import fs from "node:fs";
import os from "node:os";
import path from "node:path";
import { normalizeOptionalString } from "../../shared/string-coerce.js";

const CLAUDE_PROJECTS_DIRNAME = path.join(".claude", "projects");
const MAX_SANITIZED_PROJECT_LENGTH = 200;

function simpleHash36(input: string): string {
  let hash = 0;
  for (let index = 0; index < input.length; index += 1) {
    hash = (hash * 31 + input.charCodeAt(index)) >>> 0;
  }
  return hash.toString(36);
}

function sanitizeClaudeCliProjectKey(workspaceDir: string): string {
  const sanitized = workspaceDir.replace(/[^a-zA-Z0-9]/g, "-");
  if (sanitized.length <= MAX_SANITIZED_PROJECT_LENGTH) {
    return sanitized;
  }
  return `${sanitized.slice(0, MAX_SANITIZED_PROJECT_LENGTH)}-${simpleHash36(workspaceDir)}`;
}

function canonicalizeWorkspaceDir(workspaceDir: string): string {
  const resolved = path.resolve(workspaceDir).normalize("NFC");
  try {
    return fs.realpathSync.native(resolved).normalize("NFC");
  } catch {
    return resolved;
  }
}

export function resolveClaudeCliProjectDirForWorkspace(params: {
  workspaceDir: string;
  homeDir?: string;
}): string {
  const homeDir = normalizeOptionalString(params.homeDir) || process.env.HOME || os.homedir();
  const canonicalWorkspaceDir = canonicalizeWorkspaceDir(params.workspaceDir);
  return path.join(
    homeDir,
    CLAUDE_PROJECTS_DIRNAME,
    sanitizeClaudeCliProjectKey(canonicalWorkspaceDir),
  );
}