<?php
/**
 * @package AKSRT
 */

namespace AKSRT\Finance;

use AKSRT\Ledger\LedgerCommand;

defined('ABSPATH') || exit;

final class FinancialFlowService {

	private const MAX_NUMBER_ATTEMPTS = 5;
	private static ?self $instance = null;

	private function __construct() {}

	public static function get_instance(): self {
		if (self::$instance === null) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	/**
	 * Persist an asset-ledger event inside the caller-owned transaction.
	 *
	 * @param array<int,array<string,mixed>> $entries
	 * @return string|\WP_Error
	 */
	public function record_ledger(LedgerCommand $command, int $transaction_id, array $entries, string $created_at) {
		$order_number = $command->ref_type === 'order' ? $command->ref_key : (string) ($command->metadata['order_number'] ?? '');
		$order = $order_number !== '' ? $this->resolve_order($order_number) : [];
		$withdrawal_number = '';
		if ($command->ref_type === 'withdraw') {
			$withdrawal_number = $this->resolve_withdrawal_number($command, $transaction_id);
		}
		$provider_transaction_id = (string) ($order['payment_transaction_id'] ?? '');

		$flow_entries = [];
		foreach ($entries as $entry) {
			$delta = (int) ($entry['delta_minor'] ?? 0);
			$flow_entries[] = [
				'user_id' => max(0, (int) ($entry['user_id'] ?? 0)),
				'asset' => sanitize_key((string) ($entry['asset'] ?? '')),
				'direction' => $delta > 0 ? 'in' : 'out',
				'entry_type' => sanitize_key((string) ($entry['entry_type'] ?? 'adjustment')),
				'delta_minor' => $delta,
				'balance_after_minor' => max(0, (int) ($entry['balance_after_minor'] ?? 0)),
				'counterparty_user_id' => max(0, (int) ($entry['counterparty_user_id'] ?? 0)),
				'remark' => (string) ($entry['remark'] ?? ''),
			];
		}
		$event_type = $command->reason;
		$metadata = $command->metadata;
		if ($order !== [] && $this->is_successful_order_payment($order, $flow_entries)) {
			$event_type = 'order_payment';
			$metadata['ledger_reason'] = $command->reason;
			if ($this->is_external_recharge($order, $flow_entries)) {
				try {
					$cash_minor = \AKSRT\Ledger\AssetAmount::balance((string) ($order['amount'] ?? ''))->minor();
				} catch (\InvalidArgumentException $e) {
					return new \WP_Error('aksrt_flow_amount', __('充值支付流水金额无效', 'aksrt'), ['status' => 500]);
				}
				$flow_entries[] = [
					'user_id' => max(0, (int) ($order['user_id'] ?? 0)),
					'asset' => 'cash',
					'direction' => 'out',
					'entry_type' => 'payment',
					'delta_minor' => -$cash_minor,
					'counterparty_user_id' => 0,
					'remark' => __('充值订单支付', 'aksrt'),
				];
			}
		}

		return $this->record([
			'operation_key' => $command->operation_key,
			'event_type' => $event_type,
			'ref_type' => $command->ref_type,
			'ref_key' => $command->ref_key,
			'order_number' => $order_number,
			'withdrawal_number' => $withdrawal_number,
			'ledger_transaction_id' => $transaction_id,
			'provider_transaction_id' => $provider_transaction_id,
			'metadata' => $metadata,
			'created_at' => $created_at,
		], $flow_entries, true);
	}

	/** @return string|\WP_Error */
	public function record_order_payment(array $order, bool $caller_transaction = false) {
		return $this->record_order_event($order, 'order_payment', -1, $caller_transaction);
	}

	/** @return string|\WP_Error */
	public function record_order_refund(array $order, bool $caller_transaction = false) {
		return $this->record_order_event($order, 'order_refund', 1, $caller_transaction);
	}

