/**
 * ScheduledTask Model
 *
 * Multi-project calendar and reminder system for governance, framework reviews,
 * and project-specific tasks. Integrated with session-init.js for startup reminders.
 *
 * Copyright 2025 Tractatus Project
 * Licensed under Apache License 2.0
 */

const mongoose = require('mongoose');

const scheduledTaskSchema = new mongoose.Schema({
  title: {
    type: String,
    required: true,
    trim: true,
    maxlength: 200
  },

  description: {
    type: String,
    required: true,
    maxlength: 2000
  },

  dueDate: {
    type: Date,
    required: true,
    index: true
  },

  priority: {
    type: String,
    enum: ['LOW', 'MEDIUM', 'HIGH', 'CRITICAL'],
    default: 'MEDIUM',
    index: true
  },

  category: {
    type: String,
    enum: ['framework', 'governance', 'security', 'project', 'research', 'deployment', 'other'],
    default: 'other',
    index: true
  },

  // Optional: Link to specific project (null for cross-project or framework tasks)
  projectId: {
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Project',
    default: null,
    index: true
  },

  projectName: {
    type: String,
    default: null // e.g., "tractatus", "family-history", "sydigital"
  },

  recurrence: {
    type: String,
    enum: ['once', 'daily', 'weekly', 'monthly', 'quarterly', 'yearly'],
    default: 'once'
  },

  // For recurring tasks: when was this instance generated from?
  parentTaskId: {
    type: mongoose.Schema.Types.ObjectId,
    ref: 'ScheduledTask',
    default: null
  },

  status: {
    type: String,
    enum: ['pending', 'in_progress', 'completed', 'dismissed', 'overdue'],
    default: 'pending',
    index: true
  },

  // Reference to documentation or related files
  documentRef: {
    type: String,
    default: null // e.g., "docs/AUTONOMOUS_FRAMEWORK_WORK_2025-10-23.md"
  },

  // Links to external resources or admin pages
  links: [{
    label: String,
    url: String
  }],

  createdBy: {
    type: String,
    enum: ['system', 'user', 'session-init', 'migration'],
    default: 'system'
  },

  assignedTo: {
    type: String, // User email or "PM" or "Framework"
    default: 'PM' // Default to human PM
  },

  completedDate: {
    type: Date,
    default: null
  },

  dismissedDate: {
    type: Date,
    default: null
  },

  dismissedReason: {
    type: String,
    default: null
  },

  // Flexible metadata for filtering and grouping
  metadata: {
    type: Map,
    of: mongoose.Schema.Types.Mixed,
    default: {}
  },

  // Tags for flexible categorization
  tags: [{
    type: String,
    lowercase: true,
    trim: true
  }],

  // Session-init display configuration
  showInSessionInit: {
    type: Boolean,
    default: true
  },

  // How many days before due date to show in session-init
  reminderDaysBefore: {
    type: Number,
    default: 7
  }

}, {
  timestamps: true
});

// Indexes for common queries
scheduledTaskSchema.index({ dueDate: 1, status: 1 });
scheduledTaskSchema.index({ category: 1, status: 1 });
scheduledTaskSchema.index({ projectId: 1, status: 1 });
scheduledTaskSchema.index({ status: 1, priority: -1, dueDate: 1 });

// Virtual: days until due
scheduledTaskSchema.virtual('daysUntilDue').get(function() {
  const now = new Date();
  const due = new Date(this.dueDate);
  const diffTime = due - now;
  const diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24));
  return diffDays;
});

// Virtual: is overdue
scheduledTaskSchema.virtual('isOverdue').get(function() {
  return this.status === 'pending' && new Date(this.dueDate) < new Date();
});

// Method: Complete task
scheduledTaskSchema.methods.complete = function() {
  this.status = 'completed';
  this.completedDate = new Date();
  return this.save();
};

// Method: Dismiss task
scheduledTaskSchema.methods.dismiss = function(reason) {
  this.status = 'dismissed';
  this.dismissedDate = new Date();
  this.dismissedReason = reason || 'Dismissed by user';
  return this.save();
};

// Static: Get tasks due soon (for session-init)
scheduledTaskSchema.statics.getDueSoon = function(daysAhead = 7) {
  const now = new Date();
  const futureDate = new Date(now.getTime() + (daysAhead * 24 * 60 * 60 * 1000));

  return this.find({
    dueDate: { $lte: futureDate },
    status: 'pending',
    showInSessionInit: true
  })
    .sort({ priority: -1, dueDate: 1 })
    .limit(10);
};

// Static: Get overdue tasks
scheduledTaskSchema.statics.getOverdue = function() {
  return this.find({
    dueDate: { $lt: new Date() },
    status: 'pending'
  })
    .sort({ priority: -1, dueDate: 1 });
};

// Static: Get tasks by category
scheduledTaskSchema.statics.getByCategory = function(category, includeCompleted = false) {
  const query = { category };
  if (!includeCompleted) {
    query.status = { $in: ['pending', 'in_progress'] };
  }
  return this.find(query).sort({ dueDate: 1 });
};

// Static: Get tasks by project
scheduledTaskSchema.statics.getByProject = function(projectId, includeCompleted = false) {
  const query = { projectId };
  if (!includeCompleted) {
    query.status = { $in: ['pending', 'in_progress'] };
  }
  return this.find(query).sort({ dueDate: 1 });
};

// Pre-save hook: Update overdue status
scheduledTaskSchema.pre('save', function(next) {
  if (this.status === 'pending' && this.dueDate < new Date()) {
    this.status = 'overdue';
  }
  next();
});

// Enable virtuals in JSON
scheduledTaskSchema.set('toJSON', { virtuals: true });
scheduledTaskSchema.set('toObject', { virtuals: true });

const ScheduledTask = mongoose.model('ScheduledTask', scheduledTaskSchema);

module.exports = ScheduledTask;