import type { SearchMatch } from "../types.js";
const DEFAULT_MAX_LINES = parseInt(process.env.PTY_MAX_BUFFER_LINES || "50000", 10);
/**
* Ring buffer for storing PTY output lines.
* Automatically evicts oldest lines when capacity is reached.
*/
export class RingBuffer {
private lines: string[] = [];
private maxLines: number;
constructor(maxLines: number = DEFAULT_MAX_LINES) {
this.maxLines = maxLines;
}
/**
* Append data to the buffer, splitting on newlines.
* Evicts oldest lines if buffer is full.
*/
append(data: string): void {
const newLines = data.split("\n");
for (const line of newLines) {
this.lines.push(line);
if (this.lines.length > this.maxLines) {
this.lines.shift();
}
}
}
/**
* Read lines from the buffer with pagination.
* @param offset - Starting line index (0-based)
* @param limit - Maximum number of lines to return
*/
read(offset: number = 0, limit?: number): string[] {
const start = Math.max(0, offset);
const end = limit !== undefined ? start + limit : this.lines.length;
return this.lines.slice(start, end);
}
/**
* Search buffer for lines matching a regex pattern.
* Returns all matches with their original line numbers (1-based).
*/
search(pattern: RegExp): SearchMatch[] {
const matches: SearchMatch[] = [];
for (let i = 0; i < this.lines.length; i++) {
const line = this.lines[i];
if (line !== undefined && pattern.test(line)) {
matches.push({ lineNumber: i + 1, text: line });
}
}
return matches;
}
/**
* Get the current number of lines in the buffer.
*/
get length(): number {
return this.lines.length;
}
/**
* Clear all lines from the buffer.
*/
clear(): void {
this.lines = [];
}
}
