const mongoose = require('mongoose');

const editLogEntrySchema = new mongoose.Schema(
  {
    user: { type: mongoose.Schema.Types.ObjectId, ref: 'User', required: true },
    timestamp: { type: Date, default: Date.now },
    changes: { type: String, required: true }, // human-readable diff string
  },
  { _id: false }
);

const expenseSchema = new mongoose.Schema(
  {
    title: { type: String, required: true, trim: true }, // e.g. "Ali's Salary - July"
    category: {
      type: String,
      enum: ['Salary', 'Rent', 'Utilities', 'Raw Material', 'Maintenance', 'Misc'],
      required: true,
    },
    amount: { type: Number, required: true, min: 0 },
    date: { type: Date, required: true },
    note: { type: String, default: '' },
    // No receiptImage — receipts are generated on-demand from data
    recurring: { type: Boolean, default: false },
    frequency: { type: String, enum: ['monthly', 'weekly', null], default: null },
    createdBy: { type: mongoose.Schema.Types.ObjectId, ref: 'User', required: true },
    editLog: { type: [editLogEntrySchema], default: [] },
  },
  { timestamps: true }
);

expenseSchema.index({ date: -1 });
expenseSchema.index({ category: 1, date: -1 });

module.exports = mongoose.model('Expense', expenseSchema);