import {
  useState,
  useContext,
  useEffect,
  useLayoutEffect,
  useRef,
  useCallback
} from 'react'
import PropTypes from 'prop-types'
import { Flex, Button, Input, InputNumber, Select, Card, Popover } from 'antd'
import PlusIcon from '../../Icons/PlusIcon.jsx'
import MinusIcon from '../../Icons/MinusIcon.jsx'
import InfoCircleIcon from '../../Icons/InfoCircleIcon.jsx'
import PanIcon from '../../Icons/PanIcon.jsx'
import PanFilledIcon from '../../Icons/PanFilledIcon.jsx'
import ObjectProperty from '../common/ObjectProperty.jsx'
import PDFViewer from './PDFViewer.jsx'
import ScrollBox from './ScrollBox.jsx'
import { ApiServerContext } from '../context/ApiServerContext.jsx'
import ProgressDisplay from './ProgressDisplay.jsx'
import { CaretDownFilled } from '@ant-design/icons'
const noop = () => {}

const TemplatePreview = ({
  objectData,
  documentTemplate,
  content = null,
  template,
  templateType = 'documentTemplate',
  capabilities = {},
  loading,
  isEditing,
  onTestObjectOpen = noop,
  onPreviewMessage = noop,
  showTestObject = false,
  showPreviewSwitch = true
}) => {
  const currentTemplate = template || documentTemplate
  const htmlOnly = capabilities.htmlOnly === true
  const showWidthControl = capabilities.widthControl === true
  const defaultPreviewWidth = capabilities.defaultWidth || 600
  const iframeRef = useRef(null)
  const scrollElementRef = useRef(null)
  const savedScrollRef = useRef({ top: 0, left: 0 })
  const iframeSizeObserverRef = useRef(null)
  const previewRequestIdRef = useRef(0)
  const renderUnsubscribeRef = useRef(null)
  const {
    fetchTemplatePreview,
    fetchTemplateDownload,
    subscribeToObjectEvent
  } = useContext(ApiServerContext)
  const [previewContentHTML, setPreviewContentHTML] = useState('')
  const [pdfBlob, setPDFBlob] = useState(null)
  const [reloadLoading, setReloadLoading] = useState(false)
  const [downloadProgress, setDownloadProgress] = useState(null)
  const [previewScale, setPreviewScale] = useState(1)
  const [previewType, setPreviewType] = useState('HTML')
  const [previewWidth, setPreviewWidth] = useState(defaultPreviewWidth)
  const [panMode, setPanMode] = useState(false)
  const [isPanning, setIsPanning] = useState(false)
  const panStartRef = useRef({ x: 0, y: 0, scrollLeft: 0, scrollTop: 0 })
  const [iframeSize, setIframeSize] = useState({
    width: '100%',
    height: 'auto'
  })

  const toolbarRef = useRef(null)
  const [usePopoverSettings, setUsePopoverSettings] = useState(false)

  useLayoutEffect(() => {
    const toolbar = toolbarRef.current
    if (!toolbar) return undefined

    const updateLayout = () => {
      const { width, height } = toolbar.getBoundingClientRect()
      console.log('Preview card size', { width, height })
      setUsePopoverSettings(width < 620)
    }

    updateLayout()

    const observer = new ResizeObserver(updateLayout)
    observer.observe(toolbar)

    return () => observer.disconnect()
  }, [])

  const applyIframeContentSize = useCallback(() => {
    const iframe = iframeRef.current
    const doc = iframe?.contentDocument
    if (!iframe || !doc?.documentElement) {
      return
    }

    const wrappers = doc.querySelectorAll('.previewWrapper')
    wrappers.forEach((wrapper) => {
      const page = wrapper.querySelector('.previewDocument')
      if (!page) {
        return
      }
      const pageVisual = page.getBoundingClientRect()
      if (pageVisual.width <= 0 && pageVisual.height <= 0) {
        return
      }
      wrapper.style.width = `${pageVisual.width}px`
      wrapper.style.height = `${pageVisual.height}px`
    })

    const documentEl =
      doc.querySelector('.previewPages') ||
      doc.querySelector('.previewDocument') ||
      doc.querySelector('.previewWrapper') ||
      doc.body
    const container = doc.querySelector('.previewContainer')
    const visual = documentEl.getBoundingClientRect()
    if (visual.width <= 0 && visual.height <= 0) {
      return
    }

