<?php
/**
 * Builds the numbers for an emailed report and its PDF.
 *
 * @package TurtleReport
 */

namespace TurtleReport\Reports;

use TurtleReport\Auth\ApiException;
use TurtleReport\Policy\TrafficMetrics;
use TurtleReport\Profiles\Profile;
use TurtleReport\Support\Periods;

defined( 'ABSPATH' ) || exit;

/**
 * Runs a site's reports server-side and condenses them into a summary.
 *
 * Uses the same Report classes (and therefore the same cache) as the report
 * screen, and the same calculations as the frontend reporting models.
 *
 * Each section is built independently. A section that fails carries an
 * 'error', the ApiException 'reason' and status 'error'; it never turns into
 * zeros. Sections that load carry a 'status':
 *
 * - ok:      data for the period;
 * - zero:    the source works and has data in other periods, this one is zero;
 * - no_data: the source returned nothing at all yet (new property, wrong
 *            property, or tracking not set up).
 *
 * Delivery\Readiness turns these into a Ready / Warning / Blocked verdict.
 *
 * With $full (PDF attachments, secure links and insights) the summary also
 * holds daily and monthly series, page detail and AI detail: what the
 * two-page client PDF and the insights need. Without it, only the compact
 * summary is fetched.
 */
final class Summary {

	/** Rows in the PDF's winning/losing page tables, as on the report screen. */
	const PAGE_ROWS = 10;

	/** Rows in the email's page lists. */
	const EMAIL_ROWS = 5;

	/** Days looked back to check that configured GA4 events exist at all. */
	const SEEN_DAYS = 90;

	/**
	 * Reports keyed by ID.
	 *
	 * @var Report[]
	 */
	private $reports = array();

	/**
	 * Constructor.
	 *
	 * @param Report[] $reports Registered reports.
	 */
	public function __construct( array $reports ) {
		foreach ( $reports as $report ) {
			$this->reports[ $report->id() ] = $report;
		}
	}

	/**
	 * Summary for a site and period.
	 *
	 * @param Profile $site   Site.
	 * @param array   $period Period with s, e, ps and pe.
	 * @param bool    $full   Also build the detail the PDF and insights need.
	 * @return array Sections keyed by name; each holds data and a status, or an 'error'.
	 */
	public function build( Profile $site, array $period, $full = false ) {
		$out = array();
		if ( $site->wants( Profile::SECTION_SEARCH ) ) {
			$out['search'] = $this->section( array( $this, 'search' ), $site, $period, $full );
		}
		if ( $site->wants( Profile::SECTION_CONVERSIONS ) ) {
			$out['conversions'] = $this->section( array( $this, 'conversions' ), $site, $period, $full );
		}
		if ( $site->wants( Profile::SECTION_TRAFFIC ) && $site->traffic_metrics ) {
			$out['traffic'] = $this->section( array( $this, 'traffic' ), $site, $period, $full );
		}
		if ( $site->wants( Profile::SECTION_AI ) ) {
			$out['ai'] = $this->section( array( $this, 'ai' ), $site, $period, $full );
		}
		if ( $site->wants( Profile::SECTION_BUSINESS ) ) {
			$out['business'] = $this->section( array( $this, 'business' ), $site, $period, $full );
		}
		if ( $full && isset( $out['search']['pages'], $out['conversions']['page_totals'] ) ) {
			$out['search'] = self::join_page_leads( $out['search'], $out['conversions']['page_totals'] );
		}
		return $out;
	}

	/**
	 * Runs one section, turning errors into a message and a reason.
	 *
	 * @param callable $builder Section builder.
	 * @param Profile  $site    Site.
	 * @param array    $period  Period.
	 * @param bool     $full    Full detail.
	 * @return array
	 */
	private function section( callable $builder, Profile $site, array $period, $full ) {
		try {
			return $builder( $site, $period, $full );
		} catch ( ApiException $e ) {
			return array(
				'error'  => $e->getMessage(),
				'reason' => $e->reason(),
				'status' => 'error',
			);
		} catch ( \Throwable $e ) {
			// A broken or removed report (see the turtlereport_reports filter) costs one section, not the whole email.
			return array(
				'error'  => __( 'An unexpected error stopped this section from loading.', 'turtlereport' ),
				'reason' => ApiException::GOOGLE,
				'status' => 'error',
			);
		}
	}

