import { readFile, writeFile, mkdir, rename } from 'node:fs/promises';
import { dirname } from 'node:path';
import { existsSync } from 'node:fs';
import type { FileEdit, TextEdit } from '../types/index.js';
/**
* Apply a list of text edits to a file's content
* Edits are applied in reverse order to avoid position shifting
*/
function applyTextEdits(content: string, edits: TextEdit[]): string {
// Convert content to array of lines
const lines = content.split('\n');
// Sort edits in reverse order (bottom to top, right to left)
const sortedEdits = [...edits].sort((a, b) => {
if (a.start.line !== b.start.line) {
return b.start.line - a.start.line;
}
return b.start.offset - a.start.offset;
});
// Apply each edit
for (const edit of sortedEdits) {
const startLine = edit.start.line - 1; // tsserver uses 1-indexed lines
const endLine = edit.end.line - 1;
const startOffset = edit.start.offset - 1; // tsserver uses 1-indexed offsets
const endOffset = edit.end.offset - 1;
if (startLine === endLine) {
// Single line edit
const line = lines[startLine];
lines[startLine] =
line.slice(0, startOffset) + edit.newText + line.slice(endOffset);
} else {
// Multi-line edit
const firstLine = lines[startLine];
const lastLine = lines[endLine];
const newLine = firstLine.slice(0, startOffset) + edit.newText + lastLine.slice(endOffset);
// Replace the range of lines with the new content
lines.splice(startLine, endLine - startLine + 1, newLine);
}
}
return lines.join('\n');
}
/**
* Validate that all edits can be applied
* Throws an error if any edit is invalid
*/
async function validateEdits(edits: FileEdit[]): Promise<void> {
for (const fileEdit of edits) {
if (!existsSync(fileEdit.filePath)) {
throw new Error(`File does not exist: ${fileEdit.filePath}`);
}
// Read file to validate it's accessible
try {
await readFile(fileEdit.filePath, 'utf-8');
} catch (error) {
throw new Error(
`Cannot read file ${fileEdit.filePath}: ${error instanceof Error ? error.message : String(error)}`
);
}
// Validate edit positions
for (const edit of fileEdit.textEdits) {
if (edit.start.line < 1 || edit.start.offset < 1) {
throw new Error(
`Invalid edit position in ${fileEdit.filePath}: line ${edit.start.line}, offset ${edit.start.offset}`
);
}
if (edit.end.line < edit.start.line) {
throw new Error(
`Invalid edit range in ${fileEdit.filePath}: end line ${edit.end.line} before start line ${edit.start.line}`
);
}
if (
edit.end.line === edit.start.line &&
edit.end.offset < edit.start.offset
) {
throw new Error(
`Invalid edit range in ${fileEdit.filePath}: end offset ${edit.end.offset} before start offset ${edit.start.offset}`
);
}
}
}
}
/**
* Apply a list of file edits atomically
* Either all edits succeed or none are applied
*/
export async function applyEdits(edits: FileEdit[]): Promise<void> {
// Validate all edits first
await validateEdits(edits);
// Read all files and compute new content
const filesToWrite: Array<{ path: string; content: string }> = [];
for (const fileEdit of edits) {
const originalContent = await readFile(fileEdit.filePath, 'utf-8');
const newContent = applyTextEdits(originalContent, fileEdit.textEdits);
filesToWrite.push({ path: fileEdit.filePath, content: newContent });
}
// Write all files
for (const { path, content } of filesToWrite) {
await writeFile(path, content, 'utf-8');
}
}
/**
* Move a file from oldPath to newPath
* Creates parent directories if needed
*/
export async function moveFile(oldPath: string, newPath: string): Promise<void> {
if (!existsSync(oldPath)) {
throw new Error(`Source file does not exist: ${oldPath}`);
}
// Create parent directory if it doesn't exist
const newDir = dirname(newPath);
if (!existsSync(newDir)) {
await mkdir(newDir, { recursive: true });
}
// Move the file
await rename(oldPath, newPath);
}
/**
* Apply edits and move a file atomically
* This is the main operation for the moveFile tool
*/
export async function applyEditsAndMoveFile(
edits: FileEdit[],
oldPath: string,
newPath: string
): Promise<void> {
// First apply all edits
if (edits.length > 0) {
await applyEdits(edits);
}
// Then move the file
await moveFile(oldPath, newPath);
}
