<?php
/**
 * Configuration value object.
 *
 * @package AdPix\Analytics
 */

declare( strict_types = 1 );

namespace AdPix\Analytics\Model;

defined( 'ABSPATH' ) || exit;

/**
 * The plugin's configuration, as one immutable value.
 *
 * Passing this around instead of a settings service means nothing downstream can mutate
 * configuration mid-request, and a test can construct any state it likes in one line without
 * touching the options table.
 */
final class Settings {

	/**
	 * Option name. Prefixed with the plugin slug, per the WordPress.org naming requirement that a
	 * plugin claim only names it can be sure no other plugin will choose.
	 */
	public const OPTION = 'adpix_analytics_settings';

	/**
	 * wp-config.php constants that override the stored value, so a site can keep the write
	 * credential out of the database and out of every database backup.
	 *
	 * @var array<string,string[]>
	 */
	private const CONSTANTS = array(
		'property_id'    => array( 'ADPIX_ANALYTICS_PROPERTY_ID', 'ADPIX_PROPERTY_ID' ),
		'measurement_id' => array( 'ADPIX_ANALYTICS_MEASUREMENT_ID', 'ADPIX_MEASUREMENT_ID' ),
		'server_key'     => array( 'ADPIX_ANALYTICS_SERVER_KEY', 'ADPIX_SERVER_KEY' ),
		'api_token'      => array( 'ADPIX_ANALYTICS_API_TOKEN' ),
	);

	/**
	 * The AdPix hosts, each with the wp-config.php constants that may replace it, first match wins.
	 *
	 * Not settings: every hosted property uses these same addresses, and a field for each only gave
	 * site owners a way to paste the wrong one. The platform splits the work — the server-to-server
	 * and reporting APIs are on the api host, the tag script on the CDN, and the browser's own events
	 * on the collect host, which is the only one that accepts them.
	 *
	 * The constants remain for a self-hosted platform or a first-party tag gateway. A single-host
	 * self-hosted install set only the collector constant before the hosts were split, so the browser
	 * endpoint falls back to it.
	 *
	 * @var array<string,array{0:string,1:string[]}>
	 */
	private const HOSTS = array(
		'collector' => array( 'https://api.adpix.io', array( 'ADPIX_ANALYTICS_COLLECTOR_URL', 'ADPIX_COLLECTOR' ) ),
		'tracker'   => array( 'https://cdn.adpix.net', array( 'ADPIX_ANALYTICS_TRACKER_URL', 'ADPIX_TRACKER' ) ),
		'endpoint'  => array( 'https://collect.adpix.net', array( 'ADPIX_ANALYTICS_ENDPOINT', 'ADPIX_ANALYTICS_COLLECTOR_URL', 'ADPIX_COLLECTOR' ) ),
		'api'       => array( 'https://api.adpix.io', array( 'ADPIX_ANALYTICS_API_URL' ) ),
	);

	/**
	 * Settings shown only in the advanced mode of the settings screen.
	 *
	 * Kept here, next to the schema, because two places must agree on it: the form leaves these out
	 * in simple mode, and the sanitizer must then keep their stored values rather than read the
	 * absence as "cleared" or "unticked".
	 *
	 * @var string[]
	 */
	private const ADVANCED_ONLY = array(
		'use_hmac',
		'force_ssl',
		'send_ip',
		'default_cc',
		'custom_tag_code',
		'custom_code',
		'custom_code_location',
	);

	/**
	 * Every setting with its default, which doubles as the schema: a key absent from here is not a
	 * setting and is dropped on save.
	 *
	 * @var array<string,mixed>
	 */
	private const DEFAULTS = array(
		'property_id'            => '',
		'measurement_id'         => '',
		'server_key'             => '',
		'api_token'              => '',
		'use_hmac'               => false,
		'force_ssl'              => false,
		'default_cc'             => '',
		'inject_tag'             => true,
		'track_commerce'         => true,
		'track_users'            => true,
		'track_forms'            => true,
		'respect_consent'        => true,
		'send_ip'                => true,
		'tag_location'           => 'head',
		'tag_admin_area'         => false,
		'exclude_roles'          => array(),
		'exclude_post_ids'       => '',
		'exclude_search_archive' => false,
		'custom_tag_code'        => '',
		'custom_code'            => '',
		'custom_code_location'   => 'head',
		'debug'                  => false,
		'delete_on_uninstall'    => false,
	);

