from flask import session
import re
import os
import sqlite3
from datetime import datetime, timedelta
from typing import Optional

log_db = sqlite3.connect("access_log.db", check_same_thread=False)



# Precompiled regex to find date-like patterns: either dotted X.Y.Z or ISO dashed YYYY-MM-DD
_DATE_REGEX = re.compile(
    r"("  # start group
    r"\d{4}-\d{1,2}-\d{1,2}"          # ISO: YYYY-M-D or YYYY-MM-DD
    r"|"                              # or
    r"\d{1,4}\.\d{1,2}\.\d{1,4}"      # dotted: X.Y.Z, where each is 1–4 digits (year may be 1–4)
    r")"
)


def _try_parse(date_str: str, fmt: str) -> Optional[datetime]:
    """Try to parse date_str with fmt, return datetime or None."""
    try:
        return datetime.strptime(date_str, fmt)
    except ValueError:
        return None


def extract_date_from_string(text: str) -> Optional[str]:
    """
    Extract the first date-like substring from text and return it in ISO format (YYYY-MM-DD).
    Supports:
    - ISO-style dates with dashes (YYYY-M-D or YYYY-MM-DD)
    - Dotted dates (DD.MM.YYYY, YYYY.MM.DD, DD.MM.YY, YY.MM.DD)
    """
    match = _DATE_REGEX.search(text)
    if not match:
        return None

    date_str = match.group(1)

    # 1) ISO dashed format takes priority
    if '-' in date_str:
        dt = _try_parse(date_str, '%Y-%m-%d')
        return dt.strftime('%Y-%m-%d') if dt else None

    # 2) Dotted formats
    parts = date_str.split('.')
    candidates = []

    # Unambiguous: last part 4 digits → DD.MM.YYYY
    if len(parts) == 3 and len(parts[2]) == 4:
        candidates.append('%d.%m.%Y')
    # Unambiguous: first part 4 digits → YYYY.MM.DD
    if len(parts) == 3 and len(parts[0]) == 4:
        candidates.append('%Y.%m.%d')
    # Ambiguous two-digit groups: try DD.MM.YY, then YY.MM.DD
    if len(parts) == 3 and all(len(p) == 2 for p in parts):
        candidates.extend(['%d.%m.%y', '%y.%m.%d'])

    # Try each candidate
    for fmt in candidates:
        dt = _try_parse(date_str, fmt)
        if dt:
            return dt.strftime('%Y-%m-%d')

    # no valid parse
    return None


def extract_structure_from_string(input_string):
    # extract category and titel from filename
    filepathname_ext = os.path.splitext(input_string)[0] # remove file extension
    filename_ext = os.path.basename(filepathname_ext) # get only the filename
    left_side, right_side = filename_ext.split('-', 1) if '-' in filename_ext else (filename_ext, None)

    try:
        int(left_side.strip())
        # first part is only a number
        previous_right_side = right_side
        left_side, right_side = previous_right_side.split('-', 1) if '-' in previous_right_side else (previous_right_side, None)
    except:
        # first part not a number
        pass
    
    if 'predig' in left_side.lower() or 'thema' in left_side.lower():
        category = 'Predigt'
    elif 'wort' in left_side.lower() or 'einladung' in left_side.lower() or 'begrüßung' in left_side.lower() or 'ansprache' in left_side.lower() or 'einleitung' in left_side.lower() or 'aufruf zum' in left_side.lower() or 'zuruf zum' in left_side.lower():
        category = 'Vorwort'
    elif 'kinderchor' in left_side.lower():
        category = 'Kinderchor'
    elif 'jugendchor' in left_side.lower():
        category = 'Jugendchor'
    elif 'orchester' in input_string.lower() or 'sinfonie' in input_string.lower() or 'symphonie' in input_string.lower():
        category = 'Orchester'
    elif 'chor' in left_side.lower():
        category = 'Chor'
    elif 'gemeinsam' in left_side.lower() or 'gemeindelied' in left_side.lower() or 'gemeinsamer gesang' in input_string.lower():
        category = 'Gemeinsamer Gesang'
    elif 'gruppenlied' in left_side.lower() or 'jugend' in left_side.lower() or 'lied' in left_side.lower():
        category = 'Gruppenlied'
    elif 'gedicht' in left_side.lower():
        category = 'Gedicht'
    elif 'vortrag' in left_side.lower() or 'erzä' in left_side.lower() or 'program' in left_side.lower():
        category = 'Erzählung'
    elif 'instrumental' in input_string.lower() or 'musikstück' in left_side.lower() or 'harfenstück' in left_side.lower():
        category = 'Instrumental'
    else:
        category = None

    if right_side:
        titel, name = right_side.split('-', 1) if '-' in right_side else (right_side, None)
        if category == 'Predigt' or category == 'Vorwort' or category == 'Gedicht':
            if not name: # kein Titel, nur Name
                name = titel
                titel = None
    else:
        titel = None
        name = None

    return category, titel, name

def generate_top_list(category):
    
    now = datetime.now()

    # We'll compare the timestamp
    start_dt = now - timedelta(days=14)
    start_str = start_dt.isoformat()
    
    # Filter for mimes that start with the given type
    params_for_filter = (start_str,)

    # 1. Top files by access count
    query = f'''
        SELECT rel_path, COUNT(*) as access_count
        FROM file_access_log
        WHERE timestamp >= ? AND mime LIKE 'audio/%'
        GROUP BY rel_path
        ORDER BY access_count DESC
        LIMIT 1000
    '''
    with log_db:
        cursor = log_db.execute(query, params_for_filter)
        rows = cursor.fetchall()

    # Filter by allowed basefolders
    allowed_basefolders = list(session['folders'].keys())
    rows = [
        (rel_path, access_count) for rel_path, access_count in rows
        if any(rel_path.startswith(folder) for folder in allowed_basefolders)
    ]

    # Convert rows to a list of dictionaries and add category
    rows = [
        {
            'rel_path': rel_path,
            'access_count': access_count,
            'category': extract_structure_from_string(rel_path)[0]
        }
        for rel_path, access_count in rows
    ]
    rows = [r for r in rows if r['category'] == category][:20]

    filelist = [
        {
            'name': rel_path.split('/')[-1],
            'path': rel_path,
            'file_type': 'music'
        }
        for rel_path in [r['rel_path'] for r in rows]
    ]

    return filelist