"""
ch_writer.py — Dolphin ClickHouse fire-and-forget writer.

All inserts are async (CH async_insert=1, wait_for_async_insert=0).
Uses HTTP INSERT with JSONEachRow — zero external dependencies.

OTel transport note:
  This file is the single integration point. To switch to OTel transport
  (e.g., when Uptrace is the primary sink), replace _flush() internals only.
  All caller code (ch_put calls across services) stays unchanged.

Usage:
    from ch_writer import ch_put
    ch_put("eigen_scans", {"ts": int(time.time() * 1e6), "scan_number": n, ...})

Environment overrides (optional):
    CH_URL   — default: http://localhost:8123
    CH_USER  — default: dolphin
    CH_PASS  — default: dolphin_ch_2026
    CH_DB    — default: dolphin
"""
import json
import logging
import os
import random
import struct
import threading
import time
import urllib.request
from collections import defaultdict
from queue import Full, Queue

log = logging.getLogger("ch_writer")

CH_URL  = os.environ.get("CH_URL",  "http://localhost:8123")
CH_USER = os.environ.get("CH_USER", "dolphin")
CH_PASS = os.environ.get("CH_PASS", "dolphin_ch_2026")
CH_DB   = os.environ.get("CH_DB",   "dolphin")

# ─── Timestamp helpers ────────────────────────────────────────────────────────

def ts_us() -> int:
    """Current UTC time as microseconds — for DateTime64(6) fields."""
    return int(time.time() * 1_000_000)

def ts_ms() -> int:
    """Current UTC time as milliseconds — for DateTime64(3) fields."""
    return int(time.time() * 1_000)


# ─── UUIDv7 — time-ordered distributed trace ID ───────────────────────────────

def uuid7() -> str:
    """
    Generate a UUIDv7 — RFC 9562 time-ordered UUID.

    Layout (128 bits):
      [0:48]  Unix timestamp milliseconds   — sortable, embeds timing
      [48:52] Version = 0b0111 (7)
      [52:64] rand_a (12 bits)              — sub-ms uniqueness
      [64:66] Variant = 0b10
      [66:128] rand_b (62 bits)             — entropy

    Properties:
      - Lexicographically sortable by time (no JOIN to recover timestamp)
      - CH can use as ORDER BY component alongside ts columns
      - Drop-in for UUIDv4 (same string format, same String column type)
      - Pure stdlib — no dependencies

    Usage:
        scan_uuid = uuid7()   # NG7: one per scan
        # Pass downstream to trade_events, obf_fast_intrade, posture_events
        # This IS the distributed trace ID across the causal chain.
    """
    ts_ms_val = int(time.time() * 1_000)
    rand_a    = random.getrandbits(12)
    rand_b    = random.getrandbits(62)

    hi = (ts_ms_val << 16) | 0x7000 | rand_a
    lo = (0b10 << 62) | rand_b

    b = struct.pack(">QQ", hi, lo)
    return (
        f"{b[0:4].hex()}-{b[4:6].hex()}-"
        f"{b[6:8].hex()}-{b[8:10].hex()}-{b[10:16].hex()}"
    )


# ─── Internal writer ──────────────────────────────────────────────────────────

class _CHWriter:
    """
    Thread-safe, non-blocking ClickHouse writer.
    Batches rows per table and flushes every flush_interval_s.
    The caller's thread is NEVER blocked — queue.put_nowait() drops
    silently if the queue is full (observability is best-effort).
    """

    def __init__(self, flush_interval_s: float = 1.0, maxqueue: int = 50_000, db: str = CH_DB):
        self._q: Queue = Queue(maxsize=maxqueue)
        self._interval = flush_interval_s
        self._db = db
        self._dropped = 0
        self._t = threading.Thread(
            target=self._run, daemon=True, name=f"ch-writer-{db}"
        )
        self._t.start()

    def put(self, table: str, row: dict) -> None:
        """Non-blocking enqueue. Silently drops on full queue."""
        try:
            self._q.put_nowait((table, row))
        except Full:
            self._dropped += 1
            if self._dropped % 1000 == 1:
                log.warning("ch_writer: %d rows dropped (queue full)", self._dropped)

    def _run(self):
        batch: dict[str, list] = defaultdict(list)
        deadline = time.monotonic() + self._interval
        while True:
            remaining = max(0.005, deadline - time.monotonic())
            try:
                table, row = self._q.get(timeout=remaining)
                batch[table].append(row)
            except Exception:
                pass  # timeout — fall through to flush check
            if time.monotonic() >= deadline:
                if batch:
                    self._flush(batch)
                    batch = defaultdict(list)
                deadline = time.monotonic() + self._interval

    def _flush(self, batch: dict[str, list]):
        for table, rows in batch.items():
            if not rows:
                continue
            body = "\n".join(json.dumps(r) for r in rows).encode()
            url  = (
                f"{CH_URL}/?database={self._db}"
                f"&query=INSERT+INTO+{table}+FORMAT+JSONEachRow"
                f"&async_insert=1&wait_for_async_insert=0"
            )
            req = urllib.request.Request(url, data=body, method="POST")
            req.add_header("X-ClickHouse-User", CH_USER)
            req.add_header("X-ClickHouse-Key",  CH_PASS)
            req.add_header("Content-Type", "application/octet-stream")
            try:
                with urllib.request.urlopen(req, timeout=5) as resp:
                    if resp.status not in (200, 201):
                        log.debug(
                            "CH flush [%s]: HTTP %s", table, resp.status
                        )
            except Exception as e:
                # Observability writes must never surface to callers
                log.debug("CH flush error [%s]: %s", table, e)


# ─── Module-level singletons ─────────────────────────────────────────────────

_writer       = _CHWriter(db="dolphin")
_writer_green = _CHWriter(db="dolphin_green")


def ch_put(table: str, row: dict) -> None:
    """
    Fire-and-forget insert into dolphin.<table> (BLUE environment).

    Args:
        table: ClickHouse table name (without database prefix), e.g. "eigen_scans"
        row:   Dict of column_name → value. Timestamps should be:
               - DateTime64(6) fields: int microseconds  (use ts_us())
               - DateTime64(3) fields: int milliseconds  (use ts_ms())
               - Date fields:          "YYYY-MM-DD" string
    """
    _writer.put(table, row)


def ch_put_green(table: str, row: dict) -> None:
    """
    Fire-and-forget insert into dolphin_green.<table> (GREEN / NT TradingNode environment).

    Same signature as ch_put — drop-in for GREEN services.
    """
    _writer_green.put(table, row)