/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

// Copies type definitions from the sibling `agent-host-protocol` repo into
// `src/vs/platform/agentHost/common/state/protocol/`. Run via:
//
//   npx tsx scripts/sync-agent-host-protocol.ts
//
// Transformations applied:
//   1. Converts 2-space indentation to tabs.
//   2. Merges duplicate imports from the same module.
//   3. Formats with the project's tsfmt.json settings.
//   4. Adds Microsoft copyright header.
//
// URI stays as `string` (the protocol's canonical representation). VS Code code
// should call `URI.parse()` at point-of-use where a URI class is needed.

import * as fs from 'fs';
import * as path from 'path';
import { execSync } from 'child_process';
import * as ts from 'typescript';

const ROOT = path.resolve(__dirname, '..');
const PROTOCOL_REPO = path.resolve(ROOT, '../agent-host-protocol');
const TYPES_DIR = path.join(PROTOCOL_REPO, 'types');
const DEST_DIR = path.join(ROOT, 'src/vs/platform/agentHost/common/state/protocol');

// Load tsfmt.json formatting options once
const TSFMT_PATH = path.join(ROOT, 'tsfmt.json');
const FORMAT_OPTIONS: ts.FormatCodeSettings = JSON.parse(fs.readFileSync(TSFMT_PATH, 'utf-8'));

/**
 * Formats a TypeScript source string using the TypeScript language service
 * formatter with the project's tsfmt.json settings.
 */
function formatTypeScript(content: string, fileName: string): string {
	const host: ts.LanguageServiceHost = {
		getCompilationSettings: () => ({}),
		getScriptFileNames: () => [fileName],
		getScriptVersion: () => '1',
		getScriptSnapshot: (name: string) => name === fileName ? ts.ScriptSnapshot.fromString(content) : undefined,
		getCurrentDirectory: () => ROOT,
		getDefaultLibFileName: () => '',
		fileExists: () => false,
		readFile: () => undefined,
	};
	const ls = ts.createLanguageService(host);
	const edits = ls.getFormattingEditsForDocument(fileName, FORMAT_OPTIONS);
	// Apply edits in reverse order to preserve offsets
	for (let i = edits.length - 1; i >= 0; i--) {
		const edit = edits[i];
		content = content.substring(0, edit.span.start) + edit.newText + content.substring(edit.span.start + edit.span.length);
	}
	ls.dispose();
	return content;
}

const COPYRIGHT = `/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/`;

const BANNER = '// allow-any-unicode-comment-file\n// DO NOT EDIT -- auto-generated by scripts/sync-agent-host-protocol.ts';

// Files to copy. All go into protocol/.
const FILES: { src: string; dest: string }[] = [
	{ src: 'state.ts', dest: 'state.ts' },
	{ src: 'actions.ts', dest: 'actions.ts' },
	{ src: 'action-origin.generated.ts', dest: 'action-origin.generated.ts' },
	{ src: 'reducers.ts', dest: 'reducers.ts' },
	{ src: 'commands.ts', dest: 'commands.ts' },
	{ src: 'errors.ts', dest: 'errors.ts' },
	{ src: 'notifications.ts', dest: 'notifications.ts' },
	{ src: 'messages.ts', dest: 'messages.ts' },
	{ src: 'version/registry.ts', dest: 'version/registry.ts' },
];

function getSourceCommitHash(): string {
	try {
		return execSync('git rev-parse --short HEAD', { cwd: PROTOCOL_REPO, encoding: 'utf-8' }).trim();
	} catch {
		return 'unknown';
	}
}

function stripExistingHeader(content: string): string {
	return content.replace(/^\/\*\*?[\s\S]*?\*\/\s*/, '');
}

function convertIndentation(content: string): string {
	const lines = content.split('\n');
	return lines.map(line => {
		const match = line.match(/^( +)/);
		if (!match) {
			return line;
		}
		const spaces = match[1].length;
		const tabs = Math.floor(spaces / 2);
		const remainder = spaces % 2;
		return '\t'.repeat(tabs) + ' '.repeat(remainder) + line.slice(spaces);
	}).join('\n');
}