	/**
	 * 记录卡密核销产生的订单支付流水。
	 *
	 * 卡密是平台自发的预付凭证：核销那一刻既没有第三方现金流入，也不产生账本资产分录，
	 * 订单金额还可能为 0（会员卡）或以积分计价（积分卡）。因此这里只落一条与订单关联的
	 * order_payment 流水，不生成任何现金/资产分录，让订单在详情页具备可追溯的「账本流水号」。
	 *
	 * 余额卡与积分卡的核销走账本（LedgerService::credit），其流水由 record_ledger() 落库；
	 * 本方法供会员卡这类无账本参与的卡种调用。
	 *
	 * @param array<string,mixed> $order
	 * @return string|\WP_Error
	 */
	public function record_card_pass_payment(array $order, bool $caller_transaction = false) {
		return $this->record_order_event($order, 'order_payment', -1, $caller_transaction, true);
	}

	/**
	 * 把账本流水挂到卡密核销订单上（订单号 + 渠道交易号 + 事件类型归一）。
	 *
	 * 卡密核销的资产入账走账本，但订单号是随机生成的、不能进 LedgerCommand
	 * （payload_hash 覆盖 metadata，塞入随机号会破坏账本幂等重放）。因此账本
	 * 提交之后再调用本方法补挂关联；同时把 event_type 归一为 order_payment，
	 * 让订单详情页的「账本流水号」能反查到它。
	 *
	 * @return bool 是否发生了更新
	 */
	public function attach_order_to_ledger_flow(int $ledger_transaction_id, string $order_number, string $provider_transaction_id = ''): bool {
		global $wpdb;
		if ($ledger_transaction_id <= 0 || $order_number === '') {
			return false;
		}
		$order_number = substr(sanitize_text_field($order_number), 0, 32);
		$order = $wpdb->get_row($wpdb->prepare(
			"SELECT status, payment_method, payment_transaction_id FROM {$this->order_table()} WHERE order_number = %s LIMIT 1",
			$order_number
		), ARRAY_A);
		if (!is_array($order)
			|| sanitize_key((string) ($order['status'] ?? '')) !== \AKSRT\Payment\Order::STATUS_PAID
			|| sanitize_key((string) ($order['payment_method'] ?? '')) !== 'card_pass'
		) {
			return false;
		}
		if ($provider_transaction_id === '') {
			$provider_transaction_id = (string) ($order['payment_transaction_id'] ?? '');
		}
		$updated = $wpdb->query($wpdb->prepare(
			"UPDATE {$this->flow_table()}
			 SET order_number = %s,
			     provider_transaction_id = CASE WHEN provider_transaction_id IS NULL OR provider_transaction_id = '' THEN %s ELSE provider_transaction_id END,
			     event_type = 'order_payment'
			 WHERE ledger_transaction_id = %d AND (order_number IS NULL OR order_number = '')",
			$order_number,
			substr(sanitize_text_field($provider_transaction_id), 0, 128),
			$ledger_transaction_id
		));
		return $updated === 1;
	}

	private function order_table(): string {
		return \AKSRT\Core\DBMigrator::table('order');
	}

	/** @return string|\WP_Error */
	public function record_withdrawal_payout(array $withdrawal, string $operation_key, string $created_at, bool $caller_transaction = false) {
		$user_id = max(0, (int) ($withdrawal['user_id'] ?? 0));
		$number = sanitize_text_field((string) ($withdrawal['withdrawal_number'] ?? ''));
		try {
			$amount_minor = \AKSRT\Ledger\AssetAmount::balance((string) ($withdrawal['amount'] ?? ''))->minor();
		} catch (\InvalidArgumentException $e) {
			return new \WP_Error('aksrt_flow_amount', __('提现流水金额无效', 'aksrt'), ['status' => 500]);
		}

		return $this->record([
			'operation_key' => $operation_key,
			'event_type' => 'withdraw_payout',
			'ref_type' => 'withdraw',
			'ref_key' => $number,
			'withdrawal_number' => $number,
			'metadata' => ['method' => sanitize_key((string) ($withdrawal['method'] ?? ''))],
			'created_at' => $created_at,
		], [[
			'user_id' => $user_id,
			'asset' => 'cash',
			'direction' => 'in',
			'entry_type' => 'payout',
			'delta_minor' => $amount_minor,
			'remark' => __('提现打款完成', 'aksrt'),
		]], $caller_transaction);
	}

