<?php
/**
 * Who a user is, when there is no email address.
 *
 * The identity of a Sirius Press account is a CashAddress, and the proof of
 * that identity is a signature. Everything else about WordPress users —
 * roles, capabilities, nonces, the session cookie — is untouched, because
 * those parts were never the problem. Only the "prove you can read this
 * mailbox" step is replaced.
 *
 * **Where the address lives.** In user meta, not a new `wp_users` column.
 * The roadmap sketched replacing `user_email` with a `wallet_addr` column,
 * but a schema change to a core table is the one thing that makes every
 * future upstream merge and every `dbDelta()` run a negotiation, and it buys
 * nothing here: meta lookups are indexed, and a plugin that reads
 * `$user->user_email` keeps reading something instead of crashing.
 *
 * **Why every user still has an email string.** `user_email` is populated
 * with a unique, permanently unroutable address under a `.invalid` domain
 * (RFC 2606 reserves it so it can never resolve). This is not a fallback path
 * that might one day deliver mail — it is a placeholder that exists so the
 * ecosystem's thousands of `$user->user_email` reads return a string. Mail to
 * it cannot leave the building. See docs/plugin-compatibility.md.
 *
 * @package SiriusPress
 */

defined( 'ABSPATH' ) || exit;

final class SP_Identity {

	const META_ADDRESS = 'sirius_wallet_address';
	const META_ADDED   = 'sirius_wallet_added';

	/**
	 * The wallet address for a user, or '' if they have none (an account
	 * created before the plugin was active, or by a plugin that made its own).
	 */
	public static function address_of( $user_id ) {
		return (string) get_user_meta( (int) $user_id, self::META_ADDRESS, true );
	}

	/**
	 * Find the account that owns an address.
	 *
	 * @return WP_User|null
	 */
	public static function user_by_address( $address ) {
		$address = SP_CashAddr::normalize( $address );
		if ( '' === $address ) {
			return null;
		}
		$found = get_users(
			array(
				'meta_key'    => self::META_ADDRESS,
				'meta_value'  => $address,
				'number'      => 2,
				'fields'      => 'all',
				'count_total' => false,
			)
		);
		// Two accounts on one address should be impossible — set_address()
		// refuses it — but if a direct database edit ever produced one,
		// authenticating an ambiguous identity is the wrong move.
		if ( 1 !== count( $found ) ) {
			return null;
		}
		return $found[0];
	}

	/**
	 * Attach an address to an account.
	 *
	 * @return true|WP_Error
	 */
	public static function set_address( $user_id, $address ) {
		$user_id = (int) $user_id;
		$address = SP_CashAddr::normalize( $address );
		if ( '' === $address ) {
			return new WP_Error( 'sirius_bad_address', __( 'That is not a valid Bitcoin Cash address.', 'sirius-press' ) );
		}
		if ( SP_CashAddr::decode( $address )['prefix'] !== SP_Settings::prefix() ) {
			return new WP_Error(
				'sirius_wrong_network',
				sprintf(
					/* translators: %s: the network prefix this site expects, e.g. bitcoincash */
					__( 'This site uses %s addresses. That address is on a different network.', 'sirius-press' ),
					SP_Settings::prefix()
				)
			);
		}
		$existing = self::user_by_address( $address );
		if ( $existing && (int) $existing->ID !== $user_id ) {
			return new WP_Error( 'sirius_address_taken', __( 'Another account already uses that address.', 'sirius-press' ) );
		}
		update_user_meta( $user_id, self::META_ADDRESS, $address );
		if ( ! get_user_meta( $user_id, self::META_ADDED, true ) ) {
			update_user_meta( $user_id, self::META_ADDED, gmdate( 'c' ) );
		}
		return true;
	}

	/**
	 * A stable, unroutable placeholder email for an address.
	 *
	 * Derived from the address so it is deterministic: re-running a migration
	 * does not churn every user's `user_email`, and two accounts never collide
	 * on one placeholder.
	 */
	public static function stub_email( $address ) {
		$address = SP_CashAddr::normalize( $address );
		$tag     = $address ? substr( hash( 'sha256', $address ), 0, 16 ) : wp_generate_password( 16, false );
		return 'noreply+' . $tag . '@' . SP_Settings::stub_email_domain();
	}

	/**
	 * A login name derived from an address.
	 *
	 * Addresses are 42 characters of base32 and make miserable usernames, so
	 * the default is the last eight characters of the payload — short enough
	 * to type, long enough not to collide in practice, and disambiguated with
	 * a counter if it does.
	 */
	public static function suggest_login( $address ) {
		$address = SP_CashAddr::normalize( $address );
		$body    = substr( (string) strstr( $address, ':' ), 1 );
		$base    = 'bch_' . substr( $body, -8 );
		$login   = $base;
		$n       = 2;
		while ( username_exists( $login ) ) {
			$login = $base . '_' . $n;
			$n++;
			if ( $n > 50 ) {
				$login = $base . '_' . wp_generate_password( 4, false );
				break;
			}
		}
		return $login;
	}

