#!/usr/bin/env tsx
/**
 * TGN Migration Tool
 *
 * Converts old TGN files with lowercase "pass" and "resign" to uppercase "Pass" and "Resign"
 * to match the updated TGN specification.
 *
 * Usage:
 *   npm run migrate:tgn -- <directory>
 *   npm run migrate:tgn -- <directory> --dry-run
 *   npm run migrate:tgn -- <directory> --backup
 */

import * as fs from "fs";
import * as path from "path";
import yargs from "yargs";
import { hideBin } from "yargs/helpers";


interface MigrationOptions {
	directory: string;
	dryRun: boolean;
	backup: boolean;
	recursive: boolean;
}

interface MigrationStats {
	filesScanned: number;
	filesModified: number;
	passReplacements: number;
	resignReplacements: number;
	errors: string[];
}


/**
 * Check if a file is a TGN file
 */
function isTGNFile(filePath: string): boolean {
	return path.extname(filePath).toLowerCase() === ".tgn";
}


/**
 * Find all TGN files in a directory
 */
function findTGNFiles(dir: string, recursive: boolean): string[] {
	const files: string[] = [];

	try {
		const entries = fs.readdirSync(dir, { withFileTypes: true });

		for (const entry of entries) {
			const fullPath = path.join(dir, entry.name);

			if (entry.isDirectory() && recursive) {
				files.push(...findTGNFiles(fullPath, recursive));
			} else if (entry.isFile() && isTGNFile(fullPath)) {
				files.push(fullPath);
			}
		}
	} catch (error) {
		console.error(`Error reading directory ${dir}:`, error);
	}

	return files;
}


/**
 * Migrate TGN content from lowercase to uppercase
 */
function migrateTGNContent(content: string): { newContent: string; passCount: number; resignCount: number } {
	let passCount = 0;
	let resignCount = 0;

	// Replace "pass" with "Pass" (as a standalone word in move notation)
	// Use word boundary to avoid replacing "pass" in other contexts
	const newContent = content
		.replace(/\bpass\b/g, () => {
			passCount++;
			return "Pass";
		})
		.replace(/\bresign\b/g, () => {
			resignCount++;
			return "Resign";
		});

	return { newContent, passCount, resignCount };
}


/**
 * Create backup of a file
 */
function backupFile(filePath: string): string {
	const backupPath = filePath + ".backup";
	fs.copyFileSync(filePath, backupPath);
	return backupPath;
}


/**
 * Migrate a single TGN file
 */
function migrateFile(
	filePath: string,
	options: MigrationOptions,
	stats: MigrationStats
): void {
	stats.filesScanned++;

	try {
		// Read file content
		const content = fs.readFileSync(filePath, "utf-8");

		// Migrate content
		const { newContent, passCount, resignCount } = migrateTGNContent(content);

		// Check if file needs migration
		if (passCount === 0 && resignCount === 0) {
			return; // File already up to date
		}

		// Update statistics
		stats.passReplacements += passCount;
		stats.resignReplacements += resignCount;
		stats.filesModified++;

		// Log changes
		console.log(`\n📄 ${path.basename(filePath)}`);
		if (passCount > 0) {
			console.log(`   ✓ Replaced ${passCount} "pass" → "Pass"`);
		}
		if (resignCount > 0) {
			console.log(`   ✓ Replaced ${resignCount} "resign" → "Resign"`);
		}

		// Skip write in dry-run mode
		if (options.dryRun) {
			console.log("   (dry-run: no changes written)");
			return;
		}

		// Create backup if requested
		if (options.backup) {
			const backupPath = backupFile(filePath);
			console.log(`   📦 Backup created: ${path.basename(backupPath)}`);
		}

		// Write migrated content
		fs.writeFileSync(filePath, newContent, "utf-8");
		console.log(`   ✅ File updated`);
	} catch (error) {
		const errorMsg = `Error processing ${filePath}: ${error}`;
		stats.errors.push(errorMsg);
		console.error(`   ❌ ${errorMsg}`);
	}
}


/**
 * Main migration function
 */
function migrateTGNFiles(options: MigrationOptions): MigrationStats {
	const stats: MigrationStats = {
		filesScanned: 0,
		filesModified: 0,
		passReplacements: 0,
		resignReplacements: 0,
		errors: []
	};

	console.log("🔄 TGN Migration Tool");
	console.log("=" .repeat(50));
	console.log(`Directory: ${options.directory}`);
	console.log(`Recursive: ${options.recursive}`);
	console.log(`Dry run: ${options.dryRun}`);
	console.log(`Backup: ${options.backup}`);
	console.log("=" .repeat(50));

	// Check if directory exists
	if (!fs.existsSync(options.directory)) {
		console.error(`❌ Directory not found: ${options.directory}`);
		process.exit(1);
	}

	// Find all TGN files
	const files = findTGNFiles(options.directory, options.recursive);

	if (files.length === 0) {
		console.log("\n⚠️  No TGN files found.");
		return stats;
	}

	console.log(`\n📁 Found ${files.length} TGN file(s)\n`);

	// Migrate each file
	for (const file of files) {
		migrateFile(file, options, stats);
	}

	// Print summary
	console.log("\n" + "=".repeat(50));
	console.log("📊 Migration Summary");
	console.log("=".repeat(50));
	console.log(`Files scanned: ${stats.filesScanned}`);
	console.log(`Files modified: ${stats.filesModified}`);
	console.log(`Total "pass" → "Pass": ${stats.passReplacements}`);
	console.log(`Total "resign" → "Resign": ${stats.resignReplacements}`);

	if (stats.errors.length > 0) {
		console.log(`\n❌ Errors: ${stats.errors.length}`);
		stats.errors.forEach((error) => console.error(`   - ${error}`));
	}

	if (options.dryRun) {
		console.log("\n⚠️  Dry run mode - no files were modified");
	} else if (stats.filesModified > 0) {
		console.log("\n✅ Migration completed successfully!");
	} else {
		console.log("\n✨ All files are already up to date!");
	}

	return stats;
}


/**
 * CLI Entry Point
 */
async function main() {
	const argv = await yargs(hideBin(process.argv))
		.usage("Usage: $0 <directory> [options]")
		.command("$0 <directory>", "Migrate TGN files to uppercase Pass/Resign format", (yargs) => {
			return yargs.positional("directory", {
				describe: "Directory containing TGN files",
				type: "string",
				demandOption: true
			});
		})
		.option("dry-run", {
			alias: "n",
			type: "boolean",
			default: false,
			description: "Preview changes without modifying files"
		})
		.option("backup", {
			alias: "b",
			type: "boolean",
			default: false,
			description: "Create .backup files before modifying"
		})
		.option("recursive", {
			alias: "r",
			type: "boolean",
			default: false,
			description: "Process subdirectories recursively"
		})
		.example([
			["$0 output", "Migrate all TGN files in output directory"],
			["$0 output --dry-run", "Preview changes without modifying files"],
			["$0 output --backup", "Create backups before modifying"],
			["$0 output --recursive", "Process all subdirectories"]
		])
		.help("h")
		.alias("h", "help")
		.strict()
		.parse();

	const options: MigrationOptions = {
		directory: argv.directory as string,
		dryRun: argv["dry-run"] as boolean,
		backup: argv.backup as boolean,
		recursive: argv.recursive as boolean
	};

	migrateTGNFiles(options);
}


// Run the CLI when executed directly
if (process.argv[1] === new URL(import.meta.url).pathname) {
	main().catch((error) => {
		console.error("Fatal error:", error);
		process.exit(1);
	});
}


export { migrateTGNFiles, migrateTGNContent, MigrationOptions, MigrationStats };