<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Search extends CI_Controller {

	function __construct() {
		parent::__construct();

		$this->load->helper(array('form', 'url'));
		if(!$this->user_model->authorize(2)) { $this->session->set_flashdata('error', __("You're not allowed to do that!")); redirect('dashboard'); }
	}

	public function index() {
		$data['page_title'] = __("Search");

		$data['stations_active_log_only'] = !empty($this->session->userdata('user_stations_active_log_only'));

		$this->load->view('interface_assets/header', $data);
		$this->load->view('search/main');
		$this->load->view('interface_assets/footer');
	}

	// Filter is for advanced searching and filtering of the logbook
	public function filter() {
		$data['page_title'] = __("Search & Filter Logbook");

		$this->load->library('form_validation');

		$this->load->model('Search_filter');

		$data['get_table_names'] = $this->Search_filter->get_table_columns();
		$data['stored_queries'] = $this->Search_filter->get_stored_queries();

		$data['stations_active_log_only'] = !empty($this->session->userdata('user_stations_active_log_only'));

		//print_r($this->Search_filter->get_table_columns());

		if ($this->form_validation->run() == FALSE)
		{
			$this->load->view('interface_assets/header', $data);
			$this->load->view('search/filter');
			$this->load->view('interface_assets/footer');
		} else {
			$this->load->view('interface_assets/header', $data);
			$this->load->view('search/filter');
			$this->load->view('interface_assets/footer');
		}
	}

	// Searches for unconfirmed Lotw QSOs where QSO partner has uploaded to LoTW after the QSO date
	public function lotw_unconfirmed() {
		$this->load->model('stations');

		if (!empty($this->session->userdata('user_stations_active_log_only'))) {
			$data['station_profile'] = $this->logbooks_model->list_logbooks_linked($this->session->userdata('active_station_logbook'));
			$data['stations_active_log_only'] = true;
		} else {
			$data['station_profile'] = $this->stations->all_of_user();
			$data['stations_active_log_only'] = false;
		}
		$data['page_title'] = __("QSOs unconfirmed on LoTW, but the callsign has uploaded to LoTW after QSO date");

		$this->load->view('interface_assets/header', $data);
		$this->load->view('search/lotw_unconfirmed');
		$this->load->view('interface_assets/footer');
	}

	function json_result() {
		$result = $this->fetchQueryResult(($this->input->post('search', TRUE) ?? ''), FALSE);
		echo json_encode($result->result_array());
	}

	function get_stored_queries() {
		$this->load->model('Search_filter');
		$data['result'] = $this->Search_filter->get_stored_queries();
		$this->load->view('search/stored_queries', $data);
	}

	function search_result() {
		$sstring = str_replace('Ø', "0", $this->input->post("search", TRUE) ?? '');
		$data['results'] = $this->fetchQueryResult($sstring, FALSE);
		$this->load->view('search/search_result_ajax', $data);
	}

	function export_to_adif() {
		$sstring = str_replace('Ø', "0", $this->input->post("search", TRUE) ?? '');
		$data['qsos'] = $this->fetchQueryResult($sstring, FALSE);
		$this->load->view('adif/data/exportall', $data);
	}

	function export_stored_query_to_adif() {
		$this->db->where('id', xss_clean($this->input->post('id')));
		$this->db->where('userid', $this->session->userdata['user_id']);
		$sql = $this->db->get('queries')->result();

		$query = $sql[0]->query;

		// Security: Validate query only accesses allowed tables
		if (!$this->_validate_query_tables($query)) {
			show_error("Invalid query: unauthorized table access detected", 403);
			return;
		}

		// Security: Block dangerous SQL keywords to prevent SQL injection
		// Note: 'join' is NOT blocked because legitimate queries use JOINs
		$blocked = ['insert', 'drop', 'alter', 'create', 'exec', 'script', 'into outfile', 'load_file', 'update', 'delete', 'truncate', 'replace', 'rename', 'grant', 'revoke'];
		foreach ($blocked as $word) {
			if (stristr($query, $word)) {
				show_error("Invalid query: contains blocked keyword", 403);
				return;
			}
		}

