dropdown({
  options,
  defaultValue,
  blockId,
  subBlockId,
  value: propValue,
  isPreview = false,
  previewValue,
  disabled,
  placeholder = 'Select an option...',
  multiSelect = false,
  fetchOptions,
  fetchOptionById,
  dependsOn,
  searchable = false,
}: DropdownProps) {
  const [storeValue, setStoreValue] = useSubBlockValue<string | string[]>(blockId, subBlockId) as [
    string | string[] | null | undefined,
    (value: string | string[]) => void,
  ]

  const dependsOnFields = useMemo(() => getDependsOnFields(dependsOn), [dependsOn])

  const activeWorkflowId = useWorkflowRegistry((s) => s.activeWorkflowId)
  const blockState = useWorkflowStore((state) => state.blocks[blockId])
  const blockConfig = blockState?.type ? getBlock(blockState.type) : null
  const canonicalIndex = useMemo(
    () => buildCanonicalIndex(blockConfig?.subBlocks || []),
    [blockConfig?.subBlocks]
  )
  const canonicalModeOverrides = blockState?.data?.canonicalModes
  const dependencyValues = useStoreWithEqualityFn(
    useSubBlockStore,
    useCallback(
      (state) => {
        if (dependsOnFields.length === 0 || !activeWorkflowId) return []
        const workflowValues = state.workflowValues[activeWorkflowId] || {}
        const blockValues = workflowValues[blockId] || {}
        return dependsOnFields.map((depKey) =>
          resolveDependencyValue(depKey, blockValues, canonicalIndex, canonicalModeOverrides)
        )
      },
      [dependsOnFields, activeWorkflowId, blockId, canonicalIndex, canonicalModeOverrides]
    ),
    isEqual
  )

  const [fetchedOptions, setFetchedOptions] = useState<Array<{ label: string; id: string }>>([])
  const [isLoadingOptions, setIsLoadingOptions] = useState(false)
  const [fetchError, setFetchError] = useState<string | null>(null)
  const [hydratedOption, setHydratedOption] = useState<{ label: string; id: string } | null>(null)

  const previousModeRef = useRef<string | null>(null)
  const previousDependencyValuesRef = useRef<string>('')

  const [builderData, setBuilderData] = useSubBlockValue<any[]>(blockId, 'builderData')
  const [data, setData] = useSubBlockValue<string>(blockId, 'data')

  const builderDataRef = useRef(builderData)
  const dataRef = useRef(data)

  useEffect(() => {
    builderDataRef.current = builderData
    dataRef.current = data
  }, [builderData, data])

  const value = isPreview ? previewValue : propValue !== undefined ? propValue : storeValue

  const singleValue = multiSelect ? null : (value as string | null | undefined)
  const multiValues = multiSelect
    ? Array.isArray(value)
      ? value
      : value
        ? [value as string]
        : []
    : null

  const fetchOptionsIfNeeded = useCallback(async () => {
    if (!fetchOptions || isPreview || disabled) return

    setIsLoadingOptions(true)
    setFetchError(null)
    try {
      const options = await fetchOptions(blockId)
      setFetchedOptions(options)
    } catch (error) {
      const errorMessage = error instanceof Error ? error.message : 'Failed to fetch options'
      setFetchError(errorMessage)
      setFetchedOptions([])
    } finally {
      setIsLoadingOptions(false)
    }
  }, [fetchOptions, blockId, isPreview, disabled])

  /**
   * Handles combobox open state changes to trigger option fetching
   */
  const handleOpenChange = useCallback(
    (open: boolean) => {
      if (open) {
        void fetchOptionsIfNeeded()
      }
    },
    [fetchOptionsIfNeeded]
  )

  const evaluatedOptions = useMemo(() => {
    return typeof options === 'function' ? options() : options
  }, [options])

  const normalizedFetchedOptions = useMemo(() => {
    return fetchedOptions.map((opt) => ({ label: opt.label, id: opt.id }))
  }, [fetchedOptions])

  const allOptions = useMemo(() => {
    let opts: DropdownOption[] =
      fetchOptions && normalizedFetchedOptions.length > 0
        ? normalizedFetchedOptions
        : evaluatedOptions

    if (hydratedOption) {
      const alreadyPresent = opts.some((o) =>
        typeof o === 'string' ? o === hydratedOption.id : o.id === hydratedOption.id
      )
      if (!alreadyPresent) {
        opts = [hydratedOption, ...opts]
      }
    }

