<?php
/**
 * AF Translate — PO Gettext Parser & Compiler Processor
 * Refactored to guarantee structural array index uniformity across all context lifecycles.
 *
 * @package af-translate
 */

if ( ! defined( 'ABSPATH' ) ) { 
    exit; 
}

class AF_Translate_PO_Processor {

    /**
     * Fallback utility to safely guarantee a variable behaves as a clean string.
     */
    public static function ensure_string( $input ) {
        if ( is_array( $input ) ) {
            return implode( ' ', array_map( array( __CLASS__, 'ensure_string' ), $input ) );
        }
        return (string) $input;
    }

    /**
     * Cleans raw PO lines, strips msgid/msgstr prefixes without destroying duplicate phrases.
     */
    public static function clean_po_line( $line, $prefix ) {
        if ( is_array( $line ) ) {
            return '';
        }
        
        $line = trim( (string) $line );
        
        if ( ! empty( $prefix ) && 0 === strpos( $line, $prefix ) ) {
            $line = trim( substr( $line, strlen( $prefix ) ) );
        }

        $line = trim( $line, '"' );
        $parts = preg_split( '/"\s+"/', $line );
        
        if ( is_array( $parts ) && ! empty( $parts ) ) {
            $string_parts = array_map( 'strval', $parts );
            $line = implode( '', $string_parts );
        }

        return stripcslashes( $line );
    }

    /**
     * Escapes real control characters back into explicit, safe Gettext string syntax.
     */
    public static function safe_escape_gettext( $value ) {
        $value = self::ensure_string( $value );
        
        $value = str_replace( '\\', '\\\\', $value );
        $value = str_replace( '"', '\"', $value );
        $value = str_replace( "\n", '\\n', $value );
        $value = str_replace( "\r", '\\r', $value );
        $value = str_replace( "\t", '\\t', $value );
        
        return $value;
    }

    /**
     * Parses baseline target PO files into structured internal associative arrays.
     * Fixed: Removed dynamic, non-deterministic action-name context matching to keep indexes safe.
     *
     * @param string $po_file     Absolute filesystem road path to target file asset.
     * @param bool   $skip_header Set to true inside UI view loops to automatically filter away configuration metadata.
     */
    public static function parse_file( $po_file, $skip_header = false ) {
        $strings = array();
        
        if ( empty( $po_file ) || ! file_exists( $po_file ) || ! is_readable( $po_file ) ) {
            return $strings;
        }

        $file_lines = file( $po_file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES );
        $current_entry = array( 'msgctxt' => '', 'msgid' => '', 'msgid_plural' => '', 'msgstr' => array() );
        $parsing_state = ''; 
        $current_str_index = 0;

        foreach ( $file_lines as $line ) {
            $line = trim( self::ensure_string( $line ) );

            if ( empty( $line ) || 0 === strpos( $line, '#' ) ) {
                continue;
            }

            if ( 0 === strpos( $line, 'msgctxt' ) ) {
                if ( ! empty( $current_entry['msgid'] ) || ( '' === $current_entry['msgid'] && ! empty( $current_entry['msgstr'][0] ) ) ) {
                    $strings[] = $current_entry;
                    $current_entry = array( 'msgctxt' => '', 'msgid' => '', 'msgid_plural' => '', 'msgstr' => array() );
                }
                $current_entry['msgctxt'] = self::clean_po_line( $line, 'msgctxt' );
                $parsing_state = 'CTXT';
                continue;
            }

            if ( 0 === strpos( $line, 'msgid_plural' ) ) {
                $current_entry['msgid_plural'] = self::clean_po_line( $line, 'msgid_plural' );
                $parsing_state = 'PLURAL';
                continue;
            }

            if ( 0 === strpos( $line, 'msgid' ) ) {
                if ( ! empty( $current_entry['msgid'] ) || ( '' === $current_entry['msgid'] && ! empty( $current_entry['msgstr'][0] ) ) ) {
                    $strings[] = $current_entry;
                    $current_entry = array( 'msgctxt' => '', 'msgid' => '', 'msgid_plural' => '', 'msgstr' => array() );
                }
                $current_entry['msgid'] = self::clean_po_line( $line, 'msgid' );
                $parsing_state = 'ID';
                continue;
            }

            if ( 0 === strpos( $line, 'msgstr' ) ) {
                if ( preg_match( '/^msgstr\[(\d+)\]/', $line, $matches ) ) {
                    $current_str_index = (int) $matches[1];
                    $current_entry['msgstr'][$current_str_index] = self::clean_po_line( $line, "msgstr[{$current_str_index}]" );
                } else {
                    $current_str_index = 0;
                    $current_entry['msgstr'][$current_str_index] = self::clean_po_line( $line, 'msgstr' );
                }
                $parsing_state = 'STR';
                continue;
            }