	/**
	 * @param array<string,mixed> $flow
	 * @param array<int,array<string,mixed>> $entries
	 * @param bool $allow_empty_entries 卡密核销等「无现金/资产分录」的凭证型流水，允许分录为空。
	 * @return string|\WP_Error
	 */
	private function record(array $flow, array $entries, bool $caller_transaction, bool $allow_empty_entries = false) {
		global $wpdb;
		$operation_key = substr(sanitize_text_field((string) ($flow['operation_key'] ?? '')), 0, 191);
		$event_type = sanitize_key((string) ($flow['event_type'] ?? ''));
		if ($operation_key === '' || $event_type === '' || ($entries === [] && !$allow_empty_entries)) {
			return new \WP_Error('aksrt_flow_invalid', __('资金流水参数无效', 'aksrt'), ['status' => 500]);
		}

		$prepared_entries = $this->prepare_entries($entries);
		if (is_wp_error($prepared_entries)) {
			return $prepared_entries;
		}

		$existing = $this->number_for_operation($operation_key);
		if ($existing !== '') {
			return $existing;
		}
		$owns_transaction = !$caller_transaction;
		if ($owns_transaction && $wpdb->query('START TRANSACTION') === false) {
			return new \WP_Error('aksrt_flow_db', __('无法开启资金流水事务', 'aksrt'), ['status' => 500]);
		}

		$flow_id = 0;
		$flow_number = '';
		for ($attempt = 1; $attempt <= self::MAX_NUMBER_ATTEMPTS; $attempt++) {
			$flow_number = BusinessNumber::allocate();
			$metadata = is_array($flow['metadata'] ?? null) ? $flow['metadata'] : [];
			$inserted = $wpdb->insert($this->flow_table(), [
				'flow_number' => $flow_number,
				'operation_key' => $operation_key,
				'event_type' => $event_type,
				'ref_type' => ($flow['ref_type'] ?? '') !== '' ? sanitize_key((string) $flow['ref_type']) : null,
				'ref_key' => ($flow['ref_key'] ?? '') !== '' ? substr(sanitize_text_field((string) $flow['ref_key']), 0, 191) : null,
				'order_number' => ($flow['order_number'] ?? '') !== '' ? substr(sanitize_text_field((string) $flow['order_number']), 0, 32) : null,
				'withdrawal_number' => ($flow['withdrawal_number'] ?? '') !== '' ? substr(sanitize_text_field((string) $flow['withdrawal_number']), 0, 32) : null,
				'ledger_transaction_id' => max(0, (int) ($flow['ledger_transaction_id'] ?? 0)) ?: null,
				'provider_transaction_id' => ($flow['provider_transaction_id'] ?? '') !== '' ? substr(sanitize_text_field((string) $flow['provider_transaction_id']), 0, 128) : null,
				'metadata' => $metadata !== [] ? wp_json_encode($metadata, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) : null,
				'created_at' => (string) ($flow['created_at'] ?? self::utc_now()),
			], ['%s', '%s', '%s', '%s', '%s', '%s', '%s', '%d', '%s', '%s', '%s']);
			if ($inserted === 1) {
				$flow_id = (int) $wpdb->insert_id;
				break;
			}
			$existing = $this->number_for_operation($operation_key);
			if ($existing !== '') {
				if ($owns_transaction) {
					$wpdb->query('ROLLBACK');
				}
				return $existing;
			}
		}
		if ($flow_id <= 0) {
			if ($owns_transaction) {
				$wpdb->query('ROLLBACK');
			}
			return new \WP_Error('aksrt_flow_number', __('无法生成唯一流水号', 'aksrt'), ['status' => 500]);
		}