    let padX = 0
    let padY = 0
    if (container) {
      const containerStyle = doc.defaultView.getComputedStyle(container)
      padX =
        parseFloat(containerStyle.paddingLeft) +
        parseFloat(containerStyle.paddingRight)
      padY =
        parseFloat(containerStyle.paddingTop) +
        parseFloat(containerStyle.paddingBottom)
    }

    const contentWidth = showWidthControl
      ? previewWidth
      : Math.ceil(visual.width + padX)
    const contentHeight = Math.ceil(
      Math.max(visual.height + padY, doc.documentElement.scrollHeight)
    )

    if (!doc.head?.querySelector('style[data-preview-outer-scroll]')) {
      const styleEl = doc.createElement('style')
      styleEl.setAttribute('data-preview-outer-scroll', 'true')
      styleEl.textContent =
        'html, body { overflow: hidden !important; height: auto !important; }'
      doc.head?.appendChild(styleEl)
    }

    setIframeSize((prev) => {
      const width = `${contentWidth}px`
      const height = `${contentHeight}px`
      if (prev.width === width && prev.height === height) {
        return prev
      }
      return { width, height }
    })
  }, [previewWidth, showWidthControl])

  const restoreScrollPosition = useCallback(() => {
    const scrollEl = scrollElementRef.current
    if (!scrollEl) {
      return
    }
    scrollEl.scrollTo(savedScrollRef.current.left, savedScrollRef.current.top)
  }, [])

  const handleIframeLoad = useCallback(() => {
    iframeSizeObserverRef.current?.disconnect()
    iframeSizeObserverRef.current = null

    if (previewType != 'HTML') {
      return
    }

    applyIframeContentSize()

    const doc = iframeRef.current?.contentDocument
    const observed =
      doc?.querySelector('.previewPages') ||
      doc?.querySelector('.previewContainer') ||
      doc?.querySelector('.previewDocument') ||
      doc?.body
    if (observed && typeof ResizeObserver === 'function') {
      const observer = new ResizeObserver(() => {
        applyIframeContentSize()
      })
      observer.observe(observed)
      iframeSizeObserverRef.current = observer
    }
  }, [applyIframeContentSize, previewType])

  useLayoutEffect(() => {
    restoreScrollPosition()
  }, [iframeSize, restoreScrollPosition])

  const updatePreviewContentHTML = (html) => {
    const scrollEl = scrollElementRef.current
    if (scrollEl) {
      savedScrollRef.current = {
        top: scrollEl.scrollTop,
        left: scrollEl.scrollLeft
      }
    }
    setPreviewContentHTML(html)
  }

  const clearIframeContents = useCallback(() => {
    iframeSizeObserverRef.current?.disconnect()
    iframeSizeObserverRef.current = null

    const iframe = iframeRef.current
    if (iframe) {
      iframe.srcdoc = ''
    }

    setPreviewContentHTML('')
    setIframeSize({
      width: showWidthControl ? `${previewWidth}px` : '100%',
      height: 'auto'
    })
  }, [previewWidth, showWidthControl])

  const stopRenderProgressListener = useCallback(() => {
    if (typeof renderUnsubscribeRef.current === 'function') {
      renderUnsubscribeRef.current()
    }
    renderUnsubscribeRef.current = null
  }, [])

  const applyPdfResult = useCallback(
    (result, requestId) => {
      if (requestId !== previewRequestIdRef.current) {
        return
      }
      setReloadLoading(false)
      setDownloadProgress(null)
      stopRenderProgressListener()
      if (result?.error) {
        onPreviewMessage(result.error, true)
        return
      }
      setPDFBlob(
        new Blob([result.buffer || result.pdf], {
          type: result.mime || 'application/pdf'
        })
      )
      onPreviewMessage('No issues found.', false)
    },
    [onPreviewMessage, stopRenderProgressListener]
  )

  const reloadPreviewPDF = useCallback(
    (content, testObject = {}) => {
      const templateId = currentTemplate?._id
      if (!templateId) {
        return
      }

      const requestId = ++previewRequestIdRef.current
      stopRenderProgressListener()
      setPDFBlob(null)
      setReloadLoading(true)
      setDownloadProgress({ progress: 0, message: 'Starting render...' })

