# Copyright (c) 2011-2022, Manfred Moitzi
# License: MIT License
from __future__ import annotations
from typing import (
    TYPE_CHECKING,
    Iterable,
    Iterator,
    Union,
    cast,
    Optional,
)
import logging

from ezdxf.audit import Auditor, AuditError
from ezdxf.layouts.blocklayout import BlockLayout
from ezdxf.lldxf import const, validator
from ezdxf.lldxf.const import (
    DXFBlockInUseError,
    DXFKeyError,
    DXFStructureError,
    DXFTableEntryError,
)
from ezdxf.entities import (
    Attrib,
    Block,
    BlockRecord,
    EndBlk,
    entity_linker,
    factory,
    is_graphic_entity,
)
from ezdxf.math import UVec, NULLVEC, Vec3
from ezdxf.render.arrows import ARROWS

if TYPE_CHECKING:
    from ezdxf.document import Drawing
    from ezdxf.entities import DXFEntity, DXFTagStorage
    from ezdxf.entitydb import EntityDB
    from ezdxf.lldxf.tagwriter import AbstractTagWriter
    from ezdxf.sections.table import Table

logger = logging.getLogger("ezdxf")


def is_special_block(name: str) -> bool:
    name = name.upper()
    # Anonymous dimension, groups and table blocks do not have explicit
    # references by an INSERT entity:
    if is_anonymous_block(name):
        return True

    # Arrow blocks maybe used in DIMENSION or LEADER override without an
    # INSERT reference:
    if ARROWS.is_ezdxf_arrow(name):
        return True
    if name.startswith("_"):
        if ARROWS.is_acad_arrow(ARROWS.arrow_name(name)):
            return True

    return False


def is_anonymous_block(name: str) -> bool:
    # *U### = anonymous BLOCK, require an explicit INSERT to be in use
    # *E### = anonymous non-uniformly scaled BLOCK, requires INSERT?
    # *X### = anonymous HATCH graphic, requires INSERT?
    # *D### = anonymous DIMENSION graphic, has no explicit INSERT
    # *A### = anonymous GROUP, requires INSERT?
    # *T### = anonymous block for ACAD_TABLE, has no explicit INSERT
    return len(name) > 1 and name[0] == "*" and name[1] in "UEXDAT"


_MISSING_BLOCK_ = Block()


class BlocksSection:
    """
    Manages BLOCK definitions in a dict(), block names are case insensitive
    e.g. 'Test' == 'TEST'.

    """

    def __init__(
        self,
        doc: Optional[Drawing] = None,
        entities: Optional[list[DXFEntity]] = None,
    ):
        self.doc = doc
        if entities is not None:
            self.load(entities)
        self._reconstruct_orphaned_block_records()
        self._anonymous_block_counter = 0

    def __len__(self):
        return len(self.block_records)

    @staticmethod
    def key(entity: Union[str, BlockLayout]) -> str:
        if not isinstance(entity, str):
            entity = entity.name
        return entity.lower()  # block key is lower case

    @property
    def block_records(self) -> Table:
        return self.doc.block_records  # type: ignore

    @property
    def entitydb(self) -> EntityDB:
        return self.doc.entitydb  # type: ignore

    def load(self, entities: list[DXFEntity]) -> None:
        """
        Load DXF entities into BlockLayouts. `entities` is a list of
        entity tags, separated by BLOCK and ENDBLK entities.

        """

        def load_block_record(
            block: Block,
            endblk: EndBlk,
            block_entities: list[DXFEntity],
        ) -> BlockRecord:
            try:
                block_record = cast(
                    "BlockRecord", block_records.get(block.dxf.name)
                )
            # Special case DXF R12 - has no BLOCK_RECORD table
            except DXFTableEntryError:
                block_record = cast(
                    "BlockRecord",
                    block_records.new(block.dxf.name, dxfattribs={"scale": 0}),
                )

            # The BLOCK_RECORD is the central object which stores all the
            # information about a BLOCK and also owns all the entities of
            # this block definition.
            block_record.set_block(block, endblk)
            for entity in block_entities:
                block_record.add_entity(entity)  # type: ignore
            return block_record

        def link_entities() -> Iterable["DXFEntity"]:
            linked = entity_linker()
            for entity in entities:
                # Do not store linked entities (VERTEX, ATTRIB, SEQEND) in
                # the block layout, linked entities ares stored in their
                # parent entity e.g. VERTEX -> POLYLINE:
                if not linked(entity):
                    yield entity

