<?php

namespace WPO\IPS\EDI;

use WPO\IPS\Documents\OrderDocument;

if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly
}

class Document {

	public string $syntax;
	public string $format;
	public OrderDocument $order_document;
	public \WC_Abstract_Order $order;
	public array $order_tax_data;
	public ?object $format_document;
	public string $output;

	/**
	 * Constructor
	 *
	 * @param string $syntax
	 * @param string $format
	 * @param OrderDocument $order_document
	 */
	public function __construct( string $syntax, string $format, OrderDocument $order_document ) {
		$this->syntax          = $syntax;
		$this->format          = $format;
		$this->order_document  = $order_document;
		$this->order           = $this->order_document->order;
		$this->order_tax_data  = $this->get_tax_rates();
		$this->format_document = $this->get_format_document();

		if ( ! $this->format_document ) {
			$error = sprintf( 'Format "%s" for syntax "%s" is not available.', $format, $syntax );
			wpo_ips_edi_log( $error, 'critical' );
			throw new \Exception( esc_html( $error ) );
		}
	}

	/**
	 * Get the format document instance
	 *
	 * @return object|null
	 */
	public function get_format_document(): ?object {
		$format        = wpo_ips_edi_syntax_formats( $this->syntax, $this->format );
		$document_type = $this->order_document->get_type();

		if ( ! $format ) {
			wpo_ips_edi_log(
				sprintf(
					'Format "%s" for syntax "%s" is not available.',
					$this->format,
					$this->syntax
				),
				'critical'
			);
			return null;
		}

		if ( ! in_array( $document_type, array_keys( $format['documents'] ) ) ) {
			wpo_ips_edi_log(
				sprintf(
					'Document type "%s" is not supported for format "%s".',
					$document_type,
					$this->format
				),
				'critical'
			);
			return null;
		}

		return new $format['documents'][ $document_type ]();
	}

	/**
	 * Get the document structure
	 *
	 * @return array|false
	 */
	public function get_structure() {
		$structure = apply_filters(
			'wpo_ips_edi_document_structure',
			$this->format_document->get_structure(),
			$this
		);

		if ( empty( $structure ) ) {
			wpo_ips_edi_log( 'Document structure is empty.', 'error' );
			return false;
		}

		foreach ( $structure as $key => $element ) {
			if ( false === ( $element['enabled'] ?? true ) ) {
				unset( $structure[ $key ] );
			}
		}

		return $structure;
	}

	/**
	 * Get the document type code
	 *
	 * @return string
	 */
	public function get_type_code(): string {
		return apply_filters(
			'wpo_ips_edi_document_type_code',
			$this->format_document->get_type_code(),
			$this
		);
	}

	/**
	 * Get the document quantity role (UBL formats only)
	 *
	 * @return string
	 */
	public function get_quantity_role(): string {
		return apply_filters(
			'wpo_ips_edi_document_quantity_role',
			is_callable( array( $this->format_document, 'get_quantity_role' ) )
				? $this->format_document->get_quantity_role()
				: '',
			$this
		);
	}

	/**
	 * Get the document root element
	 *
	 * @return string
	 */
	public function get_root_element(): string {
		return apply_filters(
			'wpo_ips_edi_document_root_element',
			$this->format_document->get_root_element(),
			$this
		);
	}

	/**
	 * Get the document additional attributes
	 *
	 * @return array
	 */
	public function get_additional_attributes(): array {
		return apply_filters(
			'wpo_ips_edi_document_additional_attributes',
			$this->format_document->get_additional_attributes(),
			$this
		);
	}

	/**
	 * Get the document namespaces
	 *
	 * @return array
	 */
	public function get_namespaces(): array {
		return apply_filters(
			'wpo_ips_edi_document_namespaces',
			$this->format_document->get_namespaces(),
			$this
		);
	}

	/**
	 * Assemble the element list for the XML writer.
	 *
	 * Works for both UBL and CII syntaxes:
	 *
	 * • If a handler sets `options[root]`, its output is wrapped in that tag
	 *   (e.g. `cac:AccountingSupplierParty`, `ram:SupplyChainTradeTransaction`).
	 * • Without a root option, the fragment is written directly under the
	 *   document root.
	 * • The order of handlers in `get_structure()` is preserved, so the final
	 *   sequence respects the schema of either standard.
	 *
	 * @return array Structured data ready for the XML builder.
	 */
	public function get_data(): array {
		$data_by_root = array();
		$structure    = $this->get_structure();

		if ( ! $structure ) {
			return array();
		}

		foreach ( $structure as $key => $value ) {
			// skip disabled or mis-configured entries
			if ( empty( $value['enabled'] ) || empty( $value['handler'] ) ) {
				continue;
			}