      const startDownload = async () => {
        try {
          const startResult = await fetchTemplateDownload(
            templateId,
            content,
            testObject,
            'pdf',
            { async: true }
          )
          if (requestId !== previewRequestIdRef.current) {
            return
          }
          if (startResult?.error || !startResult?.renderRequestId) {
            applyPdfResult(startResult, requestId)
            return
          }

          const renderRequestId = startResult.renderRequestId
          const eventType = `render:${renderRequestId}`
          let fetched = false

          const fetchRenderedFile = async () => {
            if (fetched) {
              return true
            }
            try {
              const result = await fetchTemplateDownload(
                templateId,
                content,
                testObject,
                'pdf',
                { renderRequestId }
              )
              fetched = true
              applyPdfResult(result, requestId)
              return true
            } catch (err) {
              if (err?.response?.status === 404) {
                return false
              }
              applyPdfResult(
                {
                  error: err?.message || 'Failed to download rendered template.'
                },
                requestId
              )
              return true
            }
          }

          const unsubscribe = subscribeToObjectEvent(
            renderRequestId,
            'render',
            eventType,
            (event) => {
              if (requestId !== previewRequestIdRef.current) {
                return
              }
              setDownloadProgress({
                progress: Number(event?.progress) || 0,
                message: event?.message || ''
              })
              if (event?.error) {
                applyPdfResult({ error: event.error }, requestId)
                return
              }
              if (Number(event?.progress) >= 1) {
                fetchRenderedFile()
              }
            }
          )

          const pollId = window.setInterval(async () => {
            if (requestId !== previewRequestIdRef.current) {
              window.clearInterval(pollId)
              return
            }
            const didFetch = await fetchRenderedFile()
            if (didFetch) {
              window.clearInterval(pollId)
            }
          }, 1000)

          renderUnsubscribeRef.current = () => {
            window.clearInterval(pollId)
            if (typeof unsubscribe === 'function') {
              unsubscribe()
            }
          }
        } catch (err) {
          applyPdfResult(
            { error: err?.message || 'Failed to start template download.' },
            requestId
          )
        }
      }

      startDownload()
    },
    [
      applyPdfResult,
      currentTemplate?._id,
      fetchTemplateDownload,
      stopRenderProgressListener,
      subscribeToObjectEvent
    ]
  )

  const reloadPreview = useCallback(
    (content, testObject = {}, scale = 1) => {
      const templateId = currentTemplate?._id
      if (!templateId) {
        return
      }

      const requestId = ++previewRequestIdRef.current
      setReloadLoading(true)
      fetchTemplatePreview(
        templateId,
        content,
        testObject,
        scale,
        (result) => {
          if (requestId !== previewRequestIdRef.current) {
            return
          }
          setReloadLoading(false)
          if (result?.error) {
            onPreviewMessage(result.error, true)
          } else {
            updatePreviewContentHTML(result.html)
            onPreviewMessage('No issues found.', false)
          }
        },
        templateType,
        showWidthControl ? { width: previewWidth } : {}
      )
    },
    [
      currentTemplate?._id,
      fetchTemplatePreview,
      onPreviewMessage,
      previewWidth,
      showWidthControl,
      templateType
    ]
  )

  const templateContent = currentTemplate?.content
  const templateId = currentTemplate?._id

  useEffect(() => {
    if (content != null) {
      updatePreviewContentHTML(content)
      return
    }

    if (!templateId || !templateContent || previewType != 'HTML') {
      return
    }

    const timeoutId = window.setTimeout(() => {
      if (content == null) {
        reloadPreview(templateContent, objectData, previewScale)
      }
    }, 300)

    return () => {
      window.clearTimeout(timeoutId)
    }
  }, [
    objectData,
    templateContent,
    templateId,
    previewScale,
    previewWidth,
    previewType,
    reloadPreview,
    content
  ])

  useEffect(() => {
    if (!templateId || !templateContent || previewType != 'PDF') {
      return
    }

    setPDFBlob(null)

    const timeoutId = window.setTimeout(() => {
      reloadPreviewPDF(templateContent, objectData)
    }, 300)

