import { useState, useEffect } from 'react';
import { useToast } from '@/hooks/use-toast';
import { useUserRole } from '@/hooks/useUserRole';
import { useAuth } from '@/hooks/useAuth';
import { handleError } from '@/lib/errorHandler';
import { 
  fetchSubmissionItems, 
  buildDependencyTree, 
  detectDependencyConflicts,
  approveSubmissionItems,
  rejectSubmissionItems,
  escalateSubmission,
  type SubmissionItemWithDeps,
  type DependencyConflict 
} 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 } 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 { validateMultipleItems, ValidationResult } from '@/lib/entityValidationSchemas';

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

export function SubmissionReviewManager({ 
  submissionId, 
  open, 
  onOpenChange,
  onComplete 
}: SubmissionReviewManagerProps) {
  const [items, setItems] = useState<SubmissionItemWithDeps[]>([]);
  const [selectedItemIds, setSelectedItemIds] = useState<Set<string>>(new Set());
  const [conflicts, setConflicts] = useState<DependencyConflict[]>([]);
  const [loading, setLoading] = useState(false);
  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 { toast } = useToast();
  const { isAdmin, isSuperuser } = useUserRole();
  const { user } = useAuth();
  const isMobile = useIsMobile();
  const Container = isMobile ? Sheet : Dialog;

  useEffect(() => {
    if (open && submissionId) {
      loadSubmissionItems();
    }
  }, [open, submissionId]);

  const loadSubmissionItems = async () => {
    setLoading(true);
    try {
      const { supabase } = await import('@/integrations/supabase/client');
      
      // Fetch submission type
      const { data: submission } = await supabase
        .from('content_submissions')
        .select('submission_type')
        .eq('id', submissionId)
        .single();
      
      if (submission) {
        setSubmissionType(submission.submission_type || 'submission');
      }

      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));
    } catch (error: unknown) {
      handleError(error, {
        action: 'Load Submission Items',
        userId: user?.id,
        metadata: { submissionId, submissionType }
      });
    } finally {
      setLoading(false);
    }
  };

  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 () => {
    setLoading(true);
    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 }
      });
    } finally {
      setLoading(false);
    }
  };

  const handleApprove = async () => {
    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));
    
    setLoading(true);
    try {
      // 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);
        setLoading(false);
        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);
        setLoading(false);
        return; // Ask for confirmation
      }
      
      // Proceed with approval
      const { supabase } = await import('@/integrations/supabase/client');
      
      // Call the edge function for backend processing
      const { data, error } = await supabase.functions.invoke('process-selective-approval', {
        body: {
          itemIds: Array.from(selectedItemIds),
          submissionId
        }
      });

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

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

      const successCount = data.results.filter((r: any) => r.success).length;
      const failCount = data.results.filter((r: any) => !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) {
        setLoading(false);
        return;
      }

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

  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) => {
    if (!user?.id) return;

    setLoading(true);
    try {
      const selectedItems = items.filter(item => selectedItemIds.has(item.id));
      await rejectSubmissionItems(selectedItems, reason, user.id, cascade);
      
      toast({
        title: 'Items Rejected',
        description: `Successfully rejected ${selectedItems.length} item${selectedItems.length !== 1 ? 's' : ''}`,
      });

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

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

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

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

      if (error) {
        console.error('Edge function error:', 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)
        }
      });
    } finally {
      setLoading(false);
    }
  };

  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;
    }

    setLoading(true);
    try {
      if (status === 'approved') {
        const { supabase } = await import('@/integrations/supabase/client');
        const { data, error } = await supabase.functions.invoke('process-selective-approval', {
          body: {
            itemIds: [itemId],
            submissionId
          }
        });

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

        toast({
          title: 'Item Approved',
          description: 'Successfully approved the item',
        });
      } 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
        }
      });
    } finally {
      setLoading(false);
    }
  };

  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 => 
          i.item_data?.name || i.item_type.replace('_', ' ')
        )}
      />

      <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 => 
          i.item_data?.name || i.item_type.replace('_', ' ')
        )}
      />
    </>
  );

  function ReviewContent() {
    // Protection 2: UI detection of empty submissions
    if (items.length === 0 && !loading) {
      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') {
              setActiveTab(v);
            }
          }} 
          className="flex-1 flex flex-col"
        >
          <TabsList className="grid w-full grid-cols-2">
            <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>
          </TabsList>

          <TabsContent value="items" className="flex-1 overflow-hidden">
            <ScrollArea className="h-full pr-4">
              <div className="space-y-4">
                {items.length === 0 && !loading && (
                  <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>
        </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 || loading || hasBlockingErrors}
            className="flex-1"
          >
            <CheckCircle2 className="w-4 h-4 mr-2" />
            Approve Selected ({selectedCount})
          </Button>

          <Button
            onClick={handleRejectSelected}
            disabled={selectedCount === 0 || loading}
            variant="destructive"
            className="flex-1"
          >
            <XCircle className="w-4 h-4 mr-2" />
            Reject Selected
          </Button>

          <Button
            onClick={() => setShowEscalationDialog(true)}
            variant="outline"
            disabled={loading}
          >
            <ArrowUp className="w-4 h-4 mr-2" />
            Escalate
          </Button>
        </div>
      </div>
    );
  }
}