	/**
	 * Runs a registered report.
	 *
	 * @param string  $id     Report ID.
	 * @param Profile $site   Site.
	 * @param array   $params Parameters.
	 * @return mixed
	 * @throws ApiException When the report isn't registered or Google fails.
	 */
	private function run( $id, Profile $site, array $params ) {
		if ( ! isset( $this->reports[ $id ] ) ) {
			throw new ApiException( __( 'This part of the report isn\'t available.', 'turtlereport' ), ApiException::UNSUPPORTED ); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped -- Caught by the plugin; escaped where the message is shown.
		}
		return $this->reports[ $id ]->run( $site, array_merge( array( 'segment' => '' ), $params ) );
	}

	/**
	 * Converts a decoded JSON object (stdClass or array) to an array.
	 *
	 * @param mixed $value Value.
	 * @return array
	 */
	private static function arr( $value ) {
		if ( $value instanceof \stdClass ) {
			$value = get_object_vars( $value );
		}
		return is_array( $value ) ? $value : array();
	}

	/**
	 * Search Console totals and the biggest page movers; with $full, daily and
	 * monthly series and page detail.
	 *
	 * @param Profile $site   Site.
	 * @param array   $period Period.
	 * @param bool    $full   Full detail.
	 * @return array
	 */
	private function search( Profile $site, array $period, $full = false ) {
		$q        = function ( $dimension, $s, $e ) use ( $site ) {
			return (array) $this->run(
				'search-console',
				$site,
				array(
					'dimension' => $dimension,
					'start'     => $s,
					'end'       => $e,
				)
			);
		};
		$cur_rows = $q( 'date', $period['s'], $period['e'] );
		$cur      = self::gsc_totals( $cur_rows );
		$prev     = self::gsc_totals( $q( 'date', $period['ps'], $period['pe'] ) );
		$pages    = self::join_rows( $q( 'page', $period['s'], $period['e'] ), $q( 'page', $period['ps'], $period['pe'] ) );

		$winners = array();
		$losers  = array();
		foreach ( self::movers( $pages, 1 ) as $row ) {
			$winners[] = array(
				'page'   => $row['key'],
				'clicks' => $row['clicks'],
				'delta'  => $row['dClicks'],
			);
		}
		foreach ( self::movers( $pages, -1 ) as $row ) {
			$losers[] = array(
				'page'   => $row['key'],
				'clicks' => $row['clicks'],
				'delta'  => $row['dClicks'],
			);
		}
		$out = array(
			'cur'       => $cur,
			'prev'      => $prev,
			'winners'   => array_slice( $winners, 0, self::EMAIL_ROWS ),
			'losers'    => array_slice( $losers, 0, self::EMAIL_ROWS ),
			'last_date' => self::last_date( $cur_rows ),
		);

		$trend = array();
		if ( $full ) {
			$t     = Periods::trend( $period['e'] );
			$trend = $q( 'date', $t['s'], $t['e'] );
			$daily = array();
			foreach ( $cur_rows as $row ) {
				$daily[ (string) $row['keys'][0] ] = array(
					'clicks'      => (float) $row['clicks'],
					'impressions' => (float) $row['impressions'],
				);
			}
			$monthly = array();
			foreach ( $trend as $row ) {
				$month             = substr( (string) $row['keys'][0], 0, 7 );
				$monthly[ $month ] = ( isset( $monthly[ $month ] ) ? $monthly[ $month ] : 0.0 ) + (float) $row['clicks'];
			}
			$days = self::days( $period['s'], $period['e'] );

			$out['daily']     = $daily;
			$out['monthly']   = $monthly;
			$out['trend']     = Periods::trend( $period['e'] );
			$out['pages']     = array(
				'up'   => self::movers( $pages, 1, self::PAGE_ROWS ),
				'down' => self::movers( $pages, -1, self::PAGE_ROWS ),
			);
			$out['page_rows'] = count( $pages );
			$out['gaining']   = count(
				array_filter(
					$pages,
					static function ( $r ) {
						return $r['dClicks'] > 0;
					}
				)
			);
			$out['losing']    = count(
				array_filter(
					$pages,
					static function ( $r ) {
						return $r['dClicks'] < 0;
					}
				)
			);
			$out['low_ctr']   = self::low_ctr( $pages, $cur['ctr'], $days );
			$out['top_pages'] = self::top_by_clicks( $pages, 25 );
		}

