#!/usr/bin/env node
/**
 * MCP server: npm package & semver validator (read-only).
 *
 * Tools:
 *   - validate_semver         : check that a version string is valid semver
 *                                and optionally reject ranges/latest
 *   - check_lockfile_package  : look up a package in the root package-lock.json
 *                                and return its locked version without touching
 *                                the registry
 *
 * No network access, no CLI invocations. Pure parsing over local files.
 */

import fs from "node:fs";
import path from "node:path";
import { runMCPServer } from "./lib/mcp-server.mjs";
import { getProjectRoot } from "../lib/project-root.mjs";

const projectRoot = getProjectRoot();

// SemVer 2.0.0 regex from https://semver.org/ (BSD-licensed).
const SEMVER_RE =
  /^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$/;

function loadLockfile() {
  const lockPath = path.join(projectRoot, "package-lock.json");
  if (!fs.existsSync(lockPath)) return null;
  try {
    return JSON.parse(fs.readFileSync(lockPath, "utf8"));
  } catch {
    return null;
  }
}

const tools = [
  {
    name: "validate_semver",
    description:
      "Validate a version string as strict SemVer 2.0.0. When `rejectRanges` is true, reject caret/tilde/latest and require an exact pinned version (the KIS-TOiR version policy). Returns parsed components on success.",
    inputSchema: {
      type: "object",
      properties: {
        version: { type: "string", description: "Version string to validate" },
        rejectRanges: {
          type: "boolean",
          description:
            "If true, treat ^, ~, >, <, *, latest as invalid. Default true.",
        },
      },
      required: ["version"],
    },
    execute: async ({ version, rejectRanges = true }) => {
      if (typeof version !== "string" || !version.trim()) {
        return { success: false, error: "version must be a non-empty string" };
      }

      const trimmed = version.trim();

      if (rejectRanges) {
        if (/^[\^~><=*]/.test(trimmed) || trimmed === "latest") {
          return {
            success: false,
            error: `version '${trimmed}' is a range or tag; policy requires an exact pinned version`,
          };
        }
      }

      // Strip a leading range operator if ranges are allowed.
      const candidate = rejectRanges ? trimmed : trimmed.replace(/^[\^~><=]+/, "");

      const m = candidate.match(SEMVER_RE);
      if (!m) {
        return {
          success: false,
          error: `'${trimmed}' is not a valid SemVer 2.0.0 version`,
        };
      }

      return {
        success: true,
        result: {
          raw: trimmed,
          major: Number(m[1]),
          minor: Number(m[2]),
          patch: Number(m[3]),
          prerelease: m[4] ?? null,
          build: m[5] ?? null,
        },
      };
    },
  },
  {
    name: "check_lockfile_package",
    description:
      "Look up a package inside the root package-lock.json and return its locked version. Read-only; does not contact the npm registry. Returns { found: boolean, version?: string, paths: string[] }.",
    inputSchema: {
      type: "object",
      properties: {
        name: { type: "string", description: "Package name, e.g. @nestjs/core" },
      },
      required: ["name"],
    },
    execute: async ({ name }) => {
      if (typeof name !== "string" || !name.trim()) {
        return { success: false, error: "name must be a non-empty string" };
      }

      const lock = loadLockfile();
      if (!lock) {
        return {
          success: false,
          error: "package-lock.json not found or unreadable at project root",
        };
      }

      const matches = [];
      const packages = lock.packages ?? {};
      for (const [key, value] of Object.entries(packages)) {
        // npm v7+ lockfile: keys look like "node_modules/<pkg>" or
        // "node_modules/<scope>/<pkg>". Strip the prefix and compare.
        if (!key) continue;
        const stripped = key.replace(/^.*node_modules\//, "");
        if (stripped === name) {
          matches.push({ path: key, version: value.version });
        }
      }

      return {
        success: true,
        result: {
          name,
          found: matches.length > 0,
          occurrences: matches,
        },
      };
    },
  },
];

runMCPServer({ name: "kis-toir-npm-validator", version: "0.1.0", tools });