		foreach ($prepared_entries as $index => $entry) {
			$inserted = $wpdb->insert($this->entry_table(), [
				'flow_id' => $flow_id,
				'line_no' => $index + 1,
				'user_id' => max(0, (int) ($entry['user_id'] ?? 0)),
				'asset' => $entry['asset'],
				'direction' => $entry['direction'],
				'entry_type' => substr(sanitize_key((string) ($entry['entry_type'] ?? 'adjustment')), 0, 32),
				'delta_minor' => $entry['delta_minor'],
				'balance_after_minor' => $entry['balance_after_minor'],
				'counterparty_user_id' => max(0, (int) ($entry['counterparty_user_id'] ?? 0)) ?: null,
				'remark' => ($entry['remark'] ?? '') !== '' ? substr(sanitize_text_field((string) $entry['remark']), 0, 255) : null,
			], ['%d', '%d', '%d', '%s', '%s', '%s', '%d', '%d', '%d', '%s']);
			if ($inserted !== 1) {
				if ($owns_transaction) {
					$wpdb->query('ROLLBACK');
				}
				return new \WP_Error('aksrt_flow_entry', __('资金流水分录写入失败', 'aksrt'), ['status' => 500]);
			}
		}
		if ($owns_transaction && $wpdb->query('COMMIT') === false) {
			$wpdb->query('ROLLBACK');
			return new \WP_Error('aksrt_flow_db', __('资金流水提交失败', 'aksrt'), ['status' => 500]);
		}

		return $flow_number;
	}

	/**
	 * Validate every entry before the flow head is inserted.
	 *
	 * @param array<int,array<string,mixed>> $entries
	 * @return array<int,array<string,mixed>>|\WP_Error
	 */
	private function prepare_entries(array $entries) {
		$prepared = [];
		foreach (array_values($entries) as $entry) {
			$delta = (int) ($entry['delta_minor'] ?? 0);
			$asset = sanitize_key((string) ($entry['asset'] ?? ''));
			$direction = sanitize_key((string) ($entry['direction'] ?? ($delta > 0 ? 'in' : 'out')));
			if (!in_array($asset, ['cash', 'balance', 'points'], true) || $delta === 0) {
				return new \WP_Error('aksrt_flow_entry', __('资金流水分录无效', 'aksrt'), ['status' => 500]);
			}
			if (!in_array($direction, ['in', 'out'], true) || ($delta > 0) !== ($direction === 'in')) {
				return new \WP_Error('aksrt_flow_entry', __('资金流水方向无效', 'aksrt'), ['status' => 500]);
			}
			$prepared[] = [
				'user_id' => max(0, (int) ($entry['user_id'] ?? 0)),
				'asset' => $asset,
				'direction' => $direction,
				'entry_type' => substr(sanitize_key((string) ($entry['entry_type'] ?? 'adjustment')), 0, 32),
				'delta_minor' => $delta,
				'balance_after_minor' => array_key_exists('balance_after_minor', $entry) ? max(0, (int) $entry['balance_after_minor']) : null,
				'counterparty_user_id' => max(0, (int) ($entry['counterparty_user_id'] ?? 0)) ?: null,
				'remark' => ($entry['remark'] ?? '') !== '' ? substr(sanitize_text_field((string) $entry['remark']), 0, 255) : null,
			];
		}
		return $prepared;
	}

	public function number_for_operation(string $operation_key): string {
		global $wpdb;
		return (string) $wpdb->get_var($wpdb->prepare(
			"SELECT flow_number FROM {$this->flow_table()} WHERE operation_key = %s LIMIT 1",
			$operation_key
		));
	}

	public function number_for_ledger_transaction(int $transaction_id): string {
		global $wpdb;
		if ($transaction_id <= 0) {
			return '';
		}
		return (string) $wpdb->get_var($wpdb->prepare(
			"SELECT flow_number FROM {$this->flow_table()} WHERE ledger_transaction_id = %d LIMIT 1",
			$transaction_id
		));
	}