/**
 * Merges duplicate imports from the same module.
 * Combines `import type { A }` and `import { B }` from the same module into
 * `import { B, type A }` to satisfy the no-duplicate-imports lint rule.
 */
function mergeDuplicateImports(content: string): string {
	// Collapse multi-line imports into single lines first
	content = content.replace(/import\s+(type\s+)?\{([^}]+)\}\s+from\s+'([^']+)';/g, (_match, typeKeyword, names, mod) => {
		const collapsed = names.replace(/\s+/g, ' ').trim();
		return typeKeyword ? `import type { ${collapsed} } from '${mod}';` : `import { ${collapsed} } from '${mod}';`;
	});

	const importsByModule = new Map<string, { typeNames: string[]; valueNames: string[] }>();
	const otherLines: string[] = [];
	const seenModules = new Set<string>();

	for (const line of content.split('\n')) {
		const typeMatch = line.match(/^import type \{([^}]+)\} from '([^']+)';$/);
		const valueMatch = line.match(/^import \{([^}]+)\} from '([^']+)';$/);

		if (typeMatch) {
			const [, names, mod] = typeMatch;
			if (!importsByModule.has(mod)) {
				importsByModule.set(mod, { typeNames: [], valueNames: [] });
			}
			importsByModule.get(mod)!.typeNames.push(...names.split(',').map(s => s.trim()).filter(s => s.length > 0));
			if (!seenModules.has(mod)) {
				seenModules.add(mod);
				otherLines.push(`__IMPORT_PLACEHOLDER__${mod}`);
			}
		} else if (valueMatch) {
			const [, names, mod] = valueMatch;
			if (!importsByModule.has(mod)) {
				importsByModule.set(mod, { typeNames: [], valueNames: [] });
			}
			importsByModule.get(mod)!.valueNames.push(...names.split(',').map(s => s.trim()).filter(s => s.length > 0));
			if (!seenModules.has(mod)) {
				seenModules.add(mod);
				otherLines.push(`__IMPORT_PLACEHOLDER__${mod}`);
			}
		} else {
			otherLines.push(line);
		}
	}

	return otherLines.map(line => {
		if (line.startsWith('__IMPORT_PLACEHOLDER__')) {
			const mod = line.substring('__IMPORT_PLACEHOLDER__'.length);
			const entry = importsByModule.get(mod)!;
			const uniqueTypes = [...new Set(entry.typeNames)];
			const uniqueValues = [...new Set(entry.valueNames)];

			if (uniqueValues.length > 0 && uniqueTypes.length > 0) {
				const allNames = [...uniqueValues, ...uniqueTypes.map(n => `type ${n}`)];
				return `import { ${allNames.join(', ')} } from '${mod}';`;
			} else if (uniqueValues.length > 0) {
				return `import { ${uniqueValues.join(', ')} } from '${mod}';`;
			} else {
				return `import type { ${uniqueTypes.join(', ')} } from '${mod}';`;
			}
		}
		return line;
	}).join('\n');
}





function processFile(src: string, dest: string): void {
	let content = fs.readFileSync(src, 'utf-8');
	content = stripExistingHeader(content);

	// Merge duplicate imports from the same module
	content = mergeDuplicateImports(content);

	content = convertIndentation(content);
	content = content.split('\n').map(line => line.trimEnd()).join('\n');

	const header = `${COPYRIGHT}\n\n${BANNER}\n`;
	content = header + '\n' + content;

	if (!content.endsWith('\n')) {
		content += '\n';
	}

	const destPath = path.join(DEST_DIR, dest);
	fs.mkdirSync(path.dirname(destPath), { recursive: true });
	content = formatTypeScript(content, dest);
	fs.writeFileSync(destPath, content, 'utf-8');
	console.log(`  ${dest}`);
}

// ---- Main -------------------------------------------------------------------

function main() {
	if (!fs.existsSync(TYPES_DIR)) {
		console.error(`ERROR: Cannot find ${TYPES_DIR}`);
		console.error('Clone agent-host-protocol as a sibling of the VS Code repo:');
		console.error('  git clone git@github.com:microsoft/agent-host-protocol.git ../agent-host-protocol');
		process.exit(1);
	}

	const commitHash = getSourceCommitHash();
	console.log(`Syncing from agent-host-protocol @ ${commitHash}`);
	console.log(`  Source: ${TYPES_DIR}`);
	console.log(`  Dest:   ${DEST_DIR}`);
	console.log();

	// Copy protocol files
	for (const file of FILES) {
		const srcPath = path.join(TYPES_DIR, file.src);
		if (!fs.existsSync(srcPath)) {
			console.error(`  SKIP (not found): ${file.src}`);
			continue;
		}
		processFile(srcPath, file.dest);
	}

	// Write the source commit hash to a single version file
	const versionFile = path.join(DEST_DIR, '.ahp-version');
	fs.writeFileSync(versionFile, commitHash + '\n', 'utf-8');
	console.log(`  .ahp-version -> ${commitHash}`);

	console.log();
	console.log('Done.');
}

main();