"""Vector-PDF composition for a main roster plus a nursery-only strip."""

from __future__ import annotations

from dataclasses import dataclass
from os import PathLike
from pathlib import Path

import fitz  # type: ignore


@dataclass(frozen=True)
class SectionPlacement:
    x: float
    y: float
    scale: float


@dataclass(frozen=True)
class PlacedSection:
    source: fitz.Rect
    destination: fitz.Rect


@dataclass(frozen=True)
class CombinedComposition:
    main: PlacedSection
    nursery: PlacedSection


def useful_content_bounds(page: fitz.Page, padding: float = 1.5) -> fitz.Rect:
    """Find useful table bounds from vector drawings and extracted content.

    Near-full-page rectangles are ignored so a PDF background cannot defeat the
    crop. Subsplash table cells and text remain part of the union.
    """

    page_rect = page.rect
    maximum_background_area = page_rect.get_area() * 0.95
    text_rectangles: list[fitz.Rect] = []
    for block in page.get_text("blocks"):
        if len(block) > 6 and block[6] != 0:
            continue
        rect = fitz.Rect(block[:4]) & page_rect
        if not rect.is_empty and rect.get_area() < maximum_background_area:
            text_rectangles.append(rect)

    text_bounds: fitz.Rect | None = None
    if text_rectangles:
        text_bounds = fitz.Rect(text_rectangles[0])
        for rectangle in text_rectangles[1:]:
            text_bounds.include_rect(rectangle)

    # A clipped PDF form can expose drawing metadata for content outside its
    # visible clip. Anchor drawings to the actual extracted-text rows so hidden
    # table lines cannot expand a nursery strip back to a full page.
    visible_rows = None
    if text_bounds is not None:
        visible_rows = fitz.Rect(
            page_rect.x0,
            max(page_rect.y0, text_bounds.y0 - 8),
            page_rect.x1,
            min(page_rect.y1, text_bounds.y1 + 8),
        )

    drawing_rectangles: list[fitz.Rect] = []
    for drawing in page.get_drawings():
        rect = fitz.Rect(drawing["rect"])
        if rect.width == 0 and rect.height > 0:
            rect.x0 -= 0.35
            rect.x1 += 0.35
        if rect.height == 0 and rect.width > 0:
            rect.y0 -= 0.35
            rect.y1 += 0.35
        rect &= page_rect
        if rect.is_empty or rect.get_area() >= maximum_background_area:
            continue
        if visible_rows is not None and (rect & visible_rows).is_empty:
            continue
        drawing_rectangles.append(rect)

    candidates = text_rectangles + drawing_rectangles

    if not candidates:
        raise ValueError("No table content could be found in the roster PDF.")

    bounds = fitz.Rect(candidates[0])
    for candidate in candidates[1:]:
        bounds.include_rect(candidate)
    if text_bounds is not None:
        bounds.y1 = min(bounds.y1, text_bounds.y1 + 8)
    return fitz.Rect(
        max(page_rect.x0, bounds.x0 - padding),
        max(page_rect.y0, bounds.y0 - padding),
        min(page_rect.x1, bounds.x1 + padding),
        min(page_rect.y1, bounds.y1 + padding),
    )


def _place_section(
    destination_page: fitz.Page,
    source_document: fitz.Document,
    placement: SectionPlacement,
) -> PlacedSection:
    source = useful_content_bounds(source_document[0])
    destination = fitz.Rect(
        placement.x,
        placement.y,
        placement.x + source.width * placement.scale,
        placement.y + source.height * placement.scale,
    )
    destination_page.show_pdf_page(
        destination,
        source_document,
        0,
        clip=source,
        keep_proportion=False,
        overlay=True,
    )
    return PlacedSection(source=source, destination=destination)


def compose_combined_pdf(
    main_pdf: str | PathLike[str],
    nursery_pdf: str | PathLike[str],
    output_pdf: str | PathLike[str],
    *,
    page_width: float,
    page_height: float,
    main_placement: SectionPlacement,
    nursery_placement: SectionPlacement,
    logo_path: str | PathLike[str],
    logo_position: tuple[float, float],
    logo_scale: float,
    month_label: str,
    font_path: str | PathLike[str],
    date_position: tuple[float, float],
    date_font_size: float,
) -> CombinedComposition:
    """Compose both source tables and the shared header into one vector PDF."""

    main_document = fitz.open(main_pdf)
    nursery_document = fitz.open(nursery_pdf)
    output_document = fitz.open()
    try:
        page = output_document.new_page(width=page_width, height=page_height)
        page.draw_rect(page.rect, color=None, fill=(1, 1, 1), overlay=False)

        main_section = _place_section(page, main_document, main_placement)
        nursery_section = _place_section(page, nursery_document, nursery_placement)

        logo_pixmap = fitz.Pixmap(str(Path(logo_path).resolve()))
        logo_width = logo_pixmap.width * logo_scale
        logo_height = logo_pixmap.height * logo_scale
        logo_pixmap = None
        logo_x, logo_y = logo_position
        page.insert_image(
            fitz.Rect(logo_x, logo_y, logo_x + logo_width, logo_y + logo_height),
            filename=str(Path(logo_path).resolve()),
            overlay=True,
        )

        resolved_font = str(Path(font_path).resolve())
        page.insert_font(fontname="custom", fontfile=resolved_font)
        date_x, date_y = date_position
        page.insert_text(
            (date_x, date_y),
            month_label,
            fontname="custom",
            fontsize=date_font_size,
            color=(0, 0, 0),
            overlay=True,
        )

        output_document.save(output_pdf)
        return CombinedComposition(main=main_section, nursery=nursery_section)
    finally:
        output_document.close()
        nursery_document.close()
        main_document.close()