		$data['qsos'] = $this->db->query($query);
		$this->load->view('adif/data/exportall', $data);
	}

	function run_query() {
		$this->db->where('id', xss_clean($this->input->post('id')));
		$this->db->where('userid', $this->session->userdata['user_id']);
		$sql = $this->db->get('queries')->result();
		$sql = $sql[0]->query;

		// Security: Only allow SELECT queries
		if (stristr($sql, 'select') && !stristr($sql, 'delete') && !stristr($sql, 'update')) {
			// Security: Validate query only accesses allowed tables
			if (!$this->_validate_query_tables($sql)) {
				show_error("Invalid query: unauthorized table access detected", 403);
				return;
			}

			// Security: Block dangerous SQL keywords to prevent SQL injection
			// Note: 'join' is NOT blocked because legitimate queries use JOINs
			$blocked = ['insert', 'drop', 'alter', 'create', 'exec', 'script', 'into outfile', 'load_file', 'update', 'delete', 'truncate', 'replace', 'rename', 'grant', 'revoke'];
			foreach ($blocked as $word) {
				if (stristr($sql, $word)) {
					show_error("Invalid query: contains blocked keyword", 403);
					return;
				}
			}

			if (!(strpos(strtolower($sql),'limit'))) {
				$sql.=' limit 5000';
			}
			$data['results'] = $this->db->query($sql);

			$this->load->view('search/search_result_ajax', $data);
		}
	}

	function save_query() {
		$search_param = $this->input->post('search', TRUE);
		$description = $this->input->post('description', TRUE);

		$query = $this->fetchQueryResult($search_param, TRUE);

		$data = array(
			'userid' => xss_clean($this->session->userdata('user_id')),
			'query' => $query,
			'description' => $description
		);

		$this->db->insert('queries', $data);
		$last_id = $this->db->insert_id();
		header('Content-Type: application/json');
		echo json_encode(array('id' => $last_id, 'description' => $description));
	}

	function delete_query() {
		$id = xss_clean($this->input->post('id'));
		$this->load->model('search_filter');
		$this->search_filter->delete_query($id);
	}

	function save_edited_query() {
		$data = array(
			'description' => xss_clean($this->input->post('description')),
		);

		$this->db->where('id', xss_clean($this->input->post('id')));
		$this->db->where('userid', $this->session->userdata['user_id']);
		$this->db->update('queries', $data);
	}

	/**
	 * Returns the list of valid searchable column names from the main logbook table.
	 * Cached statically so the DESCRIBE query runs only once per request.
	 *
	 * @return array<string> Column names (e.g. ['COL_CALL', 'COL_BAND', ...])
	 */
	private function _get_valid_search_fields(): array {
		static $valid_fields = null;
		if ($valid_fields === null) {
			$columns = $this->db->query('DESCRIBE ' . $this->config->item('table_name'))->result();
			$valid_fields = array_map(function($col) {
				return $col->Field;
			}, $columns);
		}
		return $valid_fields;
	}

	function buildWhere(array $object, ?string $condition = null): void {
		/*
		 * The $object is one of the following:
		 * - a group, with 'condition' and 'rules' keys
		 * - a condition, that is either 'AND' or 'OR' depending on the parent group setting
		 */
		$objectIsGroup = isset($object['condition']);
		if ($objectIsGroup) {
			if ($condition === null || $condition === 'AND') {
				$this->db->group_start();
			} else {
				$this->db->or_group_start();
			}
			foreach ($object['rules'] as $rule) {
				/*
				 * Now iterate over the children, that are either groups or conditions
				 */
				$this->buildWhere($rule, $object['condition']);
			}
			$this->db->group_end();
		} else {
			// Validate field name: must be alphanumeric/underscore AND exist in the table schema
			if (!is_string($object['field'] ?? null) || !preg_match('/^[A-Za-z0-9_]+$/', $object['field'])) {
				log_message('error', 'Search filter rejected: invalid field identifier');
				show_error('Invalid search field', 400);
			}
			if (!in_array($object['field'], $this->_get_valid_search_fields(), true)) {
				log_message('error', 'Search filter rejected: unknown field "' . $object['field'] . '"');
				show_error('Invalid search field', 400);
			}
			$object['field'] = $this->config->item('table_name') . '.' . $object['field'];

