import { useEffect, useMemo, useRef, useState } from 'react'
import {
  VECTOR_VIEWPORT_DEBOUNCE_MS,
  VECTOR_VIEWPORT_FEATURE_LIMIT,
  VECTOR_VIEWPORT_FEATURE_THRESHOLD,
  VECTOR_VIEWPORT_MIN_ZOOM,
} from '../config/vectorDelivery'
import { formatError } from '../lib/formatError'
import { datasetsApi } from '../services/api/datasets'
import type { DatasetCreateResponse, MapViewportState } from '../types'

interface ViewportVectorLayerOptions {
  selectedProjectId: string | null
  selectedDataset: DatasetCreateResponse | null
  featureCount: number | null
  isVectorDatasetType: (datasetType: string) => boolean
}

export function useViewportVectorLayer({
  selectedProjectId,
  selectedDataset,
  featureCount,
  isVectorDatasetType,
}: ViewportVectorLayerOptions) {
  const [viewport, setViewport] = useState<MapViewportState | null>(null)
  const [data, setData] = useState<GeoJSON.FeatureCollection | null>(null)
  const [loading, setLoading] = useState(false)
  const [error, setError] = useState<string | null>(null)
  const [truncated, setTruncated] = useState(false)
  const [loadedFeatureCount, setLoadedFeatureCount] = useState(0)
  const requestSequence = useRef(0)

  const enabled = Boolean(
    selectedProjectId &&
      selectedDataset &&
      isVectorDatasetType(selectedDataset.dataset_type) &&
      (featureCount ?? 0) > VECTOR_VIEWPORT_FEATURE_THRESHOLD,
  )
  const zoom = viewport?.zoom ?? null
  const zoomRequired = enabled && (zoom === null || zoom < VECTOR_VIEWPORT_MIN_ZOOM)

  useEffect(() => {
    requestSequence.current += 1
    setData(null)
    setLoading(false)
    setError(null)
    setTruncated(false)
    setLoadedFeatureCount(0)
  }, [enabled, selectedDataset?.id, selectedProjectId])

  useEffect(() => {
    if (!enabled || !selectedProjectId || !selectedDataset || !viewport) {
      return
    }
    if (viewport.zoom < VECTOR_VIEWPORT_MIN_ZOOM) {
      requestSequence.current += 1
      setData(null)
      setLoading(false)
      setError(null)
      setTruncated(false)
      setLoadedFeatureCount(0)
      return
    }

    const sequence = requestSequence.current + 1
    requestSequence.current = sequence
    const timer = window.setTimeout(async () => {
      setLoading(true)
      setError(null)
      try {
        const response = await datasetsApi.selectVectorFeatures(selectedProjectId, selectedDataset.id, {
          bbox: viewport.bbox,
          limit: VECTOR_VIEWPORT_FEATURE_LIMIT,
        })
        if (requestSequence.current !== sequence) {
          return
        }
        setData(response.geojson)
        setLoadedFeatureCount(response.feature_count)
        setTruncated(response.truncated)
      } catch (requestError) {
        if (requestSequence.current !== sequence) {
          return
        }
        setData(null)
        setLoadedFeatureCount(0)
        setTruncated(false)
        setError(formatError(requestError, 'Unable to load visible vector features'))
      } finally {
        if (requestSequence.current === sequence) {
          setLoading(false)
        }
      }
    }, VECTOR_VIEWPORT_DEBOUNCE_MS)

    return () => {
      window.clearTimeout(timer)
    }
  }, [enabled, selectedDataset, selectedProjectId, viewport])

  const statusMessage = useMemo(() => {
    if (!enabled) {
      return null
    }
    if (zoomRequired) {
      return `Zoom in to level ${VECTOR_VIEWPORT_MIN_ZOOM} to load buildings from PostGIS.`
    }
    if (loading) {
      return 'Loading visible features from PostGIS...'
    }
    if (error) {
      return error
    }
    if (truncated) {
      return `${loadedFeatureCount.toLocaleString()} visible features loaded; zoom in further because this view exceeds the ${VECTOR_VIEWPORT_FEATURE_LIMIT.toLocaleString()} feature limit.`
    }
    return `${loadedFeatureCount.toLocaleString()} visible of ${(featureCount ?? 0).toLocaleString()} total features loaded from PostGIS.`
  }, [enabled, error, featureCount, loadedFeatureCount, loading, truncated, zoomRequired])

  return {
    enabled,
    data,
    loading,
    error,
    truncated,
    loadedFeatureCount,
    featureLimit: VECTOR_VIEWPORT_FEATURE_LIMIT,
    minZoom: VECTOR_VIEWPORT_MIN_ZOOM,
    zoom,
    zoomRequired,
    statusMessage,
    setViewport,
  }
}