"""
Inference functions for document parsing
"""

import logging
from typing import Literal, Optional, List
from pathlib import Path

from PIL import Image

from app.schemas import ParsedDocument, ParsedPage, ParsedBlock, BBox
from app.runtime.model_loader import get_model
from app.runtime.preprocessing import (
    convert_pdf_to_images, load_image, prepare_images_for_model
)
from app.runtime.postprocessing import build_parsed_document
from app.core.config import settings

logger = logging.getLogger(__name__)


def parse_document_from_images(
    images: List[Image.Image],
    output_mode: Literal["raw_json", "markdown", "qa_pairs", "chunks"] = "raw_json",
    doc_id: Optional[str] = None,
    doc_type: Literal["pdf", "image"] = "image"
) -> ParsedDocument:
    """
    Parse document from list of images using dots.ocr model
    
    Args:
        images: List of PIL Images (pages)
        output_mode: Output format mode
        doc_id: Document ID
        doc_type: Document type (pdf or image)
    
    Returns:
        ParsedDocument with structured content
    """
    # Check if we should use dummy parser
    if settings.USE_DUMMY_PARSER:
        logger.info("Using dummy parser (USE_DUMMY_PARSER=true)")
        return dummy_parse_document_from_images(images, doc_id, doc_type)
    
    # Try to get model
    model = get_model()
    
    if model is None:
        if settings.ALLOW_DUMMY_FALLBACK:
            logger.warning("Model not loaded, falling back to dummy parser")
            return dummy_parse_document_from_images(images, doc_id, doc_type)
        else:
            raise RuntimeError("Model not loaded and dummy fallback is disabled")
    
    # Prepare images for model
    prepared_images = prepare_images_for_model(images)
    
    if not prepared_images:
        raise ValueError("No valid images to process")
    
    # Process with model
    pages_data = []
    
    for idx, image in enumerate(prepared_images, start=1):
        try:
            # TODO: Implement actual inference with dots.ocr
            # Example:
            # inputs = model["processor"](images=image, return_tensors="pt")
            # outputs = model["model"].generate(**inputs)
            # text = model["processor"].decode(outputs[0], skip_special_tokens=True)
            # 
            # # Parse model output into blocks
            # blocks = parse_model_output_to_blocks(text, image.size)
            # 
            # pages_data.append({
            #     "blocks": blocks,
            #     "width": image.width,
            #     "height": image.height
            # })
            
            # For now, use dummy for each page
            logger.debug(f"Processing page {idx} with model (placeholder)")
            pages_data.append({
                "blocks": [
                    {
                        "type": "paragraph",
                        "text": f"Page {idx} content (model output placeholder)",
                        "bbox": {"x": 0, "y": 0, "width": image.width, "height": image.height},
                        "reading_order": 1
                    }
                ],
                "width": image.width,
                "height": image.height
            })
            
        except Exception as e:
            logger.error(f"Error processing page {idx}: {e}", exc_info=True)
            # Continue with other pages
            continue
    
    # Build ParsedDocument from model output
    return build_parsed_document(
        pages_data=pages_data,
        doc_id=doc_id or "parsed-doc",
        doc_type=doc_type,
        metadata={"model": settings.PARSER_MODEL_NAME}
    )


def parse_document(
    input_path: str,
    output_mode: Literal["raw_json", "markdown", "qa_pairs", "chunks"] = "raw_json",
    doc_id: Optional[str] = None,
    doc_type: Literal["pdf", "image"] = "image"
) -> ParsedDocument:
    """
    Parse document from file path
    
    This function handles file loading and delegates to parse_document_from_images
    
    Args:
        input_path: Path to document file (PDF or image)
        output_mode: Output format mode
        doc_id: Document ID
        doc_type: Document type (pdf or image)
    
    Returns:
        ParsedDocument with structured content
    """
    # Load file content
    with open(input_path, 'rb') as f:
        content = f.read()
    
    # Convert to images based on type
    if doc_type == "pdf":
        images = convert_pdf_to_images(content)
    else:
        image = load_image(content)
        images = [image]
    
    # Parse from images
    return parse_document_from_images(images, output_mode, doc_id, doc_type)


def dummy_parse_document_from_images(
    images: List[Image.Image],
    doc_id: Optional[str] = None,
    doc_type: Literal["pdf", "image"] = "image"
) -> ParsedDocument:
    """
    Dummy parser for testing (returns mock data from images)
    
    This will be replaced with actual dots.ocr inference
    """
    logger.info(f"Dummy parsing: {len(images)} image(s)")
    
    pages = []
    
    for idx, image in enumerate(images, start=1):
        mock_page = ParsedPage(
            page_num=idx,
            blocks=[
                ParsedBlock(
                    type="heading",
                    text=f"Page {idx} Title",
                    bbox=BBox(x=0, y=0, width=image.width, height=50),
                    reading_order=1,
                    page_num=idx
                ),
                ParsedBlock(
                    type="paragraph",
                    text=f"This is a dummy parsed document (page {idx}). "
                         f"Image size: {image.width}x{image.height}. "
                         f"Replace this with actual dots.ocr inference.",
                    bbox=BBox(x=0, y=60, width=image.width, height=100),
                    reading_order=2,
                    page_num=idx
                )
            ],
            width=image.width,
            height=image.height
        )
        pages.append(mock_page)
    
    return ParsedDocument(
        doc_id=doc_id or "dummy-doc-1",
        doc_type=doc_type,
        pages=pages,
        metadata={
            "parser": "dummy",
            "page_count": len(images)
        }
    )


def dummy_parse_document(
    input_path: str,
    output_mode: Literal["raw_json", "markdown", "qa_pairs", "chunks"] = "raw_json",
    doc_id: Optional[str] = None,
    doc_type: Literal["pdf", "image"] = "image"
) -> ParsedDocument:
    """
    Dummy parser for testing (returns mock data)
    
    This function loads the file and delegates to dummy_parse_document_from_images
    """
    # Load file content
    with open(input_path, 'rb') as f:
        content = f.read()
    
    # Convert to images
    if doc_type == "pdf":
        images = convert_pdf_to_images(content)
    else:
        image = load_image(content)
        images = [image]
    
    return dummy_parse_document_from_images(images, doc_id, doc_type)