"""
Unified Document Model for Dual-track Processing

This module defines the common data structure used by both OCR and direct extraction tracks
to ensure consistent output format regardless of processing method.
"""

from dataclasses import dataclass, field
from typing import List, Dict, Optional, Union, Literal, Any
from datetime import datetime
from enum import Enum


class ElementType(str, Enum):
    """Document element types supporting all 23 PP-StructureV3 types plus custom ones"""
    # Text elements
    TEXT = "text"
    TITLE = "title"
    HEADER = "header"
    FOOTER = "footer"
    REFERENCE = "reference"
    EQUATION = "equation"
    FOOTNOTE = "footnote"
    CAPTION = "caption"

    # List elements
    LIST = "list"
    LIST_ITEM = "list_item"

    # Table elements
    TABLE = "table"
    TABLE_CELL = "table_cell"
    TABLE_CAPTION = "table_caption"

    # Visual elements
    IMAGE = "image"
    FIGURE = "figure"
    CHART = "chart"
    DIAGRAM = "diagram"

    # Structural elements
    SECTION = "section"
    PARAGRAPH = "paragraph"
    PAGE_NUMBER = "page_number"
    WATERMARK = "watermark"
    HEADER_GROUP = "header_group"
    BODY = "body"

    # Special elements
    CODE = "code"
    FORMULA = "formula"
    SIGNATURE = "signature"
    STAMP = "stamp"
    LOGO = "logo"
    BARCODE = "barcode"
    QR_CODE = "qr_code"


class ProcessingTrack(str, Enum):
    """Processing track used for the document"""
    OCR = "ocr"           # PaddleOCR PP-StructureV3 track
    DIRECT = "direct"     # PyMuPDF direct extraction track
    HYBRID = "hybrid"     # Mixed processing (future)


@dataclass
class BoundingBox:
    """Bounding box coordinates for document elements"""
    x0: float  # Left coordinate
    y0: float  # Top coordinate
    x1: float  # Right coordinate
    y1: float  # Bottom coordinate

    @property
    def width(self) -> float:
        return self.x1 - self.x0

    @property
    def height(self) -> float:
        return self.y1 - self.y0

    @property
    def center_x(self) -> float:
        return (self.x0 + self.x1) / 2

    @property
    def center_y(self) -> float:
        return (self.y0 + self.y1) / 2

    def to_dict(self) -> Dict[str, float]:
        return {
            "x0": self.x0,
            "y0": self.y0,
            "x1": self.x1,
            "y1": self.y1,
            "width": self.width,
            "height": self.height
        }

    def overlaps(self, other: 'BoundingBox', tolerance: float = 0) -> bool:
        """Check if this bbox overlaps with another"""
        return not (
            self.x1 + tolerance < other.x0 or
            self.x0 - tolerance > other.x1 or
            self.y1 + tolerance < other.y0 or
            self.y0 - tolerance > other.y1
        )

    def contains(self, other: 'BoundingBox', tolerance: float = 0) -> bool:
        """Check if this bbox contains another"""
        return (
            self.x0 - tolerance <= other.x0 and
            self.y0 - tolerance <= other.y0 and
            self.x1 + tolerance >= other.x1 and
            self.y1 + tolerance >= other.y1
        )


@dataclass
class StyleInfo:
    """Style information for text elements"""
    font_name: Optional[str] = None
    font_size: Optional[float] = None
    font_weight: Optional[str] = None  # normal, bold
    font_style: Optional[str] = None   # normal, italic
    text_color: Optional[int] = None   # RGB as integer
    bg_color: Optional[int] = None     # Background color
    alignment: Optional[str] = None    # left, center, right, justify

    @property
    def is_bold(self) -> bool:
        return self.font_weight == "bold"

    @property
    def is_italic(self) -> bool:
        return self.font_style == "italic"

    def get_rgb_color(self) -> Optional[tuple]:
        """Convert integer color to RGB tuple"""
        if self.text_color is None:
            return None
        r = (self.text_color >> 16) & 0xFF
        g = (self.text_color >> 8) & 0xFF
        b = self.text_color & 0xFF
        return (r, g, b)

    def to_dict(self) -> Dict[str, Any]:
        result = {}
        if self.font_name:
            result["font_name"] = self.font_name
        if self.font_size:
            result["font_size"] = self.font_size
        if self.font_weight:
            result["font_weight"] = self.font_weight
        if self.font_style:
            result["font_style"] = self.font_style
        if self.text_color is not None:
            result["text_color"] = self.text_color
            result["text_color_rgb"] = self.get_rgb_color()
        if self.bg_color is not None:
            result["bg_color"] = self.bg_color
        if self.alignment:
            result["alignment"] = self.alignment
        return result


