"""
CFTC COT Data Importer

Inserts parsed CommodityBlock objects into the SQLite database.
All inserts use INSERT OR IGNORE for idempotency — safe to re-run.
"""

import sqlite3
import tempfile
from dataclasses import dataclass
from pathlib import Path
from typing import Optional

import requests

from app.db import get_db
from app.ingestion.parser import (
    CommodityBlock,
    parse_html_file,
    parse_zip_file,
)

HEADERS = {
    "User-Agent": (
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
        "AppleWebKit/537.36 (KHTML, like Gecko) "
        "Chrome/120.0.0.0 Safari/537.36"
    )
}

HISTORICAL_BASE = "https://www.cftc.gov/files/dea/history"
WEEKLY_URL = "https://www.cftc.gov/dea/options/deacbtlof.htm"


@dataclass
class ImportResult:
    source: str
    rows_inserted: int = 0
    rows_skipped: int = 0
    error: Optional[str] = None


def _upsert_commodity(conn: sqlite3.Connection, block: CommodityBlock) -> int:
    """Insert commodity if not exists; return its id."""
    conn.execute(
        """
        INSERT OR IGNORE INTO commodities
            (cftc_code, name, exchange, exchange_abbr, contract_unit)
        VALUES (?, ?, ?, ?, ?)
        """,
        (block.cftc_code, block.name, block.exchange,
         block.exchange_abbr, block.contract_unit),
    )
    row = conn.execute(
        "SELECT id FROM commodities WHERE cftc_code = ?", (block.cftc_code,)
    ).fetchone()
    return row[0]


def _upsert_report(conn: sqlite3.Connection, commodity_id: int,
                   block: CommodityBlock, source_file: str) -> Optional[int]:
    """
    Insert report row. Returns report id, or None if already exists
    (i.e. this report date was already imported for this commodity).
    """
    cur = conn.execute(
        """
        INSERT OR IGNORE INTO reports
            (commodity_id, report_date, prev_report_date, source_file)
        VALUES (?, ?, ?, ?)
        """,
        (commodity_id, block.report_date, block.prev_report_date, source_file),
    )
    if cur.rowcount == 0:
        return None  # already existed
    return cur.lastrowid


def import_commodity_block(conn: sqlite3.Connection, block: CommodityBlock,
                           source: str) -> tuple[int, int]:
    """
    Insert one CommodityBlock into the DB.
    Returns (rows_inserted, rows_skipped).
    """
    commodity_id = _upsert_commodity(conn, block)
    report_id = _upsert_report(conn, commodity_id, block, source)

    if report_id is None:
        return 0, 1  # already imported

    inserted = 0
    for row_type in ('All', 'Old', 'Other'):
        pos = block.positions.get(row_type)
        if pos is None:
            continue

        chg = block.changes if row_type == 'All' else None
        pct = block.percentages.get(row_type)
        trd = block.traders.get(row_type)

