import { basename, dirname, join, relative } from "node:path";
import { getAgentDir, SettingsManager, type PackageSource } from "@mariozechner/pi-coding-agent";
import type { ExtensionEntry } from "./types.js";

function updatePatterns(current: string[], pattern: string, enabled: boolean): string[] {
  const updated = current.filter((entry) => {
    const stripped = entry.startsWith("!") || entry.startsWith("+") || entry.startsWith("-") ? entry.slice(1) : entry;
    return stripped !== pattern;
  });
  updated.push(`${enabled ? "+" : "-"}${pattern}`);
  return updated;
}

function getTopLevelPattern(extension: ExtensionEntry, cwd: string): string {
  const baseDir = extension.scope === "project" ? join(cwd, ".pi") : getAgentDir();
  return relative(baseDir, extension.path);
}

function getPackagePattern(extension: ExtensionEntry): string {
  const baseDir = extension.baseDir ?? dirname(extension.path);
  return relative(baseDir, extension.path);
}

function hasPackageFilters(pkg: Exclude<PackageSource, string>): boolean {
  return pkg.extensions !== undefined || pkg.skills !== undefined || pkg.prompts !== undefined || pkg.themes !== undefined;
}

export async function setExtensionEnabled(cwd: string, extension: ExtensionEntry, enabled: boolean): Promise<void> {
  if (extension.scope === "temporary") {
    throw new Error("Temporary extensions cannot be toggled.");
  }

  const settingsManager = SettingsManager.create(cwd, getAgentDir());

  if (extension.origin === "top-level") {
    const settings = extension.scope === "project" ? settingsManager.getProjectSettings() : settingsManager.getGlobalSettings();
    const current = [...(settings.extensions ?? [])];
    const updated = updatePatterns(current, getTopLevelPattern(extension, cwd), enabled);

    if (extension.scope === "project") settingsManager.setProjectExtensionPaths(updated);
    else settingsManager.setExtensionPaths(updated);

    await settingsManager.flush();
    return;
  }

  const settings = extension.scope === "project" ? settingsManager.getProjectSettings() : settingsManager.getGlobalSettings();
  const packages = [...(settings.packages ?? [])];
  const packageIndex = packages.findIndex((pkg) => (typeof pkg === "string" ? pkg : pkg.source) === extension.source);
  if (packageIndex === -1) throw new Error("Could not find the package settings entry for this extension.");

  const packageEntry = packages[packageIndex];
  const packageConfig = typeof packageEntry === "string" ? { source: packageEntry } : { ...packageEntry };
  const current = [...(packageConfig.extensions ?? [])];
  const updated = updatePatterns(current, getPackagePattern(extension), enabled);
  packageConfig.extensions = updated.length > 0 ? updated : undefined;
  packages[packageIndex] = hasPackageFilters(packageConfig) ? packageConfig : packageConfig.source;

  if (extension.scope === "project") settingsManager.setProjectPackages(packages);
  else settingsManager.setPackages(packages);

  await settingsManager.flush();
}

export function getExtensionNameFromPath(path: string): string {
  const filename = basename(path);
  if (filename === "index.ts" || filename === "index.js") {
    return basename(dirname(path));
  }
  return filename.replace(/\.[^.]+$/, "");
}