@dataclass
class TableCell:
    """Table cell information"""
    row: int
    col: int
    row_span: int = 1
    col_span: int = 1
    content: str = ""
    bbox: Optional[BoundingBox] = None
    style: Optional[StyleInfo] = None

    def to_dict(self) -> Dict[str, Any]:
        return {
            "row": self.row,
            "col": self.col,
            "row_span": self.row_span,
            "col_span": self.col_span,
            "content": self.content,
            "bbox": self.bbox.to_dict() if self.bbox else None,
            "style": self.style.to_dict() if self.style else None
        }


@dataclass
class TableData:
    """Structured table data"""
    rows: int
    cols: int
    cells: List[TableCell] = field(default_factory=list)
    headers: Optional[List[str]] = None
    caption: Optional[str] = None

    def to_dict(self) -> Dict[str, Any]:
        return {
            "rows": self.rows,
            "cols": self.cols,
            "cells": [cell.to_dict() for cell in self.cells],
            "headers": self.headers,
            "caption": self.caption
        }

    def to_html(self) -> str:
        """Convert table to HTML representation"""
        html = ["<table>"]

        if self.caption:
            html.append(f"<caption>{self.caption}</caption>")

        # Group cells by row and column for quick lookup
        cell_map = {}
        for cell in self.cells:
            cell_map[(cell.row, cell.col)] = cell

        # Track which cells are covered by row/col spans
        covered = set()
        for cell in self.cells:
            if cell.row_span > 1 or cell.col_span > 1:
                for r in range(cell.row, cell.row + cell.row_span):
                    for c in range(cell.col, cell.col + cell.col_span):
                        if (r, c) != (cell.row, cell.col):
                            covered.add((r, c))

        # Generate HTML with proper column filling
        for row_idx in range(self.rows):
            html.append("<tr>")
            for col_idx in range(self.cols):
                # Skip cells covered by row/col spans
                if (row_idx, col_idx) in covered:
                    continue

                cell = cell_map.get((row_idx, col_idx))
                tag = "th" if row_idx == 0 and self.headers else "td"

                if cell:
                    span_attrs = []
                    if cell.row_span > 1:
                        span_attrs.append(f'rowspan="{cell.row_span}"')
                    if cell.col_span > 1:
                        span_attrs.append(f'colspan="{cell.col_span}"')
                    span_str = " ".join(span_attrs)
                    content = cell.content if cell.content else ""
                    html.append(f'<{tag} {span_str}>{content}</{tag}>')
                else:
                    # Fill in empty cell for missing positions
                    html.append(f'<{tag}></{tag}>')

            html.append("</tr>")

        html.append("</table>")
        return "\n".join(html)


@dataclass
class DocumentElement:
    """Individual document element (text, image, table, etc.)"""
    element_id: str
    type: ElementType
    content: Union[str, TableData, bytes, Dict[str, Any]]
    bbox: BoundingBox
    confidence: Optional[float] = None  # OCR confidence (0-1)
    style: Optional[StyleInfo] = None
    metadata: Dict[str, Any] = field(default_factory=dict)
    children: List['DocumentElement'] = field(default_factory=list)

    @property
    def is_text(self) -> bool:
        return self.type in [
            ElementType.TEXT, ElementType.TITLE, ElementType.HEADER,
            ElementType.FOOTER, ElementType.CAPTION, ElementType.PARAGRAPH
        ]

    @property
    def is_visual(self) -> bool:
        return self.type in [
            ElementType.IMAGE, ElementType.FIGURE, ElementType.CHART,
            ElementType.DIAGRAM, ElementType.LOGO
        ]

