import { useState, useEffect, useReducer } from 'react';
import { useToast } from '@/hooks/use-toast';
import { useUserRole } from '@/hooks/useUserRole';
import { useAuth } from '@/hooks/useAuth';
import { handleError, getErrorMessage } from '@/lib/errorHandler';
import { invokeWithTracking } from '@/lib/edgeFunctionTracking';
import { moderationReducer, canApprove, canReject, hasActiveLock } from '@/lib/moderationStateMachine';
import { useLockMonitor } from '@/lib/moderation/lockMonitor';
import { 
  fetchSubmissionItems, 
  buildDependencyTree, 
  detectDependencyConflicts,
  approveSubmissionItems,
  rejectSubmissionItems,
  escalateSubmission,
  checkSubmissionConflict,
  type SubmissionItemWithDeps,
  type DependencyConflict,
  type ConflictCheckResult 
} from '@/lib/submissionItemsService';
import { Sheet, SheetContent, SheetHeader, SheetTitle, SheetDescription } from '@/components/ui/sheet';
import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogDescription } from '@/components/ui/dialog';
import { Button } from '@/components/ui/button';
import { Checkbox } from '@/components/ui/checkbox';
import { Badge } from '@/components/ui/badge';
import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
import { AlertCircle, CheckCircle2, XCircle, Edit, Network, ArrowUp, History } from 'lucide-react';
import { Alert, AlertDescription } from '@/components/ui/alert';
import { ScrollArea } from '@/components/ui/scroll-area';
import { useIsMobile } from '@/hooks/use-mobile';
import { ItemReviewCard } from './ItemReviewCard';
import { DependencyVisualizer } from './DependencyVisualizer';
import { ConflictResolutionDialog } from './ConflictResolutionDialog';
import { EscalationDialog } from './EscalationDialog';
import { RejectionDialog } from './RejectionDialog';
import { ItemEditDialog } from './ItemEditDialog';
import { ValidationBlockerDialog } from './ValidationBlockerDialog';
import { WarningConfirmDialog } from './WarningConfirmDialog';
import { ConflictResolutionModal } from './ConflictResolutionModal';
import { EditHistoryAccordion } from './EditHistoryAccordion';
import { validateMultipleItems, ValidationResult } from '@/lib/entityValidationSchemas';
import { logger } from '@/lib/logger';

interface SubmissionReviewManagerProps {
  submissionId: string;
  open: boolean;
  onOpenChange: (open: boolean) => void;
  onComplete: () => void;
}

export function SubmissionReviewManager({ 
  submissionId, 
  open, 
  onOpenChange,
  onComplete 
}: SubmissionReviewManagerProps) {
  // State machine for moderation workflow
  const [state, dispatch] = useReducer(moderationReducer, { status: 'idle' });
  
  // UI-specific state (kept separate from state machine)
  const [items, setItems] = useState<SubmissionItemWithDeps[]>([]);
  const [selectedItemIds, setSelectedItemIds] = useState<Set<string>>(new Set());
  const [conflicts, setConflicts] = useState<DependencyConflict[]>([]);
  const [showConflictDialog, setShowConflictDialog] = useState(false);
  const [showEscalationDialog, setShowEscalationDialog] = useState(false);
  const [showRejectionDialog, setShowRejectionDialog] = useState(false);
  const [showEditDialog, setShowEditDialog] = useState(false);
  const [editingItem, setEditingItem] = useState<SubmissionItemWithDeps | null>(null);
  const [activeTab, setActiveTab] = useState<'items' | 'dependencies'>('items');
  const [submissionType, setSubmissionType] = useState<string>('submission');
  const [showValidationBlockerDialog, setShowValidationBlockerDialog] = useState(false);
  const [showWarningConfirmDialog, setShowWarningConfirmDialog] = useState(false);
  const [validationResults, setValidationResults] = useState<Map<string, ValidationResult>>(new Map());
  const [userConfirmedWarnings, setUserConfirmedWarnings] = useState(false);
  const [hasBlockingErrors, setHasBlockingErrors] = useState(false);
  const [globalValidationKey, setGlobalValidationKey] = useState(0);
  const [conflictData, setConflictData] = useState<ConflictCheckResult | null>(null);
  const [showConflictResolutionModal, setShowConflictResolutionModal] = useState(false);
  const [lastModifiedTimestamp, setLastModifiedTimestamp] = useState<string | null>(null);
  
  const { toast } = useToast();
  const { isAdmin, isSuperuser } = useUserRole();
  const { user } = useAuth();
  const isMobile = useIsMobile();
  const Container = isMobile ? Sheet : Dialog;

