# parser.py
# Utilities to extract text from the PDF and parse rows into records.
# Assumes two tables: first is Harbor A, second is Harbor B.


from __future__ import annotations
from csv import reader
import re
from typing import List, Dict, Any, Tuple


# Optional: If you want OCR fallback later, wire in pdf2image + pytesseract here.


def extract_text_lines(pdf_path: str) -> List[str]:
    """Extract text lines from a PDF using pdfplumber (preferred) with a
    light fallback to PyPDF2. Returns a list of raw lines."""
    text = ""
    
    try:
        import pdfplumber
        with pdfplumber.open(pdf_path) as pdf:
            pages_text = []
            for p in pdf.pages:
                t = p.extract_text() or ""
                pages_text.append(t)
            text = "\n".join(pages_text)
    except Exception:

        try:
            from PyPDF2 import PdfReader
            reader = PdfReader(pdf_path)
            pages_text = []
            for page in reader.pages:
                pages_text.append(page.extract_text() or "")
                text = "\n".join(pages_text)
        except Exception:
            text = ""


    if not text.strip():
        raise RuntimeError("No text extracted. If the PDF is scanned, add OCR fallback (pytesseract).")


    # Normalize to individual lines
    lines = [ln.strip() for ln in text.splitlines()]
    return lines


HEADER_PATTERNS = [
re.compile(r"\bSchiff\b.*\bETA\b.*\bETS\b", re.IGNORECASE),
re.compile(r"Nächster Hafen|Liegeplatz|Ladung|Lotse", re.IGNORECASE),
]


DATE_TOKEN = re.compile(r"\b\d{1,2}\.\d{1,2}\.(?:\d{4})?")
TIME_FRAGMENT = r"(?:\s*/\s*\d{1,2}\.\d{2}\s*Uhr\s*\*?)?"
DT_TOKEN_WITH_TIME = re.compile(r"\d{1,2}\.\d{1,2}\.(?:\d{4})?" + TIME_FRAGMENT)




def cleanse_lines(lines: List[str]) -> List[str]:
    """Remove known header lines and keep data/blank lines."""
    out: List[str] = []
    for ln in lines:
        if not ln:
            out.append("")
            continue
        if any(p.search(ln) for p in HEADER_PATTERNS):
            continue
        out.append(ln)
    return out

def split_into_tables(lines: List[str]) -> List[List[str]]:
    """Find candidate data lines (those containing a date token) and split them
    into up to two blocks separated by at least one blank line. Returns a list
    of blocks (1 or 2)."""
    candidate = [ln for ln in lines if (ln == "" or DATE_TOKEN.search(ln))]


    blocks: List[List[str]] = []
    current: List[str] = []
    seen_data = False
    for ln in candidate:
        if ln == "":
            if seen_data and current:
                blocks.append(current)
                current = []
                seen_data = False
            continue
        current.append(ln)
        seen_data = True
    if current:
        blocks.append(current)


    if len(blocks) > 2:
        # Merge any extra blocks into the second
        blocks = [blocks[0], sum(blocks[1:], [])]
    return blocks