import { Schema, model, models, Model, Types, Document } from "mongoose";

export interface IProduct extends Document {
  _id: Types.ObjectId;
  businessId: Types.ObjectId; // tenant this product belongs to
  label: string;
  // Size measured in `unit` (litres for water, a count for side items).
  // The field keeps its historical name so existing data needs no migration.
  sizeLiters: number;
  unit: string; // see PRODUCT_UNITS in src/lib/units.ts: "L", "pcs", "tray"...
  category: string; // e.g. "Water", "Eggs"
  unitPrice: number;
  sortOrder: number;
  isActive: boolean;
  lowStockThreshold: number; // a branch at or below this many units shows a low-stock warning
  createdAt: Date;
  updatedAt: Date;
}

const productSchema = new Schema<IProduct>(
  {
    businessId: { type: Schema.Types.ObjectId, ref: "Business", required: true, index: true },
    label: { type: String, required: true, trim: true },
    sizeLiters: { type: Number, required: true, min: 0.1 },
    unit: { type: String, default: "L", trim: true },
    category: { type: String, default: "Water", trim: true },
    unitPrice: { type: Number, required: true, min: 0 },
    sortOrder: { type: Number, default: 0 },
    isActive: { type: Boolean, default: true, index: true },
    lowStockThreshold: { type: Number, default: 10, min: 0 },
  },
  { timestamps: true }
);

export const Product =
  (models.Product as Model<IProduct>) || model<IProduct>("Product", productSchema);

// Branch-specific price override — optional, falls back to Product.unitPrice.
export interface IBranchPricing extends Document {
  businessId: Types.ObjectId;
  branchId: Types.ObjectId;
  productId: Types.ObjectId;
  unitPrice: number;
  updatedBy: Types.ObjectId | null;
  updatedAt: Date;
}

const branchPricingSchema = new Schema<IBranchPricing>(
  {
    businessId: { type: Schema.Types.ObjectId, ref: "Business", required: true, index: true },
    branchId: { type: Schema.Types.ObjectId, ref: "Branch", required: true },
    productId: { type: Schema.Types.ObjectId, ref: "Product", required: true },
    unitPrice: { type: Number, required: true, min: 0 },
    updatedBy: { type: Schema.Types.ObjectId, ref: "User", default: null },
  },
  { timestamps: { createdAt: false, updatedAt: true } }
);
branchPricingSchema.index({ branchId: 1, productId: 1 }, { unique: true });

export const BranchPricing =
  (models.BranchPricing as Model<IBranchPricing>) ||
  model<IBranchPricing>("BranchPricing", branchPricingSchema);