    @property
    def is_table(self) -> bool:
        return self.type in [ElementType.TABLE, ElementType.TABLE_CELL]

    def get_text(self) -> str:
        """Extract text content from element"""
        if isinstance(self.content, str):
            return self.content
        elif isinstance(self.content, TableData):
            # Extract text from table cells
            texts = []
            for cell in self.content.cells:
                if cell.content:
                    texts.append(cell.content)
            return " ".join(texts)
        elif isinstance(self.content, dict) and "text" in self.content:
            return self.content["text"]
        return ""

    def to_dict(self) -> Dict[str, Any]:
        """Convert to dictionary for JSON serialization"""
        result = {
            "element_id": self.element_id,
            "type": self.type.value,
            "bbox": self.bbox.to_dict(),
        }

        # Handle different content types
        if isinstance(self.content, str):
            result["content"] = self.content
        elif isinstance(self.content, TableData):
            result["content"] = self.content.to_dict()
            result["content_type"] = "table"
        elif isinstance(self.content, bytes):
            result["content_type"] = "binary"
            result["content_length"] = len(self.content)
        elif isinstance(self.content, dict):
            result["content"] = self.content

        if self.confidence is not None:
            result["confidence"] = self.confidence

        if self.style:
            result["style"] = self.style.to_dict()

        if self.metadata:
            result["metadata"] = self.metadata

        if self.children:
            result["children"] = [child.to_dict() for child in self.children]

        return result


@dataclass
class Dimensions:
    """Page or image dimensions"""
    width: float
    height: float
    dpi: Optional[int] = None

    def to_dict(self) -> Dict[str, Any]:
        result = {"width": self.width, "height": self.height}
        if self.dpi:
            result["dpi"] = self.dpi
        return result


@dataclass
class Page:
    """Single page in a document"""
    page_number: int  # 1-based page number
    elements: List[DocumentElement]
    dimensions: Dimensions
    metadata: Dict[str, Any] = field(default_factory=dict)

    def get_reading_order(self) -> List[DocumentElement]:
        """Get elements in reading order (top to bottom, left to right)"""
        return sorted(
            self.elements,
            key=lambda e: (e.bbox.y0, e.bbox.x0)
        )

    def get_elements_by_type(self, element_type: ElementType) -> List[DocumentElement]:
        """Get all elements of a specific type"""
        return [e for e in self.elements if e.type == element_type]

    def get_text_elements(self) -> List[DocumentElement]:
        """Get all text-containing elements"""
        return [e for e in self.elements if e.is_text]

    def get_tables(self) -> List[DocumentElement]:
        """Get all table elements"""
        return [e for e in self.elements if e.type == ElementType.TABLE]

    def get_images(self) -> List[DocumentElement]:
        """Get all image elements"""
        return [e for e in self.elements if e.is_visual]

    def extract_text(self, separator: str = "\n") -> str:
        """Extract all text from the page in reading order"""
        texts = []
        for element in self.get_reading_order():
            text = element.get_text()
            if text:
                texts.append(text)
        return separator.join(texts)

    def to_dict(self) -> Dict[str, Any]:
        """Convert to dictionary for JSON serialization"""
        return {
            "page_number": self.page_number,
            "elements": [e.to_dict() for e in self.elements],
            "dimensions": self.dimensions.to_dict(),
            "metadata": self.metadata,
            "statistics": {
                "total_elements": len(self.elements),
                "text_elements": len(self.get_text_elements()),
                "tables": len(self.get_tables()),
                "images": len(self.get_images())
            }
        }


@dataclass
class DocumentMetadata:
    """Document-level metadata"""
    filename: str
    file_type: str
    file_size: int
    created_at: datetime
    processing_track: ProcessingTrack
    processing_time: float  # seconds
    language: Optional[str] = None
    title: Optional[str] = None
    author: Optional[str] = None
    subject: Optional[str] = None
    keywords: Optional[List[str]] = None
    producer: Optional[str] = None
    creator: Optional[str] = None
    creation_date: Optional[datetime] = None
    modification_date: Optional[datetime] = None
    original_filename: Optional[str] = None  # Original filename before conversion (e.g., Office → PDF)

    def to_dict(self) -> Dict[str, Any]:
        """Convert to dictionary for JSON serialization"""
        result = {
            "filename": self.filename,
            "file_type": self.file_type,
            "file_size": self.file_size,
            "created_at": self.created_at.isoformat(),
            "processing_track": self.processing_track.value,
            "processing_time": self.processing_time,
        }

