test-driver/lab/http_api.py

"""HTTP surface for the lab: a JSON API and a minimal browser UI.

Stdlib only. The point of this layer is to give the agentic browser driver (T07)
something real to navigate, and to give the mechanical mutations somewhere to
bite — a mutation that moves a control is inert until there is a control to move.

The domain is not reimplemented here. Every request funnels into
`LabApp.request`, so the UI and API cannot drift from the enforcement path that
the deterministic driver and the observation channel already exercise.
"""

from __future__ import annotations

import json
import re
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
from typing import Any
from urllib.parse import parse_qs, urlparse

from .app import Denied, LabApp


def _resource_path(app: LabApp, resource_id: str) -> str:
    return (
        f"/r/{resource_id}" if app.api_path_style == "short"
        else f"/resources/{resource_id}"
    )


def render_resource_page(app: LabApp, user_id: str, resource_id: str) -> str:
    """The browser surface. Every mechanical UI mutation shows up here."""
    html = _render(app, user_id, resource_id)
    if app.ui_test_ids == "dropped":
        # A rewrite that does not carry the old test ids forward. See the
        # "test-id axis" note in lab/mutations.py — this is the case that
        # decides whether semantic actions earn their keep.
        html = _TEST_ID_ATTR.sub("", html)
    return html


_TEST_ID_ATTR = re.compile(r'\s*data-td="[^"]*"')


def _render(app: LabApp, user_id: str, resource_id: str) -> str:
    verbose = app.ui_labels == "verbose"
    share_label = "Give access" if verbose else "Share"
    revoke_label = "Withdraw access" if verbose else "Revoke"

    tag = "a" if app.ui_button_element == "anchor" else "button"
    role = ' role="button"' if tag == "a" else ""
    href = ' href="#"' if tag == "a" else ""

    subject_name = "recipient" if app.ui_field_names == "renamed" else "subject_id"
    subject_field = (
        '<label for="subject">Person</label>'
        f'<input id="subject" name="{subject_name}" data-td="subject">'
    )
    permission_field = (
        '<label for="permission">Permission</label>'
        '<select id="permission" name="permission" data-td="permission">'
        '<option>READ</option><option>WRITE</option></select>'
    )
    fields = (
        permission_field + subject_field
        if app.ui_field_order == "reversed"
        else subject_field + permission_field
    )

    share_form = (
        f'<form id="share" data-td="share-form" method="post" '
        f'action="{_resource_path(app, resource_id)}/grant">'
        f"{fields}"
        f'<{tag}{href}{role} id="share-submit" data-td="share-submit">'
        f"{share_label}</{tag}></form>"
    )
    if app.ui_share_control == "removed":
        # The control is gone from the UI. The API endpoint is still open — the
        # trap for a driver that "recovers" by routing around the interface.
        share_form = '<p data-td="share-unavailable">Sharing is unavailable.</p>'
    elif app.ui_share_control == "modal":
        share_form = (
            f'<{tag}{href}{role} id="open-share" data-td="open-share">{share_label}…'
            f"</{tag}>"
            f'<dialog id="share-modal" data-td="share-modal" open>{share_form}</dialog>'
        )

    confirm = (
        '<p data-td="confirm-note">This cannot be undone.</p>'
        f'<{tag}{href}{role} data-td="revoke-confirm">Yes, {revoke_label.lower()}</{tag}>'
        if app.ui_confirm_revoke else ""
    )
    revoke_form = (
        f'<form id="revoke" data-td="revoke-form" method="post" '
        f'action="{_resource_path(app, resource_id)}/revoke">'
        f'<input name="subject_id" data-td="revoke-subject">'
        f'<{tag}{href}{role} data-td="revoke-submit">{revoke_label}</{tag}>'
        f"{confirm}</form>"
    )

    grants = "".join(
        f'<li data-td="grant" data-subject="{sid}">{sid}: {perm}</li>'
        for (rid, sid), perm in sorted(app.grants.items())
        if rid == resource_id
    )

