const { DataTypes } = require('sequelize');
const { sequelize } = require('../config/database');

const VocabRelation = sequelize.define('VocabRelation', {
    relation_id: {
      type: DataTypes.UUID,
      defaultValue: DataTypes.UUIDV4,
      primaryKey: true,
      comment: 'Unique identifier for vocabulary relation'
    },
    vocab_id: {
      type: DataTypes.UUID,
      allowNull: false,
      references: {
        model: 'vocab',
        key: 'vocab_id'
      },
      onDelete: 'CASCADE',
      comment: 'Reference to vocabulary entry'
    },
    relation_type: {
      type: DataTypes.ENUM('synonym', 'antonym', 'related'),
      allowNull: false,
      comment: 'Type of relation (synonym, antonym, related)'
    },
    related_word: {
      type: DataTypes.STRING(100),
      allowNull: false,
      comment: 'The related word (e.g., consume, dine, fast)'
    },
    related_vocab_id: {
      type: DataTypes.UUID,
      references: {
        model: 'vocab',
        key: 'vocab_id'
      },
      onDelete: 'SET NULL',
      comment: 'Reference to related vocab entry if it exists in system'
    },
    created_at: {
      type: DataTypes.DATE,
      defaultValue: DataTypes.NOW
    }
  }, {
    tableName: 'vocab_relation',
    timestamps: true,
    createdAt: 'created_at',
    updatedAt: false,
    indexes: [
      {
        name: 'idx_vocab_relation_vocab',
        fields: ['vocab_id']
      },
      {
        name: 'idx_vocab_relation_type',
        fields: ['relation_type']
      },
      {
        name: 'idx_vocab_relation_related',
        fields: ['related_vocab_id']
      }
    ]
  });

module.exports = VocabRelation;