import logging
import threading
from pathlib import Path

import config
import db
import extractor
import sftp as sftp_module
from uploader import CalibreClient

log = logging.getLogger(__name__)

_lock = threading.Lock()
_running = False


def is_running() -> bool:
    return _running


def run_sync() -> None:
    global _running
    if not _lock.acquire(blocking=False):
        log.warning("Sync already running, skipping")
        return

    _running = True
    run_id = db.start_sync_run()
    counters = dict(zips_found=0, zips_new=0, books_uploaded=0, books_skipped=0, books_errored=0)

    try:
        cfg = config.load()
        _validate_config(cfg)

        work_dir = Path(cfg.local_work_dir)
        work_dir.mkdir(parents=True, exist_ok=True)

        log.info("Listing remote zips at %s@%s:%s", cfg.sftp.user, cfg.sftp.host, cfg.sftp.remote_path)
        new_zips = sftp_module.list_new_zips(cfg.sftp)
        counters["zips_found"] = len(new_zips)
        counters["zips_new"] = len(new_zips)

        client = CalibreClient(cfg.calibre)

        for remote_zip in new_zips:
            zip_status = "success"
            zip_error = None
            local_zip = None
            try:
                local_zip = sftp_module.download(cfg.sftp, remote_zip, str(work_dir / "downloads"))
                books = extractor.extract(local_zip, work_dir / "extracted")

                for book in books:
                    status = client.upload(book, zip_source=remote_zip.remote_path)
                    if status == "uploaded":
                        counters["books_uploaded"] += 1
                    elif status == "skipped_duplicate":
                        counters["books_skipped"] += 1
                    else:
                        counters["books_errored"] += 1

                extractor.cleanup(work_dir / "extracted" / local_zip.stem)
            except Exception as e:
                log.error("Error processing %s: %s", remote_zip.remote_path, e)
                zip_status = "error"
                zip_error = str(e)
            finally:
                if local_zip and local_zip.exists():
                    extractor.cleanup(local_zip)
                db.mark_zip_processed(remote_zip.remote_path, remote_zip.file_size, zip_status, zip_error)

        db.finish_sync_run(run_id, status="success", **counters)
        log.info(
            "Sync done. Zips: %d, Uploaded: %d, Skipped: %d, Errors: %d",
            counters["zips_new"], counters["books_uploaded"],
            counters["books_skipped"], counters["books_errored"],
        )
    except Exception as e:
        log.exception("Sync run failed: %s", e)
        db.finish_sync_run(run_id, status="error", error_msg=str(e), **counters)
    finally:
        _running = False
        _lock.release()


def _validate_config(cfg) -> None:
    missing = []
    if not cfg.sftp.host:
        missing.append("SFTP host")
    if not cfg.sftp.user:
        missing.append("SFTP user")
    if not cfg.sftp.remote_path:
        missing.append("SFTP remote path")
    if cfg.sftp.auth_method == "key" and not cfg.sftp.key:
        missing.append("SSH private key")
    if cfg.sftp.auth_method == "password" and not cfg.sftp.password:
        missing.append("SSH password")
    if not cfg.calibre.url:
        missing.append("Calibre-Web URL")
    if not cfg.calibre.user:
        missing.append("Calibre-Web username")
    if missing:
        raise ValueError(f"Missing configuration: {', '.join(missing)}")