		$out['status'] = self::search_status( $cur_rows, $prev, $trend );
		return $out;
	}

	/**
	 * Status for a Search Console section: zero clicks is only "no data" when
	 * the property has nothing at all, not even last period.
	 *
	 * @param array $cur_rows Current date rows.
	 * @param array $prev     Previous totals.
	 * @param array $trend    Six-month rows (may be empty without full detail).
	 * @return string
	 */
	private static function search_status( array $cur_rows, array $prev, array $trend ) {
		if ( $cur_rows ) {
			return 'ok';
		}
		return ( $prev['impressions'] > 0 || $trend ) ? 'zero' : 'no_data';
	}

	/**
	 * Conversion totals per group, plus a total that counts each event once.
	 *
	 * Groups may share an event (for example "generate_lead" in "Forms" and
	 * "All leads"). Each group's own number includes it, but the overall
	 * total doesn't count it twice. 'overlaps' names the shared events so the
	 * report can say so.
	 *
	 * @param Profile $site   Site.
	 * @param array   $period Period.
	 * @param bool    $full   Full detail.
	 * @return array
	 */
	private function conversions( Profile $site, array $period, $full = false ) {
		$events = $site->all_conversion_events();
		$out    = array(
			'label'    => $site->conversion_label(),
			'events'   => $events,
			'overlaps' => $site->overlapping_events(),
		);
		if ( ! $events ) {
			return array_merge(
				$out,
				array(
					'cur'            => 0,
					'prev'           => 0,
					'groups'         => array(),
					'missing_events' => array(),
					'status'         => 'no_events',
				)
			);
		}
		$q    = function ( $kind, $s, $e ) use ( $site ) {
			return self::arr(
				$this->run(
					'conversions',
					$site,
					array(
						'kind'  => $kind,
						'start' => $s,
						'end'   => $e,
					)
				)
			);
		};
		$cur  = $q( 'totals', $period['s'], $period['e'] );
		$prev = $q( 'totals', $period['ps'], $period['pe'] );
		$seen = $q( 'seen', Periods::add_days( $period['e'], -( self::SEEN_DAYS - 1 ) ), $period['e'] );

		$split  = self::split( $site, $cur );
		$psplit = self::split( $site, $prev );
		$groups = array();
		foreach ( $site->conversion_groups as $i => $group ) {
			$groups[] = array(
				'label' => $group['label'],
				'cur'   => $split['groups'][ $i ],
				'prev'  => $psplit['groups'][ $i ],
			);
		}

		$missing = array_values(
			array_filter(
				$events,
				static function ( $event ) use ( $seen, $cur, $prev ) {
					return empty( $seen[ $event ] ) && empty( $cur[ $event ] ) && empty( $prev[ $event ] );
				}
			)
		);
		if ( $split['total'] > 0 ) {
			$status = 'ok';
		} elseif ( count( $missing ) === count( $events ) ) {
			$status = 'no_data';
		} else {
			$status = 'zero';
		}

		$out = array_merge(
			$out,
			array(
				'cur'            => $split['total'],
				'prev'           => $psplit['total'],
				'groups'         => $groups,
				'by_event'       => array(
					'cur'  => array_map( 'intval', $cur ),
					'prev' => array_map( 'intval', $prev ),
				),
				'missing_events' => $missing,
				'status'         => $status,
			)
		);

