/**
 * Chat Input Component
 * Textarea with send button and universal file upload support.
 * Enter to send, Shift+Enter for new line.
 * Supports: native file picker, clipboard paste, drag & drop.
 * Files are staged to disk via IPC — only lightweight path references
 * are sent with the message (no base64 over WebSocket).
 */
import { useState, useRef, useEffect, useCallback } from 'react';
import { Send, Square, X, Paperclip, FileText, Film, Music, FileArchive, File, Loader2 } from 'lucide-react';
import { Button } from '@/components/ui/button';
import { Textarea } from '@/components/ui/textarea';

// ── Types ────────────────────────────────────────────────────────

export interface FileAttachment {
  id: string;
  fileName: string;
  mimeType: string;
  fileSize: number;
  stagedPath: string;        // disk path for gateway
  preview: string | null;    // data URL for images, null for others
  status: 'staging' | 'ready' | 'error';
  error?: string;
}

interface ChatInputProps {
  onSend: (text: string, attachments?: FileAttachment[]) => void;
  onStop?: () => void;
  disabled?: boolean;
  sending?: boolean;
}

// ── Helpers ──────────────────────────────────────────────────────

function formatFileSize(bytes: number): string {
  if (bytes < 1024) return `${bytes} B`;
  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
  if (bytes < 1024 * 1024 * 1024) return `${(bytes / (1024 * 1024)).toFixed(2)} MB`;
  return `${(bytes / (1024 * 1024 * 1024)).toFixed(2)} GB`;
}

function FileIcon({ mimeType, className }: { mimeType: string; className?: string }) {
  if (mimeType.startsWith('video/')) return <Film className={className} />;
  if (mimeType.startsWith('audio/')) return <Music className={className} />;
  if (mimeType.startsWith('text/') || mimeType === 'application/json' || mimeType === 'application/xml') return <FileText className={className} />;
  if (mimeType.includes('zip') || mimeType.includes('compressed') || mimeType.includes('archive') || mimeType.includes('tar') || mimeType.includes('rar') || mimeType.includes('7z')) return <FileArchive className={className} />;
  if (mimeType === 'application/pdf') return <FileText className={className} />;
  return <File className={className} />;
}

/**
 * Read a browser File object as base64 string (without the data URL prefix).
 */
function readFileAsBase64(file: globalThis.File): Promise<string> {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = () => {
      const dataUrl = reader.result as string;
      if (!dataUrl || !dataUrl.includes(',')) {
        reject(new Error(`Invalid data URL from FileReader for ${file.name}`));
        return;
      }
      const base64 = dataUrl.split(',')[1];
      if (!base64) {
        reject(new Error(`Empty base64 data for ${file.name}`));
        return;
      }
      resolve(base64);
    };
    reader.onerror = () => reject(new Error(`Failed to read file: ${file.name}`));
    reader.readAsDataURL(file);
  });
}

// ── Component ────────────────────────────────────────────────────

export function ChatInput({ onSend, onStop, disabled = false, sending = false }: ChatInputProps) {
  const [input, setInput] = useState('');
  const [attachments, setAttachments] = useState<FileAttachment[]>([]);
  const textareaRef = useRef<HTMLTextAreaElement>(null);
  const isComposingRef = useRef(false);

  // Auto-resize textarea
  useEffect(() => {
    if (textareaRef.current) {
      textareaRef.current.style.height = 'auto';
      textareaRef.current.style.height = `${Math.min(textareaRef.current.scrollHeight, 200)}px`;
    }
  }, [input]);

  // Focus textarea on mount (avoids Windows focus loss after session delete + native dialog)
  useEffect(() => {
    if (!disabled && textareaRef.current) {
      textareaRef.current.focus();
    }
  }, [disabled]);

  // ── File staging via native dialog ─────────────────────────────

  const pickFiles = useCallback(async () => {
    try {
      const result = await window.electron.ipcRenderer.invoke('dialog:open', {
        properties: ['openFile', 'multiSelections'],
      }) as { canceled: boolean; filePaths?: string[] };
      if (result.canceled || !result.filePaths?.length) return;

      // Add placeholder entries immediately
      const tempIds: string[] = [];
      for (const filePath of result.filePaths) {
        const tempId = crypto.randomUUID();
        tempIds.push(tempId);
        // Handle both Unix (/) and Windows (\) path separators
        const fileName = filePath.split(/[\\/]/).pop() || 'file';
        setAttachments(prev => [...prev, {
          id: tempId,
          fileName,
          mimeType: '',
          fileSize: 0,
          stagedPath: '',
          preview: null,
          status: 'staging' as const,
        }]);
      }

      // Stage all files via IPC
      console.log('[pickFiles] Staging files:', result.filePaths);
      const staged = await window.electron.ipcRenderer.invoke(
        'file:stage',
        result.filePaths,
      ) as Array<{
        id: string;
        fileName: string;
        mimeType: string;
        fileSize: number;
        stagedPath: string;
        preview: string | null;
      }>;
      console.log('[pickFiles] Stage result:', staged?.map(s => ({ id: s?.id, fileName: s?.fileName, mimeType: s?.mimeType, fileSize: s?.fileSize, stagedPath: s?.stagedPath, hasPreview: !!s?.preview })));

