const Database = require('better-sqlite3');
const path = require('path');
const fs = require('fs');

const dataDir = path.join(__dirname, '../data');
if (!fs.existsSync(dataDir)) fs.mkdirSync(dataDir, { recursive: true });

const db = new Database(path.join(dataDir, 'monitor.db'));

// Create tables
db.exec(`
  CREATE TABLE IF NOT EXISTS groups (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL UNIQUE,
    description TEXT,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );

  CREATE TABLE IF NOT EXISTS resources (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL,
    url TEXT NOT NULL,
    type TEXT NOT NULL DEFAULT 'http',
    check_interval INTEGER DEFAULT 60000,
    timeout INTEGER DEFAULT 5000,
    enabled INTEGER DEFAULT 1,
    maintenance_mode INTEGER DEFAULT 0,
    group_id INTEGER REFERENCES groups(id) ON DELETE SET NULL,
    retention_days INTEGER DEFAULT NULL,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );

  CREATE TABLE IF NOT EXISTS checks (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    resource_id INTEGER NOT NULL,
    status TEXT NOT NULL,
    response_time INTEGER,
    status_code INTEGER,
    error_message TEXT,
    details TEXT,
    checked_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (resource_id) REFERENCES resources(id) ON DELETE CASCADE
  );

  CREATE TABLE IF NOT EXISTS incidents (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    resource_id INTEGER NOT NULL,
    started_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    resolved_at DATETIME,
    notified INTEGER DEFAULT 0,
    acknowledged INTEGER DEFAULT 0,
    acknowledged_at DATETIME,
    acknowledged_by TEXT,
    FOREIGN KEY (resource_id) REFERENCES resources(id) ON DELETE CASCADE
  );

  CREATE TABLE IF NOT EXISTS settings (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    key TEXT NOT NULL UNIQUE,
    value TEXT,
    updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );

  CREATE TABLE IF NOT EXISTS maintenance_windows (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    resource_id INTEGER NOT NULL,
    start_time DATETIME NOT NULL,
    end_time DATETIME NOT NULL,
    reason TEXT,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (resource_id) REFERENCES resources(id) ON DELETE CASCADE
  );

  CREATE TABLE IF NOT EXISTS alert_rules (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    resource_id INTEGER NOT NULL,
    consecutive_failures_threshold INTEGER DEFAULT 1,
    response_time_threshold INTEGER,
    response_time_baseline INTEGER,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (resource_id) REFERENCES resources(id) ON DELETE CASCADE
  );

  CREATE TABLE IF NOT EXISTS transaction_checks (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    resource_id INTEGER NOT NULL,
    step_order INTEGER NOT NULL,
    url TEXT NOT NULL,
    method TEXT DEFAULT 'GET',
    headers TEXT,
    body TEXT,
    expected_status INTEGER DEFAULT 200,
    keyword TEXT,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (resource_id) REFERENCES resources(id) ON DELETE CASCADE
  );

  CREATE TABLE IF NOT EXISTS archived_checks (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    resource_id INTEGER NOT NULL,
    status TEXT NOT NULL,
    response_time INTEGER,
    status_code INTEGER,
    error_message TEXT,
    details TEXT,
    checked_at DATETIME NOT NULL,
    archived_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (resource_id) REFERENCES resources(id) ON DELETE CASCADE
  );

  CREATE TABLE IF NOT EXISTS resource_tags (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    resource_id INTEGER NOT NULL,
    tag TEXT NOT NULL,
    FOREIGN KEY (resource_id) REFERENCES resources(id) ON DELETE CASCADE,
    UNIQUE(resource_id, tag)
  );

  CREATE TABLE IF NOT EXISTS notifications (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    resource_id INTEGER,
    incident_id INTEGER,
    type TEXT NOT NULL,
    title TEXT NOT NULL,
    message TEXT NOT NULL,
    status TEXT DEFAULT 'unread',
    read INTEGER DEFAULT 0,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (resource_id) REFERENCES resources(id) ON DELETE CASCADE,
    FOREIGN KEY (incident_id) REFERENCES incidents(id) ON DELETE CASCADE
  );

