"""
import_fuel.py — Rahama Fresh · fleet fuel-record ingestion (raw-first)
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Loads WhatsApp fuel-update records into the `fuel` schema — the source of the
FleetOps "Fuel Log" tab. The feed is produced by an n8n CDC job that exports the
client's `logistics_department.fuel_records` table to the rustfs `fuel` bucket.

RAW-FIRST: each row stores `id` (the source PK) + `raw` (the full record as jsonb).
A DB trigger (see migrations/01_fuel_schema.sql) derives the normalized columns
(plate, liters, amount, fuel_type, department, odometer, deleted_at, …) from `raw`,
so a change to the source schema needs no loader change.

Bucket layout (envelope `{ "metadata": {...}, "records": [...] }`):
    fuel_records/latest.json              full snapshot (~1.9k rows)
    fuel_records/changes/<ISO-ts>.json    hourly CDC deltas (incl. soft-deletes)

Modes (need DATABASE_URL + RUSTFS_* env; see .env.example):
    python import_fuel.py --snapshot --apply        # default: full reconcile (self-healing)
    python import_fuel.py --changes  --apply        # incremental, since the stored watermark
    python import_fuel.py --file latest.json --apply # local file (dev/testing)
Dry-run (no --apply) parses + logs counts without writing.

Pre-requisite: migration applied (run_migrations.py) — fuel.records + fuel.ingest_state
+ reporting.v_fuel_fills.
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"""

from __future__ import annotations

import argparse
import json
import math

import psycopg2.extras

from s3util import bucket, get_s3
from shared import get_conn, get_logger

log = get_logger("import_fuel")

SNAPSHOT_KEY = "fuel_records/latest.json"
CHANGES_PREFIX = "fuel_records/changes/"
_STATE_KEY = "changes"  # row key in fuel.ingest_state for the changes watermark


# ── data loading ──────────────────────────────────────────────────────────────
def _records(payload: dict | list) -> list[dict]:
    """Pull the records array out of the `{metadata, records}` envelope (or a bare list)."""
    if isinstance(payload, dict):
        recs = payload.get("records", [])
    else:
        recs = payload
    return recs if isinstance(recs, list) else []


def _load_local(path: str) -> list[dict]:
    with open(path, encoding="utf-8") as f:
        return _records(json.load(f))  # json.loads accepts NaN by default


def _load_s3_json(s3, key: str) -> list[dict]:
    log.info("fetching s3://%s/%s", bucket(), key)
    body = s3.get_object(Bucket=bucket(), Key=key)["Body"].read()
    return _records(json.loads(body.decode("utf-8")))


def _list_change_keys(s3, after: str | None) -> list[str]:
    """Change-file keys (lexically > `after`), sorted. ISO-timestamp names sort chronologically."""
    keys: list[str] = []
    paginator = s3.get_paginator("list_objects_v2")
    for page in paginator.paginate(Bucket=bucket(), Prefix=CHANGES_PREFIX):
        for obj in page.get("Contents", []):
            k = obj["Key"]
            if k.endswith(".json") and (after is None or k > after):
                keys.append(k)
    return sorted(keys)


# ── upsert (raw-first) ────────────────────────────────────────────────────────
def _scrub_nan(row: dict) -> dict:
    # Postgres jsonb rejects the JSON `NaN` token — scrub to null.
    return {k: (None if isinstance(v, float) and math.isnan(v) else v) for k, v in row.items()}


def upsert(rows: list[dict], apply: bool) -> int:
    payload = [
        (rid, psycopg2.extras.Json(_scrub_nan(r)))
        for r in rows
        if (rid := r.get("id")) is not None
    ]
    log.info("fuel.records: %d valid rows (skipped %d without id)",
             len(payload), len(rows) - len(payload))
    if not apply:
        log.info("DRY-RUN — nothing written. Use --apply.")
        return len(payload)
    if not payload:
        return 0
    with get_conn() as conn:
        with conn.cursor() as cur:
            psycopg2.extras.execute_values(
                cur,
                "INSERT INTO fuel.records (id, raw) VALUES %s "
                "ON CONFLICT (id) DO UPDATE SET raw = EXCLUDED.raw, updated_at = now()",
                payload, page_size=500,
            )
    log.info("upserted %d rows into fuel.records", len(payload))
    return len(payload)


# ── watermark (fuel.ingest_state) ─────────────────────────────────────────────
def _get_watermark() -> str | None:
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute("SELECT last_key FROM fuel.ingest_state WHERE key = %s", (_STATE_KEY,))
            row = cur.fetchone()
            return row[0] if row else None


def _set_watermark(last_key: str) -> None:
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                "INSERT INTO fuel.ingest_state (key, last_key) VALUES (%s, %s) "
                "ON CONFLICT (key) DO UPDATE SET last_key = EXCLUDED.last_key, updated_at = now()",
                (_STATE_KEY, last_key),
            )


# ── modes ─────────────────────────────────────────────────────────────────────
def ingest_snapshot(apply: bool) -> None:
    s3 = get_s3()
    upsert(_load_s3_json(s3, SNAPSHOT_KEY), apply)


def ingest_changes(apply: bool) -> None:
    s3 = get_s3()
    after = _get_watermark() if apply else None
    keys = _list_change_keys(s3, after)
    log.info("%d change file(s) to process (watermark=%s)", len(keys), after)
    total = 0
    for key in keys:
        total += upsert(_load_s3_json(s3, key), apply)
        if apply:
            _set_watermark(key)
    log.info("changes: processed %d file(s), upserted %d rows", len(keys), total)


def ingest_file(path: str, apply: bool) -> None:
    upsert(_load_local(path), apply)


# ── entrypoint ────────────────────────────────────────────────────────────────
def main() -> None:
    ap = argparse.ArgumentParser(description="Ingest fuel records (raw-first) from the rustfs bucket")
    ap.add_argument("--apply", action="store_true", help="Write to DB (default: dry-run)")
    mode = ap.add_mutually_exclusive_group()
    mode.add_argument("--snapshot", action="store_true",
                      help="Full reconcile from fuel_records/latest.json (default)")
    mode.add_argument("--changes", action="store_true",
                      help="Incremental: change files newer than the stored watermark")
    mode.add_argument("--file", default=None, help="Local JSON file (snapshot or changes envelope)")
    args = ap.parse_args()

    if args.file:
        ingest_file(args.file, args.apply)
    elif args.changes:
        ingest_changes(args.apply)
    else:  # default
        ingest_snapshot(args.apply)


if __name__ == "__main__":
    main()