  // Lock monitoring integration
  const { extendLock } = useLockMonitor(state, dispatch, submissionId);

  // Auto-claim on mount
  useEffect(() => {
    if (open && submissionId && state.status === 'idle') {
      handleClaimSubmission();
    }
  }, [open, submissionId, state.status]);

  const handleClaimSubmission = async () => {
    dispatch({ type: 'CLAIM_ITEM', payload: { itemId: submissionId } });
    
    try {
      // Assume lock is acquired by parent component or moderation queue
      const lockExpires = new Date(Date.now() + 15 * 60 * 1000).toISOString();
      dispatch({ type: 'LOCK_ACQUIRED', payload: { lockExpires } });
      
      // Load data
      dispatch({ type: 'LOAD_DATA' });
      const loadedItems = await loadSubmissionItems();
      
      // Transition to reviewing state with actual loaded data
      dispatch({ type: 'DATA_LOADED', payload: { reviewData: loadedItems || [] } });
    } catch (error: unknown) {
      dispatch({ type: 'ERROR', payload: { error: getErrorMessage(error) } });
      handleError(error, { action: 'Claim Submission', userId: user?.id });
    }
  };

  const loadSubmissionItems = async () => {
    // State machine already transitioned via handleClaimSubmission
    // This just handles the data fetching
    try {
      const { supabase } = await import('@/integrations/supabase/client');
      
      // Fetch submission type and last_modified_at
      const { data: submission } = await supabase
        .from('content_submissions')
        .select('submission_type, last_modified_at')
        .eq('id', submissionId)
        .single();
      
      if (submission) {
        setSubmissionType(submission.submission_type || 'submission');
        setLastModifiedTimestamp(submission.last_modified_at);
      }

      const fetchedItems = await fetchSubmissionItems(submissionId);
      
      // Protection 2: Detect empty submissions
      if (!fetchedItems || fetchedItems.length === 0) {
        setItems([]);
        return;
      }
      
      const itemsWithDeps = buildDependencyTree(fetchedItems);
      setItems(itemsWithDeps);
      
      // Auto-select pending items
      const pendingIds = fetchedItems
        .filter(item => item.status === 'pending')
        .map(item => item.id);
      setSelectedItemIds(new Set(pendingIds));
      
      return itemsWithDeps;
    } catch (error: unknown) {
      throw error; // Let handleClaimSubmission handle the error
    }
  };

  const toggleItemSelection = (itemId: string) => {
    setSelectedItemIds(prev => {
      const next = new Set(prev);
      if (next.has(itemId)) {
        next.delete(itemId);
      } else {
        next.add(itemId);
      }
      // Clear blocking errors and warning confirmation when selection changes
      setHasBlockingErrors(false);
      setValidationResults(new Map());
      setUserConfirmedWarnings(false);
      return next;
    });
  };

  const handleCheckConflicts = async () => {
    try {
      const detectedConflicts = await detectDependencyConflicts(items, Array.from(selectedItemIds));
      setConflicts(detectedConflicts);
      
      if (detectedConflicts.length > 0) {
        setShowConflictDialog(true);
      } else {
        // No conflicts, proceed with approval
        handleApprove();
      }
    } catch (error: unknown) {
      handleError(error, {
        action: 'Check Dependency Conflicts',
        userId: user?.id,
        metadata: { submissionId, selectedCount: selectedItemIds.size }
      });
    }
  };

  const handleApprove = async () => {
    // State machine validation
    if (!canApprove(state)) {
      toast({
        title: 'Cannot Approve',
        description: state.status === 'lock_expired' 
          ? 'Your lock has expired. Please re-claim this submission.'
          : `Invalid state for approval: ${state.status}`,
        variant: 'destructive',
      });
      return;
    }

    if (!user?.id) {
      toast({
        title: 'Authentication Required',
        description: 'You must be logged in to approve items',
        variant: 'destructive',
      });
      return;
    }

    const selectedItems = items.filter(item => selectedItemIds.has(item.id));
    
