// Renders a grep tool result grouped by file. Ported from the pi-fabric grep
// preview (src/ui/core-tool-render.ts renderGrep/renderGrepLine): match lines
// (`path:line: text`) and context lines (`path-line- text`) are parsed, each
// file gets one header line, and the whole preview obeys the shared 2000-char
// bound.

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

export interface GrepPreviewInput {
  /** The raw grep result text (one `path:line: text` line per match). */
  readonly output: string;
}

const GREP_MATCH_PATTERN = /^(.+):(\d+):\s?(.*)$/;
const GREP_CONTEXT_PATTERN = /^(.+)-(\d+)-\s?(.*)$/;
const CRLF_PATTERN = /\r\n/g;
const CR_PATTERN = /\r/g;
const TRAILING_NEWLINE_PATTERN = /\n$/;

export function renderGrepPreview(
  input: GrepPreviewInput,
  theme?: Theme
): string[] {
  const output = input.output
    .replace(CRLF_PATTERN, "\n")
    .replace(CR_PATTERN, "\n")
    .replace(TRAILING_NEWLINE_PATTERN, "");
  if (output.length === 0 || output === "No matches found") {
    return [previewStyle(theme, "muted", "No matches found")];
  }
  const lines: string[] = [];
  let currentFile: string | undefined;
  for (const raw of output.split("\n")) {
    const match =
      raw.match(GREP_MATCH_PATTERN) ?? raw.match(GREP_CONTEXT_PATTERN);
    if (match === null) {
      lines.push(previewStyle(theme, "toolOutput", raw));
      currentFile = undefined;
      continue;
    }
    const file = match[1] ?? "";
    const lineNumber = match[2] ?? "";
    const code = match[3] ?? "";
    if (file !== currentFile) {
      lines.push(previewStyle(theme, "accent", file));
      currentFile = file;
    }
    const isMatch = GREP_MATCH_PATTERN.test(raw);
    const number = isMatch
      ? previewStyle(theme, "accent", lineNumber.padStart(4, " "))
      : previewStyle(theme, "dim", lineNumber.padStart(4, " "));
    const marker = isMatch
      ? previewStyle(theme, "warning", "│")
      : previewStyle(theme, "dim", "┆");
    lines.push(
      `${previewStyle(theme, "dim", "  ")}${number} ${marker} ${previewStyle(
        theme,
        "toolOutput",
        code
      )}`
    );
  }
  return [...boundPreviewLines(lines).lines];
}