import React, { useCallback } from 'react'
import { useDropzone } from 'react-dropzone'
import { Box, Typography, Paper, LinearProgress, Alert } from '@mui/material'
import { CloudUpload, InsertDriveFile } from '@mui/icons-material'
import { useUploadStore } from '../stores/uploadStore'
import { uploadFile, getTaskInfo } from '../api/client'
import { useTaskStore } from '../stores/taskStore'

const ALLOWED_EXTENSIONS = ['.mp3', '.flac', '.wav', '.m4a', '.ogg', '.opus', '.aac', '.wma', '.aiff', '.alac', '.ac3']

export const UploadZone: React.FC = () => {
  const {
    file,
    fileName,
    fileSize,
    isUploading,
    uploadProgress,
    error,
    setFile,
    setFileName,
    setFileSize,
    setIsUploading,
    setUploadProgress,
    setError,
    setTaskId,
    setHasVideo,
    setHasAudio,
    setHasSubtitle,
    setAudioCodec,
  } = useUploadStore()

  const { setTaskId: setTaskIdStore } = useTaskStore()

  const onDrop = useCallback(
    async (acceptedFiles: File[]) => {
      if (acceptedFiles.length === 0) return

      const selectedFile = acceptedFiles[0]
      const extension = '.' + selectedFile.name.split('.').pop()?.toLowerCase()

      if (!ALLOWED_EXTENSIONS.includes(extension)) {
        setError(`Unsupported file format. Allowed: ${ALLOWED_EXTENSIONS.join(', ')}`)
        return
      }

      setFile(selectedFile)
      setFileName(selectedFile.name)
      setFileSize(selectedFile.size)
      setError(null)
      setIsUploading(true)
      setUploadProgress(0)

      try {
        const response = await uploadFile(selectedFile)
        const taskId = response.task_id
        setTaskId(taskId)
        setTaskIdStore(taskId)
        setUploadProgress(100)
        setIsUploading(false)

        // Fetch stream info
        try {
          const info = await getTaskInfo(taskId)
          setHasVideo(info.has_video)
          setHasAudio(info.has_audio)
          setHasSubtitle(info.has_subtitle)
          setAudioCodec(info.audio_codec)
        } catch (err) {
          console.error('Failed to fetch stream info:', err)
          // Don't block the upload flow if this fails; we'll just assume no video
        }
      } catch (err: any) {
        setError(err.response?.data?.detail || err.message || 'Upload failed')
        setIsUploading(false)
        setUploadProgress(0)
        setFile(null)
        setFileName('')
        setFileSize(0)
      }
    },
    [setFile, setFileName, setFileSize, setIsUploading, setUploadProgress, setError, setTaskId, setTaskIdStore]
  )

  const { getRootProps, getInputProps, isDragActive } = useDropzone({
    onDrop,
    accept: {
      'audio/*': ALLOWED_EXTENSIONS,
    },
    multiple: false,
    disabled: isUploading,
  })

  const formatFileSize = (bytes: number): string => {
    if (bytes < 1024) return `${bytes} B`
    if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`
    return `${(bytes / (1024 * 1024)).toFixed(1)} MB`
  }

  return (
    <Box>
      <Paper
        {...getRootProps()}
        sx={{
          p: 4,
          border: '2px dashed',
          borderColor: isDragActive ? 'primary.main' : 'grey.300',
          borderRadius: 2,
          backgroundColor: isDragActive ? 'action.hover' : 'background.paper',
          cursor: isUploading ? 'default' : 'pointer',
          transition: 'all 0.2s ease',
          textAlign: 'center',
        }}
      >
        <input {...getInputProps()} />

        {file ? (
          <Box>
            <InsertDriveFile sx={{ fontSize: 48, color: 'primary.main', mb: 1 }} />
            <Typography variant="h6">{fileName}</Typography>
            <Typography variant="body2" color="text.secondary">
              {formatFileSize(fileSize)}
            </Typography>
            {isUploading && (
              <Box sx={{ mt: 2, width: '100%' }}>
                <LinearProgress variant="determinate" value={uploadProgress} />
                <Typography variant="caption" color="text.secondary">
                  {uploadProgress}% uploaded
                </Typography>
              </Box>
            )}
            {!isUploading && (
              <Typography variant="caption" color="success.main" sx={{ mt: 1, display: 'block' }}>
                ✅ Uploaded successfully
              </Typography>
            )}
          </Box>
        ) : (
          <Box>
            <CloudUpload sx={{ fontSize: 64, color: 'primary.main', mb: 2 }} />
            <Typography variant="h6" color="text.secondary">
              {isDragActive ? 'Drop your audio file here' : 'Drag & drop your audio file here'}
            </Typography>
            <Typography variant="body2" color="text.secondary" sx={{ mt: 1 }}>
              or click to browse
            </Typography>
            <Typography variant="caption" color="text.secondary" sx={{ mt: 2, display: 'block' }}>
              Supported formats: {ALLOWED_EXTENSIONS.join(', ')}
            </Typography>
          </Box>
        )}
      </Paper>

      {error && (
        <Alert severity="error" sx={{ mt: 2 }}>
          {error}
        </Alert>
      )}
    </Box>
  )
}