        conn.execute(
            """
            INSERT OR IGNORE INTO positions (
                report_id, row_type,
                open_interest,
                noncomm_long, noncomm_short, noncomm_spreading,
                comm_long, comm_short,
                total_long, total_short,
                nonrept_long, nonrept_short,
                chg_open_interest,
                chg_noncomm_long, chg_noncomm_short, chg_noncomm_spreading,
                chg_comm_long, chg_comm_short,
                chg_total_long, chg_total_short,
                chg_nonrept_long, chg_nonrept_short,
                pct_open_interest,
                pct_noncomm_long, pct_noncomm_short, pct_noncomm_spreading,
                pct_comm_long, pct_comm_short,
                pct_total_long, pct_total_short,
                pct_nonrept_long, pct_nonrept_short,
                traders_total,
                traders_noncomm_long, traders_noncomm_short, traders_noncomm_spread,
                traders_comm_long, traders_comm_short,
                traders_total_long, traders_total_short
            ) VALUES (
                ?, ?,
                ?,
                ?, ?, ?,
                ?, ?,
                ?, ?,
                ?, ?,
                ?,
                ?, ?, ?,
                ?, ?,
                ?, ?,
                ?, ?,
                ?,
                ?, ?, ?,
                ?, ?,
                ?, ?,
                ?, ?,
                ?,
                ?, ?, ?,
                ?, ?,
                ?, ?
            )
            """,
            (
                report_id, row_type,
                pos.open_interest,
                pos.noncomm_long, pos.noncomm_short, pos.noncomm_spreading,
                pos.comm_long, pos.comm_short,
                pos.total_long, pos.total_short,
                pos.nonrept_long, pos.nonrept_short,
                chg.chg_open_interest if chg else None,
                chg.chg_noncomm_long if chg else None,
                chg.chg_noncomm_short if chg else None,
                chg.chg_noncomm_spreading if chg else None,
                chg.chg_comm_long if chg else None,
                chg.chg_comm_short if chg else None,
                chg.chg_total_long if chg else None,
                chg.chg_total_short if chg else None,
                chg.chg_nonrept_long if chg else None,
                chg.chg_nonrept_short if chg else None,
                pct.pct_open_interest if pct else None,
                pct.pct_noncomm_long if pct else None,
                pct.pct_noncomm_short if pct else None,
                pct.pct_noncomm_spreading if pct else None,
                pct.pct_comm_long if pct else None,
                pct.pct_comm_short if pct else None,
                pct.pct_total_long if pct else None,
                pct.pct_total_short if pct else None,
                pct.pct_nonrept_long if pct else None,
                pct.pct_nonrept_short if pct else None,
                trd.traders_total if trd else None,
                trd.traders_noncomm_long if trd else None,
                trd.traders_noncomm_short if trd else None,
                trd.traders_noncomm_spread if trd else None,
                trd.traders_comm_long if trd else None,
                trd.traders_comm_short if trd else None,
                trd.traders_total_long if trd else None,
                trd.traders_total_short if trd else None,
            ),
        )
        inserted += 1

        # Concentration
        conc = block.concentration.get(row_type)
        if conc:
            conn.execute(
                """
                INSERT OR IGNORE INTO concentration (
                    report_id, row_type,
                    conc_gross_long_4, conc_gross_short_4,
                    conc_gross_long_8, conc_gross_short_8,
                    conc_net_long_4, conc_net_short_4,
                    conc_net_long_8, conc_net_short_8
                ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
                """,
                (
                    report_id, row_type,
                    conc.conc_gross_long_4, conc.conc_gross_short_4,
                    conc.conc_gross_long_8, conc.conc_gross_short_8,
                    conc.conc_net_long_4, conc.conc_net_short_4,
                    conc.conc_net_long_8, conc.conc_net_short_8,
                ),
            )

    return inserted, 0


def import_html_file(html_path: str) -> ImportResult:
    """Import a single weekly HTML file."""
    source = Path(html_path).name
    result = ImportResult(source=source)
    with get_db() as conn:
        if _already_imported(conn, source):
            result.rows_skipped = 1
            return result
        _log_start(conn, source, 'weekly_html')
    try:
        with get_db() as conn:
            for block in parse_html_file(html_path):
                ins, skp = import_commodity_block(conn, block, source)
                result.rows_inserted += ins
                result.rows_skipped += skp
            conn.commit()
    except Exception as e:
        result.error = str(e)
    with get_db() as conn:
        _log_done(conn, source, result.rows_inserted, result.rows_skipped, result.error)
    return result


def import_zip_file(zip_path: str, source_label: Optional[str] = None) -> ImportResult:
    """Import a historical ZIP file."""
    source = source_label or Path(zip_path).name
    result = ImportResult(source=source)
    try:
        with get_db() as conn:
            for block in parse_zip_file(zip_path):
                ins, skp = import_commodity_block(conn, block, source)
                result.rows_inserted += ins
                result.rows_skipped += skp
            conn.commit()
    except Exception as e:
        result.error = str(e)
    return result


def _download_zip(url: str, dest: Path) -> bool:
    """Download a ZIP file, return True on success."""
    try:
        r = requests.get(url, headers=HEADERS, timeout=120, stream=True)
        r.raise_for_status()
        dest.write_bytes(r.content)
        return True
    except requests.RequestException:
        return False


def _log_start(conn: sqlite3.Connection, source: str, source_type: str) -> None:
    conn.execute(
        """
        INSERT OR REPLACE INTO import_log (source, source_type, status, started_at)
        VALUES (?, ?, 'running', datetime('now'))
        """,
        (source, source_type),
    )
    conn.commit()


