/**
 * KHAELOR
 * File: src/tui/components/diff.ts
 * Description: Inline edit summaries and unified diff blocks — +/− glyphs preserved for monochrome (TUI_DESIGN §7.1).
 *
 * Author: Simon-Pierre Boucher
 * Contact: contact@spboucher.ai
 */

import { highlightLine } from "../markdown/highlight.js";
import { truncateAnsi } from "../renderer/ansi.js";
import { rule } from "./tool-line.js";
import type { Theme } from "../theme.js";

export interface DiffStats {
  added: number;
  removed: number;
}

/** Never bare "Edited file": `✓ path  +31 −12   d expand diff`. */
export function renderEditSummary(
  path: string,
  stats: DiffStats,
  width: number,
  theme: Theme,
  hint = true,
): string {
  let line =
    ` ${theme.paint("success", "✓")} ${path}  ` +
    `${theme.paint("success", `+${stats.added}`)} ${theme.paint("error", `−${stats.removed}`)}`;
  if (hint) line += theme.paint("dim", "        d expand diff");
  return truncateAnsi(line, width);
}

const EXT_LANG: Record<string, string> = {
  ts: "ts",
  tsx: "tsx",
  js: "js",
  jsx: "jsx",
  py: "python",
  sh: "bash",
  rs: "rust",
  go: "go",
  json: "json",
  yaml: "yaml",
  yml: "yaml",
  toml: "toml",
};

function langFor(path: string): string | null {
  const ext = /\.([a-z]+)$/i.exec(path)?.[1]?.toLowerCase();
  return ext !== undefined ? (EXT_LANG[ext] ?? null) : null;
}

function highlight(code: string, lang: string | null, theme: Theme): string {
  return highlightLine(code, lang)
    .map((s) => (s.role === "text" ? s.text : theme.paint(s.role, s.text)))
    .join("");
}

/**
 * Unified diff as a settled block: `+` lines in the added color, `−` in the
 * removed color, glyphs preserved so monochrome terminals keep the meaning.
 * Syntax highlighting rides on the same theme palette.
 */
export function renderDiffBlock(
  path: string,
  unifiedDiff: string,
  stats: DiffStats,
  width: number,
  theme: Theme,
): string[] {
  const lang = langFor(path);
  const out: string[] = [rule(` diff · ${path} · +${stats.added} −${stats.removed} `, width, theme)];
  for (const raw of unifiedDiff.split("\n")) {
    if (raw === "" || raw.startsWith("diff ") || raw.startsWith("index ")) continue;
    let line: string;
    if (raw.startsWith("+++") || raw.startsWith("---")) {
      line = theme.paint("dim", raw);
    } else if (raw.startsWith("@@")) {
      line = theme.paint("dim", raw);
    } else if (raw.startsWith("+")) {
      line = theme.tintLine("add", theme.paint("success", "+") + highlight(raw.slice(1), lang, theme));
    } else if (raw.startsWith("-")) {
      line = theme.tintLine("del", theme.paint("error", "-") + highlight(raw.slice(1), lang, theme));
    } else {
      line = theme.paint("dim", raw);
    }
    out.push(truncateAnsi("  " + line, width));
  }
  out.push(theme.paint("dim", "─".repeat(Math.max(10, Math.min(width - 1, 60)))));
  return out;
}