/*************************************************************************/
/*  translation_loader_po.cpp                                            */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
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#include "translation_loader_po.h"

#include "core/io/file_access.h"
#include "core/string/translation.h"
#include "core/string/translation_po.h"

RES TranslationLoaderPO::load_translation(Ref<FileAccess> f, Error *r_error) {
	if (r_error) {
		*r_error = ERR_FILE_CORRUPT;
	}

	const String path = f->get_path();
	Ref<TranslationPO> translation = Ref<TranslationPO>(memnew(TranslationPO));
	String config;

	uint32_t magic = f->get_32();
	if (magic == 0x950412de) {
		// Load binary MO file.

		uint16_t version_maj = f->get_16();
		uint16_t version_min = f->get_16();
		ERR_FAIL_COND_V_MSG(version_maj > 1, RES(), vformat("Unsupported MO file %s, version %d.%d.", path, version_maj, version_min));

		uint32_t num_strings = f->get_32();
		uint32_t id_table_offset = f->get_32();
		uint32_t trans_table_offset = f->get_32();

		// Read string tables.
		for (uint32_t i = 0; i < num_strings; i++) {
			String msg_id;
			String msg_id_plural;
			String msg_context;

			// Read id strings and context.
			{
				Vector<uint8_t> data;
				f->seek(id_table_offset + i * 8);
				uint32_t str_start = 0;
				uint32_t str_len = f->get_32();
				uint32_t str_offset = f->get_32();

				data.resize(str_len + 1);
				f->seek(str_offset);
				f->get_buffer(data.ptrw(), str_len);
				data.write[str_len] = 0;

				bool is_plural = false;
				for (uint32_t j = 0; j < str_len + 1; j++) {
					if (data[j] == 0x04) {
						msg_context.parse_utf8((const char *)data.ptr(), j);
						str_start = j + 1;
					}
					if (data[j] == 0x00) {
						if (is_plural) {
							msg_id_plural.parse_utf8((const char *)(data.ptr() + str_start), j - str_start);
						} else {
							msg_id.parse_utf8((const char *)(data.ptr() + str_start), j - str_start);
							is_plural = true;
						}
						str_start = j + 1;
					}
				}
			}

			// Read translated strings.
			{
				Vector<uint8_t> data;
				f->seek(trans_table_offset + i * 8);
				uint32_t str_len = f->get_32();
				uint32_t str_offset = f->get_32();

				data.resize(str_len + 1);
				f->seek(str_offset);
				f->get_buffer(data.ptrw(), str_len);
				data.write[str_len] = 0;

				if (msg_id.is_empty()) {
					config = String::utf8((const char *)data.ptr(), str_len);
					// Record plural rule.
					int p_start = config.find("Plural-Forms");
					if (p_start != -1) {
						int p_end = config.find("\n", p_start);
						translation->set_plural_rule(config.substr(p_start, p_end - p_start));
					}
				} else {
					uint32_t str_start = 0;
					Vector<String> plural_msg;
					for (uint32_t j = 0; j < str_len + 1; j++) {
						if (data[j] == 0x00) {
							if (msg_id_plural.is_empty()) {
								translation->add_message(msg_id, String::utf8((const char *)(data.ptr() + str_start), j - str_start), msg_context);
							} else {
								plural_msg.push_back(String::utf8((const char *)(data.ptr() + str_start), j - str_start));
							}
							str_start = j + 1;
						}
					}
					if (!plural_msg.is_empty()) {
						translation->add_plural_message(msg_id, plural_msg, msg_context);
					}
				}
			}
		}

	} else {
		// Try to load as text PO file.
		f->seek(0);

		enum Status {
			STATUS_NONE,
			STATUS_READING_ID,
			STATUS_READING_STRING,
			STATUS_READING_CONTEXT,
			STATUS_READING_PLURAL,
		};

		Status status = STATUS_NONE;

		String msg_id;
		String msg_str;
		String msg_context;
		Vector<String> msgs_plural;

		if (r_error) {
			*r_error = ERR_FILE_CORRUPT;
		}

		int line = 1;
		int plural_forms = 0;
		int plural_index = -1;
		bool entered_context = false;
		bool skip_this = false;
		bool skip_next = false;
		bool is_eof = false;

		while (!is_eof) {
			String l = f->get_line().strip_edges();
			is_eof = f->eof_reached();