  CREATE INDEX IF NOT EXISTS idx_checks_resource_id ON checks(resource_id);
  CREATE INDEX IF NOT EXISTS idx_checks_checked_at ON checks(checked_at);
  CREATE INDEX IF NOT EXISTS idx_checks_resource_checked ON checks(resource_id, checked_at);
  CREATE INDEX IF NOT EXISTS idx_incidents_resource_id ON incidents(resource_id);
  CREATE INDEX IF NOT EXISTS idx_incidents_resource_started ON incidents(resource_id, started_at);
  CREATE INDEX IF NOT EXISTS idx_incidents_resolved ON incidents(resource_id, resolved_at);
  CREATE INDEX IF NOT EXISTS idx_resources_group_id ON resources(group_id);
  CREATE INDEX IF NOT EXISTS idx_maintenance_windows_resource ON maintenance_windows(resource_id);
  CREATE INDEX IF NOT EXISTS idx_alert_rules_resource ON alert_rules(resource_id);
  CREATE INDEX IF NOT EXISTS idx_transaction_checks_resource ON transaction_checks(resource_id);
  CREATE INDEX IF NOT EXISTS idx_archived_checks_resource_time ON archived_checks(resource_id, checked_at DESC);
  CREATE INDEX IF NOT EXISTS idx_notifications_created ON notifications(created_at DESC);
  CREATE INDEX IF NOT EXISTS idx_notifications_read_status ON notifications(read, created_at DESC);
  CREATE INDEX IF NOT EXISTS idx_resource_tags_resource ON resource_tags(resource_id);
  CREATE INDEX IF NOT EXISTS idx_resource_tags_tag ON resource_tags(tag);

  CREATE TABLE IF NOT EXISTS audit_logs (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    action TEXT NOT NULL,
    entity_type TEXT NOT NULL,
    entity_id TEXT,
    user_id TEXT DEFAULT 'system',
    changes TEXT,
    ip_address TEXT,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );

  CREATE TABLE IF NOT EXISTS error_logs (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    error_message TEXT NOT NULL,
    stack_trace TEXT,
    context TEXT,
    occurred_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );

  CREATE INDEX IF NOT EXISTS idx_audit_logs_entity ON audit_logs(entity_type, entity_id);
  CREATE INDEX IF NOT EXISTS idx_audit_logs_user ON audit_logs(user_id);
  CREATE INDEX IF NOT EXISTS idx_audit_logs_created ON audit_logs(created_at DESC);
  CREATE INDEX IF NOT EXISTS idx_error_logs_occurred ON error_logs(occurred_at DESC);
`);

// Lightweight migrations - for existing databases
try {
  db.prepare("ALTER TABLE checks ADD COLUMN details TEXT").run();
} catch (err) {
  // Column already exists
}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN group_id INTEGER").run();
} catch (err) {
  // Column already exists
}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN maintenance_mode INTEGER DEFAULT 0").run();
} catch (err) {
  if (err.message.includes('duplicate')) {
    // Column already exists
  }
}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN http_keyword TEXT").run();
} catch (err) {}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN http_headers TEXT").run();
} catch (err) {}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN quiet_hours_start TEXT").run();
} catch (err) {}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN quiet_hours_end TEXT").run();
} catch (err) {}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN cert_expiry_days INTEGER DEFAULT 30").run();
} catch (err) {}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN sla_target REAL DEFAULT 99.9").run();
} catch (err) {}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN email_to TEXT").run();
} catch (err) {
  if (err.message.includes('duplicate')) {
    // email_to column already exists
  } else {
    // Error adding email_to column
  }
}

try {
  db.prepare("ALTER TABLE incidents ADD COLUMN acknowledged INTEGER DEFAULT 0").run();
} catch (err) {}

try {
  db.prepare("ALTER TABLE incidents ADD COLUMN acknowledged_at DATETIME").run();
} catch (err) {}

try {
  db.prepare("ALTER TABLE incidents ADD COLUMN acknowledged_by TEXT").run();
} catch (err) {}

try {
  db.prepare("ALTER TABLE checks ADD COLUMN cert_expiry_date TEXT").run();
} catch (err) {}

