<?php
declare(strict_types=1);

namespace Unsupervised\Schedular\Guardian;

class GuardianRepository {

	private string $table;

	public function __construct( private \wpdb $db ) {
		$this->table = $db->prefix . 'us_guardians';
	}

	/**
	 * Link a child to a guardian. Returns 0 without inserting when the child
	 * already has a guardian: v1 is one guardian per child, and the check lives
	 * here so every caller (signup, the family screen, admin) gets it.
	 */
	public function insert( GuardianLink $link ): int {
		if ( null !== $this->findByStudent( $link->studentId ) ) {
			return 0;
		}

		$this->db->insert(
			$this->table,
			[
				'guardian_id'  => $link->guardianId,
				'student_id'   => $link->studentId,
				'relationship' => $link->relationship,
				'created_at'   => current_time( 'mysql' ),
			],
			[ '%d', '%d', '%s', '%s' ]
		);

		return $this->db->insert_id;
	}

	/**
	 * The link naming this child's guardian, or null when they book for
	 * themselves.
	 */
	public function findByStudent( int $studentId ): ?GuardianLink {
		$row = $this->db->get_row(
			$this->db->prepare(
				'SELECT * FROM %i WHERE student_id = %d LIMIT 1',
				$this->table,
				$studentId
			)
		);

		return $row ? GuardianLink::fromRow( $row ) : null;
	}

	/**
	 * Every child linked to a guardian, oldest link first — the order they are
	 * offered in the booking selector, so it stays stable as children are added.
	 *
	 * @return list<GuardianLink>
	 */
	public function findByGuardian( int $guardianId ): array {
		$rows = $this->db->get_results(
			$this->db->prepare(
				'SELECT * FROM %i WHERE guardian_id = %d ORDER BY created_at ASC, id ASC',
				$this->table,
				$guardianId
			)
		);

		return array_map( GuardianLink::fromRow( ... ), $rows ?? [] );
	}

	/**
	 * Whether this exact guardian↔child pair is linked — the authorisation check
	 * behind every "act for this student" boundary.
	 */
	public function isGuardianOf( int $guardianId, int $studentId ): bool {
		$found = $this->db->get_var(
			$this->db->prepare(
				'SELECT id FROM %i WHERE guardian_id = %d AND student_id = %d LIMIT 1',
				$this->table,
				$guardianId,
				$studentId
			)
		);

		return null !== $found;
	}

	/**
	 * Remove the link between a guardian and one of their children. Deleting the
	 * child user itself is the caller's decision ({@see GuardianService::removeChild()});
	 * this only unlinks.
	 */
	public function delete( int $guardianId, int $studentId ): bool {
		$deleted = $this->db->delete(
			$this->table,
			[
				'guardian_id' => $guardianId,
				'student_id'  => $studentId,
			],
			[ '%d', '%d' ]
		);

		return (int) $deleted > 0;
	}

	/**
	 * How many children a guardian has — enough to decide whether the booking
	 * page needs a "who is this for?" selector at all.
	 */
	public function countChildren( int $guardianId ): int {
		$count = $this->db->get_var(
			$this->db->prepare(
				'SELECT COUNT(*) FROM %i WHERE guardian_id = %d',
				$this->table,
				$guardianId
			)
		);

		return (int) $count;
	}
}