    return opts
  }, [fetchOptions, normalizedFetchedOptions, evaluatedOptions, hydratedOption])

  const comboboxOptions = useMemo((): ComboboxOption[] => {
    return allOptions.map((opt) => {
      if (typeof opt === 'string') {
        return { label: opt.toLowerCase(), value: opt }
      }
      return {
        label: opt.label.toLowerCase(),
        value: opt.id,
        icon: 'icon' in opt ? opt.icon : undefined,
        hidden: opt.hidden,
      }
    })
  }, [allOptions])

  const optionMap = useMemo(() => {
    return new Map(comboboxOptions.map((opt) => [opt.value, opt.label]))
  }, [comboboxOptions])

  const defaultOptionValue = useMemo(() => {
    if (multiSelect) return undefined
    if (defaultValue !== undefined) {
      return defaultValue
    }

    if (comboboxOptions.length > 0) {
      return comboboxOptions[0].value
    }

    return undefined
  }, [defaultValue, comboboxOptions, multiSelect])

  useEffect(() => {
    if (multiSelect || defaultOptionValue === undefined) {
      return
    }
    if (storeValue === null || storeValue === undefined || storeValue === '') {
      setStoreValue(defaultOptionValue)
    }
  }, [storeValue, defaultOptionValue, setStoreValue, multiSelect])

  /**
   * Normalizes variable references in JSON strings by wrapping them in quotes
   * @param jsonString - The JSON string containing variable references
   * @returns Normalized JSON string with quoted variable references
   */
  const normalizeVariableReferences = (jsonString: string): string => {
    return jsonString.replace(/([^"]<[^>]+>)/g, '"$1"')
  }

  /**
   * Converts a JSON string to builder data format for structured editing
   * @param jsonString - The JSON string to convert
   * @returns Array of field objects with id, name, type, value, and collapsed properties
   */
  const convertJsonToBuilderData = (jsonString: string): any[] => {
    try {
      const normalizedJson = normalizeVariableReferences(jsonString)
      const parsed = JSON.parse(normalizedJson)

      if (typeof parsed === 'object' && parsed !== null && !Array.isArray(parsed)) {
        return Object.entries(parsed).map(([key, value]) => {
          const fieldType = inferType(value)
          const fieldValue =
            fieldType === 'object' || fieldType === 'array' ? JSON.stringify(value, null, 2) : value

          return {
            id: generateId(),
            name: key,
            type: fieldType,
            value: fieldValue,
            collapsed: false,
          }
        })
      }

      return []
    } catch (error) {
      return []
    }
  }

  /**
   * Infers the type of a value for builder data field configuration
   * @param value - The value to infer type from
   * @returns The inferred type as a string literal
   */
  const inferType = (value: any): 'string' | 'number' | 'boolean' | 'object' | 'array' => {
    if (typeof value === 'boolean') return 'boolean'
    if (typeof value === 'number') return 'number'
    if (Array.isArray(value)) return 'array'
    if (typeof value === 'object' && value !== null) return 'object'
    return 'string'
  }

  useEffect(() => {
    if (multiSelect || subBlockId !== 'dataMode' || isPreview || disabled) return

    const currentMode = storeValue as string
    const previousMode = previousModeRef.current

    if (previousMode !== null && previousMode !== currentMode) {
      if (currentMode === 'json' && previousMode === 'structured') {
        const currentBuilderData = builderDataRef.current
        if (
          currentBuilderData &&
          Array.isArray(currentBuilderData) &&
          currentBuilderData.length > 0
        ) {
          const jsonString = ResponseBlockHandler.convertBuilderDataToJsonString(currentBuilderData)
          setData(jsonString)
        }
      } else if (currentMode === 'structured' && previousMode === 'json') {
        const currentData = dataRef.current
        if (currentData && typeof currentData === 'string' && currentData.trim().length > 0) {
          const builderArray = convertJsonToBuilderData(currentData)
          setBuilderData(builderArray)
        }
      }
    }

    previousModeRef.current = currentMode
  }, [storeValue, subBlockId, isPreview, disabled, setData, setBuilderData, multiSelect])

  /**
   * Handles selection change for both single and multi-select modes
   */
  const handleChange = useCallback(
    (selectedValue: string) => {
      if (!isPreview && !disabled) {
        setStoreValue(selectedValue)
      }
    },
    [isPreview, disabled, setStoreValue]
  )

  /**
   * Handles multi-select changes
   */
  const handleMultiSelectChange = useCallback(
    (selectedValues: string[]) => {
      if (!isPreview && !disabled) {
        setStoreValue(selectedValues)
      }
    },
    [isPreview, disabled, setStoreValue]
  )

