"""
download_attachments_v1.0.py
Nazev:  download_attachments_v1.0.py
Verze:  1.0
Datum:  2026-06-02
Autor:  vladimir.buzalka

Popis:
    Stahuje skutecne prilohy (is_inline=False) vsech emailu z MongoDB kolekce
    ordinace@buzalkova.cz primo pres Microsoft Graph API a uklada je do
    adresare /mnt/Emails/ordinace@buzalkova.cz/Attachments/.

    Deduplikace podle SHA256 hashe obsahu:
        - stejny hash = soubor uz existuje -> preskoci
        - prvni vyskytu souboru: ulozi pod puvodnimnazvem
        - kolize nazvu (stejny nazev, jiny hash): faktura_2.pdf, faktura_3.pdf ...

    Po ulozeni aktualizuje MongoDB:
        - v email dokumentu: kazda priloha dostane file_hash + local_path
        - kolekce emaily.attachments_index: _id=hash, filename, path, size_bytes,
          mime_type, first_seen_at, ref_count (pocet emailu ktery ji obsahuje)

    Bezpecne prerusit a opakovat:
        - zpravy kde jsou vsechny prilohy uz stazene (maji file_hash) se preskoci
        - --force-recheck znovu overi i uz stazene (pro pripad zmen na disku)

    POZOR: Skript pouze CIST ze schranky — zadny zapis do schranky!

Spousteni:
    python download_attachments_v1.0.py               # stahni vse co chybi
    python download_attachments_v1.0.py --limit 50    # test na prvnich 50 emailech
    python download_attachments_v1.0.py --force-recheck  # overi i uz stazene

Docker (po pridani mountu /mnt/user/Emails -> /mnt/Emails):
    docker exec -it python-runner python /scripts/download_attachments_v1.0.py

Zavislosti:
    msal, requests, pymongo, python-dateutil
    Python 3.10+

Struktura na disku:
    /mnt/Emails/
    └── ordinace@buzalkova.cz/
        └── Attachments/
            ├── faktura_2026.pdf
            ├── vysledky_lab.pdf
            ├── vysledky_lab_2.pdf   <- kolize nazvu, jiny obsah
            └── ...

Kolekce emaily.attachments_index:
    _id          SHA256 hash (hex)
    filename     nazev souboru na disku (prvni vyskytu)
    local_path   relativni cesta od Attachments/ (zatim = filename)
    size_bytes   velikost souboru
    mime_type    MIME typ
    first_seen_at  datetime UTC
    ref_count    v kolika emailech se tato priloha vyskytuje

Aktualizace v email dokumentu (kolekce ordinace@buzalkova.cz):
    attachments[i].file_hash    SHA256 hash
    attachments[i].local_path   cesta relativni od Attachments/

Historie verzi:
    1.0  2026-06-02  Inicialni verze
"""

import sys
import hashlib
import logging
import argparse
from pathlib import Path
from datetime import datetime, timezone
from typing import Optional

import msal
import requests
from pymongo import MongoClient, UpdateOne

if hasattr(sys.stdout, "reconfigure"):
    sys.stdout.reconfigure(encoding="utf-8", errors="replace")

# ─── KONFIGURACE ──────────────────────────────────────────────────────────────
GRAPH_TENANT_ID     = "7d269944-37a4-43a1-8140-c7517dc426e9"
GRAPH_CLIENT_ID     = "4b222bfd-78c9-4239-a53f-43006b3ed07f"
GRAPH_CLIENT_SECRET = "Txg8Q~MjhocuopxsJyJBhPmDfMxZ2r5WpTFj1dfk"
GRAPH_MAILBOX       = "ordinace@buzalkova.cz"
GRAPH_URL           = "https://graph.microsoft.com/v1.0"

MONGO_URI           = "mongodb://192.168.1.76:27017"
MONGO_DB            = "emaily"
MONGO_COL_EMAILS    = "ordinace@buzalkova.cz"
MONGO_COL_INDEX     = "attachments_index"

