"""
The far end of a remote session. pyrepld sends this over ssh stdin, after
the sh script in pyrepld.REMOTE_SCRIPT has found an interpreter, with
`FILES = {...}` put in front: worker.py, tk.py and vendor/, as source.

Nothing is written on that host. vendor/ is served by an import hook from
memory, placed after the normal path so a session's own packages still win,
and the sources go into linecache so tracebacks show their lines. Then
worker.py runs as the remote form (--stdio), exactly as it would from disk.

Must stay runnable on python3.6.
"""
import importlib.abc
import importlib.util
import linecache
import sys

ROOT = "<pyrepl>"


def _cache(name, src):
    linecache.cache[name] = (len(src), None, src.splitlines(True), name)


class _Vendor(importlib.abc.MetaPathFinder, importlib.abc.Loader):
    def find_spec(self, name, path=None, target=None):
        rel = "vendor/" + name.replace(".", "/")
        for key, pkg in ((rel + "/__init__.py", True), (rel + ".py", False)):
            if key in FILES:
                spec = importlib.util.spec_from_loader(name, self, origin=ROOT + "/" + key,
                                                       is_package=pkg)
                spec.has_location = True
                return spec
        return None

    def create_module(self, spec):
        return None

    def exec_module(self, module):
        name = module.__spec__.origin
        src = FILES[name[len(ROOT) + 1:]]
        _cache(name, src)
        exec(compile(src, name, "exec"), module.__dict__)


sys.meta_path.append(_Vendor())
_name = ROOT + "/worker.py"
_cache(_name, FILES["worker.py"])
sys.argv = [_name, "--stdio"]
exec(compile(FILES["worker.py"], _name, "exec"),
     {"__name__": "__main__", "__file__": _name, "__builtins__": __builtins__,
      "PYREPL_FILES": FILES})