"""Data layer for the embedding-fleet control plane.

One poll tick = bucket reads (run manifest + worker heartbeats) + Jobs API reads
(stage, durations, one metrics sample per running job). All aggregation to the
run level happens here; app.py only renders.

Cost figures are client-side estimates (flavor unit price x running time), NOT
billing — always presented as "~$".
"""

from __future__ import annotations

import json
import logging
import tempfile
import time
from concurrent.futures import ThreadPoolExecutor
from dataclasses import dataclass, field
from pathlib import Path

from huggingface_hub import (
    download_bucket_files,
    fetch_job_metrics,
    list_bucket_tree,
    list_jobs,
    list_jobs_hardware,
)

TERMINAL_OK = {"COMPLETED"}
TERMINAL_BAD = {"ERROR", "CANCELED", "DELETED"}


def _stage_name(job) -> str:
    stage = job.status.stage if job.status else None
    return getattr(stage, "value", None) or str(stage or "UNKNOWN")


@dataclass
class WorkerRow:
    rank: int
    job_id: str | None = None
    stage: str = "UNKNOWN"
    rows_done: int = 0
    rows_total: int | None = None
    rows_per_sec: float = 0.0
    tokens_done_est: int | None = None
    gpu_util: float | None = None
    cost_usd: float | None = None
    state: str | None = None  # worker-reported: running/done/error


@dataclass
class RunView:
    run_id: str
    manifest: dict
    workers: list[WorkerRow] = field(default_factory=list)

    # run-level aggregates
    rows_done: int = 0
    rows_total: int = 0
    tokens_done_est: int = 0
    cost_usd: float = 0.0
    cost_ceiling_usd: float | None = None
    eta_secs: float | None = None
    gpu_util: float | None = None
    healthy: int = 0
    errored: int = 0
    done: int = 0
    num_shards: int = 0


_PRICING: dict | None = None


def pricing() -> dict:
    global _PRICING
    if _PRICING is None:
        _PRICING = {hw.name: hw for hw in list_jobs_hardware()}
    return _PRICING


def parse_timeout_secs(timeout) -> float | None:
    """'20m' / '1h' / '90s' / plain seconds -> seconds."""
    if timeout is None:
        return None
    s = str(timeout).strip().lower()
    try:
        mult = {"s": 1, "m": 60, "h": 3600, "d": 86400}.get(s[-1])
        return float(s[:-1]) * mult if mult else float(s)
    except (ValueError, IndexError):
        return None


def list_runs(bucket: str) -> list[str]:
    """Run ids under runs/, newest first (ids are timestamp-prefixed)."""
    try:
        ids = [Path(e.path.rstrip("/")).name
               for e in list_bucket_tree(bucket, prefix="runs/", recursive=False)
               if e.__class__.__name__ == "BucketFolder"]
        # Timestamp-prefixed ids first (newest first), ad-hoc ids after.
        return sorted(set(ids), key=lambda r: (r[:8].isdigit(), r), reverse=True) if ids else []
    except Exception:
        return []


def _read_bucket_json(bucket: str, paths: list[str]) -> dict[str, dict]:
    """Fetch small JSON files from the bucket; missing files are skipped."""
    out: dict[str, dict] = {}
    if not paths:
        return out
    with tempfile.TemporaryDirectory() as td:
        pairs = [(p, Path(td) / p.replace("/", "__")) for p in paths]
        try:
            download_bucket_files(bucket, pairs, raise_on_missing_files=False)
        except Exception:
            return out
        for src, dst in pairs:
            if dst.exists():
                try:
                    out[src] = json.loads(dst.read_text())
                except (json.JSONDecodeError, OSError):
                    pass
    return out


def _sample_gpu_util(job_id: str, timeout: float = 3.0) -> float | None:
    """One metrics sample -> mean GPU utilization. Never blocks past `timeout`."""

    def _one():
        gen = iter(fetch_job_metrics(job_id=job_id))
        try:
            raw = next(gen)
        finally:
            getattr(gen, "close", lambda: None)()
        gpus = raw.get("gpus") or {}
        utils = [float(g.get("utilization") or 0) for g in gpus.values()]
        return sum(utils) / len(utils) if utils else None

    with ThreadPoolExecutor(max_workers=1) as pool:
        fut = pool.submit(_one)
        try:
            return fut.result(timeout=timeout)
        except Exception:
            return None