ATTACHMENTS_DIR     = Path("/mnt/Emails/ordinace@buzalkova.cz/Attachments")
LOG_FILE            = Path(__file__).parent / "parse_emails_errors.log"
SCRIPT_VERSION      = "1.0"
BATCH_SIZE          = 50
# ──────────────────────────────────────────────────────────────────────────────

logging.basicConfig(
    filename=str(LOG_FILE),
    level=logging.ERROR,
    format="%(asctime)s | %(message)s",
    datefmt="%Y-%m-%d %H:%M:%S",
    encoding="utf-8",
)

_graph_token: Optional[str] = None


# ─── Graph API ────────────────────────────────────────────────────────────────

def get_token() -> str:
    global _graph_token
    app = msal.ConfidentialClientApplication(
        GRAPH_CLIENT_ID,
        authority=f"https://login.microsoftonline.com/{GRAPH_TENANT_ID}",
        client_credential=GRAPH_CLIENT_SECRET,
    )
    result = app.acquire_token_for_client(scopes=["https://graph.microsoft.com/.default"])
    if "access_token" not in result:
        raise RuntimeError(f"Graph auth failed: {result}")
    _graph_token = result["access_token"]
    return _graph_token


def graph_get_bytes(url: str) -> bytes:
    """Stahne binarni obsah prilohy."""
    global _graph_token
    if not _graph_token:
        get_token()
    for attempt in range(2):
        r = requests.get(url, headers={"Authorization": f"Bearer {_graph_token}"}, timeout=120, stream=True)
        if r.status_code == 401:
            get_token()
            continue
        r.raise_for_status()
        return r.content
    raise RuntimeError(f"Graph GET bytes failed: {url}")


def graph_get_json(url: str, params: dict = None) -> dict:
    global _graph_token
    if not _graph_token:
        get_token()
    for attempt in range(2):
        r = requests.get(url, headers={"Authorization": f"Bearer {_graph_token}"}, params=params, timeout=30)
        if r.status_code == 401:
            get_token()
            continue
        r.raise_for_status()
        return r.json()
    raise RuntimeError(f"Graph GET json failed: {url}")


def fetch_attachment_content(graph_message_id: str, attachment_id: str) -> Optional[bytes]:
    """Stahne obsah prilohy pres Graph API."""
    url = f"{GRAPH_URL}/users/{GRAPH_MAILBOX}/messages/{graph_message_id}/attachments/{attachment_id}/$value"
    try:
        return graph_get_bytes(url)
    except Exception as e:
        logging.error("fetch_attachment_content failed [msg=%s att=%s]: %s", graph_message_id, attachment_id, e)
        return None


def fetch_message_attachments(graph_message_id: str) -> list[dict]:
    """Nacte seznam priloh zpravy z Graph API (metadata vcetne attachment ID)."""
    url = f"{GRAPH_URL}/users/{GRAPH_MAILBOX}/messages/{graph_message_id}/attachments"
    try:
        data = graph_get_json(url, {"$select": "id,name,contentType,size,isInline,contentId"})
        return data.get("value", [])
    except Exception as e:
        logging.error("fetch_message_attachments failed [%s]: %s", graph_message_id, e)
        return []


# ─── Dedup + ukládání ─────────────────────────────────────────────────────────

def sha256(data: bytes) -> str:
    return hashlib.sha256(data).hexdigest()


def resolve_filename(desired_name: str, att_dir: Path, hash_val: str, index_col) -> str:
    """
    Vrati nazev souboru ktery pouzit pro ulozeni.
    Pokud desired_name jiz existuje s jinym hashem, prida suffix _2, _3 ...
    """
    # Zkontroluj jestli existujici soubor se stejnym nazvem ma stejny hash
    existing = index_col.find_one({"filename": desired_name})
    if existing:
        if existing["_id"] == hash_val:
            return desired_name  # Stejny hash, stejne jmeno — dedup hit
        # Jiny hash — hledej volny suffix
        stem   = Path(desired_name).stem
        suffix = Path(desired_name).suffix
        n = 2
        while True:
            candidate = f"{stem}_{n}{suffix}"
            if not (att_dir / candidate).exists():
                # Overi ze ani v indexu neni tento kandidat s jinym hashem
                ex2 = index_col.find_one({"filename": candidate})
                if not ex2 or ex2["_id"] == hash_val:
                    return candidate
            n += 1
    return desired_name


def save_attachment(content: bytes, original_name: str, att_dir: Path, index_col) -> tuple[str, str, bool]:
    """
    Ulozi prilohu s deduplikaci.
    Vraci (hash, local_path, was_new):
        was_new=True  -> soubor byl ulozen
        was_new=False -> hash uz existoval, soubor preskocen
    """
    hash_val = sha256(content)