			$options   = $value['options'] ?? array();
			$handlers  = is_array( $value['handler'] ) ? $value['handler'] : array( $value['handler'] );
			$root_name = $options['root'] ?? null;
			$fragment  = array();

			foreach ( $handlers as $handler_class ) {
				if ( ! class_exists( $handler_class ) ) {
					wpo_ips_edi_log( sprintf(
						'Handler class does not exist: %s',
						$handler_class
					), 'error' );
					continue;
				}

				try {
					$handler  = new $handler_class( $this );
					$fragment = $handler->handle( $fragment, $options );
				} catch ( \Throwable $e ) {
					wpo_ips_edi_log( sprintf(
						'Failed handler: %s',
						$handler_class
					), 'error', $e );
					continue;
				}
			}

			if ( $root_name ) {
				// merge with any previous output for the same root
				if ( ! isset( $data_by_root[ $root_name ] ) ) {
					$data_by_root[ $root_name ] = array();
				}
				$data_by_root[ $root_name ] = array_merge( $data_by_root[ $root_name ], $fragment );
			} else {
				// append root-less fragment under a *numeric* key -> preserves order
				$data_by_root[] = $fragment;
			}
		}

		$data = array();

		foreach ( $data_by_root as $root => $value ) {
			if ( is_string( $root ) ) {
				// named root -> wrap
				$data[] = array(
					'name'  => $root,
					'value' => $value,
				);
			} else {
				// numeric key -> flatten directly
				$data = array_merge( $data, $value );
			}
		}

		return apply_filters( 'wpo_ips_edi_document_data', $data, $this );
	}

	/**
	 * Get tax rates
	 *
	 * @return array
	 */
	public function get_tax_rates(): array {
		$order_tax_data = array();
		$items          = $this->order->get_items( array( 'fee', 'line_item', 'shipping' ) );

		// Build the tax totals array
		foreach ( $items as $item_id => $item ) {
			$type  = $item->get_type();
			$taxes = $item->get_taxes();

			// For EN16931/Peppol VAT breakdown rules we need the taxable base AFTER discounts.
			$bucket        = 'total';
			$line_total_ex = (float) $item->get_total();

			$rows = ( isset( $taxes[ $bucket ] ) && is_array( $taxes[ $bucket ] ) ) ? $taxes[ $bucket ] : array();

			// Nothing taxable on this item.
			if ( empty( $rows ) ) {
				continue;
			}

			foreach ( $rows as $tax_id => $tax_amt ) {
				if ( ! is_numeric( $tax_amt ) ) {
					continue;
				}

				$tax_id  = (int) $tax_id;
				$tax_amt = (float) $tax_amt;

				if ( empty( $order_tax_data[ $tax_id ] ) ) {
					$order_tax_data[ $tax_id ] = array(
						'total_ex'  => $line_total_ex,
						'total_tax' => $tax_amt,
						'items'     => array( $item_id ),
					);
				} else {
					$order_tax_data[ $tax_id ]['total_ex']  += $line_total_ex;
					$order_tax_data[ $tax_id ]['total_tax'] += $tax_amt;
					$order_tax_data[ $tax_id ]['items'][]    = $item_id;
				}
			}
		}

		$tax_items = $this->order->get_items( array( 'tax' ) );

		if ( empty( $tax_items ) ) {
			return $order_tax_data;
		}

		$use_historical_settings = $this->order_document->use_historical_settings();

		// Loop through all the tax items...
		foreach ( $order_tax_data as $tax_data_key => $tax_data ) {
			$percentage = 0;
			$category   = '';
			$scheme     = '';
			$reason     = '';
			$name       = '';

			foreach ( $tax_items as $tax_item_key => $tax_item ) {
				if ( $tax_item['rate_id'] !== $tax_data_key ) {
					continue;
				}

				// We use the tax total from the tax item because this
				// takes into account possible line item rounding settings as well
				// we still apply rounding on the total (for non-checkout orders)
				$order_tax_data[ $tax_data_key ]['total_tax'] = wc_round_tax_total( $tax_item['tax_amount'] ) + wc_round_tax_total( $tax_item['shipping_tax_amount'] );

				if ( is_callable( array( $tax_item, 'get_rate_percent' ) ) && version_compare( '3.7.0', $this->order->get_version(), '>=' ) ) {
					$percentage = $tax_item->get_rate_percent();
				} else {
					$percentage = wc_get_order_item_meta( $tax_item_key, '_wcpdf_rate_percentage', true );
				}

