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

const Grammar = sequelize.define('Grammar', {
  id: {
    type: DataTypes.UUID,
    defaultValue: DataTypes.UUIDV4,
    primaryKey: true
  },
  grammar_code: {
    type: DataTypes.STRING(100),
    allowNull: false,
    unique: true,
    comment: 'Unique identifier for grammar rule (e.g., "gram-001-present-cont")'
  },
  title: {
    type: DataTypes.STRING(200),
    allowNull: false,
    comment: 'Grammar rule name (e.g., "Present Continuous")'
  },
  translation: {
    type: DataTypes.STRING(200),
    allowNull: true,
    comment: 'Vietnamese translation'
  },
  
  // GENERATIVE LOGIC
  structure: {
    type: DataTypes.JSON,
    allowNull: false,
    defaultValue: {},
    comment: 'Formula and pattern_logic for sentence generation. Structure: { formula: string, pattern_logic: array }'
  },
  
  // METADATA
  instructions: {
    type: DataTypes.JSON,
    allowNull: true,
    defaultValue: {},
    comment: 'Instructions and hints. Structure: { vi: string, hint: string }'
  },
  
  // ATTRIBUTES
  difficulty_score: {
    type: DataTypes.INTEGER,
    allowNull: true,
    defaultValue: 1,
    validate: {
      min: 1,
      max: 10
    },
    comment: 'Difficulty level from 1 (easiest) to 10 (hardest)'
  },
  category: {
    type: DataTypes.STRING(100),
    allowNull: true,
    comment: 'Grammar category (e.g., "Tenses", "Modal Verbs", "Questions")'
  },
  tags: {
    type: DataTypes.JSON,
    allowNull: true,
    defaultValue: [],
    comment: 'Array of tags for categorization'
  },
  
  // STATUS
  is_active: {
    type: DataTypes.BOOLEAN,
    allowNull: false,
    defaultValue: true,
    comment: 'Soft delete flag'
  }
}, {
  tableName: 'grammars',
  timestamps: true,
  indexes: [
    { fields: ['grammar_code'], unique: true },
    { fields: ['category'] },
    { fields: ['difficulty_score'] },
    { fields: ['is_active'] }
  ]
});

module.exports = Grammar;