"""
Common utility functions for the cable routing system.

This module contains frequently used helper functions for:
- File and path operations
- Environment variable handling
- JSON operations
- DXF file handling
- Dictionary operations
"""

import json
import os
import sys
from pathlib import Path
from typing import Any, Tuple

import ezdxf
from ezdxf.lldxf.const import DXFStructureError


# ============================================================================
# File Operations
# ============================================================================

def check_file_in_work(work_dir, filename) -> Tuple[Path, bool]:
    """
    Check if a file exists, either at the given path or in the work directory.

    Args:
        work_dir: Working directory to check if file not found at filename path (str or Path)
        filename: Path to the file to check (str or Path)

    Returns:
        Tuple of (resolved_path, exists_flag)
        - resolved_path: Path where file was found (or would be)
        - exists_flag: True if file exists, False otherwise
    """
    work_dir = Path(work_dir)
    filename = Path(filename)

    fexists = True
    if not filename.exists():
        mypath = work_dir.joinpath(filename)
        if not mypath.exists():
            fexists = False
    else:
        mypath = filename
    return mypath, fexists


# ============================================================================
# Environment Variable Operations
# ============================================================================

def check_environment_var(env_str: str) -> Path:
    """
    Get and validate an environment variable as a Path.

    Args:
        env_str: Name of the environment variable

    Returns:
        Path object from the environment variable

    Exits:
        Exits the program if the environment variable is not set or empty
    """
    out_path = os.environ.get(env_str)
    if out_path:
        return Path(out_path)
    else:
        print(f"Umgebungsvariable {env_str} ist nicht gesetzt oder leer.")
        exit()


# ============================================================================
# JSON Operations
# ============================================================================

def to_json(d: Any, pretty: bool = True) -> str:
    """
    Convert a Python object to a JSON string.

    Args:
        d: Object to convert to JSON
        pretty: If True, format with indentation for readability

    Returns:
        JSON string representation of the object

    Note:
        Uses ensure_ascii=False to properly display German umlauts (ä, ö, ü)
    """
    return json.dumps(d, indent=2 if pretty else None, ensure_ascii=False, default=str)


def load_json(jsonfilename: str) -> dict:
    """
    Load JSON data from a file.

    Args:
        jsonfilename: Path to the JSON file

    Returns:
        Parsed JSON data as a dictionary
    """
    with open(jsonfilename, encoding='utf-8') as fh:
        return json.load(fh)


def write_results(jsn_results: str, out_dir: Path, filename: str) -> None:
    """
    Write JSON results to a file.

    Args:
        jsn_results: JSON string to write
        out_dir: Output directory path
        filename: Name of the output file
    """
    print("writing results to a json file ...")
    outfile = Path(out_dir) / filename
    with open(outfile, 'w', encoding='utf-8') as fh:
        fh.write(jsn_results)
    print("done")


# ============================================================================
# DXF File Operations
# ============================================================================

def dxf_is_binary(dxf_path: Path) -> bool:
    """
    Check if a DXF file is in binary format.

    Args:
        dxf_path: Path to the DXF file

    Returns:
        True if the file is a binary DXF, False otherwise
    """
    with open(dxf_path, 'rb') as f:
        header = f.read(22)
        return b'AutoCAD Binary DXF' in header


def get_dxf_file(filepath: Path):
    """
    Load a DXF file using ezdxf.

    Args:
        filepath: Path to the DXF file

    Returns:
        ezdxf Drawing object

    Exits:
        Exits with code 1 for I/O errors
        Exits with code 2 for invalid/corrupted DXF files
    """
    try:
        print("reading file ..", end='')
        doc = ezdxf.filemanagement.readfile(filepath)
        print("done")
    except IOError:
        print("Not a DXF file or a generic I/O error.")
        sys.exit(1)
    except DXFStructureError:
        print("Invalid or corrupted DXF file.")
        sys.exit(2)
    return doc


# ============================================================================
# ezdxf Operations (High-Level DXF Helpers)
# ============================================================================

def extract_insert_attributes(insert, error_collector=None) -> dict:
    """
    Extrahiert alle Attribute aus einem INSERT-Block.
    Unterstützt zweistufige Blockstruktur:
    - Äußerer Block enthält LWPOLYLINE und INSERT zu Attribut-Block
    - Innerer Attribut-Block enthält die eigentlichen Attribute