			// If we reached last line and it's not a content line, break, otherwise let processing that last loop
			if (is_eof && l.is_empty()) {
				if (status == STATUS_READING_ID || status == STATUS_READING_CONTEXT || (status == STATUS_READING_PLURAL && plural_index != plural_forms - 1)) {
					ERR_FAIL_V_MSG(RES(), "Unexpected EOF while reading PO file at: " + path + ":" + itos(line));
				} else {
					break;
				}
			}

			if (l.begins_with("msgctxt")) {
				ERR_FAIL_COND_V_MSG(status != STATUS_READING_STRING && status != STATUS_READING_PLURAL, RES(), "Unexpected 'msgctxt', was expecting 'msgid_plural' or 'msgstr' before 'msgctxt' while parsing: " + path + ":" + itos(line));

				// In PO file, "msgctxt" appears before "msgid". If we encounter a "msgctxt", we add what we have read
				// and set "entered_context" to true to prevent adding twice.
				if (!skip_this && !msg_id.is_empty()) {
					if (status == STATUS_READING_STRING) {
						translation->add_message(msg_id, msg_str, msg_context);
					} else if (status == STATUS_READING_PLURAL) {
						ERR_FAIL_COND_V_MSG(plural_index != plural_forms - 1, RES(), "Number of 'msgstr[]' doesn't match with number of plural forms: " + path + ":" + itos(line));
						translation->add_plural_message(msg_id, msgs_plural, msg_context);
					}
				}
				msg_context = "";
				l = l.substr(7, l.length()).strip_edges();
				status = STATUS_READING_CONTEXT;
				entered_context = true;
			}

			if (l.begins_with("msgid_plural")) {
				if (plural_forms == 0) {
					ERR_FAIL_V_MSG(RES(), "PO file uses 'msgid_plural' but 'Plural-Forms' is invalid or missing in header: " + path + ":" + itos(line));
				} else if (status != STATUS_READING_ID) {
					ERR_FAIL_V_MSG(RES(), "Unexpected 'msgid_plural', was expecting 'msgid' before 'msgid_plural' while parsing: " + path + ":" + itos(line));
				}
				// We don't record the message in "msgid_plural" itself as tr_n(), TTRN(), RTRN() interfaces provide the plural string already.
				// We just have to reset variables related to plurals for "msgstr[]" later on.
				l = l.substr(12, l.length()).strip_edges();
				plural_index = -1;
				msgs_plural.clear();
				msgs_plural.resize(plural_forms);
				status = STATUS_READING_PLURAL;
			} else if (l.begins_with("msgid")) {
				ERR_FAIL_COND_V_MSG(status == STATUS_READING_ID, RES(), "Unexpected 'msgid', was expecting 'msgstr' while parsing: " + path + ":" + itos(line));

				if (!msg_id.is_empty()) {
					if (!skip_this && !entered_context) {
						if (status == STATUS_READING_STRING) {
							translation->add_message(msg_id, msg_str, msg_context);
						} else if (status == STATUS_READING_PLURAL) {
							ERR_FAIL_COND_V_MSG(plural_index != plural_forms - 1, RES(), "Number of 'msgstr[]' doesn't match with number of plural forms: " + path + ":" + itos(line));
							translation->add_plural_message(msg_id, msgs_plural, msg_context);
						}
					}
				} else if (config.is_empty()) {
					config = msg_str;
					// Record plural rule.
					int p_start = config.find("Plural-Forms");
					if (p_start != -1) {
						int p_end = config.find("\n", p_start);
						translation->set_plural_rule(config.substr(p_start, p_end - p_start));
						plural_forms = translation->get_plural_forms();
					}
				}

				l = l.substr(5, l.length()).strip_edges();
				status = STATUS_READING_ID;
				// If we did not encounter msgctxt, we reset context to empty to reset it.
				if (!entered_context) {
					msg_context = "";
				}
				msg_id = "";
				msg_str = "";
				skip_this = skip_next;
				skip_next = false;
				entered_context = false;
			}

			if (l.begins_with("msgstr[")) {
				ERR_FAIL_COND_V_MSG(status != STATUS_READING_PLURAL, RES(), "Unexpected 'msgstr[]', was expecting 'msgid_plural' before 'msgstr[]' while parsing: " + path + ":" + itos(line));
				plural_index++; // Increment to add to the next slot in vector msgs_plural.
				l = l.substr(9, l.length()).strip_edges();
			} else if (l.begins_with("msgstr")) {
				ERR_FAIL_COND_V_MSG(status != STATUS_READING_ID, RES(), "Unexpected 'msgstr', was expecting 'msgid' before 'msgstr' while parsing: " + path + ":" + itos(line));
				l = l.substr(6, l.length()).strip_edges();
				status = STATUS_READING_STRING;
			}

			if (l.is_empty() || l.begins_with("#")) {
				if (l.contains("fuzzy")) {
					skip_next = true;
				}
				line++;
				continue; // Nothing to read or comment.
			}