        block_records = self.block_records
        section_head = cast("DXFTagStorage", entities[0])
        if section_head.dxftype() != "SECTION" or section_head.base_class[
            1
        ] != (2, "BLOCKS"):
            raise DXFStructureError(
                "Critical structure error in BLOCKS section."
            )
        # Remove SECTION entity
        del entities[0]
        content: list["DXFEntity"] = []
        block: Block = _MISSING_BLOCK_
        for entity in link_entities():
            if isinstance(entity, Block):
                if block is not _MISSING_BLOCK_:
                    logger.warning("Missing required ENDBLK, ignoring content.")
                block = entity
                content.clear()
            elif isinstance(entity, EndBlk):
                if block is _MISSING_BLOCK_:
                    logger.warning(
                        "Found ENDBLK without a preceding BLOCK, ignoring content."
                    )
                else:
                    block_record = load_block_record(block, entity, content)
                    self.add(block_record)
                    block = _MISSING_BLOCK_
                content.clear()
            else:
                # No check for valid entities here:
                # Use the audit or the recover module to fix invalid DXF files!
                content.append(entity)

    def _reconstruct_orphaned_block_records(self):
        """Find BLOCK_RECORD entries without block definition in the blocks
        section and create block definitions for this orphaned block records.

        """
        for block_record in self.block_records:
            if block_record.block is None:
                block = factory.create_db_entry(
                    "BLOCK",
                    dxfattribs={
                        "name": block_record.dxf.name,
                        "base_point": (0, 0, 0),
                    },
                    doc=self.doc,
                )
                endblk = factory.create_db_entry(
                    "ENDBLK",
                    dxfattribs={},
                    doc=self.doc,
                )
                block_record.set_block(block, endblk)
                self.add(block_record)

    def export_dxf(self, tagwriter: AbstractTagWriter) -> None:
        tagwriter.write_str("  0\nSECTION\n  2\nBLOCKS\n")
        for block_record in self.block_records:
            assert isinstance(block_record, BlockRecord)
            block_record.export_block_definition(tagwriter)
        tagwriter.write_tag2(0, "ENDSEC")

    def add(self, block_record: BlockRecord) -> BlockLayout:
        """Add or replace a block layout object defined by its block record.
        (internal API)
        """
        block_layout = BlockLayout(block_record)
        block_record.block_layout = block_layout
        assert self.block_records.has_entry(block_record.dxf.name)
        return block_layout

    def __iter__(self) -> Iterator[BlockLayout]:
        """Iterable of all :class:`~ezdxf.layouts.BlockLayout` objects."""
        return (
            block_record.block_layout
            for block_record in self.block_records
        )

    def __contains__(self, name: str) -> bool:
        """Returns ``True`` if :class:`~ezdxf.layouts.BlockLayout` `name`
        exist.
        """
        return self.block_records.has_entry(name)

    def __getitem__(self, name: str) -> BlockLayout:
        """Returns :class:`~ezdxf.layouts.BlockLayout` `name`,
        raises :class:`DXFKeyError` if `name` not exist.
        """
        try:
            block_record = cast("BlockRecord", self.block_records.get(name))
            return block_record.block_layout  # type: ignore
        except DXFTableEntryError:
            raise DXFKeyError(name)

    def __delitem__(self, name: str) -> None:
        """Deletes :class:`~ezdxf.layouts.BlockLayout` `name` and all of
        its content, raises :class:`DXFKeyError` if `name` not exist.
        """
        if name in self:
            self.block_records.remove(name)
        else:
            raise DXFKeyError(name)

    def block_names(self) -> list[str]:
        """Returns a list of all block names."""
        return list(self.doc.block_records.entries.keys())  # type: ignore

    def get(self, name: str, default=None) -> BlockLayout:
        """Returns :class:`~ezdxf.layouts.BlockLayout` `name`, returns
        `default` if `name` not exist.
        """
        try:
            return self.__getitem__(name)
        except DXFKeyError:
            return default

    def get_block_layout_by_handle(
        self, block_record_handle: str
    ) -> BlockLayout:
        """Returns a block layout by block record handle. (internal API)"""
        return self.doc.entitydb[block_record_handle].block_layout  # type: ignore

    def new(
        self,
        name: str,
        base_point: UVec = NULLVEC,
        dxfattribs=None,
    ) -> BlockLayout:
        """Create and add a new :class:`~ezdxf.layouts.BlockLayout`, `name`
        is the BLOCK name, `base_point` is the insertion point of the BLOCK.
        """
        assert self.doc is not None
        block_record = cast(BlockRecord, self.doc.block_records.new(name))

        dxfattribs = dxfattribs or {}
        dxfattribs["owner"] = block_record.dxf.handle
        dxfattribs["name"] = name
        dxfattribs["base_point"] = Vec3(base_point)
        head = factory.create_db_entry("BLOCK", dxfattribs, self.doc)
        tail = factory.create_db_entry(
            "ENDBLK", {"owner": block_record.dxf.handle}, doc=self.doc
        )
        block_record.set_block(head, tail)  # type: ignore
        return self.add(block_record)

    def new_anonymous_block(
        self, type_char: str = "U", base_point: UVec = NULLVEC
    ) -> BlockLayout:
        """Create and add a new anonymous :class:`~ezdxf.layouts.BlockLayout`,
        `type_char` is the BLOCK type, `base_point` is the insertion point of
        the BLOCK.