			if ($object['operator'] == "equal") {
				if ($condition == "AND") {
					$this->db->where($object['field'], $object['value']);
				} else {
					$this->db->or_where($object['field'], $object['value']);
				}
			}

			if ($object['operator'] == "not_equal") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' !=', $object['value']);
				} else {
					$this->db->or_where($object['field'] . ' !=', $object['value']);
				}
			}

			if ($object['operator'] == "begins_with") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' like ', $object['value'] . "%");
				} else {
					$this->db->or_where($object['field'] . ' like ', $object['value'] . "%");
				}
			}

			if ($object['operator'] == "contains") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' like ', "%" . $object['value'] . "%");
				} else {
					$this->db->or_where($object['field'] . ' like ', "%" . $object['value'] . "%");
				}
			}

			if ($object['operator'] == "ends_with") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' like ', "%" . $object['value']);
				} else {
					$this->db->or_where($object['field'] . ' like ', "%" . $object['value']);
				}
			}

			if ($object['operator'] == "is_empty") {
				if ($condition == "AND") {
					$this->db->where($object['field'], '');
				} else {
					$this->db->or_where($object['field'], '');
				}
			}

			if ($object['operator'] == "is_not_empty") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' !=', '');
				} else {
					$this->db->or_where($object['field'] . ' !=', '');
				}
			}

			if ($object['operator'] == "is_null") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' IS NULL');
				} else {
					$this->db->or_where($object['field'] . ' IS NULL');
				}
			}

			if ($object['operator'] == "is_not_null") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' IS NOT NULL');
				} else {
					$this->db->or_where($object['field'] . ' IS NOT NULL');
				}
			}


			if ($object['operator'] == "less") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' <', $object['value']);
				} else {
					$this->db->or_where($object['field'] . ' <', $object['value']);
				}
			}

			if ($object['operator'] == "less_or_equal") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' <=', $object['value']);
				} else {
					$this->db->or_where($object['field'] . ' <=', $object['value']);
				}
			}

			if ($object['operator'] == "greater") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' >', $object['value']);
				} else {
					$this->db->or_where($object['field'] . ' >', $object['value']);
				}
			}

			if ($object['operator'] == "greater_or_equal") {
				if ($condition == "AND") {
					$this->db->where($object['field'] . ' >=', $object['value']);
				} else {
					$this->db->or_where($object['field'] . ' >=', $object['value']);
				}
			}
		}
	}

	function fetchQueryResult($json, $returnquery) {
		$search_items = json_decode($json, true);

		if (!empty($this->session->userdata('user_stations_active_log_only'))) {
			$logbooks_locations_array = $this->logbooks_model->list_logbook_relationships($this->session->userdata('active_station_logbook'));
			$this->db->where_in($this->config->item('table_name').'.station_id', $logbooks_locations_array);
		}

		$this->db->select($this->config->item('table_name').'.*, station_profile.station_profile_name, station_profile.station_gridsquare, station_profile.station_city, station_profile.station_iota, station_profile.station_callsign, station_profile.station_sota, station_profile.station_wwff, station_profile.station_dxcc, station_profile.station_pota, station_profile.station_cq, station_profile.station_itu, station_profile.station_sig, station_profile.station_sig_info, station_profile.station_cnty, station_profile.county, station_profile.state, dxcc_entities.name as station_country');

		$this->db->group_start();
		$this->buildWhere($search_items);
		$this->db->group_end();