def _accrued_cost(job, hw_pricing: dict) -> float | None:
    flavor = getattr(job.flavor, "value", None) or (str(job.flavor) if job.flavor else None)
    hw = hw_pricing.get(flavor)
    if not hw:
        return None
    secs = job.durations.running_secs if job.durations else None
    if not secs and job.started_at and _stage_name(job) == "RUNNING":
        secs = time.time() - job.started_at.timestamp()
    if not secs:
        return None
    return secs / 60.0 * hw.unit_cost_usd


def load_run(bucket: str, run_id: str, namespace: str | None = None) -> RunView | None:
    """One full poll tick: manifest + heartbeats + job stages + metrics samples -> RunView."""
    manifest = _read_bucket_json(bucket, [f"runs/{run_id}/run.json"]).get(f"runs/{run_id}/run.json")
    if not manifest:
        return None
    n = manifest["num_shards"]
    view = RunView(run_id=run_id, manifest=manifest, num_shards=n,
                   rows_total=manifest.get("rows_total") or 0)

    status_paths = [f"runs/{run_id}/status/{i:05d}.json" for i in range(n)]
    statuses = _read_bucket_json(bucket, status_paths)

    # Jobs by label (server-side filter); fall back to manifest job_ids via list comprehension.
    jobs_by_id = {}
    try:
        for j in list_jobs(labels={"embedding-fleet-run": run_id}, namespace=namespace):
            jobs_by_id[j.id] = j
    except Exception as e:
        logging.getLogger("control-plane").warning(f"list_jobs failed: {e!r}")
    manifest_job_ids = manifest.get("job_ids") or []

    hw_pricing = pricing()
    workers: list[WorkerRow] = []
    running_job_ids: list[str] = []
    for rank in range(n):
        row = WorkerRow(rank=rank)
        st = statuses.get(f"runs/{run_id}/status/{rank:05d}.json")
        if st:
            row.state = st.get("state")
            row.rows_done = st.get("rows_done") or 0
            row.rows_total = st.get("rows_total")
            row.rows_per_sec = st.get("rows_per_sec") or 0.0
            row.tokens_done_est = st.get("tokens_done_est")
            row.job_id = st.get("job_id")
        if row.job_id is None and rank < len(manifest_job_ids):
            row.job_id = manifest_job_ids[rank]
        job = jobs_by_id.get(row.job_id)
        if job is None and str(rank) in {j.labels.get("rank") for j in jobs_by_id.values() if j.labels}:
            job = next(j for j in jobs_by_id.values() if (j.labels or {}).get("rank") == str(rank))
        if job is not None:
            row.stage = _stage_name(job)
            row.cost_usd = _accrued_cost(job, hw_pricing)
            if row.stage == "RUNNING":
                running_job_ids.append(row.job_id)
        workers.append(row)

    # One GPU sample per running job, in parallel, bounded.
    if running_job_ids:
        with ThreadPoolExecutor(max_workers=min(8, len(running_job_ids))) as pool:
            samples = dict(zip(running_job_ids,
                               pool.map(_sample_gpu_util, running_job_ids)))
        for row in workers:
            if row.job_id in samples:
                row.gpu_util = samples[row.job_id]

    # Consolidator cost (labeled role=consolidate) counts toward the run.
    consolidator_cost = sum(
        _accrued_cost(j, hw_pricing) or 0.0
        for j in jobs_by_id.values()
        if (j.labels or {}).get("role") == "consolidate"
    )

    # ---- aggregate ----
    view.workers = workers
    view.rows_done = sum(w.rows_done for w in workers)
    view.tokens_done_est = sum(w.tokens_done_est or 0 for w in workers)
    view.cost_usd = sum(w.cost_usd or 0.0 for w in workers) + consolidator_cost
    view.done = sum(1 for w in workers if w.state == "done" or w.stage in TERMINAL_OK)
    view.errored = sum(1 for w in workers if w.state == "error" or w.stage in TERMINAL_BAD)
    view.healthy = n - view.errored
    gpu_vals = [w.gpu_util for w in workers if w.gpu_util is not None]
    view.gpu_util = sum(gpu_vals) / len(gpu_vals) if gpu_vals else None

    timeout_secs = parse_timeout_secs(manifest.get("timeout"))
    hw = hw_pricing.get(manifest.get("flavor"))
    if timeout_secs and hw:
        view.cost_ceiling_usd = n * timeout_secs / 60.0 * hw.unit_cost_usd

    active_rps = sum(w.rows_per_sec for w in workers
                     if w.state == "running" and w.stage not in TERMINAL_BAD)
    remaining = max((view.rows_total or 0) - view.rows_done, 0)
    if active_rps > 0 and remaining > 0:
        view.eta_secs = remaining / active_rps
    elif remaining == 0 and view.rows_total:
        view.eta_secs = 0.0
    return view