// New columns for features
try {
  db.prepare("ALTER TABLE resources ADD COLUMN tags TEXT").run();
} catch (err) {
  if (err.message.includes('duplicate')) {
    // tags column already exists
  }
}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN consecutive_failures_threshold INTEGER DEFAULT 1").run();
} catch (err) {
  if (err.message.includes('duplicate')) {
    // consecutive_failures_threshold column already exists
  }
}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN response_time_threshold INTEGER").run();
} catch (err) {
  if (err.message.includes('duplicate')) {
    // response_time_threshold column already exists
  }
}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN response_time_baseline INTEGER").run();
} catch (err) {
  if (err.message.includes('duplicate')) {
    // response_time_baseline column already exists
  }
}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN is_transaction INTEGER DEFAULT 0").run();
} catch (err) {
  if (err.message.includes('duplicate')) {
    // is_transaction column already exists
  }
}

try {
  db.prepare("ALTER TABLE resources ADD COLUMN retention_days INTEGER DEFAULT NULL").run();
} catch (err) {
  if (err.message.includes('duplicate')) {
    // retention_days column already exists
  }
}

// Add description column to incidents for incident summaries
try {
  db.prepare("ALTER TABLE incidents ADD COLUMN description TEXT").run();
} catch (err) {
  if (err.message.includes('duplicate')) {
    // description column already exists
  }
}

// Add failed_check_count to incidents to track consecutive failures at creation time
try {
  db.prepare("ALTER TABLE incidents ADD COLUMN failed_check_count INTEGER DEFAULT 0").run();
} catch (err) {
  if (err.message.includes('duplicate')) {
    // failed_check_count column already exists
  }
}

// Settings for data retention and incident thresholds
try {
  db.prepare("INSERT OR IGNORE INTO settings (key, value) VALUES ('retention_days', '30')").run();
  db.prepare("INSERT OR IGNORE INTO settings (key, value) VALUES ('incident_failure_threshold', '10')").run();
} catch (err) {}

// Feature: HTTP method + request body support
try { db.prepare("ALTER TABLE resources ADD COLUMN http_method TEXT DEFAULT 'GET'").run(); } catch(e) {}
try { db.prepare("ALTER TABLE resources ADD COLUMN http_body TEXT").run(); } catch(e) {}

// Feature: alert escalation tracking
try { db.prepare("ALTER TABLE incidents ADD COLUMN escalated INTEGER DEFAULT 0").run(); } catch(e) {}

// Feature: heartbeat / cron-job monitoring
try { db.prepare("ALTER TABLE resources ADD COLUMN heartbeat_token TEXT").run(); } catch(e) {}
try { db.prepare("ALTER TABLE resources ADD COLUMN heartbeat_timeout INTEGER DEFAULT 300000").run(); } catch(e) {}
try { db.prepare("ALTER TABLE resources ADD COLUMN last_heartbeat_at DATETIME").run(); } catch(e) {}

// Feature: status page per-resource visibility
try { db.prepare("ALTER TABLE resources ADD COLUMN is_public INTEGER DEFAULT 1").run(); } catch(e) {}

// Helpful indexes for time-range queries
db.exec(`
  CREATE INDEX IF NOT EXISTS idx_checks_resource_time ON checks(resource_id, checked_at DESC);
  CREATE INDEX IF NOT EXISTS idx_incidents_resource_time ON incidents(resource_id, started_at DESC);
  CREATE INDEX IF NOT EXISTS idx_resources_heartbeat_token ON resources(heartbeat_token);
`);

// One-time migration: null out per-resource check_interval and timeout so all resources
// inherit from the global monitoring settings. Runs once, tracked by a settings flag.
try {
  const alreadyMigrated = db.prepare("SELECT value FROM settings WHERE key = 'migrated_global_defaults_v1'").get();
  if (!alreadyMigrated) {
    db.prepare("UPDATE resources SET check_interval = NULL, timeout = NULL").run();
    db.prepare("INSERT OR IGNORE INTO settings (key, value) VALUES ('migrated_global_defaults_v1', 'true')").run();
  }
} catch (e) {}

module.exports = db;