layout.py

from abc import ABC, abstractmethod
from itertools import islice
from operator import itemgetter
from threading import RLock
from typing import (
    TYPE_CHECKING,
    Dict,
    Iterable,
    List,
    NamedTuple,
    Optional,
    Sequence,
    Tuple,
    Union,
)

from ._ratio import ratio_resolve
from .align import Align
from .console import Console, ConsoleOptions, RenderableType, RenderResult
from .highlighter import ReprHighlighter
from .panel import Panel
from .pretty import Pretty
from .repr import rich_repr, Result
from .region import Region
from .segment import Segment
from .style import StyleType

if TYPE_CHECKING:
    from rich.tree import Tree


class LayoutRender(NamedTuple):
    """An individual layout render."""

    region: Region
    render: List[List[Segment]]


RegionMap = Dict["Layout", Region]
RenderMap = Dict["Layout", LayoutRender]


class LayoutError(Exception):
    """Layout related error."""


class NoSplitter(LayoutError):
    """Requested splitter does not exist."""


class _Placeholder:
    """An internal renderable used as a Layout placeholder."""

    highlighter = ReprHighlighter()

    def __init__(self, layout: "Layout", style: StyleType = "") -> None:
        self.layout = layout
        self.style = style

    def __rich_console__(
        self, console: Console, options: ConsoleOptions
    ) -> RenderResult:
        width = options.max_width
        height = options.height or options.size.height
        layout = self.layout
        title = (
            f"{layout.name!r} ({width} x {height})"
            if layout.name
            else f"({width} x {height})"
        )
        yield Panel(
            Align.center(Pretty(layout), vertical="middle"),
            style=self.style,
            title=self.highlighter(title),
            border_style="blue",
            height=height,
        )


class Splitter(ABC):
    """Base class for a splitter."""

    name: str = ""

    @abstractmethod
    def get_tree_icon(self) -> str:
        """Get the icon (emoji) used in layout.tree"""

    @abstractmethod
    def divide(
        self, children: Sequence["Layout"], region: Region
    ) -> Iterable[Tuple["Layout", Region]]:
        """Divide a region amongst several child layouts.

        Args:
            children (Sequence(Layout)): A number of child layouts.
            region (Region): A rectangular region to divide.
        """


class RowSplitter(Splitter):
    """Split a layout region in to rows."""

    name = "row"

    def get_tree_icon(self) -> str:
        return "[layout.tree.row]⬌"

    def divide(
        self, children: Sequence["Layout"], region: Region
    ) -> Iterable[Tuple["Layout", Region]]:
        x, y, width, height = region
        render_widths = ratio_resolve(width, children)
        offset = 0
        _Region = Region
        for child, child_width in zip(children, render_widths):
            yield child, _Region(x + offset, y, child_width, height)
            offset += child_width


class ColumnSplitter(Splitter):
    """Split a layout region in to columns."""

    name = "column"

    def get_tree_icon(self) -> str:
        return "[layout.tree.column]⬍"

    def divide(
        self, children: Sequence["Layout"], region: Region
    ) -> Iterable[Tuple["Layout", Region]]:
        x, y, width, height = region
        render_heights = ratio_resolve(height, children)
        offset = 0
        _Region = Region
        for child, child_height in zip(children, render_heights):
            yield child, _Region(x, y + offset, width, child_height)
            offset += child_height


@rich_repr
class Layout:
    """A renderable to divide a fixed height in to rows or columns.

    Args:
        renderable (RenderableType, optional): Renderable content, or None for placeholder. Defaults to None.
        name (str, optional): Optional identifier for Layout. Defaults to None.
        size (int, optional): Optional fixed size of layout. Defaults to None.
        minimum_size (int, optional): Minimum size of layout. Defaults to 1.
        ratio (int, optional): Optional ratio for flexible layout. Defaults to 1.
        visible (bool, optional): Visibility of layout. Defaults to True.
    """