def _log_done(conn: sqlite3.Connection, source: str,
              inserted: int, skipped: int, error: Optional[str] = None) -> None:
    status = 'error' if error else 'done'
    conn.execute(
        """
        UPDATE import_log
        SET status = ?, rows_inserted = ?, rows_skipped = ?,
            completed_at = datetime('now'), error_message = ?
        WHERE source = ?
        """,
        (status, inserted, skipped, error, source),
    )
    conn.commit()


def _already_imported(conn: sqlite3.Connection, source: str) -> bool:
    row = conn.execute(
        "SELECT status FROM import_log WHERE source = ?", (source,)
    ).fetchone()
    return row is not None and row[0] == 'done'


def run_historical_import(start_year: int = 1995, end_year: int = 2026,
                          verbose: bool = True) -> None:
    """
    Download and import the full historical archive.
    Uses import_log to skip already-completed sources.
    """
    sources = []

    # Combined 1995-2016 archive
    sources.append((
        f"{HISTORICAL_BASE}/deahistfo_1995_2016.zip",
        "deahistfo_1995_2016.zip",
        "historical_zip",
    ))

    # Per-year archives from 2017 onwards
    for year in range(max(start_year, 2017), end_year + 1):
        sources.append((
            f"{HISTORICAL_BASE}/deahistfo{year}.zip",
            f"deahistfo{year}.zip",
            "annual_zip",
        ))

    with get_db() as conn:
        pass  # just to verify DB is accessible

    for url, label, source_type in sources:
        with get_db() as conn:
            if _already_imported(conn, label):
                if verbose:
                    print(f"  [skip] {label} (already imported)")
                continue

        if verbose:
            print(f"  [download] {label} ...")

        with tempfile.NamedTemporaryFile(suffix='.zip', delete=False) as tmp:
            tmp_path = Path(tmp.name)

        if not _download_zip(url, tmp_path):
            if verbose:
                print(f"  [error] Failed to download {url}")
            with get_db() as conn:
                _log_start(conn, label, source_type)
                _log_done(conn, label, 0, 0, f"Download failed: {url}")
            tmp_path.unlink(missing_ok=True)
            continue

        if verbose:
            print(f"  [import] {label} ...")

        with get_db() as conn:
            _log_start(conn, label, source_type)

        result = import_zip_file(str(tmp_path), source_label=label)
        tmp_path.unlink(missing_ok=True)

        with get_db() as conn:
            _log_done(conn, label, result.rows_inserted, result.rows_skipped, result.error)

        if verbose:
            status = "ERROR: " + result.error if result.error else "OK"
            print(f"  [done] {label}: {result.rows_inserted} inserted, "
                  f"{result.rows_skipped} skipped — {status}")


def download_and_import() -> ImportResult:
    """
    Download the current weekly report and import it.
    Used by the cron job.
    """
    import re
    from datetime import datetime

    result = ImportResult(source="weekly")
    try:
        r = requests.get(WEEKLY_URL, headers=HEADERS, timeout=30)
        r.raise_for_status()
        html = r.content.decode('latin-1')
    except requests.RequestException as e:
        result.error = str(e)
        return result

    # Extract report date for filename
    m = re.search(
        r'(January|February|March|April|May|June|July|August|September|'
        r'October|November|December)\s+(\d{1,2}),\s+(\d{4})',
        html,
    )
    if not m:
        result.error = "Could not extract report date"
        return result

    month, day, year = m.groups()
    months = ['January','February','March','April','May','June',
              'July','August','September','October','November','December']
    from datetime import date as dt
    report_date = dt(int(year), months.index(month) + 1, int(day)).isoformat()

    from app.db import DB_PATH
    data_dir = DB_PATH.parent
    data_dir.mkdir(exist_ok=True)
    filename = f"{report_date}_deacbtlof.htm"
    filepath = data_dir / filename

    if not filepath.exists():
        filepath.write_text(html, encoding='latin-1')

    result.source = filename
    with get_db() as conn:
        if _already_imported(conn, filename):
            result.rows_skipped = 1
            return result

    with get_db() as conn:
        _log_start(conn, filename, 'weekly_html')

    r2 = import_html_file(str(filepath))
    result.rows_inserted = r2.rows_inserted
    result.rows_skipped = r2.rows_skipped
    result.error = r2.error

    with get_db() as conn:
        _log_done(conn, filename, r2.rows_inserted, r2.rows_skipped, r2.error)

    return result