    Args:
        insert: INSERT-Entity des Blocks
        error_collector: Optional ErrorCollector für Warnungen

    Returns:
        Dictionary mit allen gefundenen Attributen {tag: text}
    """
    attributes = {}
    if insert.dxftype() != 'INSERT':
        return attributes

    # Prüfe zuerst ob der Block direkt Attribute hat (alte Struktur)
    direct_attribs = list(insert.attribs)
    if direct_attribs:
        for attrib in direct_attribs:
            tag = attrib.dxf.tag
            value = attrib.dxf.text
            attributes[tag] = value
        return attributes

    # Neue zweistufige Struktur: Suche im Block nach einem INSERT mit Attributen
    # Dies erfordert das doc-Objekt, daher nur wenn verfügbar
    if hasattr(insert, 'doc') and insert.doc:
        try:
            block_layout = insert.doc.blocks.get(insert.dxf.name)
            for entity in block_layout:
                if entity.dxftype() == 'INSERT':
                    inner_attribs = list(entity.attribs)
                    if inner_attribs:
                        # Gefunden: innerer Block mit Attributen
                        for attrib in inner_attribs:
                            tag = attrib.dxf.tag
                            value = attrib.dxf.text
                            attributes[tag] = value
                        break  # Nur das erste INSERT mit Attributen verwenden
        except Exception as e:
            if error_collector:
                error_msg = f"Fehler beim Extrahieren der Attribute aus Block '{insert.dxf.name}': {e}"
                if hasattr(error_collector, 'add_warnings'):
                    error_collector.add_warnings({"attribute_extraction_error": error_msg})

    return attributes


def extract_insert_attributes_with_doc(doc, insert, error_collector=None) -> dict:
    """
    Extrahiert alle Attribute aus einem INSERT-Block mit explizitem doc-Parameter.
    Empfohlen für neue Code, da es zweistufige Blockstrukturen besser unterstützt.

    Args:
        doc: DXF-Dokument
        insert: INSERT-Entity des Blocks
        error_collector: Optional ErrorCollector für Warnungen

    Returns:
        Dictionary mit allen gefundenen Attributen {tag: text}
    """
    attributes = {}
    if insert.dxftype() != 'INSERT':
        return attributes

    # Prüfe zuerst ob der Block direkt Attribute hat (alte Struktur)
    direct_attribs = list(insert.attribs)
    if direct_attribs:
        for attrib in direct_attribs:
            tag = attrib.dxf.tag
            value = attrib.dxf.text
            attributes[tag] = value
        return attributes

    # Neue zweistufige Struktur: Suche im Block nach einem INSERT mit Attributen
    try:
        block_layout = doc.blocks.get(insert.dxf.name)
        for entity in block_layout:
            if entity.dxftype() == 'INSERT':
                inner_attribs = list(entity.attribs)
                if inner_attribs:
                    # Gefunden: innerer Block mit Attributen
                    for attrib in inner_attribs:
                        tag = attrib.dxf.tag
                        value = attrib.dxf.text
                        attributes[tag] = value
                    break  # Nur das erste INSERT mit Attributen verwenden
    except Exception as e:
        if error_collector:
            error_msg = f"Fehler beim Extrahieren der Attribute aus Block '{insert.dxf.name}': {e}"
            if hasattr(error_collector, 'add_warnings'):
                error_collector.add_warnings({"attribute_extraction_error": error_msg})

    return attributes


def ensure_layer_exists(doc, layer_name: str, color: int = None, linetype: str = None,
                       lineweight: int = None, description: str = None):
    """
    Stellt sicher, dass ein Layer existiert und erstellt ihn falls nötig.

    Args:
        doc: DXF-Dokument
        layer_name: Name des Layers
        color: ACI Color Index (1-255), optional
        linetype: Name des Linientyps (z.B. 'CONTINUOUS', 'DASHED'), optional
        lineweight: Linienbreite in mm*100 (z.B. 25 für 0.25mm), optional
        description: Layer-Beschreibung, optional

    Returns:
        Layer-Objekt (existierend oder neu erstellt)
    """
    if layer_name in doc.layers:
        layer = doc.layers.get(layer_name)
    else:
        layer = doc.layers.add(layer_name)

    # Setze optionale Attribute
    if color is not None:
        layer.color = color
    if linetype is not None:
        layer.dxf.linetype = linetype
    if lineweight is not None:
        layer.dxf.lineweight = lineweight
    if description is not None:
        layer.dxf.description = description

    return layer


def add_rectangle_lwpolyline(msp, x: float, y: float, width: float, height: float,
                             layer: str = '0', color: int = None, rgb: tuple = None,
                             closed: bool = True):
    """
    Fügt eine rechteckige LWPOLYLINE hinzu.