    // Transition: reviewing → approving
    dispatch({ type: 'START_APPROVAL' });
    
    try {
      // Check for conflicts first (optimistic locking)
      if (lastModifiedTimestamp) {
        const conflictCheck = await checkSubmissionConflict(submissionId, lastModifiedTimestamp);
        
        if (conflictCheck.hasConflict) {
          setConflictData(conflictCheck);
          setShowConflictResolutionModal(true);
          dispatch({ type: 'RESET' }); // Return to reviewing state
          return; // Block approval until conflict resolved
        }
      }

      // Run validation on all selected items
      const validationResultsMap = await validateMultipleItems(
        selectedItems.map(item => ({
          item_type: item.item_type,
          item_data: item.item_data,
          id: item.id
        }))
      );
      
      setValidationResults(validationResultsMap);
      
      // Check for blocking errors
      const itemsWithBlockingErrors = selectedItems.filter(item => {
        const result = validationResultsMap.get(item.id);
        return result && result.blockingErrors.length > 0;
      });
      
      // CRITICAL: Blocking errors can NEVER be bypassed, regardless of warnings
      if (itemsWithBlockingErrors.length > 0) {
        setHasBlockingErrors(true);
        setShowValidationBlockerDialog(true);
        dispatch({ type: 'ERROR', payload: { error: 'Validation failed' } });
        return; // Block approval
      }
      
      // Check for warnings
      const itemsWithWarnings = selectedItems.filter(item => {
        const result = validationResultsMap.get(item.id);
        return result && result.warnings.length > 0;
      });
      
      if (itemsWithWarnings.length > 0 && !userConfirmedWarnings) {
        setShowWarningConfirmDialog(true);
        dispatch({ type: 'RESET' }); // Reset to reviewing state
        return; // Ask for confirmation
      }
      
      // Proceed with approval
      const { supabase } = await import('@/integrations/supabase/client');
      
      // Call the edge function for backend processing
      const { data, error, requestId } = await invokeWithTracking(
        'process-selective-approval',
        {
          itemIds: Array.from(selectedItemIds),
          submissionId
        },
        user?.id
      );

      if (error) {
        throw new Error(error.message || 'Failed to process approval');
      }

      if (!data?.success) {
        throw new Error(data?.error || 'Approval processing failed');
      }

      // Transition: approving → complete
      dispatch({ type: 'COMPLETE', payload: { result: 'approved' } });

      toast({
        title: 'Items Approved',
        description: `Successfully approved ${selectedItemIds.size} item(s)${requestId ? ` (Request: ${requestId.substring(0, 8)})` : ''}`,
      });

      interface ApprovalResult { success: boolean; item_id: string; error?: string }
      const successCount = data.results.filter((r: ApprovalResult) => r.success).length;
      const failCount = data.results.filter((r: ApprovalResult) => !r.success).length;

      const allFailed = failCount > 0 && successCount === 0;
      const someFailed = failCount > 0 && successCount > 0;

      toast({
        title: allFailed ? 'Approval Failed' : someFailed ? 'Partial Approval' : 'Approval Complete',
        description: failCount > 0 
          ? `Approved ${successCount} item(s), ${failCount} failed`
          : `Successfully approved ${successCount} item(s)`,
        variant: allFailed ? 'destructive' : someFailed ? 'default' : 'default',
      });

      // Reset warning confirmation state after approval
      setUserConfirmedWarnings(false);

      // If ALL items failed, don't close dialog - show errors
      if (allFailed) {
        dispatch({ type: 'ERROR', payload: { error: 'All items failed' } });
        return;
      }

