# Authors: see git history
#
# Copyright (c) 2010 Authors
# Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.

import os
import sys
from copy import deepcopy
from random import random

import inkex
from shapely import geometry as shgeo

from .i18n import N_, _
from .svg import (apply_transforms, generate_unique_id,
                  get_correction_transform, get_document, get_node_transform)
from .svg.tags import (CONNECTION_END, CONNECTION_START, CONNECTOR_TYPE,
                       INKSCAPE_LABEL, INKSTITCH_ATTRIBS, SVG_SYMBOL_TAG,
                       SVG_USE_TAG, XLINK_HREF)
from .utils import Point, cache, get_bundled_dir

COMMANDS = {
    # L10N command attached to an object
    "fill_start": N_("Fill stitch starting position"),

    # L10N command attached to an object
    "fill_end": N_("Fill stitch ending position"),

    # L10N command attached to an object
    "satin_start": N_("Auto-route satin stitch starting position"),

    # L10N command attached to an object
    "satin_end": N_("Auto-route satin stitch ending position"),

    # L10N command attached to an object
    "stop": N_("Stop (pause machine) after sewing this object"),

    # L10N command attached to an object
    "trim": N_("Trim thread after sewing this object"),

    # L10N command attached to an object
    "ignore_object": N_("Ignore this object (do not stitch)"),

    # L10N command attached to an object
    "satin_cut_point": N_("Satin cut point (use with Cut Satin Column)"),

    # L10N command that affects a layer
    "ignore_layer": N_("Ignore layer (do not stitch any objects in this layer)"),

    # L10N command that affects entire document
    "origin": N_("Origin for exported embroidery files"),

    # L10N command that affects entire document
    "stop_position": N_("Jump destination for Stop commands (a.k.a. \"Frame Out position\")."),
}

OBJECT_COMMANDS = ["fill_start", "fill_end", "satin_start", "satin_end", "stop", "trim", "ignore_object", "satin_cut_point"]
LAYER_COMMANDS = ["ignore_layer"]
GLOBAL_COMMANDS = ["origin", "stop_position"]


class CommandParseError(Exception):
    pass


class BaseCommand(object):
    @property
    @cache
    def description(self):
        return get_command_description(self.command)

    def parse_symbol(self):
        if self.symbol.tag != SVG_SYMBOL_TAG:
            raise CommandParseError("use points to non-symbol")

        self.command = self.symbol.get('id')

        if self.command.startswith('inkstitch_'):
            self.command = self.command[10:]
        else:
            raise CommandParseError("symbol is not an Ink/Stitch command")

    def get_node_by_url(self, url):
        # url will be #path12345.  Find the corresponding object.
        if url is None:
            raise CommandParseError("url is None")

        if not url.startswith('#'):
            raise CommandParseError("invalid connection url: %s" % url)

        id = url[1:]

        try:
            return self.svg.xpath(".//*[@id='%s']" % id)[0]
        except (IndexError, AttributeError):
            raise CommandParseError("could not find node by url %s" % id)


class Command(BaseCommand):
    def __init__(self, connector):
        self.connector = connector
        self.svg = self.connector.getroottree().getroot()

        self.parse_command()

    def parse_connector_path(self):
        path = inkex.paths.Path(self.connector.get('d')).to_superpath()
        return apply_transforms(path, self.connector)

    def parse_command(self):
        path = self.parse_connector_path()

        neighbors = [
            (self.get_node_by_url(self.connector.get(CONNECTION_START)), path[0][0][1]),
            (self.get_node_by_url(self.connector.get(CONNECTION_END)), path[0][-1][1])
        ]

        if neighbors[0][0].tag != SVG_USE_TAG:
            neighbors.reverse()

        if neighbors[0][0].tag != SVG_USE_TAG:
            raise CommandParseError("connector does not point to a use tag")

        self.use = neighbors[0][0]

        self.symbol = self.get_node_by_url(neighbors[0][0].get(XLINK_HREF))
        self.parse_symbol()

        self.target = neighbors[1][0]
        self.target_point = neighbors[1][1]

    def __repr__(self):
        return "Command('%s', %s)" % (self.command, self.target_point)


class StandaloneCommand(BaseCommand):
    def __init__(self, use):
        self.node = use
        self.svg = self.node.getroottree().getroot()

        self.parse_command()

    def parse_command(self):
        self.symbol = self.get_node_by_url(self.node.get(XLINK_HREF))

        if self.symbol.tag != SVG_SYMBOL_TAG:
            raise CommandParseError("use points to non-symbol")

        self.parse_symbol()