            if ( 0 === strpos( $line, '"' ) ) {
                $cleaned_append = self::clean_po_line( $line, '' );
                if ( 'ID' === $parsing_state ) {
                    $current_entry['msgid'] .= $cleaned_append;
                } elseif ( 'PLURAL' === $parsing_state ) {
                    $current_entry['msgid_plural'] .= $cleaned_append;
                } elseif ( 'CTXT' === $parsing_state ) {
                    $current_entry['msgctxt'] .= $cleaned_append;
                } elseif ( 'STR' === $parsing_state ) {
                    $current_entry['msgstr'][$current_str_index] .= $cleaned_append;
                }
            }
        }

        if ( ! empty( $current_entry['msgid'] ) || ( '' === $current_entry['msgid'] && ! empty( $current_entry['msgstr'][0] ) ) ) {
            $strings[] = $current_entry;
        }

        // Keep translation elements and predictably filter based ONLY on explicit method invocation parameters.
        return array_values( array_filter( $strings, function( $item ) use ( $skip_header ) {
            $is_header_node = ( '' === $item['msgid'] && '' === trim( (string) $item['msgctxt'] ) );
            
            if ( $is_header_node && $skip_header ) {
                return false;
            }

            return ( '' !== $item['msgid'] ) || ( '' === $item['msgid'] && ! empty( $item['msgstr'][0] ) );
        }));
    }

    /**
     * Compiles data array state changes back into a standardized Gettext string layout payload.
     */
    public static function generate_po_string( $strings ) {
        $output = "# Generated securely via AF Translate Workspace Engine Matrix\n";
        
        $header_node       = null;
        $translation_nodes = array();
        
        foreach ( $strings as $node ) {
            if ( ! isset( $node['msgid'] ) ) { 
                continue; 
            }
            if ( '' === $node['msgid'] ) {
                if ( ! empty( $node['msgstr'][0] ) || ! empty( $node['msgstr'] ) ) {
                    $header_node = $node;
                }
            } else {
                $translation_nodes[] = $node;
            }
        }

        // Always prioritize writing the original system structural header node first
        if ( $header_node ) {
            $output .= "msgid \"\"\n";
            $msgstr_val = is_array( $header_node['msgstr'] ) ? reset( $header_node['msgstr'] ) : $header_node['msgstr'];
            
            $lines = explode( "\n", trim( $msgstr_val ) );
            $output .= "msgstr \"\"\n";
            foreach ( $lines as $line ) {
                if ( '' === $line ) {
                    continue;
                }
                $clean_line = rtrim( $line, '\\n' );
                $escaped_line = self::safe_escape_gettext( $clean_line ) . '\\n';
                $output .= "\"{$escaped_line}\"\n";
            }
            $output .= "\n";
        } else {
            // Safe fallback schema structure if the file contains no pre-existing header node
            $output .= "msgid \"\"\nmsgstr \"\"\n" .
                      "\"Project-Id-Version: AF Translate Workspace Core 3.0\\n\"\n" .
                      "\"MIME-Version: 1.0\\n\"\n" .
                      "\"Content-Type: text/plain; charset=UTF-8\\n\"\n" .
                      "\"Content-Transfer-Encoding: 8bit\\n\"\n\n";
        }

        // Process standard translation keys
        foreach ( $translation_nodes as $node ) {
            if ( ! empty( $node['msgctxt'] ) ) {
                $msgctxt = self::safe_escape_gettext( $node['msgctxt'] );
                $output .= "msgctxt \"{$msgctxt}\"\n";
            }

            $msgid = self::safe_escape_gettext( $node['msgid'] );
            $output .= "msgid \"{$msgid}\"\n";

            if ( ! empty( $node['msgid_plural'] ) ) {
                $msgid_plural = self::safe_escape_gettext( $node['msgid_plural'] );
                $output .= "msgid_plural \"{$msgid_plural}\"\n";
                
                $msgstr_array = isset( $node['msgstr'] ) ? (array) $node['msgstr'] : array('', '');
                if ( count( $msgstr_array ) < 2 ) {
                    $msgstr_array = array('', '');
                }
                
                foreach ( $msgstr_array as $index => $val ) {
                    $val_escaped = self::safe_escape_gettext( $val );
                    $output .= "msgstr[{$index}] \"{$val_escaped}\"\n";
                }
            } else {
                $msgstr_val = '';
                if ( isset( $node['msgstr'] ) ) {
                    $msgstr_val = is_array( $node['msgstr'] ) ? reset( $node['msgstr'] ) : $node['msgstr'];
                }
                $msgstr_escaped = self::safe_escape_gettext( $msgstr_val );
                $output .= "msgstr \"{$msgstr_escaped}\"\n";
            }
            
            $output .= "\n";
        }
        return $output;
    }
}