    splitters = {"row": RowSplitter, "column": ColumnSplitter}

    def __init__(
        self,
        renderable: Optional[RenderableType] = None,
        *,
        name: Optional[str] = None,
        size: Optional[int] = None,
        minimum_size: int = 1,
        ratio: int = 1,
        visible: bool = True,
        height: Optional[int] = None,
    ) -> None:
        self._renderable = renderable or _Placeholder(self)
        self.size = size
        self.minimum_size = minimum_size
        self.ratio = ratio
        self.name = name
        self.visible = visible
        self.height = height
        self.splitter: Splitter = self.splitters["column"]()
        self._children: List[Layout] = []
        self._render_map: RenderMap = {}
        self._lock = RLock()

    def __rich_repr__(self) -> Result:
        yield "name", self.name, None
        yield "size", self.size, None
        yield "minimum_size", self.minimum_size, 1
        yield "ratio", self.ratio, 1

    @property
    def renderable(self) -> RenderableType:
        """Layout renderable."""
        return self if self._children else self._renderable

    @property
    def children(self) -> List["Layout"]:
        """Gets (visible) layout children."""
        return [child for child in self._children if child.visible]

    @property
    def map(self) -> RenderMap:
        """Get a map of the last render."""
        return self._render_map

    def get(self, name: str) -> Optional["Layout"]:
        """Get a named layout, or None if it doesn't exist.

        Args:
            name (str): Name of layout.

        Returns:
            Optional[Layout]: Layout instance or None if no layout was found.
        """
        if self.name == name:
            return self
        else:
            for child in self._children:
                named_layout = child.get(name)
                if named_layout is not None:
                    return named_layout
        return None

    def __getitem__(self, name: str) -> "Layout":
        layout = self.get(name)
        if layout is None:
            raise KeyError(f"No layout with name {name!r}")
        return layout

    @property
    def tree(self) -> "Tree":
        """Get a tree renderable to show layout structure."""
        from rich.styled import Styled
        from rich.table import Table
        from rich.tree import Tree

        def summary(layout: "Layout") -> Table:

            icon = layout.splitter.get_tree_icon()

            table = Table.grid(padding=(0, 1, 0, 0))

            text: RenderableType = (
                Pretty(layout) if layout.visible else Styled(Pretty(layout), "dim")
            )
            table.add_row(icon, text)
            _summary = table
            return _summary

        layout = self
        tree = Tree(
            summary(layout),
            guide_style=f"layout.tree.{layout.splitter.name}",
            highlight=True,
        )

        def recurse(tree: "Tree", layout: "Layout") -> None:
            for child in layout._children:
                recurse(
                    tree.add(
                        summary(child),
                        guide_style=f"layout.tree.{child.splitter.name}",
                    ),
                    child,
                )

        recurse(tree, self)
        return tree

    def split(
        self,
        *layouts: Union["Layout", RenderableType],
        splitter: Union[Splitter, str] = "column",
    ) -> None:
        """Split the layout in to multiple sub-layouts.

        Args:
            *layouts (Layout): Positional arguments should be (sub) Layout instances.
            splitter (Union[Splitter, str]): Splitter instance or name of splitter.
        """
        _layouts = [
            layout if isinstance(layout, Layout) else Layout(layout)
            for layout in layouts
        ]
        try:
            self.splitter = (
                splitter
                if isinstance(splitter, Splitter)
                else self.splitters[splitter]()
            )
        except KeyError:
            raise NoSplitter(f"No splitter called {splitter!r}")
        self._children[:] = _layouts

    def add_split(self, *layouts: Union["Layout", RenderableType]) -> None:
        """Add a new layout(s) to existing split.

        Args:
            *layouts (Union[Layout, RenderableType]): Positional arguments should be renderables or (sub) Layout instances.

        """
        _layouts = (
            layout if isinstance(layout, Layout) else Layout(layout)
            for layout in layouts
        )
        self._children.extend(_layouts)

    def split_row(self, *layouts: Union["Layout", RenderableType]) -> None:
        """Split the layout in tow a row (Layouts side by side).

