// CRUD operations for tasks

import { query, queryOne, execute, getNextTaskId, getProjectKey, detectProjectFromCwd } from '../db.js';
import { getEmbedding, formatEmbedding } from '../embeddings.js';
import type { Task, ChecklistItem, TaskLink } from '../types.js';
import { getRecentDelegations } from './delegations.js';
import { getTaskCommits } from './commits.js';
import * as fs from 'fs';
import * as path from 'path';
import * as os from 'os';

/**
 * Get current session ID from environment or cache file
 */
function getSessionId(): string {
  // Check environment first
  if (process.env.CLAUDE_SESSION_ID) {
    return process.env.CLAUDE_SESSION_ID;
  }

  // Try to read from cache file (usage-stats format)
  const cacheFile = path.join(os.homedir(), '.claude', 'cache', '.current_session_id');
  try {
    const sessionId = fs.readFileSync(cacheFile, 'utf-8').trim();
    if (sessionId) return sessionId;
  } catch {
    // File doesn't exist or can't be read
  }

  // Generate a new session ID
  const now = new Date();
  const timestamp = now.toISOString().replace(/[-:T]/g, '').slice(0, 15);
  return `session_${timestamp}`;
}

/**
 * Record task activity for session tracking
 */
async function recordActivity(
  task_id: string,
  activity_type: 'created' | 'updated' | 'status_change' | 'closed',
  old_value?: string,
  new_value?: string
): Promise<void> {
  const session_id = getSessionId();
  try {
    await execute(
      `INSERT INTO task_activity (task_id, session_id, activity_type, old_value, new_value)
       VALUES ($1, $2, $3, $4, $5)`,
      [task_id, session_id, activity_type, old_value || null, new_value || null]
    );
  } catch {
    // Don't fail the main operation if activity tracking fails
    console.error('Failed to record task activity');
  }
}

interface TaskAddArgs {
  title: string;
  project?: string;
  type?: string;
  priority?: string;
  description?: string;
}

interface TaskListArgs {
  project?: string;
  status?: string;
  type?: string;
  priority?: string;
  limit?: number;
}

interface TaskUpdateArgs {
  id: string;
  status?: string;
  priority?: string;
  type?: string;
  title?: string;
}

/**
 * Create a new task
 */
export async function taskAdd(args: TaskAddArgs): Promise<string> {
  const { title, project = 'Unknown', type = 'task', priority = 'P2', description = '' } = args;

  // Get project key
  const projectKey = await getProjectKey(project);

  // Generate embedding for duplicate detection
  const embedText = description ? `${title}. ${description}` : title;
  const embedding = await getEmbedding(embedText);
  const embeddingValue = embedding ? formatEmbedding(embedding) : null;

  // Check for similar/duplicate tasks (only if embedding succeeded)
  let duplicateWarning = '';
  if (embeddingValue) {
    const similarTasks = await query<{ id: string; title: string; status: string; similarity: number }>(
      `SELECT id, title, status, 1 - (embedding <=> $1) as similarity
       FROM tasks
       WHERE project = $2 AND embedding IS NOT NULL AND status != 'completed'
       ORDER BY embedding <=> $1
       LIMIT 3`,
      [embeddingValue, projectKey]
    );

    // Warn if highly similar tasks exist (>70% similarity)
    const highSimilarity = similarTasks.filter(t => t.similarity > 0.70);
    if (highSimilarity.length > 0) {
      duplicateWarning = '\n\n⚠️  Similar tasks found:\n';
      for (const t of highSimilarity) {
        const pct = Math.round(t.similarity * 100);
        duplicateWarning += `  - ${t.id}: ${t.title} (${pct}% match, ${t.status})\n`;
      }
      duplicateWarning += '\nConsider linking with: task link <from> <to> relates_to';
    }
  }

  // Get next task ID
  const taskId = await getNextTaskId(projectKey);

  // Insert task
  if (embeddingValue) {
    await execute(
      `INSERT INTO tasks (id, project, title, description, type, status, priority, embedding)
       VALUES ($1, $2, $3, $4, $5, 'open', $6, $7)`,
      [taskId, projectKey, title, description, type, priority, embeddingValue]
    );
  } else {
    await execute(
      `INSERT INTO tasks (id, project, title, description, type, status, priority)
       VALUES ($1, $2, $3, $4, $5, 'open', $6)`,
      [taskId, projectKey, title, description, type, priority]
    );
  }

