"""
The public face of Collect (docs/blueprint/adr/0006) — the "DMZ". Exactly these routes and
nothing else are reachable without signing in, and each one only calls backend/collect.py.

It is an APIRouter so the main app can include it today, and `collect_app` is the same router
as a standalone ASGI app for deploying on its own later.

Cross-origin: the snippet sends its JSON as text/plain, which browsers treat as a "simple"
request (no preflight), and this module sets Access-Control-Allow-Origin per key itself. The
site-wide CORS middleware in app.py is for the signed-in app and stays out of the way.
"""

from __future__ import annotations

import html
import json
from pathlib import Path

from fastapi import APIRouter, FastAPI, Request
from fastapi.responses import HTMLResponse, JSONResponse, Response

from backend import collect

router = APIRouter()
_SNIPPET_PATH = Path(__file__).parent / "static" / "m8ion.js"


def _client_ip(request: Request) -> str:
    # Behind a proxy the first X-Forwarded-For entry is the visitor. Only trusted as a rate-limit
    # bucket, never for anything that grants access.
    forwarded = request.headers.get("x-forwarded-for", "")
    if forwarded:
        return forwarded.split(",")[0].strip()
    return request.client.host if request.client else "unknown"


def _with_cors(response: Response, public_key: str, origin: str | None) -> Response:
    allowed = collect.allowed_origin(public_key, origin)
    if allowed:
        response.headers["Access-Control-Allow-Origin"] = allowed
        response.headers["Vary"] = "Origin"
    return response


@router.post("/collect/{public_key}")
async def submit(public_key: str, request: Request):
    origin = request.headers.get("origin")
    raw = await request.body()
    if len(raw) > 16_000:
        return _with_cors(JSONResponse({"detail": "Submission is too large"}, status_code=413), public_key, origin)
    try:
        payload = json.loads(raw)
    except ValueError:
        return _with_cors(JSONResponse({"detail": "Malformed submission"}, status_code=400), public_key, origin)
    try:
        result = collect.submit(public_key, payload, origin, _client_ip(request))
        response = JSONResponse(result)
    except collect.CollectError as exc:
        response = JSONResponse({"detail": str(exc)}, status_code=exc.status)
    return _with_cors(response, public_key, origin)


_PAGE = """<!doctype html><html lang="en"><head><meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1"><title>{title}</title>
<style>body{{font-family:system-ui,sans-serif;max-width:32rem;margin:15vh auto;padding:0 1.25rem;color:#1b1f23}}
h1{{font-size:1.4rem}}p{{color:#555;line-height:1.5}}</style></head>
<body><h1>{title}</h1><p>{message}</p></body></html>"""

_CONFIRM_TEXT = {
    "confirmed": ("You're on the list", "Thanks, your email address is confirmed. You can close this page."),
    "expired": ("This link has expired", "Please sign up again from the form to get a new confirmation email."),
    "invalid": ("This link is no longer valid", "It may already have been used. If you are not on the list yet, sign up again."),
}


@router.get("/collect/confirm/{token}", response_class=HTMLResponse)
def confirm(token: str):
    title, message = _CONFIRM_TEXT[collect.confirm(token)]
    return HTMLResponse(_PAGE.format(title=html.escape(title), message=html.escape(message)))


@router.get("/m8ion.js")
def snippet():
    return Response(
        _SNIPPET_PATH.read_text(encoding="utf-8"),
        media_type="application/javascript",
        headers={"Cache-Control": "public, max-age=300", "Access-Control-Allow-Origin": "*"},
    )


collect_app = FastAPI(title="M8ion Collect")
collect_app.include_router(router)