				$tax_rate_id = absint( $tax_item['rate_id'] );

				if ( ! is_numeric( $percentage ) ) {
					$percentage = $this->get_percentage_from_fallback( $tax_data, $tax_rate_id );
					wc_update_order_item_meta( $tax_item_key, '_wcpdf_rate_percentage', wc_format_decimal( $percentage, 2, false ) );
				}

				$fields = array( 'category', 'scheme', 'reason' );

				foreach ( $fields as $field ) {
					$meta_key = '_wpo_ips_edi_tax_' . $field;
					$value    = wc_get_order_item_meta( $tax_item_key, $meta_key, true );

					// If the value is empty, try to get it from legacy meta key
					if ( empty( $value ) ) {
						$legacy_meta_key = '_wcpdf_ubl_tax_' . $field;
						$value           = wc_get_order_item_meta( $tax_item_key, $legacy_meta_key, true ) ?: $value;

						if ( ! empty( $value ) ) {
							wc_delete_order_item_meta( $tax_item_key, $legacy_meta_key );
						}
					}

					if ( empty( $value ) || 'default' === $value || ! $use_historical_settings ) {
						$value = wpo_ips_edi_get_tax_data_from_fallback( $field, $tax_rate_id, $this->order );
					}

					if ( $use_historical_settings ) {
						wc_update_order_item_meta( $tax_item_key, $meta_key, $value );
					}

					${$field} = $value;
				}

				$name = ! empty( $tax_item['label'] ) ? $tax_item['label'] : $tax_item['name'];
			}

			// Normalize tiny float residue and keep numbers as numbers.
			$order_tax_data[ $tax_data_key ]['total_ex']   = (float) wc_format_decimal( $order_tax_data[ $tax_data_key ]['total_ex'] ?? 0.0, 2, false );
			$order_tax_data[ $tax_data_key ]['total_tax']  = (float) wc_format_decimal( $order_tax_data[ $tax_data_key ]['total_tax'] ?? 0.0, 2, false );

			$order_tax_data[ $tax_data_key ]['percentage'] = $percentage;
			$order_tax_data[ $tax_data_key ]['category']   = $category;
			$order_tax_data[ $tax_data_key ]['scheme']     = $scheme;
			$order_tax_data[ $tax_data_key ]['reason']     = $reason;
			$order_tax_data[ $tax_data_key ]['name']       = $name;
		}

		return $order_tax_data;
	}

	/**
	 * Get percentage from fallback
	 *
	 * @param array $tax_data
	 * @param int   $rate_id
	 * @return float|int
	 */
	public function get_percentage_from_fallback( array $tax_data, int $rate_id ) {
		$percentage = ( 0 != $tax_data['total_ex'] )
			? ( $tax_data['total_tax'] / $tax_data['total_ex'] ) * 100
			: 0;

		if ( class_exists( '\WC_TAX' ) && is_callable( array( '\WC_TAX', '_get_tax_rate' ) ) ) {
			$tax_rate = \WC_Tax::_get_tax_rate( $rate_id, OBJECT );

			if ( ! empty( $tax_rate ) && is_numeric( $tax_rate->tax_rate ) ) {
				$rate_value  = (float) $tax_rate->tax_rate;
				$decimals    = wc_get_price_decimals();
				$rounded_tax = wc_round_tax_total( (float) $tax_data['total_tax'] );
				$expected    = wc_round_tax_total( (float) $tax_data['total_ex'] * $rate_value / 100 );

				// Tolerances
				$amount_tolerance  = 0.01;      // one cent tolerance on totals
				$percent_tolerance = max( 0.05, // floor tolerance in percentage points
					( $tax_data['total_ex'] > 0 ? ( $amount_tolerance / (float) $tax_data['total_ex'] * 100 ) * 2 : 0 )
				);

				$amount_diff  = abs( $rounded_tax - $expected );
				$percent_diff = abs( (float) $percentage - $rate_value );

				if ( $amount_diff <= $amount_tolerance || $percent_diff <= $percent_tolerance ) {
					$percentage = $rate_value;
				}
			}
		}

		return $percentage;
	}

}