            ========= ==========
            type_char Anonymous Block Type
            ========= ==========
            ``'U'``   ``'*U###'`` anonymous BLOCK
            ``'E'``   ``'*E###'`` anonymous non-uniformly scaled BLOCK
            ``'X'``   ``'*X###'`` anonymous HATCH graphic
            ``'D'``   ``'*D###'`` anonymous DIMENSION graphic
            ``'A'``   ``'*A###'`` anonymous GROUP
            ``'T'``   ``'*T###'`` anonymous block for ACAD_TABLE content
            ========= ==========

        """
        block_name = self.anonymous_block_name(type_char)
        block = self.new(block_name, base_point, {"flags": const.BLK_ANONYMOUS})
        return block

    def anonymous_block_name(self, type_char: str) -> str:
        """Create name for an anonymous block. (internal API)

        Args:
            type_char: letter

                U = *U### anonymous blocks
                E = *E### anonymous non-uniformly scaled blocks
                X = *X### anonymous hatches
                D = *D### anonymous dimensions
                A = *A### anonymous groups
                T = *T### anonymous ACAD_TABLE content

        """
        while True:
            self._anonymous_block_counter += 1
            block_name = f"*{type_char}{self._anonymous_block_counter}"
            if not self.block_records.has_entry(block_name):
                return block_name

    def rename_block(self, old_name: str, new_name: str) -> None:
        """Rename :class:`~ezdxf.layouts.BlockLayout` `old_name` to `new_name`

        .. warning::

            This is a low-level tool and does not rename the block references,
            so all block references to `old_name` are pointing to a non-existing
            block definition!

        """
        block_record = cast(BlockRecord, self.block_records.get(old_name))
        block_record.rename(new_name)
        self.block_records.replace(old_name, block_record)
        self.add(block_record)

    def delete_block(self, name: str, safe: bool = True) -> None:
        """
        Delete block. Checks if the block is still referenced if `safe` is ``True``.

        Args:
            name: block name (case insensitive)
            safe: check if the block is still referenced or a special block without
                  explicit references

        Raises:
            DXFKeyError: if block not exists
            DXFBlockInUseError: if block is still referenced, and safe is ``True``

        """
        if safe:
            if is_special_block(name):
                raise DXFBlockInUseError(
                    f'Special block "{name}" maybe used without explicit INSERT entity.'
                )
            assert self.doc is not None
            block_refs = self.doc.query(
                f"INSERT[name=='{name}']i"
            )  # ignore case
            if len(block_refs):
                raise DXFBlockInUseError(f'Block "{name}" is still in use.')
        self.__delitem__(name)

    def delete_all_blocks(self) -> None:
        """Delete all blocks without references except modelspace- or
        paperspace layout blocks, special arrow- and anonymous blocks
        (DIMENSION, ACAD_TABLE).

        .. warning::

            There could exist references to blocks which are not documented in the DXF
            reference, hidden in extended data sections or application defined data,
            which could invalidate a DXF document if these blocks will be deleted.

        """
        assert self.doc is not None
        active_references = set(
            validator.make_table_key(entity.dxf.name)
            for entity in self.doc.query("INSERT")
        )

        def is_safe(name: str) -> bool:
            if is_special_block(name):
                return False
            return name not in active_references

        trash = set()
        for block in self:
            name = validator.make_table_key(block.name)
            if not block.is_any_layout and is_safe(name):
                trash.add(name)

        for name in trash:
            self.__delitem__(name)

    def audit(self, auditor: Auditor) -> None:
        """Audit and repair BLOCKS section.

        .. important::

            Do not delete entities during the auditing process as this will alter
            the entity database while iterating it, instead use::

                auditor.trash(entity)

            to delete invalid entities after auditing automatically.

        """
        assert self.doc is auditor.doc, "Auditor for different DXF document."

        for block_record in self.block_records:
            assert isinstance(block_record, BlockRecord)
            for entity in block_record.entity_space:
                if not is_graphic_entity(entity):
                    auditor.fixed_error(
                        code=AuditError.REMOVED_INVALID_GRAPHIC_ENTITY,
                        message=f"Removed invalid DXF entity {str(entity)} from"
                        f" BLOCK '{block_record.dxf.name}'.",
                    )
                    auditor.trash(entity)
                elif isinstance(entity, Attrib):
                    # ATTRIB can only exist as an attached entity of the INSERT
                    # entity!
                    auditor.fixed_error(
                        code=AuditError.REMOVED_STANDALONE_ATTRIB_ENTITY,
                        message=f"Removed standalone {str(entity)} entity from"
                        f" BLOCK '{block_record.dxf.name}'.",
                    )
                    auditor.trash(entity)