      // Reset warning confirmation state after approval
      setUserConfirmedWarnings(false);

      onComplete();
      onOpenChange(false);
    } catch (error: unknown) {
      dispatch({ type: 'ERROR', payload: { error: getErrorMessage(error) } });
      handleError(error, {
        action: 'Approve Submission Items',
        userId: user?.id,
        metadata: { 
          submissionId,
          itemCount: selectedItemIds.size,
          hasWarnings: userConfirmedWarnings,
          hasBlockingErrors
        }
      });
    }
  };

  const handleRejectSelected = async () => {
    if (selectedItemIds.size === 0) {
      toast({
        title: 'No Items Selected',
        description: 'Please select items to reject',
        variant: 'destructive',
      });
      return;
    }

    if (!user?.id) {
      toast({
        title: 'Authentication Required',
        description: 'You must be logged in to reject items',
        variant: 'destructive',
      });
      return;
    }

    // Check if any selected items have dependents
    const selectedItems = items.filter(item => selectedItemIds.has(item.id));
    const hasDependents = selectedItems.some(item => 
      item.dependents && item.dependents.length > 0
    );

    setShowRejectionDialog(true);
  };

  const handleReject = async (reason: string, cascade: boolean) => {
    // State machine validation
    if (!canReject(state)) {
      toast({
        title: 'Cannot Reject',
        description: 'Invalid state for rejection',
        variant: 'destructive',
      });
      return;
    }

    if (!user?.id) return;

    // Transition: reviewing → rejecting
    dispatch({ type: 'START_REJECTION' });

    try {
      const selectedItems = items.filter(item => selectedItemIds.has(item.id));
      await rejectSubmissionItems(selectedItems, reason, user.id, cascade);
      
      // Transition: rejecting → complete
      dispatch({ type: 'COMPLETE', payload: { result: 'rejected' } });
      
      toast({
        title: 'Items Rejected',
        description: `Successfully rejected ${selectedItems.length} item${selectedItems.length !== 1 ? 's' : ''}`,
      });

      onComplete();
      onOpenChange(false);
    } catch (error: unknown) {
      dispatch({ type: 'ERROR', payload: { error: getErrorMessage(error) } });
      handleError(error, {
        action: 'Reject Submission Items',
        userId: user?.id,
        metadata: { 
          submissionId,
          itemCount: selectedItemIds.size,
          cascade,
          reason: reason.substring(0, 100)
        }
      });
    }
  };

  const handleEscalate = async (reason: string) => {
    if (!user?.id) {
      toast({
        title: 'Authentication Required',
        description: 'You must be logged in to escalate submissions',
        variant: 'destructive',
      });
      return;
    }

    try {
      const { supabase } = await import('@/integrations/supabase/client');

      // Call the escalation notification edge function
      const { data, error, requestId } = await invokeWithTracking(
        'send-escalation-notification',
        {
          submissionId,
          escalationReason: reason,
          escalatedBy: user.id
        },
        user.id
      );

      if (error) {
        logger.error('Edge function failed', { error: getErrorMessage(error) });
        // Fallback to direct database update if email fails
        await escalateSubmission(submissionId, reason, user.id);
        toast({
          title: 'Escalated (Email Failed)',
          description: 'Submission escalated but notification email failed to send',
          variant: 'default',
        });
      } else {
        toast({
          title: 'Escalated Successfully',
          description: 'Submission escalated and admin notified via email',
        });
      }
      
      onComplete();
      onOpenChange(false);
    } catch (error: unknown) {
      handleError(error, {
        action: 'Escalate Submission',
        userId: user?.id,
        metadata: { 
          submissionId,
          reason: reason.substring(0, 100)
        }
      });
    }
  };

  const handleEdit = (item: SubmissionItemWithDeps) => {
    setEditingItem(item);
    setShowEditDialog(true);
  };

  const handleEditComplete = async () => {
    setShowEditDialog(false);
    setEditingItem(null);
    await loadSubmissionItems();
    setGlobalValidationKey(prev => prev + 1);
  };