    # Zkontroluj index — pokud hash uz existuje, vrat existujici zaznam
    existing = index_col.find_one({"_id": hash_val})
    if existing:
        # Zvys pocitadlo referenci
        index_col.update_one({"_id": hash_val}, {"$inc": {"ref_count": 1}})
        return hash_val, existing["local_path"], False

    # Novy soubor — urcit nazev
    safe_name = "".join(c if c.isalnum() or c in "._- " else "_" for c in original_name).strip()
    if not safe_name:
        safe_name = f"attachment_{hash_val[:8]}"

    filename  = resolve_filename(safe_name, att_dir, hash_val, index_col)
    file_path = att_dir / filename

    # Uloz soubor
    file_path.write_bytes(content)

    # Zaznamenej do indexu
    index_col.insert_one({
        "_id":          hash_val,
        "filename":     filename,
        "local_path":   filename,
        "size_bytes":   len(content),
        "mime_type":    "",
        "first_seen_at": datetime.now(timezone.utc).replace(tzinfo=None),
        "ref_count":    1,
    })

    return hash_val, filename, True


# ─── MAIN ─────────────────────────────────────────────────────────────────────

def main():
    ap = argparse.ArgumentParser(description=f"download_attachments v{SCRIPT_VERSION}")
    ap.add_argument("--limit",         type=int, default=0,
                    help="Zpracovat max N emailu (0 = vse)")
    ap.add_argument("--force-recheck", action="store_true",
                    help="Znovu overi i emaily kde prilohy uz maji file_hash")
    ap.add_argument("--no-indexes",    action="store_true",
                    help="Nevytvorit indexy na konci")
    args = ap.parse_args()

    start = datetime.now()
    print(f"=== download_attachments v{SCRIPT_VERSION} ===")
    print(f"Start:    {start.strftime('%Y-%m-%d %H:%M:%S')}")
    print(f"Schránka: {GRAPH_MAILBOX}")
    print(f"Cilovy adresar: {ATTACHMENTS_DIR}")
    print(f"MongoDB:  {MONGO_URI} -> {MONGO_DB}")

    # Adresar
    ATTACHMENTS_DIR.mkdir(parents=True, exist_ok=True)
    print(f"  Adresar OK")

    # Graph
    print("\nPřipojuji se k Graph API...")
    try:
        get_token()
        print("  Graph API OK")
    except Exception as e:
        print(f"  CHYBA: {e}")
        sys.exit(1)

    # MongoDB
    client = MongoClient(MONGO_URI, serverSelectionTimeoutMS=5000)
    try:
        client.admin.command("ping")
        print("  MongoDB OK")
    except Exception as e:
        print(f"  CHYBA: MongoDB neni dostupna -- {e}")
        sys.exit(1)

    col_emails = client[MONGO_DB][MONGO_COL_EMAILS]
    col_index  = client[MONGO_DB][MONGO_COL_INDEX]

    # Indexy na attachment index kolekci
    if not args.no_indexes:
        col_index.create_index("filename")
        col_index.create_index("mime_type")

    # Dotaz — emaily s prilohou ktere jeste nebyly zpracovany
    if args.force_recheck:
        query = {"has_attachments": True}
    else:
        query = {
            "has_attachments": True,
            "attachments": {
                "$elemMatch": {
                    "is_inline": False,
                    "file_hash":  {"$exists": False},
                }
            }
        }

    total = col_emails.count_documents(query)
    print(f"\nEmailu ke zpracovani: {total}")
    if total == 0:
        print("Neni co stahnout.")
        client.close()
        return

    cursor = col_emails.find(query, {"_id": 1, "graph_id": 1, "subject": 1, "attachments": 1})
    if args.limit:
        cursor = cursor.limit(args.limit)

    ok_count   = 0
    new_count  = 0
    skip_count = 0
    err_count  = 0
    email_i    = 0
    batch      = []

    def flush():
        if not batch:
            return
        try:
            col_emails.bulk_write(batch, ordered=False)
        except Exception as e:
            logging.error("bulk_write: %s", e)
            print(f"  CHYBA bulk_write: {e}")
        batch.clear()

    for email_doc in cursor:
        email_i += 1
        email_id   = email_doc["_id"]
        graph_id   = email_doc.get("graph_id", "")
        subject    = (email_doc.get("subject") or "")[:60]
        att_list   = email_doc.get("attachments") or []