		$this->db->order_by('COL_TIME_ON', 'DESC');
		$this->db->join('station_profile', 'station_profile.station_id = '.$this->config->item('table_name').'.station_id');
		$this->db->join('dxcc_entities', 'station_profile.station_dxcc = dxcc_entities.adif', 'left');
		$this->db->where('station_profile.user_id', $this->session->userdata('user_id'));
		$this->db->limit(5000);

		if ($returnquery) {
			$query = $this->db->get_compiled_select($this->config->item('table_name'));
		} else {
			$query = $this->db->get($this->config->item('table_name'));
		}
		return $query;
	}

	/**
	 * Validates that query only accesses allowed tables
	 * Prevents SQL injection via UNION-based attacks on other tables
	 *
	 * @param string $sql The SQL query to validate
	 * @return bool TRUE if query only uses allowed tables, FALSE otherwise
	 */
	private function _validate_query_tables($sql) {
		// Whitelist of allowed tables - users can only query these
		$allowed_tables = [
			$this->config->item('table_name'),	// Main logbook table (e.g., TABLE_HRD_CONTACTS_V01)
			'station_profile',
			'dxcc_entities',
			'lotw_users',
			'queries'
		];

		// Convert to lowercase for case-insensitive comparison
		$allowed_tables_lower = array_map('strtolower', $allowed_tables);
		$main_table_lower = strtolower($this->config->item('table_name'));

		// Normalize the SQL: remove newlines and extra spaces for easier parsing
		$normalized_sql = preg_replace('/\s+/', ' ', trim($sql));

		// Pattern 1: Check for UNION/INTO OUTFILE/LOAD FILE - these are always blocked
		if (preg_match('/\bunion\b.*?\bselect.*?\bfrom\s+(\w+)/i', $normalized_sql, $matches)) {
			$union_table = strtolower($matches[1]);
			if (!in_array($union_table, $allowed_tables_lower)) {
				log_message('error', "Search query blocked: UNION with unauthorized table - '$union_table'");
				return FALSE;
			}
		}

		// Pattern 2: Extract all table names after FROM and JOIN keywords
		// This handles: FROM `table`, JOIN `table`, FROM table, JOIN table
		preg_match_all('/\b(?:FROM|JOIN)\s+`?(\w+)`?/i', $normalized_sql, $from_join_matches);
		$found_tables = $from_join_matches[1];

		// Pattern 3: Extract table.column references that are NOT in the whitelist
		// This catches things like "users.password" or "admin.secret"
		preg_match_all('/(\w+)\.\w+/i', $normalized_sql, $column_refs);
		foreach ($column_refs[1] as $potential_table) {
			$potential_table_lower = strtolower($potential_table);
			// Only add if it's not a SQL keyword and not the main table
			$sql_keywords = ['select', 'where', 'order', 'group', 'having', 'limit', 'offset',
							'and', 'or', 'not', 'null', 'like', 'in', 'between', 'exists', 'case',
							'when', 'then', 'else', 'end', 'as', 'on', 'desc', 'asc', 'left', 'right', 'inner', 'outer'];
			if (!in_array($potential_table_lower, $sql_keywords) && $potential_table_lower !== $main_table_lower) {
				$found_tables[] = $potential_table;
			}
		}

		// Check all found tables are in whitelist
		$found_tables = array_unique($found_tables);
		foreach ($found_tables as $table) {
			if (empty($table)) {
				continue;
			}

			$table_lower = strtolower($table);

			// Skip common SQL keywords that might match
			$sql_keywords = ['select', 'where', 'order', 'group', 'having', 'limit', 'offset',
							'and', 'or', 'not', 'null', 'like', 'in', 'between', 'exists', 'case',
							'when', 'then', 'else', 'end', 'as', 'on', 'desc', 'asc', 'left', 'right', 'inner', 'outer'];
			if (in_array($table_lower, $sql_keywords)) {
				continue;
			}

			if (!in_array($table_lower, $allowed_tables_lower)) {
				log_message('error', "Search query blocked: unauthorized table access detected - '$table'");
				log_message('error', "Full query: $sql");
				return FALSE;
			}
		}

		return TRUE;
	}
}