  const handleItemStatusChange = async (itemId: string, status: 'approved' | 'rejected') => {
    if (!user?.id) {
      toast({
        title: 'Authentication Required',
        description: 'You must be logged in to change item status',
        variant: 'destructive',
      });
      return;
    }

    try {
      if (status === 'approved') {
        const { supabase } = await import('@/integrations/supabase/client');
        const { data, error, requestId } = await invokeWithTracking(
          'process-selective-approval',
          {
            itemIds: [itemId],
            submissionId
          },
          user?.id
        );

        if (error || !data?.success) {
          throw new Error(error?.message || data?.error || 'Failed to approve item');
        }

        toast({
          title: 'Item Approved',
          description: `Successfully approved the item${requestId ? ` (Request: ${requestId.substring(0, 8)})` : ''}`,
        });
      } else {
        const item = items.find(i => i.id === itemId);
        if (!item) {
          throw new Error('Item not found');
        }

        await rejectSubmissionItems([item], 'Quick rejection from review', user.id, false);
        
        toast({
          title: 'Item Rejected',
          description: 'Successfully rejected the item',
        });
      }

      await loadSubmissionItems();
    } catch (error: unknown) {
      handleError(error, {
        action: `${status === 'approved' ? 'Approve' : 'Reject'} Item`,
        userId: user?.id,
        metadata: { 
          submissionId,
          itemId,
          status
        }
      });
    }
  };

  const pendingCount = items.filter(item => item.status === 'pending').length;
  const selectedCount = selectedItemIds.size;

  return (
    <>
      <Container open={open} onOpenChange={onOpenChange}>
        {isMobile ? (
          <SheetContent side="bottom" className="h-[90vh] overflow-y-auto">
            <SheetHeader>
              <SheetTitle>Review Submission</SheetTitle>
              <SheetDescription>
                {pendingCount} pending item(s) • {selectedCount} selected
              </SheetDescription>
            </SheetHeader>
            <ReviewContent />
          </SheetContent>
        ) : (
          <DialogContent className="max-w-5xl max-h-[90vh] overflow-y-auto">
            <DialogHeader>
              <DialogTitle>Review Submission</DialogTitle>
              <DialogDescription>
                {pendingCount} pending item(s) • {selectedCount} selected
              </DialogDescription>
            </DialogHeader>
            <ReviewContent />
          </DialogContent>
        )}
      </Container>

      <ConflictResolutionDialog
        open={showConflictDialog}
        onOpenChange={setShowConflictDialog}
        conflicts={conflicts}
        items={items}
        onResolve={async () => {
          await loadSubmissionItems();
          await handleApprove();
        }}
      />

      <EscalationDialog
        open={showEscalationDialog}
        onOpenChange={setShowEscalationDialog}
        onEscalate={handleEscalate}
        submissionType={submissionType}
      />

      <RejectionDialog
        open={showRejectionDialog}
        onOpenChange={setShowRejectionDialog}
        itemCount={selectedItemIds.size}
        hasDependents={items.filter(item => selectedItemIds.has(item.id)).some(item => 
          item.dependents && item.dependents.length > 0
        )}
        onReject={handleReject}
      />

      <ItemEditDialog
        item={editingItem}
        open={showEditDialog}
        onOpenChange={setShowEditDialog}
        onComplete={handleEditComplete}
      />

      <ValidationBlockerDialog
        open={showValidationBlockerDialog}
        onClose={() => setShowValidationBlockerDialog(false)}
        blockingErrors={Array.from(validationResults.values()).flatMap(r => r.blockingErrors)}
        itemNames={items.filter(i => selectedItemIds.has(i.id)).map(i => {
          const name = typeof i.item_data === 'object' && i.item_data !== null && !Array.isArray(i.item_data) && 'name' in i.item_data
            ? String((i.item_data as Record<string, unknown>).name)
            : i.item_type.replace('_', ' ');
          return name;
        })}
      />