    return () => {
      window.clearTimeout(timeoutId)
    }
  }, [objectData, templateContent, templateId, previewType, reloadPreviewPDF])

  useEffect(() => {
    return () => {
      iframeSizeObserverRef.current?.disconnect()
      stopRenderProgressListener()
    }
  }, [stopRenderProgressListener])

  useEffect(() => {
    if (!panMode) {
      setIsPanning(false)
    }
  }, [panMode])

  useEffect(() => {
    const scrollEl = scrollElementRef.current
    if (!panMode || !scrollEl || previewType != 'HTML') {
      return
    }

    const handlePointerDown = (event) => {
      if (event.pointerType === 'mouse' && event.button !== 0) {
        return
      }
      event.preventDefault()
      panStartRef.current = {
        x: event.clientX,
        y: event.clientY,
        scrollLeft: scrollEl.scrollLeft,
        scrollTop: scrollEl.scrollTop
      }
      setIsPanning(true)
    }

    scrollEl.addEventListener('pointerdown', handlePointerDown)
    return () => {
      scrollEl.removeEventListener('pointerdown', handlePointerDown)
    }
  }, [panMode, previewType])

  useEffect(() => {
    if (!isPanning) {
      return
    }

    const previousCursor = document.body.style.cursor
    const previousUserSelect = document.body.style.userSelect
    document.body.style.cursor = 'grabbing'
    document.body.style.userSelect = 'none'

    const handlePointerMove = (event) => {
      const scrollEl = scrollElementRef.current
      if (!scrollEl) {
        return
      }
      const { x, y, scrollLeft, scrollTop } = panStartRef.current
      scrollEl.scrollLeft = scrollLeft - (event.clientX - x)
      scrollEl.scrollTop = scrollTop - (event.clientY - y)
    }

    const handlePointerUp = () => {
      setIsPanning(false)
    }

    window.addEventListener('pointermove', handlePointerMove)
    window.addEventListener('pointerup', handlePointerUp)
    window.addEventListener('pointercancel', handlePointerUp)
    return () => {
      document.body.style.cursor = previousCursor
      document.body.style.userSelect = previousUserSelect
      window.removeEventListener('pointermove', handlePointerMove)
      window.removeEventListener('pointerup', handlePointerUp)
      window.removeEventListener('pointercancel', handlePointerUp)
    }
  }, [isPanning])

  const showProgressOverlay = previewType != 'HTML' && downloadProgress != null

  const toolbarContent = (
    <>
      <Button
        icon={
          panMode ? (
            <PanFilledIcon style={{ color: 'var(--color-primary)' }} />
          ) : (
            <PanIcon />
          )
        }
        disabled={loading || reloadLoading}
        onClick={() => {
          setPanMode((prev) => !prev)
        }}
      />
      <Button
        icon={<PlusIcon />}
        onClick={() => {
          setPreviewScale((prev) => prev + 0.05)
        }}
        disabled={loading || reloadLoading}
      />
      <Button
        readOnly={true}
        style={{ width: '65px' }}
        disabled={loading || reloadLoading}
        onClick={() => {
          setPreviewScale(1)
        }}
      >
        {previewScale.toFixed(2)}x
      </Button>
      <Button
        icon={<MinusIcon />}
        onClick={() => {
          setPreviewScale((prev) => Math.max(0.1, prev - 0.05))
        }}
        disabled={loading || reloadLoading}
      />
      {showWidthControl ? (
        <InputNumber
          min={240}
          max={1600}
          step={10}
          addonAfter='px'
          value={previewWidth}
          disabled={loading || reloadLoading}
          onChange={(value) => setPreviewWidth(value || defaultPreviewWidth)}
          style={{ width: 130 }}
          aria-label='Email preview width'
        />
      ) : null}
      {showPreviewSwitch == true && !htmlOnly ? (
        <Select
          options={[
            { value: 'HTML', label: 'HTML' },
            { value: 'PDF', label: 'PDF' }
          ]}
          style
          loading={(loading || reloadLoading) && !usePopoverSettings}
          disabled={loading || reloadLoading}
          value={previewType}
          onChange={(value) => {
            if (value == 'PDF') {
              clearIframeContents()
              setPDFBlob(null)
            }
            setPreviewType(value)
          }}
        />
      ) : null}
    </>
  )