			ERR_FAIL_COND_V_MSG(!l.begins_with("\"") || status == STATUS_NONE, RES(), "Invalid line '" + l + "' while parsing: " + path + ":" + itos(line));

			l = l.substr(1, l.length());
			// Find final quote, ignoring escaped ones (\").
			// The escape_next logic is necessary to properly parse things like \\"
			// where the backslash is the one being escaped, not the quote.
			int end_pos = -1;
			bool escape_next = false;
			for (int i = 0; i < l.length(); i++) {
				if (l[i] == '\\' && !escape_next) {
					escape_next = true;
					continue;
				}

				if (l[i] == '"' && !escape_next) {
					end_pos = i;
					break;
				}

				escape_next = false;
			}

			ERR_FAIL_COND_V_MSG(end_pos == -1, RES(), "Expected '\"' at end of message while parsing: " + path + ":" + itos(line));

			l = l.substr(0, end_pos);
			l = l.c_unescape();

			if (status == STATUS_READING_ID) {
				msg_id += l;
			} else if (status == STATUS_READING_STRING) {
				msg_str += l;
			} else if (status == STATUS_READING_CONTEXT) {
				msg_context += l;
			} else if (status == STATUS_READING_PLURAL && plural_index >= 0) {
				ERR_FAIL_COND_V_MSG(plural_index >= plural_forms, RES(), "Unexpected plural form while parsing: " + path + ":" + itos(line));
				msgs_plural.write[plural_index] = msgs_plural[plural_index] + l;
			}

			line++;
		}

		// Add the last set of data from last iteration.
		if (status == STATUS_READING_STRING) {
			if (!msg_id.is_empty()) {
				if (!skip_this) {
					translation->add_message(msg_id, msg_str, msg_context);
				}
			} else if (config.is_empty()) {
				config = msg_str;
			}
		} else if (status == STATUS_READING_PLURAL) {
			if (!skip_this && !msg_id.is_empty()) {
				ERR_FAIL_COND_V_MSG(plural_index != plural_forms - 1, RES(), "Number of 'msgstr[]' doesn't match with number of plural forms: " + path + ":" + itos(line));
				translation->add_plural_message(msg_id, msgs_plural, msg_context);
			}
		}
	}

	ERR_FAIL_COND_V_MSG(config.is_empty(), RES(), "No config found in file: " + path + ".");

	Vector<String> configs = config.split("\n");
	for (int i = 0; i < configs.size(); i++) {
		String c = configs[i].strip_edges();
		int p = c.find(":");
		if (p == -1) {
			continue;
		}
		String prop = c.substr(0, p).strip_edges();
		String value = c.substr(p + 1, c.length()).strip_edges();

		if (prop == "X-Language" || prop == "Language") {
			translation->set_locale(value);
		}
	}

	if (r_error) {
		*r_error = OK;
	}

	return translation;
}

RES TranslationLoaderPO::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
	if (r_error) {
		*r_error = ERR_CANT_OPEN;
	}

	Ref<FileAccess> f = FileAccess::open(p_path, FileAccess::READ);
	ERR_FAIL_COND_V_MSG(f.is_null(), RES(), "Cannot open file '" + p_path + "'.");

	return load_translation(f, r_error);
}

void TranslationLoaderPO::get_recognized_extensions(List<String> *p_extensions) const {
	p_extensions->push_back("po");
	p_extensions->push_back("mo");
}

bool TranslationLoaderPO::handles_type(const String &p_type) const {
	return (p_type == "Translation");
}

String TranslationLoaderPO::get_resource_type(const String &p_path) const {
	if (p_path.get_extension().to_lower() == "po" || p_path.get_extension().to_lower() == "mo") {
		return "Translation";
	}
	return "";
}