import { useState, useCallback } from 'react';
import { analyzeMedia } from '../utils/api';

const ANALYSIS_STAGES = [
  { id: 'upload', label: 'Uploading media...', progress: 10 },
  { id: 'preprocess', label: 'Pre-processing media...', progress: 24 },
  { id: 'inference', label: 'Running model inference...', progress: 48 },
  { id: 'gradcam', label: 'Generating explainability layer...', progress: 68 },
  { id: 'fft', label: 'Analysing frequency spectrum (FFT)...', progress: 84 },
  { id: 'temporal', label: 'Temporal sequence analysis...', progress: 90 },
  { id: 'verdict', label: 'Compiling forensic verdict...', progress: 96 },
];

export function useAnalysis() {
  const [phase, setPhase] = useState('idle');
  const [currentStage, setCurrentStage] = useState(null);
  const [progress, setProgress] = useState(0);
  const [result, setResult] = useState(null);
  const [file, setFile] = useState(null);
  const [previewUrl, setPreviewUrl] = useState(null);
  const [error, setError] = useState(null);

  const reset = useCallback(() => {
    setPhase('idle');
    setCurrentStage(null);
    setProgress(0);
    setResult(null);
    setFile(null);
    if (previewUrl) URL.revokeObjectURL(previewUrl);
    setPreviewUrl(null);
    setError(null);
  }, [previewUrl]);

  const analyze = useCallback(async (selectedFile) => {
    if (!selectedFile) return;

    setFile(selectedFile);
    setPreviewUrl(URL.createObjectURL(selectedFile));
    setPhase('uploading');
    setError(null);
    setProgress(0);

    let ticker = null;
    try {
      const isVideo = selectedFile.type.startsWith('video/');
      const relevantStages = isVideo ? ANALYSIS_STAGES : ANALYSIS_STAGES.filter((stage) => stage.id !== 'temporal');

      for (let index = 0; index < relevantStages.length; index += 1) {
        const stage = relevantStages[index];
        setCurrentStage(stage);
        setPhase(index === 0 ? 'uploading' : 'analyzing');
        setProgress(stage.progress);
        await new Promise((resolve) => setTimeout(resolve, index === 0 ? 200 : 320));
      }

      ticker = window.setInterval(() => {
        setProgress((value) => (value < 97 ? value + 1 : value));
      }, 260);

      const apiResult = await analyzeMedia(selectedFile);
      window.clearInterval(ticker);
      setProgress(100);
      setResult({
        ...apiResult,
        filename: apiResult.filename || selectedFile.name,
        filesize: apiResult.filesize || formatFileSize(selectedFile.size),
      });
      setPhase('complete');
    } catch (analysisError) {
      if (ticker) window.clearInterval(ticker);
      setPhase('idle');
      setCurrentStage(null);
      setProgress(0);
      setResult(null);
      setError(analysisError.message || 'Analysis failed');
    }
  }, []);

  return { phase, currentStage, progress, result, file, previewUrl, error, analyze, reset };
}

function formatFileSize(bytes) {
  if (bytes < 1024) return `${bytes} B`;
  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
  return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
}