"""Record which (model, GPU) pairs the demo cannot answer.

Every refusal is a request someone wanted and did not get, so the log doubles
as a demand-ranked coverage roadmap: it says which models and which GPUs are
worth measuring or supporting next.

Only the query itself is written -- the model id, the GPU name, the scenario
and why it was refused. No identifiers, no addresses, nothing about who asked,
and never a visitor's access token. The UI discloses that this happens.

Persistence
-----------
A Hugging Face Space has an ephemeral filesystem: it is wiped whenever the
Space restarts, which for a quiet Space is often. Set two environment variables
and the log is mirrored to a Hugging Face dataset repository instead, using
`CommitScheduler` from `huggingface_hub` (already a Gradio dependency):

    WATTGPU_DEMAND_DATASET=<user>/wattgpu-demand   # may be a private repo
    WATTGPU_DATASET_TOKEN=hf_...                   # write access to that repo

Writes still go to a local file; the scheduler batches them up to the dataset
every few minutes, so a restart loses at most one interval. Without those
variables nothing changes and the log stays local.
"""

from __future__ import annotations

import collections
import glob
import json
import os
import threading
import uuid
from datetime import datetime, timezone

DATA_DIR = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "data")

# The log lives in a folder of its own: the sync uploads whatever is in it, and
# `data/` also holds the models and the GPU database, which must not be pushed.
DEFAULT_LOG_DIR = os.path.join(DATA_DIR, "demand")

# Several Space replicas would otherwise overwrite each other's file, since the
# scheduler uploads the folder wholesale. One shard per process avoids that.
INSTANCE_ID = uuid.uuid4().hex[:8]

# Appends are short, but several viewers can hit the app at once.
_LOCK = threading.Lock()

# Truncated so a pathological input cannot bloat the log.
MAX_FIELD_CHARS = 200

# How often to push to the dataset, in minutes.
DEFAULT_SYNC_MINUTES = 5.0

_scheduler = None


def log_dir() -> str:
    return os.environ.get("WATTGPU_DEMAND_LOG_DIR", DEFAULT_LOG_DIR)


def log_path() -> str:
    """The file this process appends to.

    `WATTGPU_DEMAND_LOG` still names a file directly, which keeps existing
    deployments and the tests working.
    """
    explicit = os.environ.get("WATTGPU_DEMAND_LOG")
    if explicit:
        return explicit
    suffix = f"-{INSTANCE_ID}" if is_syncing() else ""
    return os.path.join(log_dir(), f"demand_log{suffix}.jsonl")


def is_enabled() -> bool:
    """Logging is on unless explicitly disabled."""
    return os.environ.get("WATTGPU_DEMAND_LOG_DISABLED", "").lower() not in ("1", "true", "yes")


def is_syncing() -> bool:
    """Whether a dataset repository is configured to mirror the log to."""
    return bool(os.environ.get("WATTGPU_DEMAND_DATASET"))


def record_refusal(model_id: str, gpu_name: str, scenario: str, reason: str) -> None:
    """Append one refused query. Never raises: logging must not break a response."""
    if not is_enabled():
        return

    entry = {
        "at": datetime.now(timezone.utc).isoformat(timespec="seconds"),
        "model": str(model_id or "")[:MAX_FIELD_CHARS],
        "gpu": str(gpu_name or "")[:MAX_FIELD_CHARS],
        "scenario": str(scenario or "")[:MAX_FIELD_CHARS],
        "reason": reason,
    }
    try:
        path = log_path()
        directory = os.path.dirname(path)
        if directory:
            os.makedirs(directory, exist_ok=True)
        with _LOCK, open(path, "a", encoding="utf-8") as fh:
            fh.write(json.dumps(entry) + "\n")
    except OSError:
        pass  # a read-only or full filesystem must not take the demo down


def start_sync() -> str | None:
    """Begin mirroring the log folder to a dataset repository.

    Returns a short status line for the startup log, or None when no dataset is
    configured. Failures are reported and swallowed: the demo must still serve
    estimates if the sync cannot start.
    """
    global _scheduler

    repo_id = os.environ.get("WATTGPU_DEMAND_DATASET")
    if not (repo_id and is_enabled()):
        return None
    if _scheduler is not None:
        return f"demand log already syncing to {repo_id}"

    token = os.environ.get("WATTGPU_DATASET_TOKEN") or os.environ.get("HF_TOKEN")
    if not token:
        return ("demand log NOT syncing: WATTGPU_DEMAND_DATASET is set but no "
                "WATTGPU_DATASET_TOKEN (or HF_TOKEN) to write with")

    try:
        minutes = float(os.environ.get("WATTGPU_SYNC_MINUTES", DEFAULT_SYNC_MINUTES))
    except ValueError:
        minutes = DEFAULT_SYNC_MINUTES

    try:
        from huggingface_hub import CommitScheduler

        os.makedirs(log_dir(), exist_ok=True)
        _scheduler = CommitScheduler(
            repo_id=repo_id,
            repo_type="dataset",
            folder_path=log_dir(),
            every=minutes,
            token=token,
            private=True,          # only applies when the repo is created here
            allow_patterns=["*.jsonl"],
        )
        return f"demand log syncing to dataset {repo_id} every {minutes:g} min"
    except Exception as exc:  # noqa: BLE001 - never fail startup over telemetry
        return f"demand log NOT syncing ({type(exc).__name__}: {exc})"


def summarise(path: str | None = None, limit: int = 20) -> list[tuple[str, int]]:
    """Most-requested refused queries, for deciding what to cover next.

    Reads a single file when given one, otherwise every shard in the log folder.
    """
    if path:
        sources = [path]
    else:
        explicit = os.environ.get("WATTGPU_DEMAND_LOG")
        sources = [explicit] if explicit else sorted(
            glob.glob(os.path.join(log_dir(), "*.jsonl")))

    counts: collections.Counter[str] = collections.Counter()
    for source in sources:
        try:
            with open(source, encoding="utf-8") as fh:
                for line in fh:
                    try:
                        entry = json.loads(line)
                    except json.JSONDecodeError:
                        continue
                    counts[f"{entry.get('reason')}: {entry.get('model')} @ "
                           f"{entry.get('gpu')}"] += 1
        except OSError:
            continue
    return counts.most_common(limit)