    Args:
        msp: Modelspace des DXF-Dokuments
        x: X-Koordinate der unteren linken Ecke
        y: Y-Koordinate der unteren linken Ecke
        width: Breite des Rechtecks
        height: Höhe des Rechtecks
        layer: Layer-Name (default: '0')
        color: ACI Color Index (1-255), optional
        rgb: RGB-Tuple (r, g, b) mit Werten 0-255, optional
        closed: Ob die Polylinie geschlossen sein soll (default: True)

    Returns:
        LWPOLYLINE-Entity
    """
    points = [
        (x, y),
        (x + width, y),
        (x + width, y + height),
        (x, y + height)
    ]

    polyline = msp.add_lwpolyline(points, close=closed)
    polyline.dxf.layer = layer

    if color is not None:
        polyline.dxf.color = color
    if rgb is not None:
        polyline.rgb = rgb

    return polyline


def add_text_with_alignment(msp, text: str, x: float, y: float,
                            height: float = 50, layer: str = '0',
                            color: int = None, halign: int = 0, valign: int = 0,
                            rotation: float = 0.0, style: str = 'Standard'):
    """
    Fügt einen Text mit Ausrichtung hinzu.

    Args:
        msp: Modelspace des DXF-Dokuments
        text: Textinhalt
        x: X-Koordinate
        y: Y-Koordinate
        height: Texthöhe (default: 50)
        layer: Layer-Name (default: '0')
        color: ACI Color Index (1-255), optional
        halign: Horizontale Ausrichtung (0=links, 1=mitte, 2=rechts)
        valign: Vertikale Ausrichtung (0=basis, 1=unten, 2=mitte, 3=oben)
        rotation: Rotation in Grad (default: 0.0)
        style: Textstil-Name (default: 'Standard')

    Returns:
        TEXT-Entity
    """
    text_entity = msp.add_text(text, height=height)
    text_entity.dxf.layer = layer
    text_entity.dxf.style = style
    text_entity.dxf.rotation = rotation

    if color is not None:
        text_entity.dxf.color = color

    # Setze Ausrichtung
    text_entity.set_placement((x, y), align=f"{'LEFT' if halign == 0 else 'CENTER' if halign == 1 else 'RIGHT'}_{'BASELINE' if valign == 0 else 'BOTTOM' if valign == 1 else 'MIDDLE' if valign == 2 else 'TOP'}")

    return text_entity


def extract_attributes_with_positions(insert_iterable, round_decimals: int = 1):
    """
    Wandelt eine Iterable von INSERT-Objekten in zwei Listen um.
    Kompatibilität mit getpositions.py attribs_to_dicts().

    Args:
        insert_iterable: Iterable von INSERT-Entities (z.B. msp oder iterdxf.modelspace())
        round_decimals: Anzahl Nachkommastellen für Positions-Rundung (default: 1)

    Returns:
        Tuple von (all_inserts, all_positions):
        - all_inserts: Liste von Dicts mit Attribut-Tags und deren Textwerten
        - all_positions: Liste von Dicts mit Attribut-Tags und deren (x, y, z)-Positionen

    Note:
        Blöcke ohne Attribute werden übersprungen.
        Diese Funktion ist kompatibel mit der alten attribs_to_dicts() aus getpositions.py
    """
    all_inserts = []
    all_positions = []

    for insert in insert_iterable:
        if insert.dxftype() != 'INSERT':
            continue

        itemdata = {}
        positions = {}

        # Direkte Attribute (alte Struktur)
        for attrib in insert.attribs:
            if len(insert.attribs) == 0:
                continue  # Überspringe Blöcke ohne Attribute
            attr_tag = attrib.dxf.tag
            attr_text = attrib.dxf.text
            pos = attrib.dxf.insert
            itemdata[attr_tag] = attr_text
            positions[attr_tag] = (
                round(pos.x, round_decimals),
                round(pos.y, round_decimals),
                round(pos.z, round_decimals)
            )

        if len(itemdata) > 0:
            all_inserts.append(itemdata)
            all_positions.append(positions)

    return all_inserts, all_positions


def add_blockref_with_attributes(msp, block_name: str, insert_point: tuple,
                                 attributes: dict = None, layer: str = '0',
                                 scale: float = 1.0, rotation: float = 0.0):
    """
    Fügt eine Block-Referenz (INSERT) mit Attributen hinzu.

