artifact-fs

import { Chunk } from "./types";
import { createHash } from "node:crypto";

export class Chunker {
  constructor(
    private maxChunkSize: number = 1000,
    private overlap: number = 50,
  ) {}

  chunk(artifactId: string, content: string): Chunk[] {
    const chunks: Chunk[] = [];
    const lines = content.split("\n");
    let currentChunk: string[] = [];
    let currentSize = 0;
    let startLine = 0;

    for (let i = 0; i < lines.length; i++) {
      const line = lines[i];
      const lineSize = line.length + 1;

      if (currentSize + lineSize > this.maxChunkSize && currentChunk.length > 0) {
        chunks.push(this.makeChunk(artifactId, currentChunk, startLine, i - 1));
        const overlapStart = Math.max(0, currentChunk.length - this.overlap);
        currentChunk = currentChunk.slice(overlapStart);
        currentSize = currentChunk.reduce((s, l) => s + l.length + 1, 0);
        startLine = i - (currentChunk.length - overlapStart);
      }

      currentChunk.push(line);
      currentSize += lineSize;
    }

    if (currentChunk.length > 0) {
      chunks.push(this.makeChunk(artifactId, currentChunk, startLine, lines.length - 1));
    }

    return chunks;
  }

  private makeChunk(artifactId: string, lines: string[], startLine: number, endLine: number): Chunk {
    const content = lines.join("\n");
    const hash = createHash("sha256").update(`${artifactId}:${startLine}:${endLine}`).digest("hex").slice(0, 12);
    return {
      id: `chunk_${hash}`,
      artifactId,
      content,
      startLine,
      endLine,
    };
  }
}