  // Record activity for session tracking
  await recordActivity(taskId, 'created', undefined, 'open');

  return `Created: ${taskId}\n  Title: ${title}\n  Type: ${type}\n  Priority: ${priority}\n  Project: ${projectKey}${embedding ? '\n  (embedded for semantic search)' : ''}${duplicateWarning}`;
}

/**
 * List tasks with filters
 * Auto-detects project from CWD if not explicitly provided
 */
export async function taskList(args: TaskListArgs): Promise<string> {
  const { project, status, type, priority, limit = 20 } = args;

  let whereClause = 'WHERE 1=1';
  const params: unknown[] = [];
  let paramIndex = 1;

  // Auto-detect project from CWD if not explicitly provided
  const effectiveProject = project || detectProjectFromCwd();
  if (effectiveProject) {
    const projectKey = await getProjectKey(effectiveProject);
    whereClause += ` AND project = $${paramIndex++}`;
    params.push(projectKey);
  }
  if (status) {
    whereClause += ` AND status = $${paramIndex++}`;
    params.push(status);
  }
  if (type) {
    whereClause += ` AND type = $${paramIndex++}`;
    params.push(type);
  }
  if (priority) {
    whereClause += ` AND priority = $${paramIndex++}`;
    params.push(priority);
  }

  params.push(limit);

  const tasks = await query<Task>(
    `SELECT id, title, type, status, priority, project
     FROM tasks
     ${whereClause}
     ORDER BY
       CASE priority WHEN 'P0' THEN 0 WHEN 'P1' THEN 1 WHEN 'P2' THEN 2 ELSE 3 END,
       created_at DESC
     LIMIT $${paramIndex}`,
    params
  );

  if (tasks.length === 0) {
    return `No tasks found${effectiveProject ? ` for project ${effectiveProject}` : ''}`;
  }

  const lines = tasks.map(t => {
    const statusIcon = t.status === 'completed' ? '[x]' : t.status === 'in_progress' ? '[>]' : t.status === 'blocked' ? '[!]' : '[ ]';
    const typeLabel = t.type !== 'task' ? ` [${t.type}]` : '';
    return `${statusIcon} ${t.priority} ${t.id}: ${t.title}${typeLabel}`;
  });

  return `Tasks${effectiveProject ? ` (${effectiveProject})` : ''}:\n\n${lines.join('\n')}`;
}

/**
 * Show task details
 */
export async function taskShow(id: string): Promise<string> {
  const task = await queryOne<Task>(
    `SELECT id, project, title, description, type, status, priority,
            to_char(created_at, 'YYYY-MM-DD HH24:MI') as created,
            to_char(updated_at, 'YYYY-MM-DD HH24:MI') as updated,
            to_char(completed_at, 'YYYY-MM-DD HH24:MI') as completed
     FROM tasks WHERE id = $1`,
    [id]
  );

  if (!task) {
    return `Task not found: ${id}`;
  }

  let output = `# ${task.id}\n\n`;
  output += `**Title:** ${task.title}\n`;
  output += `**Project:** ${task.project}\n`;
  output += `**Type:** ${task.type}\n`;
  output += `**Status:** ${task.status}\n`;
  output += `**Priority:** ${task.priority}\n`;
  output += `**Created:** ${(task as unknown as { created: string }).created}\n`;
  output += `**Updated:** ${(task as unknown as { updated: string }).updated}\n`;

  if ((task as unknown as { completed: string }).completed) {
    output += `**Completed:** ${(task as unknown as { completed: string }).completed}\n`;
  }

  if (task.description) {
    output += `\n**Description:**\n${task.description}\n`;
  }

  // Get checklist
  const checklist = await query<ChecklistItem>(
    `SELECT id, item, checked FROM task_checklist
     WHERE task_id = $1 ORDER BY position, id`,
    [id]
  );

  if (checklist.length > 0) {
    const done = checklist.filter(c => c.checked).length;
    output += `\n**Checklist:** (${done}/${checklist.length})\n`;
    for (const item of checklist) {
      output += `  ${item.checked ? '[x]' : '[ ]'} ${item.item} (#${item.id})\n`;
    }
  }