      <WarningConfirmDialog
        open={showWarningConfirmDialog}
        onClose={() => setShowWarningConfirmDialog(false)}
        onProceed={() => {
          setUserConfirmedWarnings(true);
          setShowWarningConfirmDialog(false);
          handleApprove();
        }}
        warnings={Array.from(validationResults.values()).flatMap(r => r.warnings)}
        itemNames={items.filter(i => selectedItemIds.has(i.id)).map(i => {
          const name = typeof i.item_data === 'object' && i.item_data !== null && !Array.isArray(i.item_data) && 'name' in i.item_data
            ? String((i.item_data as Record<string, unknown>).name)
            : i.item_type.replace('_', ' ');
          return name;
        })}
      />

      <ConflictResolutionModal
        open={showConflictResolutionModal}
        onOpenChange={setShowConflictResolutionModal}
        conflictData={conflictData}
        onResolve={async (strategy) => {
          if (strategy === 'keep-mine') {
            // Log conflict resolution
            const { supabase } = await import('@/integrations/supabase/client');
            await supabase.from('conflict_resolutions').insert([{
              submission_id: submissionId,
              resolved_by: user?.id || null,
              resolution_strategy: strategy,
              conflict_details: conflictData as any,
            }]);
            
            // Force override and proceed with approval
            await handleApprove();
          } else if (strategy === 'keep-theirs') {
            // Reload data and discard local changes
            await loadSubmissionItems();
            toast({
              title: 'Changes Discarded',
              description: 'Loaded the latest version from the server',
            });
          } else if (strategy === 'reload') {
            // Just reload without approving
            await loadSubmissionItems();
            toast({
              title: 'Reloaded',
              description: 'Viewing the latest version',
            });
          }
          setShowConflictResolutionModal(false);
          setConflictData(null);
        }}
      />
    </>
  );

  function ReviewContent() {
    // Show loading states based on state machine
    if (state.status === 'claiming' || state.status === 'loading_data') {
      return (
        <div className="flex items-center justify-center h-64">
          <div className="text-center space-y-4">
            <div className="animate-spin rounded-full h-12 w-12 border-b-2 border-primary mx-auto"></div>
            <p className="text-muted-foreground">
              {state.status === 'claiming' ? 'Claiming submission...' : 'Loading items...'}
            </p>
          </div>
        </div>
      );
    }

    // Show error state
    if (state.status === 'error') {
      return (
        <Alert variant="destructive" className="my-4">
          <AlertCircle className="h-4 w-4" />
          <AlertDescription>
            {state.error || 'An error occurred while processing this submission'}
            <div className="mt-2">
              <Button 
                variant="outline" 
                size="sm"
                onClick={() => {
                  dispatch({ type: 'RESET' });
                  handleClaimSubmission();
                }}
              >
                Try Again
              </Button>
            </div>
          </AlertDescription>
        </Alert>
      );
    }

    // Show lock expired warning
    if (state.status === 'lock_expired') {
      return (
        <Alert variant="destructive" className="my-4">
          <AlertCircle className="h-4 w-4" />
          <AlertDescription>
            Your lock on this submission has expired. You need to re-claim it to continue.
            <div className="mt-2 flex gap-2">
              <Button 
                variant="outline" 
                size="sm"
                onClick={() => {
                  dispatch({ type: 'RESET' });
                  handleClaimSubmission();
                }}
              >
                Re-claim Submission
              </Button>
              <Button 
                variant="outline" 
                size="sm"
                onClick={() => onOpenChange(false)}
              >
                Cancel
              </Button>
            </div>
          </AlertDescription>
        </Alert>
      );
    }

    // Protection 2: UI detection of empty submissions
    if (items.length === 0 && state.status === 'reviewing') {
      return (
        <Alert variant="destructive" className="my-4">
          <AlertCircle className="h-4 w-4" />
          <AlertDescription>
            This submission has no items and appears to be corrupted or incomplete. 
            This usually happens when the submission creation process was interrupted.
            <div className="mt-2 flex gap-2">
              <Button 
                variant="outline" 
                size="sm"
                onClick={async () => {
                  try {
                    const { supabase } = await import('@/integrations/supabase/client');
                    await supabase
                      .from('content_submissions')
                      .delete()
                      .eq('id', submissionId);
                    