        # Add optional fields if present
        optional_fields = [
            "language", "title", "author", "subject",
            "keywords", "producer", "creator", "original_filename"
        ]
        for field in optional_fields:
            value = getattr(self, field)
            if value is not None:
                result[field] = value

        if self.creation_date:
            result["creation_date"] = self.creation_date.isoformat()
        if self.modification_date:
            result["modification_date"] = self.modification_date.isoformat()

        return result


@dataclass
class UnifiedDocument:
    """
    Unified document representation for both OCR and direct extraction tracks.

    This is the primary output format that ensures consistency across different
    processing methods and enables seamless downstream processing.
    """
    document_id: str
    metadata: DocumentMetadata
    pages: List[Page]
    processing_errors: List[Dict[str, Any]] = field(default_factory=list)

    @property
    def page_count(self) -> int:
        return len(self.pages)

    @property
    def total_elements(self) -> int:
        return sum(len(page.elements) for page in self.pages)

    def get_page(self, page_number: int) -> Optional[Page]:
        """Get page by number (1-based)"""
        for page in self.pages:
            if page.page_number == page_number:
                return page
        return None

    def extract_all_text(self, page_separator: str = "\n\n") -> str:
        """Extract all text from the document"""
        texts = []
        for page in self.pages:
            page_text = page.extract_text()
            if page_text:
                texts.append(page_text)
        return page_separator.join(texts)

    def get_all_tables(self) -> List[DocumentElement]:
        """Get all tables from all pages"""
        tables = []
        for page in self.pages:
            tables.extend(page.get_tables())
        return tables

    def get_all_images(self) -> List[DocumentElement]:
        """Get all images from all pages"""
        images = []
        for page in self.pages:
            images.extend(page.get_images())
        return images

    def to_dict(self) -> Dict[str, Any]:
        """Convert to dictionary for JSON serialization"""
        return {
            "document_id": self.document_id,
            "metadata": self.metadata.to_dict(),
            "pages": [page.to_dict() for page in self.pages],
            "statistics": {
                "page_count": self.page_count,
                "total_elements": self.total_elements,
                "total_tables": len(self.get_all_tables()),
                "total_images": len(self.get_all_images()),
            },
            "processing_errors": self.processing_errors
        }

    def to_legacy_format(self) -> Dict[str, Any]:
        """
        Convert to legacy format for backward compatibility.

        This ensures existing API clients continue to work while we transition
        to the new unified format.
        """
        # Extract text regions in legacy format
        text_regions = []
        layout_data = []
        images_metadata = []

        for page in self.pages:
            page_num = page.page_number

            for element in page.elements:
                if element.is_text:
                    # Legacy text region format
                    text_regions.append({
                        "page": page_num,
                        "text": element.get_text(),
                        "confidence": element.confidence or 1.0,
                        "bbox": {
                            "x_min": element.bbox.x0,
                            "y_min": element.bbox.y0,
                            "x_max": element.bbox.x1,
                            "y_max": element.bbox.y1
                        }
                    })

                # Legacy layout data
                layout_item = {
                    "element_id": element.element_id,
                    "type": element.type.value,
                    "page": page_num - 1,  # Legacy uses 0-based
                    "bbox": [element.bbox.x0, element.bbox.y0,
                            element.bbox.x1, element.bbox.y1]
                }

                if element.is_table and isinstance(element.content, TableData):
                    layout_item["content"] = element.content.to_html()
                elif element.is_text:
                    layout_item["content"] = element.get_text()

                layout_data.append(layout_item)

                # Legacy image metadata
                if element.is_visual:
                    images_metadata.append({
                        "element_id": element.element_id,
                        "type": "image",
                        "page": page_num - 1,  # Legacy uses 0-based
                        "bbox": [element.bbox.x0, element.bbox.y0,
                                element.bbox.x1, element.bbox.y1]
                    })