	/**
	 * Settings whose value must be one of a fixed set, with the first entry as the fallback. Kept
	 * here rather than in the sanitizer so the form and the validator cannot drift apart.
	 *
	 * @var array<string,string[]>
	 */
	private const CHOICES = array(
		'tag_location'         => array( 'head', 'footer' ),
		'custom_code_location' => array( 'head', 'footer' ),
	);

	/**
	 * Resolved values.
	 *
	 * @var array<string,mixed>
	 */
	private $values;

	/**
	 * Keys whose value came from a constant and so cannot be edited in the admin.
	 *
	 * @var string[]
	 */
	private $locked;

	/**
	 * @param array<string,mixed> $values Resolved values.
	 * @param string[]            $locked Keys fixed by a wp-config constant.
	 */
	private function __construct( array $values, array $locked = array() ) {
		$this->values = $values;
		$this->locked = $locked;
	}

	/**
	 * Build from a stored array, applying defaults and any wp-config overrides.
	 *
	 * @param array<string,mixed> $stored Raw option value.
	 * @return self
	 */
	public static function from_array( array $stored ): self {
		$values = array();
		$locked = array();

		foreach ( self::DEFAULTS as $key => $default ) {
			$value = array_key_exists( $key, $stored ) ? $stored[ $key ] : $default;

			foreach ( self::CONSTANTS[ $key ] ?? array() as $constant ) {
				if ( defined( $constant ) && '' !== (string) constant( $constant ) ) {
					$value    = constant( $constant );
					$locked[] = $key;
					break;
				}
			}

			if ( is_bool( $default ) ) {
				$value = (bool) $value;
			} elseif ( is_array( $default ) ) {
				$value = is_array( $value ) ? array_values( array_map( 'strval', $value ) ) : array();
			} elseif ( isset( self::CHOICES[ $key ] ) && ! in_array( (string) $value, self::CHOICES[ $key ], true ) ) {
				// A value outside the set can only come from a hand-edited option row or an older
				// schema. Falling back to the first choice keeps the form and the behaviour agreeing.
				$value = self::CHOICES[ $key ][0];
			}

			$values[ $key ] = $value;
		}

		return new self( $values, $locked );
	}

	/**
	 * The permitted values for a fixed-choice setting.
	 *
	 * @param string $key Setting name.
	 * @return string[] Empty when the setting is not a fixed-choice one.
	 */
	public static function choices( string $key ): array {
		return self::CHOICES[ $key ] ?? array();
	}

	/**
	 * The schema, for callers that enumerate settings (the sanitizer, the admin form).
	 *
	 * @return array<string,mixed>
	 */
	public static function defaults(): array {
		return self::DEFAULTS;
	}

	/**
	 * Settings the simple mode leaves off the form.
	 *
	 * @return string[]
	 */
	public static function advanced_only(): array {
		return self::ADVANCED_ONLY;
	}

	/**
	 * One value.
	 *
	 * @param string $key Setting name.
	 * @return mixed Null when the key is not part of the schema.
	 */
	public function get( string $key ) {
		return $this->values[ $key ] ?? null;
	}

	/**
	 * One value as a trimmed string.
	 *
	 * @param string $key Setting name.
	 * @return string
	 */
	public function str( string $key ): string {
		$value = $this->values[ $key ] ?? '';

		return is_scalar( $value ) ? trim( (string) $value ) : '';
	}

	/**
	 * One value as a list of strings.
	 *
	 * @param string $key Setting name.
	 * @return string[]
	 */
	public function arr( string $key ): array {
		$value = $this->values[ $key ] ?? array();

		return is_array( $value ) ? array_values( array_map( 'strval', $value ) ) : array();
	}

	/**
	 * One value as a boolean.
	 *
	 * @param string $key Setting name.
	 * @return bool
	 */
	public function flag( string $key ): bool {
		return ! empty( $this->values[ $key ] );
	}

	/**
	 * Whether a wp-config constant fixes this key, so the admin form must show it read-only.
	 *
	 * @param string $key Setting name.
	 * @return bool
	 */
	public function is_locked( string $key ): bool {
		return in_array( $key, $this->locked, true );
	}

	/**
	 * A copy with some values replaced. The object itself never changes.
	 *
	 * @param array<string,mixed> $changes Values to override.
	 * @return self
	 */
	public function with( array $changes ): self {
		return new self( array_merge( $this->values, array_intersect_key( $changes, self::DEFAULTS ) ), $this->locked );
	}

	/**
	 * The storable form.
	 *
	 * @return array<string,mixed>
	 */
	public function to_array(): array {
		return $this->values;
	}

