"""Console HTTP surface. Loopback-only by deployment (compose binds 127.0.0.1);
this layer adds the Origin check and field-naming validation errors."""
from __future__ import annotations

import asyncio
import json
import queue
import re
import time
from pathlib import Path

import httpx
from fastapi import FastAPI, HTTPException, Request
from fastapi.responses import FileResponse, JSONResponse, StreamingResponse
from fastapi.staticfiles import StaticFiles

from je_validation.console import catalog
from je_validation.console.budgets import default_step_budget, default_token_ceiling
from je_validation.console.config import ConsoleSettings
from je_validation.console.models_proxy import PINNED_MODELS, fetch_models
from je_validation.console.runs import (
    BASELINES,
    DuplicateRunError,
    RunManager,
    RunRequest,
)
from je_validation.envir.llm_agent import SYSTEM_PROMPT
from je_validation.envir.run_config import DEFAULT_KNOBS, KNOB_RANGES, MIN_SEEDS_FOR_VARIANCE

BASELINE_ENTRIES = [
    {"id": "baseline:flag_everything", "name": "Baseline: flag everything",
     "prompt_price": 0.0, "completion_price": 0.0, "launchable": True},
    {"id": "baseline:no_evidence", "name": "Baseline: no evidence",
     "prompt_price": 0.0, "completion_price": 0.0, "launchable": True},
]
MODELS_CACHE_TTL = 900.0
STATIC_DIR = Path(__file__).parent / "static"
# mirrors runs.py's private _NON_TERMINAL; api.py has no access to it and must
# not import a leading-underscore name across modules, so it is redefined here
_NON_TERMINAL = {"queued", "running"}
# mirrors runs.py's private _RUN_ID_RE (same rule the manager enforces at
# launch); redefined here for the same cross-module-underscore-import reason.
_RUN_ID_RE = re.compile(r"^[A-Za-z0-9_-]{1,64}$")
# model slugs (e.g. "anthropic_claude-sonnet-4.5") legitimately contain dots,
# so the charset allows them; "." and ".." are rejected explicitly below since
# they'd otherwise be valid single path segments under this charset.
_MODELSLUG_RE = re.compile(r"^[A-Za-z0-9._-]{1,128}$")
REQUIRED_RUN_FIELDS = ("run_id", "task_id", "seed_count", "step_budget")


def _validate_run_id(run_id: str) -> None:
    if not _RUN_ID_RE.match(run_id):
        raise HTTPException(status_code=404, detail="not found")


def _validate_modelslug(modelslug: str) -> None:
    if modelslug in (".", "..") or not _MODELSLUG_RE.match(modelslug):
        raise HTTPException(status_code=404, detail="not found")


def _within_console_root(path: Path, console_root: Path) -> Path:
    """Belt-and-braces check: even with run_id/modelslug pre-validated, confirm
    the joined path did not escape the console run directory. Violations 404
    rather than reveal why, matching the charset-rejection responses above."""
    resolved = path.resolve()
    if not resolved.is_relative_to(console_root.resolve()):
        raise HTTPException(status_code=404, detail="not found")
    return resolved


def _load_models(settings: ConsoleSettings,
                 models_transport: httpx.BaseTransport | None) -> list[dict]:
    try:
        fetched = fetch_models(settings.openrouter_base_url, transport=models_transport)
        for m in fetched:
            m["launchable"] = True
        return BASELINE_ENTRIES + fetched
    except httpx.HTTPError:
        pinned = [{**m, "launchable": False} for m in PINNED_MODELS]
        return BASELINE_ENTRIES + pinned


def _field_for_value_error(msg: str) -> str:
    if "knob" in msg:
        return "knobs"
    if "prompt_version" in msg:
        return "prompt_version"
    if "tools" in msg:
        return "tools_enabled"
    if "pricing" in msg:
        return "models"
    return "request"


def _is_terminal(manager, run_id: str) -> bool:
    try:
        status = manager.status(run_id)
    except (KeyError, FileNotFoundError):
        return True
    return status.get("status") not in _NON_TERMINAL


def _parse_after(raw: str | None) -> int:
    """Parse the SSE resume position (Last-Event-ID header or ?after= query).
    Invalid input falls back to 0 rather than 500ing: the client's seq-dedupe
    makes a from-zero replay harmless."""
    try:
        return int(raw or 0)
    except ValueError:
        return 0