      // Update each placeholder with real data
      setAttachments(prev => {
        let updated = [...prev];
        for (let i = 0; i < tempIds.length; i++) {
          const tempId = tempIds[i];
          const data = staged[i];
          if (data) {
            updated = updated.map(a =>
              a.id === tempId
                ? { ...data, status: 'ready' as const }
                : a,
            );
          } else {
            console.warn(`[pickFiles] No staged data for tempId=${tempId} at index ${i}`);
            updated = updated.map(a =>
              a.id === tempId
                ? { ...a, status: 'error' as const, error: 'Staging failed' }
                : a,
            );
          }
        }
        return updated;
      });
    } catch (err) {
      console.error('[pickFiles] Failed to stage files:', err);
      // Mark any stuck 'staging' attachments as 'error' so the user can remove them
      // and the send button isn't permanently blocked
      setAttachments(prev => prev.map(a =>
        a.status === 'staging'
          ? { ...a, status: 'error' as const, error: String(err) }
          : a,
      ));
    }
  }, []);

  // ── Stage browser File objects (paste / drag-drop) ─────────────

  const stageBufferFiles = useCallback(async (files: globalThis.File[]) => {
    for (const file of files) {
      const tempId = crypto.randomUUID();
      setAttachments(prev => [...prev, {
        id: tempId,
        fileName: file.name,
        mimeType: file.type || 'application/octet-stream',
        fileSize: file.size,
        stagedPath: '',
        preview: null,
        status: 'staging' as const,
      }]);

      try {
        console.log(`[stageBuffer] Reading file: ${file.name} (${file.type}, ${file.size} bytes)`);
        const base64 = await readFileAsBase64(file);
        console.log(`[stageBuffer] Base64 length: ${base64?.length ?? 'null'}`);
        const staged = await window.electron.ipcRenderer.invoke('file:stageBuffer', {
          base64,
          fileName: file.name,
          mimeType: file.type || 'application/octet-stream',
        }) as {
          id: string;
          fileName: string;
          mimeType: string;
          fileSize: number;
          stagedPath: string;
          preview: string | null;
        };
        console.log(`[stageBuffer] Staged: id=${staged?.id}, path=${staged?.stagedPath}, size=${staged?.fileSize}`);
        setAttachments(prev => prev.map(a =>
          a.id === tempId ? { ...staged, status: 'ready' as const } : a,
        ));
      } catch (err) {
        console.error(`[stageBuffer] Error staging ${file.name}:`, err);
        setAttachments(prev => prev.map(a =>
          a.id === tempId
            ? { ...a, status: 'error' as const, error: String(err) }
            : a,
        ));
      }
    }
  }, []);

  // ── Attachment management ──────────────────────────────────────

  const removeAttachment = useCallback((id: string) => {
    setAttachments(prev => prev.filter(a => a.id !== id));
  }, []);

  const allReady = attachments.length === 0 || attachments.every(a => a.status === 'ready');
  const canSend = (input.trim() || attachments.length > 0) && allReady && !disabled && !sending;
  const canStop = sending && !disabled && !!onStop;

  const handleSend = useCallback(() => {
    if (!canSend) return;
    const readyAttachments = attachments.filter(a => a.status === 'ready');
    // Capture values before clearing — clear input immediately for snappy UX,
    // but keep attachments available for the async send
    const textToSend = input.trim();
    const attachmentsToSend = readyAttachments.length > 0 ? readyAttachments : undefined;
    console.log(`[handleSend] text="${textToSend.substring(0, 50)}", attachments=${attachments.length}, ready=${readyAttachments.length}, sending=${!!attachmentsToSend}`);
    if (attachmentsToSend) {
      console.log('[handleSend] Attachment details:', attachmentsToSend.map(a => ({
        id: a.id, fileName: a.fileName, mimeType: a.mimeType, fileSize: a.fileSize,
        stagedPath: a.stagedPath, status: a.status, hasPreview: !!a.preview,
      })));
    }
    setInput('');
    setAttachments([]);
    if (textareaRef.current) {
      textareaRef.current.style.height = 'auto';
    }
    onSend(textToSend, attachmentsToSend);
  }, [input, attachments, canSend, onSend]);

  const handleStop = useCallback(() => {
    if (!canStop) return;
    onStop?.();
  }, [canStop, onStop]);

  const handleKeyDown = useCallback(
    (e: React.KeyboardEvent) => {
      if (e.key === 'Enter' && !e.shiftKey) {
        const nativeEvent = e.nativeEvent as KeyboardEvent;
        if (isComposingRef.current || nativeEvent.isComposing || nativeEvent.keyCode === 229) {
          return;
        }
        e.preventDefault();
        handleSend();
      }
    },
    [handleSend],
  );

  // Handle paste (Ctrl/Cmd+V with files)
  const handlePaste = useCallback(
    (e: React.ClipboardEvent) => {
      const items = e.clipboardData?.items;
      if (!items) return;

      const pastedFiles: globalThis.File[] = [];
      for (const item of Array.from(items)) {
        if (item.kind === 'file') {
          const file = item.getAsFile();
          if (file) pastedFiles.push(file);
        }
      }
      if (pastedFiles.length > 0) {
        e.preventDefault();
        stageBufferFiles(pastedFiles);
      }
    },
    [stageBufferFiles],
  );