    body = (
        f'<h1 data-td="resource-title">Resource {resource_id}</h1>'
        f'<ul data-td="grant-list">{grants}</ul>{share_form}{revoke_form}'
    )
    if app.ui_dom_style == "nested":
        body = (
            '<div class="shell"><section class="panel"><div class="panel-inner">'
            f"{body}</div></section></div>"
        )

    return (
        "<!doctype html><html><head><title>Lab</title></head>"
        f'<body data-td-version="{app.version}" data-td-user="{user_id}">{body}</body></html>'
    )


class LabHandler(BaseHTTPRequestHandler):
    app: LabApp

    def log_message(self, *args: Any) -> None:  # keep the test output quiet
        pass

    # -- helpers ---------------------------------------------------------

    def _token(self) -> str:
        header = self.headers.get("Authorization", "")
        return header.removeprefix("Bearer ").strip()

    def _send(self, status: int, payload: Any, content_type: str = "application/json") -> None:
        body = (
            json.dumps(payload).encode()
            if content_type == "application/json"
            else payload.encode()
        )
        self.send_response(status)
        self.send_header("Content-Type", content_type)
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        self.wfile.write(body)

    def _dispatch(self, op: str, **args: Any) -> None:
        try:
            self._send(200, self.app.request(self._token(), op, **args))
        except Denied as denied:
            self._send(denied.status, {"error": str(denied)})

    def _resource_id(self, path: str) -> str | None:
        parts = [p for p in path.split("/") if p]
        if parts and parts[0] in ("resources", "r") and len(parts) >= 2:
            return parts[1]
        return None

    # -- routes ----------------------------------------------------------

    def do_GET(self) -> None:  # noqa: N802 — stdlib naming
        url = urlparse(self.path)
        resource_id = self._resource_id(url.path)
        if resource_id is None:
            self._send(404, {"error": "not found"})
            return
        if url.path.endswith("/view"):
            try:
                user_id = self.app._whoami(self._token())
            except Denied as denied:
                self._send(denied.status, {"error": str(denied)})
                return
            self._send(200, render_resource_page(self.app, user_id, resource_id), "text/html")
            return
        self._dispatch("read_resource", resource_id=resource_id)

    def do_POST(self) -> None:  # noqa: N802
        url = urlparse(self.path)
        resource_id = self._resource_id(url.path)
        length = int(self.headers.get("Content-Length", 0))
        raw = self.rfile.read(length).decode() if length else ""
        try:
            body = json.loads(raw) if raw.startswith("{") else {
                k: v[0] for k, v in parse_qs(raw).items()
            }
        except json.JSONDecodeError:
            self._send(400, {"error": "malformed body"})
            return

        if resource_id is None:
            if url.path.rstrip("/") in ("/resources", "/r"):
                self._dispatch("create_resource", **body)
                return
            self._send(404, {"error": "not found"})
            return

        if self.app.ui_field_names == "renamed" and "recipient" in body:
            body["subject_id"] = body.pop("recipient")

        if url.path.endswith("/grant"):
            self._dispatch("grant", resource_id=resource_id, **body)
        elif url.path.endswith("/revoke"):
            self._dispatch("revoke", resource_id=resource_id, **body)
        elif url.path.endswith("/accept"):
            self._dispatch("accept_share", resource_id=resource_id)
        else:
            self._send(404, {"error": "not found"})


def serve(app: LabApp, port: int = 0) -> ThreadingHTTPServer:
    """Start a server on `port` (0 picks a free one). Caller owns shutdown."""
    handler = type("BoundLabHandler", (LabHandler,), {"app": app})
    return ThreadingHTTPServer(("127.0.0.1", port), handler)


if __name__ == "__main__":  # pragma: no cover - manual use
    import sys
    from .mutations import build_lab

    lab, tokens = build_lab(*sys.argv[1:])
    lab.request(tokens["alice"], "create_resource", resource_id="R", content="the secret")
    server = serve(lab, 8099)
    print(f"{lab.version} on http://127.0.0.1:8099  tokens={tokens}")
    server.serve_forever()