const mongoose = require('mongoose');

const conversationSchema = new mongoose.Schema({
  type: {
    type: String,
    enum: ['direct', 'group'],
    required: true
  },
  name: {
    type: String,
    required: function() { return this.type !== 'direct'; }
  },
  description: {
    type: String,
    maxlength: 500,
    default: ''
  },
  avatar: {
    type: String,
    default: null
  },
  createdBy: {
    type: mongoose.Schema.Types.ObjectId,
    ref: 'User',
    required: true
  },
  participants: [{
    user: {
      type: mongoose.Schema.Types.ObjectId,
      ref: 'User',
      required: true
    },
    role: {
      type: String,
      enum: ['member', 'admin', 'owner'],
      default: 'member'
    },
    joinedAt: {
      type: Date,
      default: Date.now
    },
    lastRead: {
      type: Date,
      default: Date.now
    }
  }],
  lastMessage: {
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Message',
    default: null
  },
  settings: {
    isPublic: {
      type: Boolean,
      default: false
    },
    allowInvites: {
      type: Boolean,
      default: true
    },
    adminOnlyMessages: {
      type: Boolean,
      default: false
    }
  },
  inviteLinks: [{
    code: String,
    createdBy: mongoose.Schema.Types.ObjectId,
    expiresAt: Date,
    maxUses: Number,
    uses: { type: Number, default: 0 },
    isActive: { type: Boolean, default: true },
    createdAt: { type: Date, default: Date.now }
  }]
}, {
  timestamps: true
});

// Index for better performance
conversationSchema.index({ 'participants.user': 1 });
conversationSchema.index({ type: 1, updatedAt: -1 });
conversationSchema.index({ lastMessage: 1 });

// Static method to find direct conversation between two users
conversationSchema.statics.findDirectConversation = async function(userId1, userId2) {
  return this.findOne({
    type: 'direct',
    'participants.user': { $all: [userId1, userId2] },
    $expr: { $eq: [{ $size: '$participants' }, 2] }
  });
};

module.exports = mongoose.model('Conversation', conversationSchema);