import { execSync } from "node:child_process";
import { readFileSync, writeFileSync } from "node:fs";
import { join } from "node:path";
import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { Type } from "typebox";

// ============================================================
// License Templates
// ============================================================

// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
const LICENSE_DIR = join(__dirname ?? ".", "licenses");

const LICENSE_TYPES = [
  "mit",
  "apache-2.0",
  "bsd-3",
  "isc",
  "gpl-3.0",
  "agpl-3.0",
  "lgpl-3.0",
  "mpl-2.0",
  "unlicense",
] as const;

type LicenseType = (typeof LICENSE_TYPES)[number];

function loadTemplate(type: LicenseType): (name: string, year: string) => string {
  const raw = readFileSync(join(LICENSE_DIR, `${type}.txt`), "utf-8");
  return (name, year) => raw.replaceAll("{name}", name).replaceAll("{year}", year);
}

// ============================================================
// Core Logic
// ============================================================

function generateLicense(type: LicenseType, name: string, year: string, cwd: string): string {
  const template = loadTemplate(type);
  const filePath = join(cwd, "LICENSE");
  writeFileSync(filePath, template(name, year), "utf-8");
  return filePath;
}

function isValidLicenseType(type: string): type is LicenseType {
  return LICENSE_TYPES.includes(type as LicenseType);
}

function getGitUserName(cwd: string): string {
  try {
    return execSync("git config user.name", { cwd, encoding: "utf-8" }).trim();
  } catch {
    return "Your Name";
  }
}

// ============================================================
// Extension Entry
// ============================================================

export default function (pi: ExtensionAPI) {
  // Tool - LLM calls automatically
  pi.registerTool({
    name: "generate_license",
    label: "Generate License",
    description:
      "Generate a license file in the current directory. Supported types: mit, apache-2.0, bsd-3, isc, gpl-3.0, agpl-3.0, lgpl-3.0, mpl-2.0, unlicense.",
    parameters: Type.Object({
      type: Type.Optional(
        Type.String({
          description:
            "License type: mit, apache-2.0, bsd-3, isc, gpl-3.0, agpl-3.0, lgpl-3.0, mpl-2.0, unlicense",
        }),
      ),
      name: Type.Optional(Type.String({ description: "Copyright holder name" })),
    }),
    async execute(_id, params, _signal, _onUpdate, ctx) {
      const { type = "mit", name } = params as {
        type?: string;
        name?: string;
      };
      const year = new Date().getFullYear().toString();
      const licenseType = isValidLicenseType(type) ? type : "mit";
      const authorName = name || getGitUserName(ctx.cwd);

      const filePath = generateLicense(licenseType, authorName, year, ctx.cwd);
      return {
        content: [
          {
            type: "text",
            text: `✓ LICENSE created at ${filePath} (${licenseType}, ${authorName}, ${year})`,
          },
        ],
        details: { type: licenseType, name: authorName, year },
      };
    },
  });

  // Command - User calls directly with /license
  pi.registerCommand("gen-license", {
    description:
      "Generate a license file (mit, apache-2.0, bsd-3, isc, gpl-3.0, agpl-3.0, lgpl-3.0, mpl-2.0, unlicense)",
    getArgumentCompletions: (prefix: string) => {
      const items = LICENSE_TYPES.map((t) => ({ value: t, label: t }));
      const filtered = items.filter((i) => i.value.startsWith(prefix));
      return filtered.length > 0 ? filtered : null;
    },
    handler: async (args, ctx) => {
      const parts = (args || "").trim().split(/\s+/);
      const type = (parts[0] || "mit").toLowerCase();
      const name = parts[1] || getGitUserName(ctx.cwd);
      const year = new Date().getFullYear().toString();

      if (!isValidLicenseType(type)) {
        ctx.ui.notify(`Unknown license: ${type}. Available: ${LICENSE_TYPES.join(", ")}`, "error");
        return;
      }

      generateLicense(type, name, year, ctx.cwd);
      ctx.ui.notify(`✓ LICENSE created (${type}, ${name}, ${year})`, "info");
    },
  });
}