import type { WorkspaceFileSelector } from "@paperclipai/shared";

export interface ParsedWorkspaceFileRef {
  path: string;
  resourceKind?: "file" | "directory";
  line: number | null;
  column: number | null;
  projectId?: string | null;
  projectName?: string | null;
  workspaceId?: string | null;
  /**
   * Workspace selector the reference is bound to. Set once availability has
   * confirmed which workspace serves the path; defaults to `auto` otherwise.
   */
  workspace?: WorkspaceFileSelector;
  /** The original matched text (useful for rendering) */
  raw: string;
}

/**
 * Match a workspace file reference inside an inline code span.
 *
 * Accepts POSIX-style relative paths with at least one slash or a recognizable
 * file extension. Supports optional line/column suffixes:
 *
 *  - `path/to/file.ext`
 *  - `path/to/file.ext:42`
 *  - `path/to/file.ext:42:3`
 *  - `path/to/file.ext#L42`
 *  - `path/to/file.ext#L42C3`
 */
const WORKSPACE_FILE_REF_RE =
  /^([A-Za-z0-9_.\-+][A-Za-z0-9_./\-+]*\.[A-Za-z0-9_+\-]{1,10})(?::([1-9]\d*)(?::([1-9]\d*))?|#L([1-9]\d*)(?:C([1-9]\d*))?)?$/;

const BARE_NO_EXT_RE = /^([A-Za-z0-9_.\-+][A-Za-z0-9_./\-+]+\/[A-Za-z0-9_.\-+]+)(?::([1-9]\d*)(?::([1-9]\d*))?|#L([1-9]\d*)(?:C([1-9]\d*))?)?$/;

const WORKSPACE_DIRECTORY_REF_RE = /^([A-Za-z0-9_.\-+][A-Za-z0-9_./\-+]*\/)$/;

const INVALID_PREFIXES = ["/", "./", "../", "~/"];

function toPositiveInt(value: string | undefined): number | null {
  if (!value) return null;
  const n = Number.parseInt(value, 10);
  if (!Number.isFinite(n) || n <= 0) return null;
  return n;
}

function looksLikeWorkspacePath(input: string, opts: { allowTrailingSlash: boolean }): boolean {
  if (!input || input.length > 512) return false;
  if (input.includes("\\") || input.includes("\0")) return false;
  if (input.startsWith("/") || input.startsWith("~") || /^[A-Za-z]:/.test(input)) return false;
  if (input.includes("//")) return false;
  if (INVALID_PREFIXES.some((prefix) => input === prefix.slice(0, -1))) return false;
  const path = opts.allowTrailingSlash && input.endsWith("/") ? input.slice(0, -1) : input;
  if (!path || /^\.+$/.test(path)) return false;
  const segments = path.split("/");
  for (const segment of segments) {
    if (segment === "" || segment === "." || segment === "..") return false;
  }
  return true;
}

/**
 * Attempt to parse the given text as a workspace file reference.
 * Returns null if the text does not look like one.
 */
export function parseWorkspaceFileRef(input: string): ParsedWorkspaceFileRef | null {
  if (typeof input !== "string") return null;
  const trimmed = input.trim();
  if (!trimmed) return null;

  const directoryMatch = trimmed.match(WORKSPACE_DIRECTORY_REF_RE);
  if (directoryMatch) {
    const [, rawPath] = directoryMatch;
    if (!rawPath || !looksLikeWorkspacePath(rawPath, { allowTrailingSlash: true })) return null;
    if (!rawPath.slice(0, -1).includes("/")) return null;
    return {
      path: rawPath,
      resourceKind: "directory",
      line: null,
      column: null,
      raw: trimmed,
    };
  }

  const match = trimmed.match(WORKSPACE_FILE_REF_RE) ?? trimmed.match(BARE_NO_EXT_RE);
  if (!match) return null;
  const [, rawPath, colonLine, colonCol, hashLine, hashCol] = match;
  if (!rawPath) return null;
  if (!looksLikeWorkspacePath(rawPath, { allowTrailingSlash: false })) return null;

  const line = toPositiveInt(colonLine) ?? toPositiveInt(hashLine);
  const column = toPositiveInt(colonCol) ?? toPositiveInt(hashCol);

  // Disambiguate against plain prose filenames like `README.md`:
  // require either a slash in the path or a line anchor.
  if (!rawPath.includes("/") && line === null) return null;

  return {
    path: rawPath,
    resourceKind: "file",
    line,
    column,
    raw: trimmed,
  };
}

export function formatWorkspaceFileRefDisplay(ref: ParsedWorkspaceFileRef): string {
  const path = ref.line && ref.column
    ? `${ref.path}:${ref.line}:${ref.column}`
    : ref.line
      ? `${ref.path}:${ref.line}`
      : ref.path;
  return ref.projectName ? `${ref.projectName} / ${path}` : path;
}