#!/usr/bin/env python3
"""
fetch_chargelab.py — pull completed transactions from the ChargeLab API
and save to data/ChargeLab Exports/chargelab_transactions_<date>.csv

Usage:
  python3 fetch_chargelab.py [--from YYYY-MM-DD] [--to YYYY-MM-DD]

Defaults to fetching all available history (no --from) through today (--to).

Requires CHARGELAB_API_KEY in a .env file (or environment variable).
"""

import csv
import os
import sys
import argparse
from datetime import datetime, timezone
from pathlib import Path

try:
    import urllib.request
    import urllib.parse
    import json
except ImportError:
    print("ERROR: Python standard library missing — check your Python install.")
    sys.exit(1)

BASE = Path(__file__).parent
ENV_FILE = BASE / ".env"

# ─── Load .env ────────────────────────────────────────────────────────────────

def load_env():
    if ENV_FILE.exists():
        with open(ENV_FILE) as f:
            for line in f:
                line = line.strip()
                if line and not line.startswith("#") and "=" in line:
                    k, _, v = line.partition("=")
                    os.environ.setdefault(k.strip(), v.strip().strip('"').strip("'"))

load_env()

API_KEY  = os.environ.get("CHARGELAB_API_KEY", "")
BASE_URL = "https://api.chargelab.io/core/v1"

if not API_KEY:
    print("ERROR: CHARGELAB_API_KEY not set. Add it to .env:")
    print("  CHARGELAB_API_KEY=your_key_here")
    sys.exit(1)

# ─── HTTP helper ──────────────────────────────────────────────────────────────

def get(path: str, params: dict) -> dict:
    qs = urllib.parse.urlencode(params)
    url = f"{BASE_URL}{path}?{qs}"
    req = urllib.request.Request(url, headers={"Authorization": f"x-auth {API_KEY}"})
    with urllib.request.urlopen(req, timeout=30) as resp:
        return json.loads(resp.read().decode())

# ─── Fetch all transactions (paginated) ───────────────────────────────────────

def fetch_transactions(from_dt: str | None, to_dt: str | None) -> list[dict]:
    params = {"role": "COMPANY", "limit": 1000, "offset": 0}
    if from_dt:
        params["filter_ge[startTime]"] = from_dt
    if to_dt:
        params["filter_le[stopTime]"] = to_dt

    all_txns = []
    total = None

    while True:
        print(f"  Fetching offset={params['offset']} ...", end=" ", flush=True)
        data = get("/completedTransactions", params)
        if total is None:
            total = data.get("totalCount", "?")
            print(f"(totalCount={total})", flush=True)
        else:
            print(flush=True)

        entities = data.get("entities", [])
        all_txns.extend(entities)

        if len(entities) < params["limit"]:
            break
        params["offset"] += params["limit"]

    print(f"  Fetched {len(all_txns)} transactions total.")
    return all_txns

# ─── Flatten to rows ──────────────────────────────────────────────────────────

COLUMNS = [
    "transactionId",
    "chargerId",
    "chargerName",
    "locationId",
    "locationName",
    "portId",
    "startTime",
    "stopTime",
    "consumedEnergyKilowattHours",
    "pluggedInTimeSeconds",
    "effectiveChargingTimeSeconds",
    "billedTotalAmount",
    "billedCurrency",
]

def flatten(txn: dict) -> dict:
    charger = txn.get("charger", {})
    loc     = charger.get("location", {})
    return {
        "transactionId":                 txn.get("transactionId", ""),
        "chargerId":                     charger.get("chargerId", ""),
        "chargerName":                   charger.get("name", ""),
        "locationId":                    loc.get("locationId", ""),
        "locationName":                  loc.get("name", ""),
        "portId":                        txn.get("portId", ""),
        "startTime":                     txn.get("startTime", ""),
        "stopTime":                      txn.get("stopTime", ""),
        "consumedEnergyKilowattHours":   txn.get("consumedEnergyKilowattHours", ""),
        "pluggedInTimeSeconds":          txn.get("pluggedInTimeSeconds", ""),
        "effectiveChargingTimeSeconds":  txn.get("effectiveChargingTimeSeconds", ""),
        "billedTotalAmount":             txn.get("billedTotalAmount", ""),
        "billedCurrency":                txn.get("billedCurrency", ""),
    }

# ─── Main ─────────────────────────────────────────────────────────────────────

def main():
    parser = argparse.ArgumentParser(description="Fetch ChargeLab completed transactions.")
    parser.add_argument("--from", dest="from_dt", metavar="YYYY-MM-DD",
                        help="Start date (inclusive). Defaults to all history.")
    parser.add_argument("--to", dest="to_dt", metavar="YYYY-MM-DD",
                        help="End date (inclusive). Defaults to today.")
    args = parser.parse_args()

    # Convert bare dates to ISO-8601 timestamps (UTC)
    from_iso = f"{args.from_dt}T00:00:00Z" if args.from_dt else None
    to_iso   = f"{args.to_dt}T23:59:59Z"   if args.to_dt   else None

    print(f"ChargeLab API pull")
    print(f"  from : {from_iso or '(all history)'}")
    print(f"  to   : {to_iso   or '(today)'}")

    txns = fetch_transactions(from_iso, to_iso)
    if not txns:
        print("No transactions returned.")
        return

    # Sort by startTime
    txns.sort(key=lambda t: t.get("startTime", ""))

    # Write CSV
    today = datetime.now(timezone.utc).strftime("%Y-%m-%d")
    out_dir = BASE / "data" / "ChargeLab Exports"
    out_dir.mkdir(parents=True, exist_ok=True)
    out_path = out_dir / f"chargelab_transactions_{today}.csv"

    with open(out_path, "w", newline="") as f:
        writer = csv.DictWriter(f, fieldnames=COLUMNS)
        writer.writeheader()
        for txn in txns:
            writer.writerow(flatten(txn))

    print(f"Saved {len(txns)} rows → {out_path.relative_to(BASE)}")

    # Quick summary
    kwh_total = sum(
        float(r.get("consumedEnergyKilowattHours") or 0)
        for r in (flatten(t) for t in txns)
        if r["consumedEnergyKilowattHours"] != ""
    )
    chargers = sorted({flatten(t)["chargerName"] for t in txns if t.get("charger", {}).get("name")})
    print(f"  Total kWh: {kwh_total:.1f}")
    print(f"  Chargers : {', '.join(chargers) or '(none named)'}")

if __name__ == "__main__":
    main()