  // Get dependencies
  const blockedBy = await query<{ id: string; title: string }>(
    `SELECT t.id, t.title FROM task_links l
     JOIN tasks t ON t.id = l.from_task_id
     WHERE l.to_task_id = $1 AND l.link_type = 'blocks'`,
    [id]
  );

  const blocks = await query<{ id: string; title: string }>(
    `SELECT t.id, t.title FROM task_links l
     JOIN tasks t ON t.id = l.to_task_id
     WHERE l.from_task_id = $1 AND l.link_type = 'blocks'`,
    [id]
  );

  if (blockedBy.length > 0) {
    output += `\n**Blocked by:**\n`;
    for (const t of blockedBy) {
      output += `  - ${t.id}: ${t.title}\n`;
    }
  }

  if (blocks.length > 0) {
    output += `\n**Blocks:**\n`;
    for (const t of blocks) {
      output += `  - ${t.id}: ${t.title}\n`;
    }
  }

  // Get related tasks (bidirectional - only need to query one direction since links are symmetric)
  const relatesTo = await query<{ id: string; title: string }>(
    `SELECT t.id, t.title FROM task_links l
     JOIN tasks t ON t.id = l.to_task_id
     WHERE l.from_task_id = $1 AND l.link_type = 'relates_to'`,
    [id]
  );

  if (relatesTo.length > 0) {
    output += `\n**Related:**\n`;
    for (const t of relatesTo) {
      output += `  - ${t.id}: ${t.title}\n`;
    }
  }

  // Get duplicates (bidirectional)
  const duplicates = await query<{ id: string; title: string }>(
    `SELECT t.id, t.title FROM task_links l
     JOIN tasks t ON t.id = l.to_task_id
     WHERE l.from_task_id = $1 AND l.link_type = 'duplicates'`,
    [id]
  );

  if (duplicates.length > 0) {
    output += `\n**Duplicates:**\n`;
    for (const t of duplicates) {
      output += `  - ${t.id}: ${t.title}\n`;
    }
  }

  // Get commits
  const commitHistory = await getTaskCommits(id);
  if (commitHistory) {
    output += commitHistory;
  }

  // Get recent delegations
  const delegationHistory = await getRecentDelegations(id);
  if (delegationHistory) {
    output += delegationHistory;
  }

  return output;
}

/**
 * Close a task
 */
export async function taskClose(id: string): Promise<string> {
  // Get current status for activity tracking
  const task = await queryOne<{ status: string }>(`SELECT status FROM tasks WHERE id = $1`, [id]);

  const result = await execute(
    `UPDATE tasks
     SET status = 'completed', completed_at = NOW(), updated_at = NOW()
     WHERE id = $1`,
    [id]
  );

  if (result === 0) {
    return `Task not found: ${id}`;
  }

  // Record activity
  await recordActivity(id, 'closed', task?.status, 'completed');

  return `Closed: ${id}`;
}

/**
 * Update a task
 */
export async function taskUpdate(args: TaskUpdateArgs): Promise<string> {
  const { id, status, priority, type, title } = args;

  // Get current values for activity tracking
  const task = await queryOne<{ status: string }>(`SELECT status FROM tasks WHERE id = $1`, [id]);
  if (!task) {
    return `Task not found: ${id}`;
  }

  const updates: string[] = [];
  const params: unknown[] = [];
  let paramIndex = 1;

  if (status) {
    updates.push(`status = $${paramIndex++}`);
    params.push(status);
    if (status === 'completed') {
      updates.push(`completed_at = NOW()`);
    }
  }
  if (priority) {
    updates.push(`priority = $${paramIndex++}`);
    params.push(priority);
  }
  if (type) {
    updates.push(`type = $${paramIndex++}`);
    params.push(type);
  }
  if (title) {
    updates.push(`title = $${paramIndex++}`);
    params.push(title);
  }

  if (updates.length === 0) {
    return 'No updates specified';
  }

  updates.push('updated_at = NOW()');
  params.push(id);

  const result = await execute(
    `UPDATE tasks SET ${updates.join(', ')} WHERE id = $${paramIndex}`,
    params
  );

  if (result === 0) {
    return `Task not found: ${id}`;
  }

  // Record activity
  if (status && status !== task.status) {
    await recordActivity(id, 'status_change', task.status, status);
  } else {
    await recordActivity(id, 'updated');
  }

  return `Updated: ${id}`;
}