  // Handle drag & drop
  const [dragOver, setDragOver] = useState(false);

  const handleDragOver = useCallback((e: React.DragEvent) => {
    e.preventDefault();
    e.stopPropagation();
    setDragOver(true);
  }, []);

  const handleDragLeave = useCallback((e: React.DragEvent) => {
    e.preventDefault();
    e.stopPropagation();
    setDragOver(false);
  }, []);

  const handleDrop = useCallback(
    (e: React.DragEvent) => {
      e.preventDefault();
      e.stopPropagation();
      setDragOver(false);
      if (e.dataTransfer?.files?.length) {
        stageBufferFiles(Array.from(e.dataTransfer.files));
      }
    },
    [stageBufferFiles],
  );

  return (
    <div
      className="bg-background p-4"
      onDragOver={handleDragOver}
      onDragLeave={handleDragLeave}
      onDrop={handleDrop}
    >
      <div className="max-w-4xl mx-auto">
        {/* Attachment Previews */}
        {attachments.length > 0 && (
          <div className="flex gap-2 mb-2 flex-wrap">
            {attachments.map((att) => (
              <AttachmentPreview
                key={att.id}
                attachment={att}
                onRemove={() => removeAttachment(att.id)}
              />
            ))}
          </div>
        )}

        {/* Input Row */}
        <div className={`flex items-end gap-2 ${dragOver ? 'ring-2 ring-primary rounded-lg' : ''}`}>

          {/* Attach Button */}
          <Button
            variant="ghost"
            size="icon"
            className="shrink-0 h-[44px] w-[44px]"
            onClick={pickFiles}
            disabled={disabled || sending}
            title="Attach files"
          >
            <Paperclip className="h-4 w-4" />
          </Button>

          {/* Textarea */}
          <div className="flex-1 relative">
            <Textarea
              ref={textareaRef}
              value={input}
              onChange={(e) => setInput(e.target.value)}
              onKeyDown={handleKeyDown}
              onCompositionStart={() => {
                isComposingRef.current = true;
              }}
              onCompositionEnd={() => {
                isComposingRef.current = false;
              }}
              onPaste={handlePaste}
              placeholder={disabled ? 'Gateway not connected...' : 'Message (Enter to send, Shift+Enter for new line)'}
              disabled={disabled}
              className="min-h-[44px] max-h-[200px] resize-none pr-4"
              rows={1}
            />
          </div>

          {/* Send Button */}
          <Button
            onClick={sending ? handleStop : handleSend}
            disabled={sending ? !canStop : !canSend}
            size="icon"
            className="shrink-0 h-[44px] w-[44px]"
            variant={sending ? 'destructive' : 'default'}
            title={sending ? 'Stop' : 'Send'}
          >
            {sending ? (
              <Square className="h-4 w-4" />
            ) : (
              <Send className="h-4 w-4" />
            )}
          </Button>
        </div>
      </div>
    </div>
  );
}

// ── Attachment Preview ───────────────────────────────────────────

function AttachmentPreview({
  attachment,
  onRemove,
}: {
  attachment: FileAttachment;
  onRemove: () => void;
}) {
  const isImage = attachment.mimeType.startsWith('image/') && attachment.preview;

  return (
    <div className="relative group rounded-lg overflow-hidden border border-border">
      {isImage ? (
        // Image thumbnail
        <div className="w-16 h-16">
          <img
            src={attachment.preview!}
            alt={attachment.fileName}
            className="w-full h-full object-cover"
          />
        </div>
      ) : (
        // Generic file card
        <div className="flex items-center gap-2 px-3 py-2 bg-muted/50 max-w-[200px]">
          <FileIcon mimeType={attachment.mimeType} className="h-5 w-5 shrink-0 text-muted-foreground" />
          <div className="min-w-0 overflow-hidden">
            <p className="text-xs font-medium truncate">{attachment.fileName}</p>
            <p className="text-[10px] text-muted-foreground">
              {attachment.fileSize > 0 ? formatFileSize(attachment.fileSize) : '...'}
            </p>
          </div>
        </div>
      )}

      {/* Staging overlay */}
      {attachment.status === 'staging' && (
        <div className="absolute inset-0 bg-black/40 flex items-center justify-center">
          <Loader2 className="h-4 w-4 text-white animate-spin" />
        </div>
      )}

      {/* Error overlay */}
      {attachment.status === 'error' && (
        <div className="absolute inset-0 bg-destructive/20 flex items-center justify-center">
          <span className="text-[10px] text-destructive font-medium px-1">Error</span>
        </div>
      )}

      {/* Remove button */}
      <button
        onClick={onRemove}
        className="absolute -top-1 -right-1 bg-destructive text-destructive-foreground rounded-full p-0.5 opacity-0 group-hover:opacity-100 transition-opacity"
      >
        <X className="h-3 w-3" />
      </button>
    </div>
  );
}