	// ---------------------------------------------------------------------
	// Derived questions the rest of the plugin actually asks.
	// ---------------------------------------------------------------------

	/**
	 * Server-to-server base URL, without a trailing slash: where orders, sign-ups and leads are sent.
	 *
	 * @return string
	 */
	public function collector_url(): string {
		return $this->host( 'collector' );
	}

	/**
	 * Where the browser tag sends its own events, without a trailing slash.
	 *
	 * @return string
	 */
	public function endpoint_url(): string {
		return $this->host( 'endpoint' );
	}

	/**
	 * One AdPix host: a wp-config.php override when there is one, otherwise the hosted address.
	 *
	 * @param string $which Key of self::HOSTS.
	 * @return string
	 */
	private function host( string $which ): string {
		list( $url, $constants ) = self::HOSTS[ $which ];

		foreach ( $constants as $constant ) {
			if ( defined( $constant ) && '' !== (string) constant( $constant ) ) {
				$url = (string) constant( $constant );
				break;
			}
		}

		return $this->secure( untrailingslashit( $url ) );
	}

	/**
	 * Upgrade a URL to HTTPS when the site has asked for it.
	 *
	 * Applied at the point of use rather than on save, so turning the setting off restores the
	 * address the owner actually typed instead of leaving a rewritten one behind.
	 *
	 * @param string $url Configured address.
	 * @return string
	 */
	private function secure( string $url ): string {
		if ( '' === $url || ! $this->flag( 'force_ssl' ) ) {
			return $url;
		}

		return (string) preg_replace( '#^http://#i', 'https://', $url );
	}

	/**
	 * Where the tag JavaScript is served from, without a trailing slash.
	 *
	 * @return string
	 */
	public function tracker_url(): string {
		return $this->host( 'tracker' );
	}

	/**
	 * Whether server-to-server calls can be made at all.
	 *
	 * @return bool
	 */
	public function is_connected(): bool {
		return '' !== $this->str( 'property_id' )
			&& '' !== $this->str( 'server_key' );
	}

	/**
	 * Reporting API base URL, without a trailing slash. Always the hosted API unless a wp-config.php
	 * constant names a self-hosted one.
	 *
	 * The AdPix dashboard shows this address with its version on the end (https://api.adpix.io/v1),
	 * and that is exactly what an owner will copy into the constant. The report client adds /v1
	 * itself, so a pasted version is dropped here rather than turned into /v1/v1 and a 404 nobody can
	 * explain.
	 *
	 * @return string
	 */
	public function api_base_url(): string {
		return (string) preg_replace( '#/v1$#i', '', $this->host( 'api' ) );
	}

	/**
	 * Whether the statistics screen has what it needs to ask for a report.
	 *
	 * Deliberately no mention of the server key. That credential can write to the property and never
	 * leaves the collector's own requests; reports are read with a token that can do nothing else.
	 * A site can therefore show its statistics without the write credential being configured at all,
	 * and can send measurements without granting anybody read access to them.
	 *
	 * @return bool
	 */
	public function can_report(): bool {
		return '' !== $this->api_base_url()
			&& '' !== $this->str( 'property_id' )
			&& '' !== $this->str( 'api_token' );
	}

	/**
	 * Whether the browser tag should be printed.
	 *
	 * @return bool
	 */
	public function can_inject_tag(): bool {
		return $this->flag( 'inject_tag' )
			&& '' !== $this->str( 'measurement_id' )
			&& '' !== $this->tracker_url();
	}

	/**
	 * Whether the tag belongs at the end of the document rather than in the head.
	 *
	 * The head is what the platform recommends, because a tag that loads later measures fewer of the
	 * visitors who leave quickly. The footer is offered because on a slow site that trade is
	 * sometimes worth making.
	 *
	 * @return bool
	 */
	public function tag_in_footer(): bool {
		return 'footer' === $this->str( 'tag_location' );
	}

	/**
	 * Whether the site's own extra markup belongs at the end of the document.
	 *
	 * @return bool
	 */
	public function custom_code_in_footer(): bool {
		return 'footer' === $this->str( 'custom_code_location' );
	}

	/**
	 * Post IDs the tag must not appear on.
	 *
	 * @return int[]
	 */
	public function excluded_post_ids(): array {
		$raw = preg_split( '/[\s,]+/', $this->str( 'exclude_post_ids' ), -1, PREG_SPLIT_NO_EMPTY );
		$ids = array_map( 'absint', is_array( $raw ) ? $raw : array() );

		return array_values( array_unique( array_filter( $ids ) ) );
	}
}