		if ( $full ) {
			$t      = Periods::trend( $period['e'] );
			$pages  = $q( 'pages', $period['s'], $period['e'] );
			$ppages = $q( 'pages', $period['ps'], $period['pe'] );
			$totals = array();
			foreach ( $pages as $path => $map ) {
				$totals[ $path ] = array( self::split( $site, self::arr( $map ) )['total'], 0 );
			}
			foreach ( $ppages as $path => $map ) {
				$totals[ $path ] = array( isset( $totals[ $path ] ) ? $totals[ $path ][0] : 0, self::split( $site, self::arr( $map ) )['total'] );
			}
			$top = array();
			foreach ( $totals as $path => $pair ) {
				if ( $pair[0] > 0 && '(not set)' !== $path ) {
					$top[] = array(
						'page'  => (string) $path,
						'total' => $pair[0],
						'prev'  => $pair[1],
					);
				}
			}
			usort(
				$top,
				static function ( $a, $b ) {
					return $b['total'] <=> $a['total'];
				}
			);
			$out['daily']       = array_map( 'intval', $q( 'daily', $period['s'], $period['e'] ) );
			$out['monthly']     = array_map( 'intval', $q( 'monthly', $t['s'], $t['e'] ) );
			$out['top_pages']   = array_slice( $top, 0, self::EMAIL_ROWS );
			$out['page_totals'] = $totals;
		}
		return $out;
	}

	/**
	 * Splits event counts into the site's groups, and totals each event once.
	 *
	 * Mirrors splitConversions() in the frontend reporting metric model.
	 *
	 * @param Profile $site   Site.
	 * @param array   $counts Event name => count.
	 * @return array{groups:int[],total:int}
	 */
	public static function split( Profile $site, array $counts ) {
		$groups = array();
		foreach ( $site->conversion_groups as $i => $group ) {
			$n = 0;
			foreach ( array_unique( $group['events'] ) as $event ) {
				$n += isset( $counts[ $event ] ) ? (int) $counts[ $event ] : 0;
			}
			$groups[ $i ] = $n;
		}
		$total = 0;
		foreach ( $site->all_conversion_events() as $event ) {
			$total += isset( $counts[ $event ] ) ? (int) $counts[ $event ] : 0;
		}
		return array(
			'groups' => $groups,
			'total'  => $total,
		);
	}

	/**
	 * Chosen GA4 traffic metrics.
	 *
	 * @param Profile $site   Site.
	 * @param array   $period Period.
	 * @return array
	 */
	private function traffic( Profile $site, array $period ) {
		$data    = self::arr(
			$this->run(
				'traffic',
				$site,
				array(
					'start'      => $period['s'],
					'end'        => $period['e'],
					'prev_start' => $period['ps'],
					'prev_end'   => $period['pe'],
				)
			)
		);
		$cur     = self::arr( isset( $data['cur'] ) ? $data['cur'] : array() );
		$prev    = self::arr( isset( $data['prev'] ) ? $data['prev'] : array() );
		$defs    = TrafficMetrics::all();
		$metrics = array();
		$any     = false;
		foreach ( $site->traffic_metrics as $key ) {
			if ( isset( $defs[ $key ] ) ) {
				$c         = isset( $cur[ $key ] ) ? (float) $cur[ $key ] : 0.0;
				$p         = isset( $prev[ $key ] ) ? (float) $prev[ $key ] : 0.0;
				$any       = $any || $c > 0 || $p > 0;
				$metrics[] = array_merge(
					$defs[ $key ],
					array(
						'key'  => $key,
						'cur'  => $c,
						'prev' => $p,
					)
				);
			}
		}
		return array(
			'scope'   => $site->traffic_scope,
			'metrics' => $metrics,
			'status'  => $any ? 'ok' : 'no_data',
		);
	}