    @property
    @cache
    def point(self):
        pos = [float(self.node.get("x", 0)), float(self.node.get("y", 0))]
        transform = get_node_transform(self.node)
        pos = inkex.transforms.Transform(transform).apply_to_point(pos)

        return Point(*pos)


def get_command_description(command):
    return COMMANDS[command]


def find_commands(node):
    """Find the symbols this node is connected to and return them as Commands"""

    # find all paths that have this object as a connection
    xpath = ".//*[@inkscape:connection-start='#%(id)s' or @inkscape:connection-end='#%(id)s']" % dict(id=node.get('id'))
    connectors = node.getroottree().getroot().xpath(xpath, namespaces=inkex.NSS)

    # try to turn them into commands
    commands = []
    for connector in connectors:
        try:
            commands.append(Command(connector))
        except CommandParseError:
            # Parsing the connector failed, meaning it's not actually an Ink/Stitch command.
            pass

    return commands


def layer_commands(layer, command):
    """Find standalone (unconnected) command symbols in this layer."""

    for global_command in global_commands(layer.getroottree().getroot(), command):
        if layer in global_command.node.iterancestors():
            yield global_command


def global_commands(svg, command):
    """Find standalone (unconnected) command symbols anywhere in the document."""

    for standalone_command in _standalone_commands(svg):
        if standalone_command.command == command:
            yield standalone_command


@cache
def global_command(svg, command):
    """Find a single command of the specified type.

    If more than one is found, print an error and exit.
    """

    commands = list(global_commands(svg, command))

    if len(commands) == 1:
        return commands[0]
    elif len(commands) > 1:
        print(_("Error: there is more than one %(command)s command in the document, but there can only be one.  "
                "Please remove all but one.") % dict(command=command), file=sys.stderr)

        # L10N This is a continuation of the previous error message, letting the user know
        # what command we're talking about since we don't normally expose the actual
        # command name to them.  Contents of %(description)s are in a separate translation
        # string.
        print(_("%(command)s: %(description)s") % dict(command=command, description=_(get_command_description(command))), file=sys.stderr)

        sys.exit(1)
    else:
        return None


def _standalone_commands(svg):
    """Find all unconnected command symbols in the SVG."""

    xpath = ".//svg:use[starts-with(@xlink:href, '#inkstitch_')]"
    symbols = svg.xpath(xpath, namespaces=inkex.NSS)

    for symbol in symbols:
        try:
            yield StandaloneCommand(symbol)
        except CommandParseError:
            pass


def is_command(node):
    return CONNECTION_START in node.attrib or CONNECTION_END in node.attrib


def is_command_symbol(node):
    symbol = None
    xlink = node.get(XLINK_HREF, "")
    if xlink.startswith("#inkstitch_"):
        symbol = node.get(XLINK_HREF)[11:]
    return symbol in COMMANDS


@cache
def symbols_path():
    return os.path.join(get_bundled_dir("symbols"), "inkstitch.svg")


@cache
def symbols_svg():
    with open(symbols_path()) as symbols_file:
        return inkex.load_svg(symbols_file).getroot()


@cache
def symbol_defs():
    return symbols_svg().defs


@cache
def ensure_symbol(svg, command):
    """Make sure the command's symbol definition exists in the <svg:defs> tag."""

