"""
DocumentModule - PDF/DOCX/OCR with layout-aware parsing for MORPH-AI v6.
"""

import re
from dataclasses import dataclass, field
from typing import Any, Dict, List, Optional

import torch
import torch.nn as nn
import torch.nn.functional as F

from architecture import MorphConfig


@dataclass
class DocumentFacts:
    text: str = ""
    pages: int = 0
    format: str = ""
    tables: List[List[List[str]]] = field(default_factory=list)
    metadata: Dict[str, str] = field(default_factory=dict)
    embedding: Optional[torch.Tensor] = None

    def to_text(self) -> str:
        parts = [f"document {self.format} {self.pages}p"]
        if self.text:
            parts.append(f"text: {self.text[:500]}")
        if self.tables:
            parts.append(f"tables: {len(self.tables)}")
        return " | ".join(parts)

    def to_dict(self) -> Dict[str, Any]:
        return {
            "text": self.text,
            "pages": self.pages,
            "format": self.format,
            "tables": self.tables,
            "metadata": self.metadata,
        }


class DocumentModule(nn.Module):
    """PDF/DOCX/OCR with layout-aware parsing for document understanding."""

    def __init__(self, config: MorphConfig, hidden_dim: int):
        super().__init__()
        self.max_pages = config.doc_max_pages
        self.page_proj = nn.Linear(hidden_dim, config.doc_hidden)
        self.layout_encoder = nn.Sequential(
            nn.Linear(config.doc_hidden + 4, config.doc_hidden),
            nn.GELU(),
            nn.Linear(config.doc_hidden, hidden_dim),
        )
        nn.init.zeros_(self.layout_encoder[-1].weight)
        nn.init.zeros_(self.layout_encoder[-1].bias)

    def forward(self, hidden: torch.Tensor, layout_info: Optional[torch.Tensor] = None) -> torch.Tensor:
        B, T, H = hidden.shape
        page_emb = self.page_proj(hidden)
        if layout_info is not None:
            layout = layout_info.to(hidden.dtype)
            page_emb = self.layout_encoder(torch.cat([page_emb, layout], dim=-1))
        return hidden + page_emb

    def extract_text(self, source) -> str:
        """Extract text from PDF/DOCX/image with OCR fallback."""
        try:
            if hasattr(source, 'endswith'):
                if source.endswith('.pdf'):
                    return self._extract_pdf(source)
                elif source.endswith('.docx'):
                    return self._extract_docx(source)
                elif source.endswith(('.png', '.jpg', '.jpeg', '.bmp', '.tiff')):
                    return self._extract_image_ocr(source)
            return self._extract_image_ocr(source)
        except Exception as e:
            return f"[document extraction error: {e}]"

    def _extract_pdf(self, path: str) -> str:
        try:
            import fitz
            doc = fitz.open(path)
            pages = []
            for i in range(min(len(doc), self.max_pages)):
                page = doc[i]
                text = page.get_text()
                tables = page.find_tables()
                if tables.tables:
                    for table in tables.tables:
                        pages.append(f"[TABLE]\n{table.to_pandas().to_string()}")
                pages.append(text)
            return "\n\n".join(pages)
        except ImportError:
            return "[PDF extraction requires PyMuPDF: pip install pymupdf]"

    def _extract_docx(self, path: str) -> str:
        try:
            import docx2txt
            return docx2txt.process(path)
        except ImportError:
            return "[DOCX extraction requires docx2txt: pip install docx2txt]"

    def _extract_image_ocr(self, source) -> str:
        try:
            import pytesseract
            from PIL import Image
            img = Image.open(source)
            text = pytesseract.image_to_string(img)
            data = pytesseract.image_to_data(img, output_type=pytesseract.Output.DICT)
            lines = []
            for i, word in enumerate(data['text']):
                if word.strip():
                    lines.append(word)
            return text + "\n\n[LAYOUT]\n" + " ".join(lines)
        except ImportError:
            return "[OCR requires pytesseract + Pillow: pip install pytesseract pillow]"
        except Exception as e:
            return f"[OCR error: {e}]"

    def analyze(self, source) -> DocumentFacts:
        """Full document analysis returning structured facts."""
        facts = DocumentFacts()
        try:
            text = self.extract_text(source)
            facts.text = text
            facts.pages = len(text.split('\n\n'))
            if hasattr(source, 'endswith'):
                if source.endswith('.pdf'):
                    facts.format = 'PDF'
                elif source.endswith('.docx'):
                    facts.format = 'DOCX'
                else:
                    facts.format = 'IMAGE'
            else:
                facts.format = 'UNKNOWN'
        except Exception as e:
            facts.text = f"[analysis error: {e}]"
        return facts