backend/models/userModel.js

import mongoose from 'mongoose';

const deviceSchema = new mongoose.Schema(
  {
    deviceId:  { type: String, required: true },
    label:     { type: String, default: 'Unknown Device' },
    lastSeen:  { type: Date,   default: Date.now },
  },
  { _id: false },
);

const UserSchema = new mongoose.Schema(
  {
    name:        { type: String, required: true },
    email:       { type: String, required: true, unique: true },
    password:    { type: String },             // optional: Google/OAuth users have no password
    role:        { type: String, enum: ['farmer', 'expert', 'admin'], default: 'farmer' },
    img:         { type: String },
    country:     { type: String },
    phone:       { type: String },
    desc:        { type: String },
    isSeller:    { type: Boolean, default: false },
    // ── Firebase / Google OAuth link ─────────────────────────────────────
    // Stored so that register-device and other routes can look up the user
    // by Firebase UID instead of MongoDB _id when using Google sign-in.
    firebaseUid: { type: String, sparse: true, index: true },
    language: { type: String, default: 'en' },
    // ── Cross-device login tracking ──────────────────────────────────────
    devices:     { type: [deviceSchema], default: [] },
  },
  { timestamps: true },
);

export default mongoose.models.User || mongoose.model('User', UserSchema);