// Renders a read tool result as bounded lines with file offsets. Ported from
// the pi-fabric read preview (src/ui/core-tool-render.ts renderContent): the
// same `NN │ text` shape, first-line offset from the read call's offset arg,
// and the shared 2000-char preview bound.

import type { Theme } from "@earendil-works/pi-coding-agent";
import { boundPreviewLines } from "./bound.ts";
import { previewStyle } from "./style.ts";

export interface ReadPreviewInput {
  /** Line limit of the read call; the read tool already bounds the output. */
  readonly limit?: number;
  /** First line of the read (defaults to 1). */
  readonly offset?: number;
  /** The read result text. */
  readonly output: string;
  /** File that was read; the row title already shows it (call context). */
  readonly path: string;
}

export function renderReadPreview(
  input: ReadPreviewInput,
  theme?: Theme
): string[] {
  if (input.output.trim().length === 0) {
    return [previewStyle(theme, "muted", "(empty file)")];
  }
  const firstLine = Math.max(1, Math.floor(input.offset ?? 1));
  const lines = input.output
    .replace(/\r\n/g, "\n")
    .replace(/\r/g, "\n")
    .split("\n");
  if (lines.length > 1 && (lines.at(-1) ?? "") === "") {
    lines.pop();
  }
  const width = String(firstLine + lines.length - 1).length;
  const rendered = lines.map((text, index) => {
    const lineNumber = String(firstLine + index).padStart(width, " ");
    const content = text.length === 0 ? " " : text;
    return `${previewStyle(theme, "dim", `${lineNumber} │ `)}${previewStyle(
      theme,
      "toolOutput",
      content
    )}`;
  });
  return [...boundPreviewLines(rendered).lines];
}