        # Jen skutecne prilohy
        real_atts = [a for a in att_list if not a.get("is_inline", False)]
        if not real_atts:
            continue

        print(f"\n  {email_i:>5}/{total}  {subject}")

        # Nacti attachment IDs z Graph API
        graph_atts = fetch_message_attachments(graph_id)
        graph_att_map = {a["name"]: a for a in graph_atts if not a.get("isInline", False)}

        updated_atts = list(att_list)
        email_ok = True

        for i, att in enumerate(updated_atts):
            if att.get("is_inline", False):
                continue
            if not args.force_recheck and att.get("file_hash"):
                skip_count += 1
                print(f"         SKIP  {att['filename']}")
                continue

            att_name    = att.get("filename", "")
            graph_att   = graph_att_map.get(att_name)

            if not graph_att:
                # Zkus najit podle casti nazvu
                for gname, ga in graph_att_map.items():
                    if att_name.lower() in gname.lower():
                        graph_att = ga
                        break

            if not graph_att:
                logging.error("attachment not found in Graph [email=%s att=%s]", email_id, att_name)
                print(f"         ERR   {att_name} (nenalezeno v Graph)")
                err_count += 1
                email_ok = False
                continue

            # Stahni obsah
            content = fetch_attachment_content(graph_id, graph_att["id"])
            if content is None:
                err_count += 1
                email_ok = False
                print(f"         ERR   {att_name} (stazeni selhalo)")
                continue

            # Uloz s dedupem
            hash_val, local_path, was_new = save_attachment(content, att_name, ATTACHMENTS_DIR, col_index)

            # Aktualizuj MIME typ v indexu
            col_index.update_one(
                {"_id": hash_val},
                {"$set": {"mime_type": att.get("mime_type", graph_att.get("contentType", ""))}},
            )

            # Zaznamenej do emailu
            updated_atts[i] = {**att, "file_hash": hash_val, "local_path": local_path}

            if was_new:
                new_count += 1
                print(f"         NEW   {local_path}  ({len(content):,} B)")
            else:
                skip_count += 1
                print(f"         DUP   {att_name} -> {local_path}")

        if email_ok:
            ok_count += 1

        # Uloz aktualizovane prilohy zpet do emailu
        batch.append(UpdateOne(
            {"_id": email_id},
            {"$set": {"attachments": updated_atts}}
        ))

        if len(batch) >= BATCH_SIZE:
            flush()

        if email_i % 100 == 0:
            elapsed = (datetime.now() - start).total_seconds()
            print(f"  {'─'*60}")
            print(f"  Průběh: emaily={email_i}/{total}  nove={new_count}  dup={skip_count}  err={err_count}")
            print(f"  {'─'*60}")

    flush()

    elapsed_total = (datetime.now() - start).total_seconds()
    files_total   = col_index.count_documents({})
    size_total    = sum(d.get("size_bytes", 0) for d in col_index.find({}, {"size_bytes": 1}))

    print(f"\n{'='*52}")
    print(f"Vysledek:  emaily={ok_count}  |  nove soubory={new_count}  |  duplikaty={skip_count}  |  err={err_count}")
    print(f"Souboru v indexu: {files_total}  ({size_total/1024/1024:.1f} MB)")
    print(f"Celkovy cas: {int(elapsed_total//3600)}h {int((elapsed_total%3600)//60)}m {int(elapsed_total%60)}s")
    print(f"\nKonec: {datetime.now().strftime('%Y-%m-%d %H:%M:%S')}")
    if err_count:
        print(f"Chyby logovany do: {LOG_FILE}")

    client.close()


if __name__ == "__main__":
    main()