import { readdir, writeFile, readFile } from 'fs/promises';
import { existsSync } from 'fs';
import { join, resolve } from 'path';
import os from 'os';
import AdmZip from 'adm-zip';

// --- Constants ---
const GERMAN_LOCALE_DIR = 'en';
const LOCALE_DIR = 'locale';
const BASE_LOCALE_FILENAME = 'base.cfg';
const OUTPUT_CSV_FILENAME = 'factorio_english_items.csv';
const LOCALE_TARGET_SECTIONS = new Set([
    'entity-name',
    'item-name',
    'fluid-name',
    'equipment-name',
    'virtual-signal-name',
]);
const LOCALE_KEY_VALUE_DELIMITER = '=';
const LOCALE_COMMENT_PREFIXES = ['#', ';'];
const MOD_FILE_EXTENSION = '.zip';
const CSV_HEADER = 'section,item_key,localized_name\n';
const DEFAULT_ENCODING: BufferEncoding = 'utf8';
const LOCALE_FILE_REGEX = new RegExp(`[\\\\/]?${LOCALE_DIR}[\\\\/]${GERMAN_LOCALE_DIR}[\\\\/].*\\.cfg$`, 'i');

/**
* A list of common Factorio installation directories checked in order.
* Add non-standard installation paths here if needed.
*/
const FACTORIO_INSTALL_PATHS: string[] = [
    'C:\\Program Files (x86)\\Steam\\steamapps\\common\\Factorio',
    'C:\\Program Files\\Steam\\steamapps\\common\\Factorio',
    'C:\\Program Files\\Factorio',
];

const FACTORIO_USERDATA_PATHS: Record<string, string> = {
    win32: join(process.env.APPDATA ?? '', 'Factorio'),
    darwin: join(os.homedir(), 'Library', 'Application Support', 'factorio'),
    linux: join(os.homedir(), '.factorio'),
};

/**
* Resolves the Factorio installation and user data directories for the current platform.
* @returns An object with `installPath` and `userdataPath`, each null if not found.
*/
function getFactorioPaths(): { installPath: string | null; userdataPath: string | null } {
    const installPath = FACTORIO_INSTALL_PATHS.find(existsSync) ?? null;
    const userdataPath = FACTORIO_USERDATA_PATHS[os.platform()] ?? null;
    return {
        installPath,
        userdataPath: userdataPath && existsSync(userdataPath) ? userdataPath : null,
    };
}

/**
* Parses INI/CFG file content to extract key-value pairs from all target sections.
* @param content The raw text content of the .cfg file.
* @returns A map of `"section/key"` to `{ section, key, value }`.
*/
function parseLocale(content: string): Map<string, { section: string; key: string; value: string }> {
    const items = new Map<string, { section: string; key: string; value: string }>();
    const lines = content.split(/\r?\n/);
    let currentSection: string | null = null;

    for (const line of lines) {
        const trimmedLine = line.trim();
        if (trimmedLine.startsWith('[') && trimmedLine.endsWith(']')) {
            const sectionName = trimmedLine.slice(1, -1);
            currentSection = LOCALE_TARGET_SECTIONS.has(sectionName) ? sectionName : null;
            continue;
        }

        const isComment = LOCALE_COMMENT_PREFIXES.some(prefix => trimmedLine.startsWith(prefix));
        if (currentSection && trimmedLine && !isComment) {
            const parts = trimmedLine.split(LOCALE_KEY_VALUE_DELIMITER, 2);
            if (parts.length === 2) {
                const [key, value] = parts;
                if (key && value) {
                    const compositeKey = `${currentSection}/${key.trim()}`;
                    if (!items.has(compositeKey)) {
                        items.set(compositeKey, { section: currentSection, key: key.trim(), value: value.trim() });
                    }
                }
            }
        }
    }
    return items;
}

/**
* Escapes a string for use in a CSV field, quoting where necessary.
* @param value The value to escape.
* @returns The CSV-safe value.
*/
function toCsvField(value: string): string {
    if (/[",\n]/.test(value)) {
        return `"${value.replace(/"/g, '""')}"`;
    }
    return value;
}

/**
* Main function to orchestrate the scanning, parsing, and exporting process.
*/
async function run(): Promise<void> {
    const allItems = new Map<string, { section: string; key: string; value: string }>();
    const { installPath, userdataPath } = getFactorioPaths();

    const mergeItems = (source: Map<string, { section: string; key: string; value: string }>) => {
        for (const [compositeKey, entry] of source) {
            if (!allItems.has(compositeKey)) allItems.set(compositeKey, entry);
        }
    };

    // --- Process Base Game File First ---
    if (installPath) {
        const baseLocalePath = join(installPath, 'data', 'base', LOCALE_DIR, GERMAN_LOCALE_DIR, BASE_LOCALE_FILENAME);
        console.log(`Attempting to read base game locale from: ${baseLocalePath}`);
        if (existsSync(baseLocalePath)) {
            try {
                const content = await readFile(baseLocalePath, DEFAULT_ENCODING);
                console.log(` -> Reading ${baseLocalePath}`);
                mergeItems(parseLocale(content));
            } catch (err) {
                console.warn(`[WARN] Could not read or parse base game locale file.`, err);
            }
        } else {
            console.warn(`[WARN] Base game locale file not found at the expected path. Skipping.`);
        }
    } else {
        console.warn(`[WARN] Factorio installation not found. Searched paths defined in FACTORIO_INSTALL_PATHS. Skipping base game file.`);
    }

    // --- Process Mods ---
    if (userdataPath) {
        const modsPath = join(userdataPath, 'mods');
        console.log(`\nScanning for mods in: ${modsPath}`);
        if (!existsSync(modsPath)) {
            console.error(`[ERROR] Mods directory not found at the expected user data path.`);
        } else {
            const files = await readdir(modsPath);
            const zipFiles = files.filter(file => file.toLowerCase().endsWith(MOD_FILE_EXTENSION));
            console.log(`Found ${zipFiles.length} zip archives to process.`);

            for (const zipFile of zipFiles) {
                const zipPath = join(modsPath, zipFile);
                try {
                    const zip = new AdmZip(zipPath);
                    for (const entry of zip.getEntries()) {
                        if (LOCALE_FILE_REGEX.test(entry.entryName)) {
                            console.log(` -> Reading ${entry.entryName} from ${zipFile}`);
                            const content = entry.getData().toString(DEFAULT_ENCODING);
                            mergeItems(parseLocale(content));
                        }
                    }
                } catch (err) {
                    console.warn(`[WARN] Could not process ${zipFile}. It may be corrupted or unreadable.`, err);
                }
            }
        }
    } else {
        console.warn(`[WARN] Factorio user data directory not found. Skipping mod processing.`);
    }

    if (allItems.size === 0) {
        console.log('\nFinished. No entries were found for the target sections.');
        return;
    }

    console.log(`\nFound a total of ${allItems.size} unique entries across all files.`);
    const csvRows = Array.from(allItems.values()).map(({ section, key, value }) =>
        `${toCsvField(section)},${toCsvField(key)},${toCsvField(value)}`
    );
    const outputCsvPath = resolve(process.cwd(), OUTPUT_CSV_FILENAME);
    await writeFile(outputCsvPath, CSV_HEADER + csvRows.join('\n'), DEFAULT_ENCODING);
    console.log(`Successfully exported all entries to: ${outputCsvPath}`);
}

run().catch(err => {
    console.error("\n[FATAL] An unexpected error occurred:", err);
});