import { unzipSync, strFromU8 } from "fflate";
import type { FileKind, ParsedFile } from "./ruleCatalog";

const LANG_BY_EXT: Record<string, string> = {
  sh: "shell",
  bash: "shell",
  zsh: "shell",
  py: "python",
  js: "javascript",
  mjs: "javascript",
  cjs: "javascript",
  ts: "typescript",
  rb: "ruby",
  pl: "perl",
  php: "php",
  ps1: "powershell",
  go: "go",
  rs: "rust",
  md: "markdown",
  txt: "text",
  json: "json",
  yaml: "yaml",
  yml: "yaml",
  toml: "toml",
  env: "dotenv",
};

const SCRIPT_EXTS = new Set([
  "sh",
  "bash",
  "zsh",
  "py",
  "js",
  "mjs",
  "cjs",
  "ts",
  "rb",
  "pl",
  "php",
  "ps1",
  "go",
  "rs",
]);

const SKIP_DIRS = ["__macosx/", ".git/", "node_modules/"];

const MAX_ZIP_FILES = 2000;
const MAX_ZIP_TOTAL_BYTES = 60 * 1024 * 1024;
const MAX_ZIP_FILE_BYTES = 5 * 1024 * 1024;

function extOf(path: string): string {
  const base = path.split("/").pop() ?? path;
  const dot = base.lastIndexOf(".");
  return dot >= 0 ? base.slice(dot + 1).toLowerCase() : "";
}

function classify(path: string): FileKind {
  const base = (path.split("/").pop() ?? path).toLowerCase();
  const ext = extOf(path);
  if (base === "skill.md") return "instruction";
  if (SCRIPT_EXTS.has(ext)) return "script";
  if (ext === "md" || ext === "txt") return "instruction";
  return "resource";
}

function isProbablyBinary(bytes: Uint8Array): boolean {
  const len = Math.min(bytes.length, 4000);
  let nontext = 0;
  for (let i = 0; i < len; i++) {
    const b = bytes[i];
    if (b === 0) return true;
    if (b < 9 || (b > 13 && b < 32)) nontext++;
  }
  return len > 0 && nontext / len > 0.3;
}

export function parseZip(buffer: Buffer): ParsedFile[] {
  const files = unzipSync(new Uint8Array(buffer));
  const result: ParsedFile[] = [];
  let totalBytes = 0;
  let processed = 0;
  for (const [rawPath, bytes] of Object.entries(files)) {
    const path = rawPath.replace(/\\/g, "/");
    if (path.endsWith("/")) continue;
    const lower = path.toLowerCase();
    if (SKIP_DIRS.some((d) => lower.includes(d))) continue;
    if (bytes.length === 0) continue;
    if (bytes.length > MAX_ZIP_FILE_BYTES) continue;
    totalBytes += bytes.length;
    if (totalBytes > MAX_ZIP_TOTAL_BYTES) {
      throw new Error("ZIP-Archiv ist zu groß (entpackt).");
    }
    processed += 1;
    if (processed > MAX_ZIP_FILES) {
      throw new Error("ZIP-Archiv enthält zu viele Dateien.");
    }
    if (isProbablyBinary(bytes)) {
      result.push({
        path,
        kind: "resource",
        language: null,
        content: "",
        size: bytes.length,
      });
      continue;
    }
    result.push({
      path,
      kind: classify(path),
      language: LANG_BY_EXT[extOf(path)] ?? null,
      content: strFromU8(bytes),
      size: bytes.length,
    });
  }
  return result;
}

export function parseSingleFile(filename: string, buffer: Buffer): ParsedFile {
  const path = filename.replace(/\\/g, "/").split("/").pop() ?? filename;
  if (isProbablyBinary(new Uint8Array(buffer))) {
    return {
      path,
      kind: "resource",
      language: null,
      content: "",
      size: buffer.length,
    };
  }
  return {
    path,
    kind: classify(path),
    language: LANG_BY_EXT[extOf(path)] ?? null,
    content: buffer.toString("utf-8"),
    size: buffer.length,
  };
}

export function parseText(text: string, name: string): ParsedFile {
  return {
    path: name || "SKILL.md",
    kind: "instruction",
    language: "markdown",
    content: text,
    size: Buffer.byteLength(text, "utf-8"),
  };
}

export function deriveScanName(files: ParsedFile[], fallback: string): string {
  const skillMd = files.find(
    (f) => (f.path.split("/").pop() ?? "").toLowerCase() === "skill.md",
  );
  if (skillMd) {
    const m = skillMd.content.match(/^#\s+(.+)$/m);
    if (m) return m[1].trim().slice(0, 120);
    const nameMatch = skillMd.content.match(/^name:\s*(.+)$/im);
    if (nameMatch) return nameMatch[1].trim().replace(/^["']|["']$/g, "").slice(0, 120);
  }
  const top = files[0]?.path.split("/")[0];
  return (top || fallback).slice(0, 120);
}