        Args:
            *layouts (Layout): Positional arguments should be (sub) Layout instances.
        """
        self.split(*layouts, splitter="row")

    def split_column(self, *layouts: Union["Layout", RenderableType]) -> None:
        """Split the layout in to a column (layouts stacked on top of each other).

        Args:
            *layouts (Layout): Positional arguments should be (sub) Layout instances.
        """
        self.split(*layouts, splitter="column")

    def unsplit(self) -> None:
        """Reset splits to initial state."""
        del self._children[:]

    def update(self, renderable: RenderableType) -> None:
        """Update renderable.

        Args:
            renderable (RenderableType): New renderable object.
        """
        with self._lock:
            self._renderable = renderable

    def refresh_screen(self, console: "Console", layout_name: str) -> None:
        """Refresh a sub-layout.

        Args:
            console (Console): Console instance where Layout is to be rendered.
            layout_name (str): Name of layout.
        """
        with self._lock:
            layout = self[layout_name]
            region, _lines = self._render_map[layout]
            (x, y, width, height) = region
            lines = console.render_lines(
                layout, console.options.update_dimensions(width, height)
            )
            self._render_map[layout] = LayoutRender(region, lines)
            console.update_screen_lines(lines, x, y)

    def _make_region_map(self, width: int, height: int) -> RegionMap:
        """Create a dict that maps layout on to Region."""
        stack: List[Tuple[Layout, Region]] = [(self, Region(0, 0, width, height))]
        push = stack.append
        pop = stack.pop
        layout_regions: List[Tuple[Layout, Region]] = []
        append_layout_region = layout_regions.append
        while stack:
            append_layout_region(pop())
            layout, region = layout_regions[-1]
            children = layout.children
            if children:
                for child_and_region in layout.splitter.divide(children, region):
                    push(child_and_region)

        region_map = {
            layout: region
            for layout, region in sorted(layout_regions, key=itemgetter(1))
        }
        return region_map

    def render(self, console: Console, options: ConsoleOptions) -> RenderMap:
        """Render the sub_layouts.

        Args:
            console (Console): Console instance.
            options (ConsoleOptions): Console options.

        Returns:
            RenderMap: A dict that maps Layout on to a tuple of Region, lines
        """
        render_width = options.max_width
        render_height = options.height or console.height
        region_map = self._make_region_map(render_width, render_height)
        layout_regions = [
            (layout, region)
            for layout, region in region_map.items()
            if not layout.children
        ]
        render_map: Dict["Layout", "LayoutRender"] = {}
        render_lines = console.render_lines
        update_dimensions = options.update_dimensions

        for layout, region in layout_regions:
            lines = render_lines(
                layout.renderable, update_dimensions(region.width, region.height)
            )
            render_map[layout] = LayoutRender(region, lines)
        return render_map

    def __rich_console__(
        self, console: Console, options: ConsoleOptions
    ) -> RenderResult:
        with self._lock:
            width = options.max_width or console.width
            height = options.height or console.height
            render_map = self.render(console, options.update_dimensions(width, height))
            self._render_map = render_map
            layout_lines: List[List[Segment]] = [[] for _ in range(height)]
            _islice = islice
            for (region, lines) in render_map.values():
                _x, y, _layout_width, layout_height = region
                for row, line in zip(
                    _islice(layout_lines, y, y + layout_height), lines
                ):
                    row.extend(line)

            new_line = Segment.line()
            for layout_row in layout_lines:
                yield from layout_row
                yield new_line


if __name__ == "__main__":
    from rich.console import Console

    console = Console()
    layout = Layout()

    layout.split_column(
        Layout(name="header", size=3),
        Layout(ratio=1, name="main"),
        Layout(size=10, name="footer"),
    )

    layout["main"].split_row(Layout(name="side"), Layout(name="body", ratio=2))

    layout["body"].split_row(Layout(name="content", ratio=2), Layout(name="s2"))

    layout["s2"].split_column(
        Layout(name="top"), Layout(name="middle"), Layout(name="bottom")
    )

    layout["side"].split_column(Layout(layout.tree, name="left1"), Layout(name="left2"))

    layout["content"].update("foo")

    console.print(layout)