	/**
	 * @param array<string,mixed> $order
	 * @param bool $voucher_settled 凭证结算（卡密核销）：订单可能为 0 元或以积分计价，
	 *                              且没有任何现金/资产分录，故跳过金额与资产口径校验。
	 */
	private function record_order_event(array $order, string $event_type, int $sign, bool $caller_transaction, bool $voucher_settled = false) {
		$order_number = substr(sanitize_text_field((string) ($order['order_number'] ?? '')), 0, 32);
		$user_id = max(0, (int) ($order['user_id'] ?? 0));
		if ($order_number === '') {
			return new \WP_Error('aksrt_flow_order', __('订单流水参数无效', 'aksrt'), ['status' => 500]);
		}
		$existing = $this->number_for_order_event($order_number, $event_type);
		if ($existing !== '') {
			return $existing;
		}
		$payment_method = sanitize_key((string) ($order['payment_method'] ?? ''));
		$currency = sanitize_key((string) ($order['currency'] ?? 'CNY'));
		$metadata = [
			'payment_method' => $payment_method,
			'currency' => $currency,
		];
		$entries = [];
		if ($voucher_settled) {
			// 卡密核销：凭证本身即支付凭据，订单金额可能为 0、也可能以积分计价，
			// 因此不做金额校验、也不生成现金分录；流水行即该订单的支付凭证
			// （订单详情页经 FinancialFlowQuery::order_payment_number() 反查得到）。
			$metadata['voucher'] = 'card_pass';
		} else {
			if (in_array($payment_method, ['balance', 'points'], true) || $currency === 'points') {
				return new \WP_Error('aksrt_flow_order_asset', __('余额或积分订单必须通过资产账本确认', 'aksrt'), ['status' => 500]);
			}
			try {
				$amount_minor = \AKSRT\Ledger\AssetAmount::balance((string) ($order['amount'] ?? ''))->minor();
			} catch (\InvalidArgumentException $e) {
				return new \WP_Error('aksrt_flow_amount', __('订单流水金额无效', 'aksrt'), ['status' => 500]);
			}
			if ($amount_minor <= 0) {
				return new \WP_Error('aksrt_flow_amount', __('订单流水金额无效', 'aksrt'), ['status' => 500]);
			}
			$entries[] = [
				'user_id' => $user_id,
				'asset' => 'cash',
				'direction' => $sign > 0 ? 'in' : 'out',
				'entry_type' => $event_type === 'order_payment' ? 'payment' : 'refund',
				'delta_minor' => $sign * $amount_minor,
				'remark' => $event_type === 'order_payment' ? __('订单支付', 'aksrt') : __('订单退款', 'aksrt'),
			];
		}
		$operation_key = \AKSRT\Ledger\OperationKey::deterministic(
			$event_type === 'order_payment' ? 'order-payment' : 'order-refund',
			[$order_number]
		);
		return $this->record([
			'operation_key' => $operation_key,
			'event_type' => $event_type,
			'ref_type' => 'order',
			'ref_key' => $order_number,
			'order_number' => $order_number,
			'provider_transaction_id' => (string) ($order['payment_transaction_id'] ?? ''),
			'metadata' => $metadata,
			'created_at' => self::utc_now(),
		], $entries, $caller_transaction, $voucher_settled);
	}

	private function number_for_order_event(string $order_number, string $event_type): string {
		global $wpdb;
		return (string) $wpdb->get_var($wpdb->prepare(
			"SELECT flow_number FROM {$this->flow_table()} WHERE order_number = %s AND event_type = %s ORDER BY id ASC LIMIT 1",
			$order_number,
			$event_type
		));
	}