def create_app(settings: ConsoleSettings, manager: RunManager | None = None,
               models_transport: httpx.BaseTransport | None = None) -> FastAPI:
    app = FastAPI()
    mgr = manager if manager is not None else RunManager(settings)
    allowed_origins = {f"http://localhost:{settings.port}",
                       f"http://127.0.0.1:{settings.port}"}
    if settings.space_host:
        allowed_origins.add(f"https://{settings.space_host}")

    models_cache: dict = {"models": None, "at": 0.0}

    def get_models() -> list[dict]:
        now = time.monotonic()
        cached = models_cache["models"]
        if cached is not None and now - models_cache["at"] < MODELS_CACHE_TTL:
            return cached
        models = _load_models(settings, models_transport)
        models_cache["models"] = models
        models_cache["at"] = now
        return models

    def run_dir(run_id: str) -> Path:
        return settings.data_dir / "runs" / "console" / run_id

    @app.middleware("http")
    async def origin_check(request: Request, call_next):
        origin = request.headers.get("origin")
        if origin is not None and origin not in allowed_origins:
            return JSONResponse({"error": "forbidden origin"}, status_code=403)
        return await call_next(request)

    @app.get("/api/health")
    def health():
        return {"ok": True}

    @app.get("/api/tasks")
    def list_tasks():
        out = []
        for task_id, task in catalog.built_tasks().items():
            population = catalog.default_population(task_id)
            step_budget = default_step_budget(population)
            token_ceiling = default_token_ceiling(step_budget)
            knobs = {**DEFAULT_KNOBS, "population": population}
            knob_meta = {k: {"min": lo, "max": hi} for k, (lo, hi) in KNOB_RANGES.items()}
            entry = {
                "id": task_id,
                "tier": task["tier"],
                "brief": task["brief"],
                "tools": list(task["tools"]),
                "population_editable": task_id in catalog.POPULATION_EDITABLE,
                "knob_meta": knob_meta,
                "defaults": {"knobs": knobs, "step_budget": step_budget,
                            "token_ceiling": token_ceiling},
                "weights": dict(task["weight"]),
            }
            if "dials" in task:
                entry["dials"] = list(task["dials"])
            out.append(entry)
        return out

    @app.get("/api/models")
    def list_models():
        return get_models()

    @app.get("/api/tasks/{task_id}/prompt")
    def task_prompt(task_id: str, version: str = "standard",
                    step_budget: int | None = None):
        """The exact text the agent receives: system prompt + assembled brief.
        Preview only — the episode path builds its own copy via the same
        brief_for(), so this can never drift from what actually runs."""
        task = catalog.built_tasks().get(task_id)
        if task is None:
            raise HTTPException(status_code=404, detail=f"unknown task: {task_id}")
        try:
            brief = catalog.brief_for(task, version, step_budget=step_budget)
        except ValueError as e:
            return JSONResponse({"field": "prompt_version", "error": str(e)},
                                status_code=422)
        return {"system_prompt": SYSTEM_PROMPT, "brief": brief}

    @app.get("/api/runs")
    def list_runs():
        """Run history: one summary per persisted run.json, newest first.
        Reads disk directly (like /results and /trajectory) so runs from
        earlier server processes are listed too, not just this one's."""
        console_root = settings.data_dir / "runs" / "console"
        if not console_root.exists():
            return []
        entries = []
        for child in console_root.iterdir():
            path = child / "run.json"
            try:
                data = json.loads(path.read_text(encoding="utf-8"))
                request = data["request"]
                entries.append((path.stat().st_mtime, {
                    "run_id": data["run_id"],
                    "status": data["status"],
                    "task_id": request["task_id"],
                    "tier": data.get("contract", {}).get("tier"),
                    "models": list(request.get("models") or ()),
                    "seed_count": request["seed_count"],
                    "prompt_version": request.get("prompt_version"),
                    "cost_usd": data.get("cost_usd"),
                }))
            except (OSError, ValueError, KeyError, TypeError):
                continue        # junk dir or partial write: skip, never 500
        entries.sort(key=lambda e: e[0], reverse=True)
        return [summary for _, summary in entries]