	/**
	 * Create an account for an address that has proved itself.
	 *
	 * The password is random and never shown to anyone: there is no password
	 * login path in this fork, and leaving it empty would let any plugin that
	 * calls `wp_authenticate()` with an empty password walk straight in.
	 *
	 * @param string $address
	 * @param string $login Optional preferred username.
	 * @param string $role  Defaults to the site's configured default role.
	 * @return int|WP_Error User ID.
	 */
	public static function create_user( $address, $login = '', $role = '' ) {
		$address = SP_CashAddr::normalize( $address );
		if ( '' === $address ) {
			return new WP_Error( 'sirius_bad_address', __( 'That is not a valid Bitcoin Cash address.', 'sirius-press' ) );
		}
		if ( self::user_by_address( $address ) ) {
			return new WP_Error( 'sirius_address_taken', __( 'An account already exists for that address.', 'sirius-press' ) );
		}

		$login = sanitize_user( $login, true );
		if ( '' === $login || username_exists( $login ) ) {
			$login = self::suggest_login( $address );
		}

		$user_id = wp_insert_user(
			array(
				'user_login'   => $login,
				'user_pass'    => wp_generate_password( 64, true, true ),
				'user_email'   => self::stub_email( $address ),
				'display_name' => $login,
				'role'         => '' !== $role ? $role : get_option( 'default_role', 'subscriber' ),
			)
		);
		if ( is_wp_error( $user_id ) ) {
			return $user_id;
		}
		$set = self::set_address( $user_id, $address );
		if ( is_wp_error( $set ) ) {
			// Do not leave a half-made account that can never be signed into.
			require_once ABSPATH . 'wp-admin/includes/user.php';
			wp_delete_user( $user_id );
			return $set;
		}
		/**
		 * Fires after a wallet-backed account is created.
		 *
		 * @param int    $user_id
		 * @param string $address Normalised CashAddress.
		 */
		do_action( 'sirius_press_user_registered', $user_id, $address );
		return $user_id;
	}

	// --------------------------------------------------------------- admin UI

	/** Show the address in the users list, where the email column used to be useful. */
	public static function hooks() {
		add_filter( 'manage_users_columns', array( __CLASS__, 'add_column' ) );
		add_filter( 'manage_users_custom_column', array( __CLASS__, 'render_column' ), 10, 3 );
		add_action( 'show_user_profile', array( __CLASS__, 'profile_field' ) );
		add_action( 'edit_user_profile', array( __CLASS__, 'profile_field' ) );
		add_action( 'personal_options_update', array( __CLASS__, 'save_profile_field' ) );
		add_action( 'edit_user_profile_update', array( __CLASS__, 'save_profile_field' ) );
	}

	public static function add_column( $columns ) {
		$out = array();
		foreach ( $columns as $key => $label ) {
			if ( 'email' === $key ) {
				// Replace rather than append: a column of identical .invalid
				// placeholders is worse than no column.
				$out['sirius_address'] = __( 'Wallet', 'sirius-press' );
				continue;
			}
			$out[ $key ] = $label;
		}
		if ( ! isset( $out['sirius_address'] ) ) {
			$out['sirius_address'] = __( 'Wallet', 'sirius-press' );
		}
		return $out;
	}

	public static function render_column( $value, $column, $user_id ) {
		if ( 'sirius_address' !== $column ) {
			return $value;
		}
		$address = self::address_of( $user_id );
		if ( '' === $address ) {
			return '<span style="color:#b32d2e">' . esc_html__( 'no wallet', 'sirius-press' ) . '</span>';
		}
		return '<code title="' . esc_attr( $address ) . '">' . esc_html( SP_CashAddr::shorten( $address ) ) . '</code>';
	}

	public static function profile_field( $user ) {
		$address  = self::address_of( $user->ID );
		$can_edit = current_user_can( 'edit_users' ) || get_current_user_id() === (int) $user->ID;
		?>
		<h2><?php esc_html_e( 'Wallet', 'sirius-press' ); ?></h2>
		<table class="form-table" role="presentation">
			<tr>
				<th><label for="sirius_wallet_address"><?php esc_html_e( 'Bitcoin Cash address', 'sirius-press' ); ?></label></th>
				<td>
					<input type="text" name="sirius_wallet_address" id="sirius_wallet_address"
						value="<?php echo esc_attr( $address ); ?>" class="regular-text code"
						<?php disabled( ! $can_edit ); ?> />
					<p class="description">
						<?php esc_html_e( 'This address is the account. Signing in means signing a challenge with the key that controls it — so changing it here hands the account to whoever holds the new key.', 'sirius-press' ); ?>
					</p>
				</td>
			</tr>
		</table>
		<?php
	}

	public static function save_profile_field( $user_id ) {
		if ( ! current_user_can( 'edit_user', $user_id ) ) {
			return;
		}
		// Nonce is checked by WordPress before these actions fire
		// (check_admin_referer( 'update-user_' . $user_id ) in user-edit.php).
		if ( ! isset( $_POST['sirius_wallet_address'] ) ) {
			return;
		}
		$address = sanitize_text_field( wp_unslash( $_POST['sirius_wallet_address'] ) );
		if ( '' === trim( $address ) ) {
			return;
		}
		if ( trim( $address ) === self::address_of( $user_id ) ) {
			return;
		}
		$result = self::set_address( $user_id, $address );
		if ( is_wp_error( $result ) ) {
			SP_Inbox::add(
				$user_id,
				__( 'Wallet address not changed', 'sirius-press' ),
				$result->get_error_message()
			);
		}
	}
}