    # using @cache really just makes sure that we don't bother ensuring the
    # same symbol is there twice, which would be wasted work

    path = "./*[@id='inkstitch_%s']" % command
    defs = svg.defs
    if defs.find(path) is None:
        defs.append(deepcopy(symbol_defs().find(path)))


def add_group(document, node, command):
    parent = node.getparent()
    group = inkex.Group(attrib={
        "id": generate_unique_id(document, "command_group"),
        INKSCAPE_LABEL: _("Ink/Stitch Command") + ": %s" % get_command_description(command),
        "transform": get_correction_transform(node)
    })
    parent.insert(parent.index(node) + 1, group)
    return group


def add_connector(document, symbol, element):
    # I'd like it if I could position the connector endpoint nicely but inkscape just
    # moves it to the element's center immediately after the extension runs.
    start_pos = (symbol.get('x'), symbol.get('y'))
    end_pos = element.shape.centroid

    # Make sure the element's XML node has an id so that we can reference it.
    if element.node.get('id') is None:
        element.node.set('id', generate_unique_id(document, "object"))

    path = inkex.PathElement(attrib={
        "id": generate_unique_id(document, "command_connector"),
        "d": "M %s,%s %s,%s" % (start_pos[0], start_pos[1], end_pos.x, end_pos.y),
        "style": "stroke:#000000;stroke-width:1px;stroke-opacity:0.5;fill:none;",
        CONNECTION_START: "#%s" % symbol.get('id'),
        CONNECTION_END: "#%s" % element.node.get('id'),
        CONNECTOR_TYPE: "polyline",

        # l10n: the name of the line that connects a command to the object it applies to
        INKSCAPE_LABEL: _("connector")
    })

    symbol.getparent().insert(0, path)


def add_symbol(document, group, command, pos):
    symbol = inkex.Use(attrib={
        "id": generate_unique_id(document, "command_use"),
        XLINK_HREF: "#inkstitch_%s" % command,
        "height": "100%",
        "width": "100%",
        "x": str(pos.x),
        "y": str(pos.y),

        # l10n: the name of a command symbol (example: scissors icon for trim command)
        INKSCAPE_LABEL: _("command marker"),
    })
    group.append(symbol)

    return symbol


def get_command_pos(element, index, total):
    # Put command symbols 30 pixels out from the shape, spaced evenly around it.

    # get a line running 30 pixels out from the shape
    outline = element.shape.buffer(30).exterior

    # find the top center point on the outline and start there
    top_center = shgeo.Point(outline.centroid.x, outline.bounds[1])
    start_position = outline.project(top_center, normalized=True)

    # pick this item's spot around the outline and perturb it a bit to avoid
    # stacking up commands if they add commands multiple times
    position = index / float(total)
    position += random() * 0.05
    position += start_position

    return outline.interpolate(position, normalized=True)


def remove_legacy_param(element, command):
    if command == "trim" or command == "stop":
        # If they had the old "TRIM after" or "STOP after" attributes set,
        # automatically delete them.  The new commands will do the same
        # thing.
        #
        # If we didn't delete these here, then things would get confusing.
        # If the user were to delete a "trim" symbol added by this extension
        # but the "embroider_trim_after" attribute is still set, then the
        # trim would keep happening.

        attribute = "embroider_%s_after" % command

        if attribute in element.node.attrib:
            del element.node.attrib[attribute]

        # Attributes have changed to be namespaced.
        # Let's check for them as well, they might have automatically changed.
        attribute = INKSTITCH_ATTRIBS["%s_after" % command]

        if attribute in element.node.attrib:
            del element.node.attrib[attribute]


def add_commands(element, commands):
    svg = get_document(element.node)

    for i, command in enumerate(commands):
        ensure_symbol(svg, command)
        remove_legacy_param(element, command)

        group = add_group(svg, element.node, command)
        pos = get_command_pos(element, i, len(commands))
        symbol = add_symbol(svg, group, command, pos)
        add_connector(svg, symbol, element)


def add_layer_commands(layer, commands):
    svg = layer.root
    correction_transform = get_correction_transform(layer)

    for i, command in enumerate(commands):
        ensure_symbol(svg, command)
        layer.append(inkex.Use(attrib={
            "id": generate_unique_id(svg, "use"),
            INKSCAPE_LABEL: _("Ink/Stitch Command") + ": %s" % get_command_description(command),
            XLINK_HREF: "#inkstitch_%s" % command,
            "height": "100%",
            "width": "100%",
            "x": str(i * 20),
            "y": "-10",
            "transform": correction_transform
        }))