    @app.post("/api/runs")
    async def create_run(request: Request):
        body = await request.json()
        for field_name in REQUIRED_RUN_FIELDS:
            if field_name not in body:
                return JSONResponse({"field": field_name, "error": "required"},
                                    status_code=422)
        model_index = {m["id"]: m for m in get_models()}
        pricing = {}
        for model_id in body.get("models") or []:
            if model_id in BASELINES:
                continue
            m = model_index.get(model_id)
            if m is not None and m.get("launchable", True):
                pricing[model_id] = {"prompt_price": m["prompt_price"],
                                     "completion_price": m["completion_price"]}
        tools_enabled = body.get("tools_enabled")
        if tools_enabled is None:
            # None means "the task's full tool list"; look it up via .get() so
            # an unknown task_id doesn't crash here -- it still flows through
            # unchanged to mgr.launch()'s own task lookup below.
            task = catalog.built_tasks().get(body["task_id"])
            if task is not None:
                tools_enabled = task["tools"]
        req = RunRequest(
            run_id=body["run_id"],
            task_id=body["task_id"],
            models=tuple(body.get("models") or ()),
            seed_count=body["seed_count"],
            knobs=body.get("knobs") or {},
            tools_enabled=tuple(tools_enabled) if tools_enabled is not None else None,
            step_budget=body["step_budget"],
            token_ceiling=body.get("token_ceiling"),
            pricing=pricing,
            prompt_version=body.get("prompt_version") or "standard",
        )
        try:
            contract = mgr.launch(req)
        except DuplicateRunError:
            raise HTTPException(status_code=409,
                                detail=f"duplicate run_id: {req.run_id}") from None
        except ValueError as e:
            msg = str(e)
            return JSONResponse({"field": _field_for_value_error(msg), "error": msg},
                                status_code=422)
        seed_warning = req.seed_count < MIN_SEEDS_FOR_VARIANCE
        return JSONResponse({"contract": contract, "seed_warning": seed_warning},
                            status_code=202)

    @app.get("/api/runs/{run_id}")
    def get_run(run_id: str):
        _validate_run_id(run_id)
        try:
            return mgr.status(run_id)
        except (KeyError, FileNotFoundError):
            raise HTTPException(status_code=404,
                                detail=f"unknown run: {run_id}") from None

    @app.get("/api/runs/{run_id}/events")
    async def run_events(run_id: str, request: Request):
        _validate_run_id(run_id)
        header_id = request.headers.get("Last-Event-ID")
        after = _parse_after(header_id or request.query_params.get("after"))
        backlog, q = mgr.subscribe_with_replay(run_id, after)

        async def gen():
            try:
                for evt in backlog:
                    yield f"id: {evt['seq']}\ndata: {json.dumps(evt)}\n\n"
                while True:
                    if _is_terminal(mgr, run_id) and q.empty():
                        break
                    try:
                        evt = await asyncio.to_thread(q.get, timeout=15)
                    except queue.Empty:
                        yield ": keepalive\n\n"
                        continue
                    yield f"id: {evt['seq']}\ndata: {json.dumps(evt)}\n\n"
            finally:
                mgr.unsubscribe(run_id, q)

        return StreamingResponse(gen(), media_type="text/event-stream")

    @app.get("/api/runs/{run_id}/results")
    def run_results(run_id: str):
        _validate_run_id(run_id)
        console_root = settings.data_dir / "runs" / "console"
        path = _within_console_root(run_dir(run_id) / "results.json", console_root)
        if not path.exists():
            return JSONResponse({"error": "run not finished"}, status_code=409)
        return json.loads(path.read_text(encoding="utf-8"))

    @app.get("/api/runs/{run_id}/episodes/{modelslug}/{seed}/trajectory")
    def run_trajectory(run_id: str, modelslug: str, seed: int):
        _validate_run_id(run_id)
        _validate_modelslug(modelslug)
        console_root = settings.data_dir / "runs" / "console"
        ep_dir = _within_console_root(run_dir(run_id) / modelslug / f"seed{seed}",
                                      console_root)
        jsonl_files = sorted(ep_dir.glob("*.jsonl")) if ep_dir.exists() else []
        if not jsonl_files:
            raise HTTPException(status_code=404, detail="trajectory not found")
        lines = jsonl_files[0].read_text(encoding="utf-8").splitlines()
        return [json.loads(line) for line in lines if line.strip()]

    @app.get("/")
    def root():
        return FileResponse(STATIC_DIR / "index.html")

    # static mount last: added after all API routes above
    app.mount("/static", StaticFiles(directory=STATIC_DIR), name="static")

    return app


# Module-level app for uvicorn (`uvicorn je_validation.console.api:app`).
# Guarded: on a checkout without data/ (e.g. `import api` during test
# collection, or any environment lacking JE_DATA_DIR/snapshots), instantiating
# ConsoleSettings.from_env() raises FileNotFoundError from latest_snapshot();
# importing this module must never crash, so app falls back to None and the
# real deployment (compose, with data/ present) is what actually serves it.
try:
    app = create_app(ConsoleSettings.from_env())
except Exception:
    app = None