	private function resolve_withdrawal_number(LedgerCommand $command, int $transaction_id): string {
		global $wpdb;
		$table = \AKSRT\Core\DBMigrator::table('withdrawal');
		$withdrawal_id = max(0, (int) ($command->metadata['withdrawal_id'] ?? 0));
		if ($withdrawal_id <= 0 && ctype_digit($command->ref_key)) {
			$withdrawal_id = (int) $command->ref_key;
		}
		if ($withdrawal_id > 0) {
			return (string) $wpdb->get_var($wpdb->prepare("SELECT withdrawal_number FROM {$table} WHERE id = %d LIMIT 1", $withdrawal_id));
		}
		return (string) $wpdb->get_var($wpdb->prepare("SELECT withdrawal_number FROM {$table} WHERE ledger_transaction_id = %d LIMIT 1", $transaction_id));
	}

	/** @return array<string,mixed> */
	private function resolve_order(string $order_number): array {
		global $wpdb;
		$table = \AKSRT\Core\DBMigrator::table('order');
		$row = $wpdb->get_row($wpdb->prepare(
			"SELECT order_number, user_id, product_type, amount, currency, status, payment_method, payment_transaction_id FROM {$table} WHERE order_number = %s LIMIT 1",
			$order_number
		), ARRAY_A);
		return is_array($row) ? $row : [];
	}

	/** @param array<string,mixed> $order @param array<int,array<string,mixed>> $entries */
	private function is_successful_order_payment(array $order, array $entries): bool {
		if (sanitize_key((string) ($order['status'] ?? '')) !== \AKSRT\Payment\Order::STATUS_PAID) {
			return false;
		}
		// card_pass：卡密即支付凭据，订单已支付就说明凭证已结算，不依赖现金或资产分录为凭。
		// 余额卡/积分卡的核销因此也能落成 order_payment 流水，与普通订单同口径。
		if (sanitize_key((string) ($order['payment_method'] ?? '')) === 'card_pass') {
			return true;
		}
		$buyer_id = max(0, (int) ($order['user_id'] ?? 0));
		foreach ($entries as $entry) {
			if ((int) ($entry['user_id'] ?? 0) === $buyer_id && (int) ($entry['delta_minor'] ?? 0) < 0) {
				return true;
			}
		}
		return $this->is_external_recharge($order, $entries);
	}

	/** @param array<string,mixed> $order @param array<int,array<string,mixed>> $entries */
	private function is_external_recharge(array $order, array $entries): bool {
		$method = sanitize_key((string) ($order['payment_method'] ?? ''));
		// 这些方式都在平台内部结算，核销当下没有第三方现金流入：balance / points 以已有资产支付，
		// card_pass 以平台自发凭证支付（现金在售卡时已确认），故都不生成现金分录。
		if (sanitize_key((string) ($order['product_type'] ?? '')) !== \AKSRT\Core\DomainModel::ORDER_PRODUCT_RECHARGE
			|| in_array($method, ['', 'balance', 'points', 'card_pass'], true)
		) {
			return false;
		}
		$buyer_id = max(0, (int) ($order['user_id'] ?? 0));
		foreach ($entries as $entry) {
			if ((int) ($entry['user_id'] ?? 0) === $buyer_id && (string) ($entry['asset'] ?? '') === 'balance' && (int) ($entry['delta_minor'] ?? 0) > 0) {
				return true;
			}
		}
		return false;
	}

	private function flow_table(): string {
		return \AKSRT\Core\DBMigrator::table('financial_flow');
	}

	private function entry_table(): string {
		return \AKSRT\Core\DBMigrator::table('financial_flow_entry');
	}

	private static function utc_now(): string {
		return (new \DateTimeImmutable('now', new \DateTimeZone('UTC')))->format('Y-m-d H:i:s.u');
	}

}