        # Calculate average confidence
        confidences = [r["confidence"] for r in text_regions if r.get("confidence")]
        avg_confidence = sum(confidences) / len(confidences) if confidences else 0.0

        return {
            "status": "success",
            "filename": self.metadata.filename,
            "text_regions": text_regions,
            "total_text_regions": len(text_regions),
            "average_confidence": avg_confidence,
            "processing_time": self.metadata.processing_time,
            "language": self.metadata.language or "ch",
            "layout_data": {
                "elements": layout_data,
                "total_elements": len(layout_data)
            },
            "images_metadata": images_metadata,
            "ocr_dimensions": {
                "width": self.pages[0].dimensions.width if self.pages else 0,
                "height": self.pages[0].dimensions.height if self.pages else 0
            },
            # New fields that won't break existing clients
            "_unified_format": True,
            "_processing_track": self.metadata.processing_track.value
        }


class UnifiedDocumentConverter:
    """Converter utilities for UnifiedDocument format"""

    @staticmethod
    def from_ocr_result(ocr_result: Dict[str, Any],
                        document_id: str,
                        metadata: DocumentMetadata) -> UnifiedDocument:
        """
        Convert PaddleOCR result to UnifiedDocument format.

        This handles the conversion from PP-StructureV3 output to our unified format.
        """
        pages = []

        # Handle single page or multi-page results
        if "pages" in ocr_result:
            page_results = ocr_result["pages"]
        else:
            page_results = [ocr_result]

        for page_idx, page_data in enumerate(page_results):
            page_num = page_idx + 1
            elements = []

            # Convert text regions
            for idx, text_region in enumerate(page_data.get("text_regions", [])):
                bbox_data = text_region.get("bbox", {})
                element = DocumentElement(
                    element_id=f"text_{page_num}_{idx}",
                    type=ElementType.TEXT,
                    content=text_region.get("text", ""),
                    bbox=BoundingBox(
                        x0=bbox_data.get("x_min", 0),
                        y0=bbox_data.get("y_min", 0),
                        x1=bbox_data.get("x_max", 0),
                        y1=bbox_data.get("y_max", 0)
                    ),
                    confidence=text_region.get("confidence")
                )
                elements.append(element)

            # Convert layout elements if available
            if "layout_data" in page_data and page_data["layout_data"]:
                for layout_elem in page_data["layout_data"].get("elements", []):
                    # Map layout type to ElementType
                    layout_type = layout_elem.get("type", "text")
                    element_type = ElementType.TEXT  # Default

                    if "table" in layout_type.lower():
                        element_type = ElementType.TABLE
                    elif "image" in layout_type.lower() or "figure" in layout_type.lower():
                        element_type = ElementType.IMAGE
                    elif "title" in layout_type.lower():
                        element_type = ElementType.TITLE
                    elif "list" in layout_type.lower():
                        element_type = ElementType.LIST

                    # Create element
                    bbox_list = layout_elem.get("bbox", [0, 0, 0, 0])
                    element = DocumentElement(
                        element_id=layout_elem.get("element_id", f"layout_{page_num}_{len(elements)}"),
                        type=element_type,
                        content=layout_elem.get("content", ""),
                        bbox=BoundingBox(
                            x0=bbox_list[0] if len(bbox_list) > 0 else 0,
                            y0=bbox_list[1] if len(bbox_list) > 1 else 0,
                            x1=bbox_list[2] if len(bbox_list) > 2 else 0,
                            y1=bbox_list[3] if len(bbox_list) > 3 else 0
                        )
                    )
                    elements.append(element)

            # Get page dimensions
            ocr_dims = page_data.get("ocr_dimensions", {})
            dimensions = Dimensions(
                width=ocr_dims.get("width", 0),
                height=ocr_dims.get("height", 0)
            )

            pages.append(Page(
                page_number=page_num,
                elements=elements,
                dimensions=dimensions
            ))

        return UnifiedDocument(
            document_id=document_id,
            metadata=metadata,
            pages=pages
        )

    @staticmethod
    def from_direct_extraction(extraction_result: Dict[str, Any],
                              document_id: str,
                              metadata: DocumentMetadata) -> UnifiedDocument:
        """
        Convert PyMuPDF extraction result to UnifiedDocument format.

        This will be implemented when we create the DirectExtractionEngine.
        """
        # TODO: Implement when DirectExtractionEngine is created
        pages = []
        return UnifiedDocument(
            document_id=document_id,
            metadata=metadata,
            pages=pages
        )