	/**
	 * AI assistant sessions and conversions.
	 *
	 * @param Profile $site   Site.
	 * @param array   $period Period.
	 * @param bool    $full   Full detail.
	 * @return array
	 */
	private function ai( Profile $site, array $period, $full = false ) {
		$data          = self::arr(
			$this->run(
				'ai-traffic',
				$site,
				array(
					'start'      => $period['s'],
					'end'        => $period['e'],
					'prev_start' => $period['ps'],
					'prev_end'   => $period['pe'],
				)
			)
		);
		$events        = $site->all_conversion_events();
		$sum           = static function ( $map ) use ( $events ) {
			$map = self::arr( $map );
			$n   = 0;
			foreach ( $events as $event ) {
				$n += isset( $map[ $event ] ) ? (int) $map[ $event ] : 0;
			}
			return $n;
		};
		$cur           = self::arr( isset( $data['cur'] ) ? $data['cur'] : array() );
		$prev          = self::arr( isset( $data['prev'] ) ? $data['prev'] : array() );
		$out           = array(
			'cur'       => isset( $cur['sessions'] ) ? (int) $cur['sessions'] : 0,
			'prev'      => isset( $prev['sessions'] ) ? (int) $prev['sessions'] : 0,
			'conv'      => $sum( isset( $data['ev'] ) ? $data['ev'] : array() ),
			'conv_prev' => $sum( isset( $data['pev'] ) ? $data['pev'] : array() ),
		);
		$out['status'] = $out['cur'] > 0 ? 'ok' : 'zero';
		if ( $full ) {
			$leads = self::arr( isset( $data['page_leads'] ) ? $data['page_leads'] : array() );
			$pages = array();
			foreach ( array_slice( isset( $data['pages'] ) ? (array) $data['pages'] : array(), 0, 3 ) as $row ) {
				$row     = self::arr( $row );
				$path    = strtolower( rtrim( (string) $row['p'], '/' ) );
				$path    = '' === $path ? '/' : $path;
				$pages[] = array(
					'page'     => (string) $row['p'],
					'sessions' => (int) $row['sessions'],
					'leads'    => $sum( isset( $leads[ $path ] ) ? $leads[ $path ] : array() ),
				);
			}
			$out['engaged']      = isset( $cur['engaged'] ) ? (int) $cur['engaged'] : 0;
			$out['engaged_prev'] = isset( $prev['engaged'] ) ? (int) $prev['engaged'] : 0;
			$out['all']          = isset( $data['all'] ) ? (int) $data['all'] : 0;
			$out['mode']         = isset( $data['mode'] ) ? (string) $data['mode'] : 'channel';
			$out['pages']        = $pages;
			$out['sources']      = array_slice( isset( $data['sources'] ) ? array_map( array( __CLASS__, 'arr' ), (array) $data['sources'] ) : array(), 0, 5 );
		}
		return $out;
	}

	/**
	 * Business Profile totals; with $full, daily and monthly series.
	 *
	 * @param Profile $site   Site.
	 * @param array   $period Period.
	 * @param bool    $full   Full detail.
	 * @return array
	 */
	private function business( Profile $site, array $period, $full = false ) {
		$start = min( $period['s'], $period['ps'] );
		if ( $full ) {
			$start = min( $start, Periods::trend( $period['e'] )['s'] );
		}
		$daily         = self::arr(
			$this->run(
				'business-profile',
				$site,
				array(
					'start' => $start,
					'end'   => $period['e'],
				)
			)
		);
		$sum           = static function ( $s, $e ) use ( $daily ) {
			$out = array(
				'calls' => 0,
				'web'   => 0,
				'dirs'  => 0,
				'views' => 0,
			);
			foreach ( $daily as $date => $row ) {
				$row = self::arr( $row );
				if ( $date >= $s && $date <= $e ) {
					foreach ( $out as $k => $v ) {
						$out[ $k ] = $v + ( isset( $row[ $k ] ) ? (int) $row[ $k ] : 0 );
					}
				}
			}
			return $out;
		};
		$in_period     = array_filter(
			array_keys( $daily ),
			static function ( $date ) use ( $period ) {
				return $date >= $period['s'] && $date <= $period['e'];
			}
		);
		$out           = array(
			'cur'       => $sum( $period['s'], $period['e'] ),
			'prev'      => $sum( $period['ps'], $period['pe'] ),
			'last_date' => $in_period ? (string) max( $in_period ) : '',
		);
		$out['status'] = $in_period ? ( array_sum( $out['cur'] ) > 0 ? 'ok' : 'zero' ) : ( $daily ? 'zero' : 'no_data' );
		if ( $full ) {
			$days    = array();
			$monthly = array();
			$t       = Periods::trend( $period['e'] );
			foreach ( $daily as $date => $row ) {
				$row = self::arr( $row );
				if ( $date >= $period['s'] && $date <= $period['e'] ) {
					$days[ $date ] = array(
						'calls' => isset( $row['calls'] ) ? (int) $row['calls'] : 0,
						'web'   => isset( $row['web'] ) ? (int) $row['web'] : 0,
					);
				}
				if ( $date >= $t['s'] && $date <= $t['e'] ) {
					$month             = substr( (string) $date, 0, 7 );
					$monthly[ $month ] = ( isset( $monthly[ $month ] ) ? $monthly[ $month ] : 0 ) + ( isset( $row['calls'] ) ? (int) $row['calls'] : 0 );
				}
			}
			$out['daily']   = $days;
			$out['monthly'] = $monthly;
		}
		return $out;
	}