  return (
    <Flex vertical gap={'middle'} style={{ height: '100%' }}>
      <Flex gap={'small'} ref={toolbarRef}>
        {showTestObject == true ? (
          <>
            {currentTemplate?.objectType ? (
              <ObjectProperty
                objectType={currentTemplate?.objectType}
                name={'testObject'}
                isEditing={true}
                objectData={currentTemplate}
                disabled={!isEditing || currentTemplate?.global}
                type={'object'}
                style={{ minWidth: 0 }}
              />
            ) : (
              <div style={{ flexGrow: 1 }}>
                <Input disabled={true} />
              </div>
            )}
            <Button
              icon={<InfoCircleIcon />}
              disabled={currentTemplate?.global}
              onClick={() => {
                onTestObjectOpen()
              }}
            />
          </>
        ) : null}
        {!usePopoverSettings ? (
          toolbarContent
        ) : (
          <Popover
            content={<Flex gap={'small'}>{toolbarContent}</Flex>}
            trigger={['hover', 'click']}
            placement='bottomRight'
            arrow={false}
          >
            <Button
              icon={<CaretDownFilled />}
              loading={loading || reloadLoading}
            />
          </Popover>
        )}
      </Flex>

      <div
        style={{
          flex: '1 1 auto',
          minHeight: 0,
          border: '1px solid #85858541',
          position: 'relative'
        }}
      >
        <div
          className={`previewProgressOverlay ${showProgressOverlay ? 'visible' : 'hidden'}`}
        >
          {showProgressOverlay ? (
            <Flex
              style={{ width: '100%', height: '100%' }}
              align='center'
              justify='center'
            >
              <Card
                style={{
                  maxWidth: 360,
                  minWidth: 100,
                  width: '100%',
                  margin: 24
                }}
                styles={{ body: { padding: 18 } }}
              >
                <ProgressDisplay
                  percent={Math.round(
                    (Number(downloadProgress.progress) || 0) * 100
                  )}
                  status='active'
                >
                  {downloadProgress.message || 'Rendering...'}
                </ProgressDisplay>
              </Card>
            </Flex>
          ) : null}
        </div>

        {previewType == 'HTML' ? (
          <ScrollBox
            scrollableNodeProps={{ ref: scrollElementRef }}
            style={{
              cursor: panMode ? (isPanning ? 'grabbing' : 'grab') : undefined,
              touchAction: panMode ? 'none' : undefined
            }}
          >
            <Flex
              justify='center'
              align='center'
              style={{
                minWidth: '100%',
                width: iframeSize.width,
                height: iframeSize.height
              }}
            >
              <div
                style={{
                  width: iframeSize.width,
                  height: iframeSize.height,
                  cursor: panMode
                    ? isPanning
                      ? 'grabbing'
                      : 'grab'
                    : undefined
                }}
              >
                <iframe
                  ref={iframeRef}
                  srcDoc={previewContentHTML}
                  onLoad={handleIframeLoad}
                  scrolling='no'
                  frameBorder='0'
                  style={{
                    width: '100%',
                    height: iframeSize.height === 'auto' ? 150 : '100%',
                    display: 'block',
                    border: 0,
                    overflow: 'hidden',
                    pointerEvents: panMode ? 'none' : undefined
                  }}
                />
              </div>
            </Flex>
          </ScrollBox>
        ) : (
          <PDFViewer
            file={pdfBlob}
            scale={previewScale}
            panMode={panMode}
            loading={false}
            onLoadError={() => {
              onPreviewMessage('Failed to render PDF preview.', true)
            }}
          />
        )}
      </div>
    </Flex>
  )
}

TemplatePreview.propTypes = {
  loading: PropTypes.bool,
  objectData: PropTypes.oneOfType([PropTypes.object, PropTypes.string]),
  documentTemplate: PropTypes.object,
  template: PropTypes.object,
  templateType: PropTypes.string,
  capabilities: PropTypes.object,
  isEditing: PropTypes.bool,
  style: PropTypes.object,
  showTestObject: PropTypes.bool,
  onTestObjectOpen: PropTypes.func,
  onPreviewMessage: PropTypes.func,
  showPreviewSwitch: PropTypes.bool,
  content: PropTypes.string
}

export default TemplatePreview