  /**
   * Effect to clear fetched options and hydrated option when dependencies actually change
   * This ensures options are refetched with new dependency values (e.g., new credentials)
   */
  useEffect(() => {
    if (fetchOptions && dependsOnFields.length > 0) {
      const currentDependencyValuesStr = JSON.stringify(dependencyValues)
      const previousDependencyValuesStr = previousDependencyValuesRef.current

      if (
        previousDependencyValuesStr &&
        currentDependencyValuesStr !== previousDependencyValuesStr
      ) {
        setFetchedOptions([])
        setHydratedOption(null)
      }

      previousDependencyValuesRef.current = currentDependencyValuesStr
    }
  }, [dependencyValues, fetchOptions, dependsOnFields.length])

  /**
   * Effect to fetch options when needed (on mount, when enabled, or when dependencies change)
   */
  useEffect(() => {
    if (
      fetchOptions &&
      !isPreview &&
      !disabled &&
      fetchedOptions.length === 0 &&
      !isLoadingOptions &&
      !fetchError
    ) {
      fetchOptionsIfNeeded()
    }
    // eslint-disable-next-line react-hooks/exhaustive-deps -- fetchOptionsIfNeeded deps already covered above
  }, [
    fetchOptions,
    isPreview,
    disabled,
    fetchedOptions.length,
    isLoadingOptions,
    fetchError,
    dependencyValues,
  ])

  /**
   * Effect to hydrate the stored value's label by fetching it individually
   * This ensures the correct label is shown before the full options list loads
   */
  useEffect(() => {
    if (!fetchOptionById || isPreview || disabled) return

    // Get the value to hydrate (single value only, not multi-select)
    const valueToHydrate = multiSelect ? null : (singleValue as string | null | undefined)
    if (!valueToHydrate) return

    // Skip if value is an expression (not a real ID)
    if (valueToHydrate.startsWith('<') || valueToHydrate.includes('{{')) return

    // Skip if already hydrated with the same value
    if (hydratedOption?.id === valueToHydrate) return

    // Skip if value is already in fetched options or static options
    const alreadyInFetchedOptions = fetchedOptions.some((opt) => opt.id === valueToHydrate)
    const alreadyInStaticOptions = evaluatedOptions.some((opt) =>
      typeof opt === 'string' ? opt === valueToHydrate : opt.id === valueToHydrate
    )
    if (alreadyInFetchedOptions || alreadyInStaticOptions) return

    // Track if effect is still active (cleanup on unmount or value change)
    let isActive = true

    // Fetch the hydrated option
    fetchOptionById(blockId, valueToHydrate)
      .then((option) => {
        if (isActive) setHydratedOption(option)
      })
      .catch(() => {
        if (isActive) setHydratedOption(null)
      })

    return () => {
      isActive = false
    }
  }, [
    fetchOptionById,
    singleValue,
    multiSelect,
    blockId,
    isPreview,
    disabled,
    fetchedOptions,
    evaluatedOptions,
    hydratedOption?.id,
  ])

  /**
   * Custom overlay content for multi-select mode showing badges
   */
  const multiSelectOverlay = useMemo(() => {
    if (!multiSelect || !multiValues || multiValues.length === 0) return undefined

    return (
      <div className='flex items-center gap-1 overflow-hidden whitespace-nowrap'>
        {multiValues.map((selectedValue: string) => (
          <Badge key={selectedValue} className='shrink-0 rounded-lg py-1 text-caption leading-none'>
            {(optionMap.get(selectedValue) || selectedValue).toLowerCase()}
          </Badge>
        ))}
      </div>
    )
  }, [multiSelect, multiValues, optionMap])

  const isSearchable = searchable || (subBlockId === 'operation' && comboboxOptions.length > 5)

  return (
    <Combobox
      options={comboboxOptions}
      value={multiSelect ? undefined : (singleValue ?? undefined)}
      multiSelectValues={multiSelect ? (multiValues ?? undefined) : undefined}
      onChange={handleChange}
      onMultiSelectChange={handleMultiSelectChange}
      placeholder={placeholder}
      disabled={disabled}
      editable={false}
      onOpenChange={handleOpenChange}
      overlayContent={multiSelectOverlay}
      multiSelect={multiSelect}
      isLoading={isLoadingOptions}
      error={fetchError}
      searchable={isSearchable}
      searchPlaceholder='Search...'
    />
  )
})