	/**
	 * Totals from Search Console date rows.
	 *
	 * @param array $rows Rows.
	 * @return array{clicks:float,impressions:float,ctr:float,position:float}
	 */
	public static function gsc_totals( array $rows ) {
		$clicks = 0.0;
		$impr   = 0.0;
		$pos    = 0.0;
		foreach ( $rows as $row ) {
			$clicks += (float) $row['clicks'];
			$impr   += (float) $row['impressions'];
			$pos    += (float) $row['position'] * (float) $row['impressions'];
		}
		return array(
			'clicks'      => $clicks,
			'impressions' => $impr,
			'ctr'         => $impr ? $clicks / $impr : 0.0,
			'position'    => $impr ? $pos / $impr : 0.0,
		);
	}

	/**
	 * Joins this period's and last period's rows by key (joinRows() in the frontend reporting selectors).
	 *
	 * @param array $cur  Current rows.
	 * @param array $prev Previous rows.
	 * @return array[] Rows with key, clicks, impressions, ctr, position, pClicks, pImpr, pPos, inCur, inPrev, dClicks, dPos.
	 */
	public static function join_rows( array $cur, array $prev ) {
		$m = array();
		foreach ( $cur as $x ) {
			$k       = (string) $x['keys'][0];
			$m[ $k ] = array(
				'key'         => $k,
				'clicks'      => (float) $x['clicks'],
				'impressions' => (float) ( isset( $x['impressions'] ) ? $x['impressions'] : 0 ),
				'ctr'         => (float) ( isset( $x['ctr'] ) ? $x['ctr'] : 0 ),
				'position'    => (float) ( isset( $x['position'] ) ? $x['position'] : 0 ),
				'pClicks'     => 0.0,
				'pImpr'       => 0.0,
				'pPos'        => null,
				'inCur'       => true,
				'inPrev'      => false,
			);
		}
		foreach ( $prev as $x ) {
			$k = (string) $x['keys'][0];
			if ( ! isset( $m[ $k ] ) ) {
				$m[ $k ] = array(
					'key'         => $k,
					'clicks'      => 0.0,
					'impressions' => 0.0,
					'ctr'         => 0.0,
					'position'    => null,
					'inCur'       => false,
				);
			}
			$m[ $k ]['pClicks'] = (float) $x['clicks'];
			$m[ $k ]['pImpr']   = (float) ( isset( $x['impressions'] ) ? $x['impressions'] : 0 );
			$m[ $k ]['pPos']    = (float) ( isset( $x['position'] ) ? $x['position'] : 0 );
			$m[ $k ]['inPrev']  = true;
		}
		foreach ( $m as $k => $r ) {
			$m[ $k ]['dClicks'] = $r['clicks'] - $r['pClicks'];
			$m[ $k ]['dPos']    = $r['inCur'] && $r['inPrev'] ? $r['position'] - $r['pPos'] : null;
		}
		return array_values( $m );
	}

	/**
	 * Rows that gained ($dir 1) or lost ($dir -1) the most clicks.
	 *
	 * @param array[] $rows  Joined rows.
	 * @param int     $dir   1 or -1.
	 * @param int     $limit Most rows.
	 * @return array[]
	 */
	private static function movers( array $rows, $dir, $limit = 10 ) {
		$rows = array_values(
			array_filter(
				$rows,
				static function ( $r ) use ( $dir ) {
					return $dir > 0 ? $r['dClicks'] > 0 : $r['dClicks'] < 0;
				}
			)
		);
		usort(
			$rows,
			static function ( $a, $b ) use ( $dir ) {
				return $dir > 0 ? $b['dClicks'] <=> $a['dClicks'] : $a['dClicks'] <=> $b['dClicks'];
			}
		);
		return array_slice( $rows, 0, $limit );
	}