    Args:
        msp: Modelspace des DXF-Dokuments
        block_name: Name des Blocks
        insert_point: Einfügepunkt als (x, y) oder (x, y, z) Tuple
        attributes: Dictionary mit Attribut-Namen und -Werten (optional)
        layer: Layer-Name (default: '0')
        scale: Skalierungsfaktor (default: 1.0)
        rotation: Rotation in Grad (default: 0.0)

    Returns:
        INSERT-Entity mit gesetzten Attributen
    """
    # Füge Block-Referenz hinzu
    blockref = msp.add_blockref(block_name, insert_point)
    blockref.dxf.layer = layer

    if scale != 1.0:
        blockref.dxf.xscale = scale
        blockref.dxf.yscale = scale
        blockref.dxf.zscale = scale

    if rotation != 0.0:
        blockref.dxf.rotation = rotation

    # Füge Attribute hinzu falls vorhanden
    if attributes:
        blockref.add_auto_attribs(attributes)

    return blockref


def query_entities_by_layer(msp, entity_type: str = None, layers: list = None,
                            exclude_layers: list = None):
    """
    Filtert Entities nach Typ und Layer.

    Args:
        msp: Modelspace des DXF-Dokuments
        entity_type: Entity-Typ (z.B. 'INSERT', 'LINE', 'TEXT'), None für alle
        layers: Liste der zu inkludierenden Layer (None = alle außer exclude_layers)
        exclude_layers: Liste der zu exkludierenden Layer (None = keine Exklusion)

    Returns:
        Liste der gefilterten Entities

    Examples:
        # Alle INSERTs auf Layer 'ILS_MOTOR'
        query_entities_by_layer(msp, 'INSERT', layers=['ILS_MOTOR'])

        # Alle Entities außer auf Layer '0'
        query_entities_by_layer(msp, exclude_layers=['0'])

        # Alle LINEs auf ILS_* Layern (manuelles Filtern nötig)
        all_lines = query_entities_by_layer(msp, 'LINE')
        ils_lines = [e for e in all_lines if e.dxf.layer.startswith('ILS_')]
    """
    # Baue Query-String
    if entity_type:
        entities = msp.query(entity_type)
    else:
        entities = msp

    # Filtere nach Layern
    result = []
    for entity in entities:
        layer = entity.dxf.layer

        # Prüfe Exklusion
        if exclude_layers and layer in exclude_layers:
            continue

        # Prüfe Inklusion
        if layers is None or layer in layers:
            result.append(entity)

    return result


def create_layers_from_config(doc, layer_definitions: dict):
    """
    Erstellt mehrere Layer aus einer Konfiguration.

    Args:
        doc: DXF-Dokument
        layer_definitions: Dictionary mit Layer-Definitionen
            Format: {
                'layer_name': {
                    'color': int (optional),
                    'linetype': str (optional),
                    'lineweight': int (optional),
                    'description': str (optional)
                },
                ...
            }

    Example:
        layer_config = {
            'ILS_MOTOR': {'color': 1, 'description': 'Motor layer'},
            'ILS_SENSOR': {'color': 3, 'lineweight': 25},
            'ILS_CABLE': {'color': 5, 'linetype': 'DASHED'}
        }
        create_layers_from_config(doc, layer_config)
    """
    for layer_name, props in layer_definitions.items():
        ensure_layer_exists(
            doc,
            layer_name,
            color=props.get('color'),
            linetype=props.get('linetype'),
            lineweight=props.get('lineweight'),
            description=props.get('description')
        )


# ============================================================================
# Dictionary Operations
# ============================================================================

def merge_two_dicts(x: dict, y: dict) -> dict:
    """
    Merge two dictionaries, with values from y overwriting those in x.

    Args:
        x: First dictionary (base)
        y: Second dictionary (override values)

    Returns:
        New dictionary with merged values
    """
    z = x.copy()
    z.update(y)
    return z