import mongoose, { Document, Schema } from 'mongoose';

export interface IExpense extends Document {
  category: string;
  description: string;
  amount: number;
  date: Date;
  taxDeductible: boolean;
  vendor?: string;
  reference?: string;
  receiptUrl?: string;
  notes?: string;
  userId: mongoose.Types.ObjectId;
  dateCreated: Date;
  dateUpdated: Date;
}

const ExpenseSchema: Schema = new Schema({
  category: { type: String, required: true },
  description: { type: String, required: true, trim: true },
  amount: { type: Number, required: true, min: 0 },
  date: { type: Date, required: true },
  taxDeductible: { type: Boolean, default: false },
  vendor: { type: String },
  reference: { type: String },
  receiptUrl: { type: String },
  notes: { type: String },
  userId: { type: Schema.Types.ObjectId, ref: 'User', required: true, index: true },
  dateCreated: { type: Date, default: Date.now },
  dateUpdated: { type: Date, default: Date.now },
});

ExpenseSchema.pre('save', function (next) {
  this.dateUpdated = new Date();
  next();
});

// Create compound index to prevent duplicate expenses with same reference, vendor, and user
ExpenseSchema.index({ 
  reference: 1, 
  vendor: 1, 
  userId: 1, 
  amount: 1, 
  date: 1 
}, { 
  unique: true, 
  partialFilterExpression: { 
    reference: { $exists: true, $ne: null },
    vendor: { $exists: true, $ne: null }
  } 
});

export default mongoose.model<IExpense>('Expense', ExpenseSchema);