	/**
	 * Rows with the most clicks this period.
	 *
	 * @param array[] $rows  Joined rows.
	 * @param int     $limit Most rows.
	 * @return array[]
	 */
	private static function top_by_clicks( array $rows, $limit ) {
		$rows = array_values(
			array_filter(
				$rows,
				static function ( $r ) {
					return $r['inCur'] && $r['clicks'] > 0;
				}
			)
		);
		usort(
			$rows,
			static function ( $a, $b ) {
				return $b['clicks'] <=> $a['clicks'];
			}
		);
		return array_slice( $rows, 0, $limit );
	}

	/**
	 * Pages on page 1 of Google with a click-through rate well below the site's own.
	 *
	 * @param array[] $pages    Joined page rows.
	 * @param float   $site_ctr The site's CTR this period.
	 * @param int     $days     Days in the period.
	 * @return array[]
	 */
	private static function low_ctr( array $pages, $site_ctr, $days ) {
		$min  = max( 100, self::min_impressions( $days ) * 10 );
		$rows = array_values(
			array_filter(
				$pages,
				static function ( $r ) use ( $min, $site_ctr ) {
					return $r['inCur'] && $r['impressions'] >= $min && $r['position'] > 0 && $r['position'] <= 10 && $site_ctr > 0 && $r['ctr'] < $site_ctr * 0.5;
				}
			)
		);
		usort(
			$rows,
			static function ( $a, $b ) {
				return $b['impressions'] <=> $a['impressions'];
			}
		);
		return array_map(
			static function ( $r ) {
				return array_intersect_key( $r, array_flip( array( 'key', 'clicks', 'impressions', 'ctr', 'position' ) ) );
			},
			array_slice( $rows, 0, 3 )
		);
	}

	/**
	 * Impressions a keyword needs to count as a mover (minImpr() in the frontend reporting selectors).
	 *
	 * @param int $days Days in the period.
	 * @return int
	 */
	public static function min_impressions( $days ) {
		return (int) max( 10, round( 20 * (int) $days / 28 ) );
	}

	/**
	 * Adds conversion counts to the page tables, matched by landing path.
	 *
	 * @param array $search Search section.
	 * @param array $totals Path => [current, previous] conversions.
	 * @return array
	 */
	private static function join_page_leads( array $search, array $totals ) {
		$lookup = static function ( $url ) use ( $totals ) {
			$path = wp_parse_url( (string) $url, PHP_URL_PATH );
			$path = strtolower( is_string( $path ) && '' !== $path ? $path : (string) $url );
			if ( strlen( $path ) > 1 && '/' === substr( $path, -1 ) ) {
				$path = substr( $path, 0, -1 );
			}
			return isset( $totals[ $path ] ) ? $totals[ $path ] : array( 0, 0 );
		};
		foreach ( array( 'up', 'down' ) as $dir ) {
			foreach ( $search['pages'][ $dir ] as $i => $row ) {
				$pair                                     = $lookup( $row['key'] );
				$search['pages'][ $dir ][ $i ]['leads']   = $pair[0];
				$search['pages'][ $dir ][ $i ]['p_leads'] = $pair[1];
			}
		}
		foreach ( $search['top_pages'] as $i => $row ) {
			$search['top_pages'][ $i ]['leads'] = $lookup( $row['key'] )[0];
		}
		$search['has_leads'] = true;
		return $search;
	}

	/**
	 * Latest date in Search Console date rows.
	 *
	 * @param array $rows Rows.
	 * @return string Y-m-d, or '' when there are none.
	 */
	private static function last_date( array $rows ) {
		$last = '';
		foreach ( $rows as $row ) {
			$date = (string) $row['keys'][0];
			$last = $date > $last ? $date : $last;
		}
		return $last;
	}

	/**
	 * Days in a range, inclusive.
	 *
	 * @param string $s Start.
	 * @param string $e End.
	 * @return int
	 */
	public static function days( $s, $e ) {
		$a = new \DateTimeImmutable( $s . ' 00:00:00', new \DateTimeZone( 'UTC' ) );
		$b = new \DateTimeImmutable( $e . ' 00:00:00', new \DateTimeZone( 'UTC' ) );
		return (int) $a->diff( $b )->days + 1;
	}
}