                    toast({
                      title: 'Submission Archived',
                      description: 'The corrupted submission has been removed',
                    });
                    onComplete();
                    onOpenChange(false);
                  } catch (error: unknown) {
                    handleError(error, {
                      action: 'Archive Corrupted Submission',
                      userId: user?.id,
                      metadata: { submissionId }
                    });
                  }
                }}
              >
                Archive Submission
              </Button>
            </div>
          </AlertDescription>
        </Alert>
      );
    }

    return (
      <div className="flex flex-col gap-4 h-full">
        <Tabs 
          value={activeTab} 
          onValueChange={(v) => {
            if (v === 'items' || v === 'dependencies' || v === 'history') {
              setActiveTab(v as 'items' | 'dependencies');
            }
          }} 
          className="flex-1 flex flex-col"
        >
          <TabsList className="grid w-full grid-cols-3">
            <TabsTrigger value="items">
              <CheckCircle2 className="w-4 h-4 mr-2" />
              Items ({items.length})
            </TabsTrigger>
            <TabsTrigger value="dependencies">
              <Network className="w-4 h-4 mr-2" />
              Dependencies
            </TabsTrigger>
            <TabsTrigger value="history">
              <History className="w-4 h-4 mr-2" />
              History
            </TabsTrigger>
          </TabsList>

          <TabsContent value="items" className="flex-1 overflow-hidden">
            <ScrollArea className="h-full pr-4">
              <div className="space-y-4">
                {items.length === 0 && state.status === 'reviewing' && (
                  <Alert>
                    <AlertCircle className="h-4 w-4" />
                    <AlertDescription>
                      No items found in this submission
                    </AlertDescription>
                  </Alert>
                )}

                {items.map((item) => (
                  <div key={item.id} className="flex gap-3 items-start">
                    <Checkbox
                      checked={selectedItemIds.has(item.id)}
                      onCheckedChange={() => toggleItemSelection(item.id)}
                      disabled={item.status !== 'pending'}
                    />
                    <ItemReviewCard
                      item={item}
                      onEdit={() => handleEdit(item)}
                      onStatusChange={async () => {
                        // Status changes handled via approve/reject actions
                        await loadSubmissionItems();
                      }}
                      submissionId={submissionId}
                    />
                  </div>
                ))}
              </div>
            </ScrollArea>
          </TabsContent>

          <TabsContent value="dependencies" className="flex-1 overflow-hidden">
            <DependencyVisualizer items={items} selectedIds={selectedItemIds} />
          </TabsContent>

          <TabsContent value="history" className="flex-1 overflow-hidden">
            <ScrollArea className="h-full pr-4">
              <EditHistoryAccordion submissionId={submissionId} />
            </ScrollArea>
          </TabsContent>
        </Tabs>

        {/* Blocking error alert */}
        {hasBlockingErrors && (
          <Alert variant="destructive">
            <AlertCircle className="w-4 h-4" />
            <AlertDescription>
              Cannot approve: Selected items have validation errors that must be fixed first.
            </AlertDescription>
          </Alert>
        )}

        {/* Action buttons */}
        <div className="flex flex-col sm:flex-row gap-2 pt-4 border-t">
          <Button
            onClick={handleCheckConflicts}
            disabled={
              selectedCount === 0 || 
              !canApprove(state) || 
              hasBlockingErrors
            }
            className="flex-1"
          >
            <CheckCircle2 className="w-4 h-4 mr-2" />
            {state.status === 'approving' ? 'Approving...' : `Approve Selected (${selectedCount})`}
          </Button>

          <Button
            onClick={handleRejectSelected}
            disabled={
              selectedCount === 0 || 
              !canReject(state)
            }
            variant="destructive"
            className="flex-1"
          >
            <XCircle className="w-4 h-4 mr-2" />
            {state.status === 'rejecting' ? 'Rejecting...' : 'Reject Selected'}
          </Button>

          <Button
            onClick={() => setShowEscalationDialog(true)}
            variant="outline"
            disabled={state.status !== 'reviewing'}
          >
            <ArrowUp className="w-4 h-4 mr-2" />
            Escalate
          </Button>
        </div>
      </div>
    );
  }
}
