import gettext
import logging

import PIL
import PIL.Image
import pyocr
import pyocr.builders

import openpaperwork_core

from ... import sync


LOGGER = logging.getLogger(__name__)
_ = gettext.gettext

ID = "orientation_guesser"


class OrientationTransaction(sync.BaseTransaction):
    def __init__(self, plugin, sync, total_expected=-1):
        super().__init__(plugin.core, total_expected)
        self.priority = plugin.PRIORITY

        self.plugin = plugin
        self.sync = sync

        # for each document, we need to track on which pages we have already
        # guessed the orientation and on which page we didn't yet.
        self.page_tracker = self.core.call_success("page_tracker_get", ID)

    def __enter__(self):
        pass

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.cancel()

    def _guess_page_orientation(self, doc_id, doc_url, page_idx):
        self.notify_progress(
            ID, _("Guessing orientation on document %s page %d") % (
                doc_id, page_idx
            )
        )
        self.plugin.guess_page_orientation_by_url(doc_url, page_idx)

    def _guess_new_page_orientations(self, doc_id):
        doc_url = self.core.call_success("doc_id_to_url", doc_id)

        modified_pages = self.page_tracker.find_changes(doc_id, doc_url)

        for (change, page_idx) in modified_pages:
            # Guess page orientation on new pages, but only if we are
            # not synchronizing with the work directory
            if not self.sync and change == 'new':
                if self.core.call_one(
                            "mainloop_execute", self.core.call_success,
                            "page_has_text_by_url", doc_url, page_idx
                        ):
                    LOGGER.debug(
                        "Document %s page %d has already some text",
                        doc_id, page_idx
                    )
                else:
                    self._guess_page_orientation(doc_id, doc_url, page_idx)
            self.page_tracker.ack_page(doc_id, doc_url, page_idx)

    def add_obj(self, doc_id):
        self._guess_new_page_orientations(doc_id)
        super().add_obj(doc_id)

    def upd_obj(self, doc_id):
        self._guess_new_page_orientations(doc_id)
        super().upd_obj(doc_id)

    def del_obj(self, doc_id):
        self.page_tracker.delete_doc(doc_id)
        super().del_obj(doc_id)

    def cancel(self):
        self.page_tracker.cancel()
        self.notify_done(ID)

    def commit(self):
        self.page_tracker.commit()
        self.notify_done(ID)


class Plugin(openpaperwork_core.PluginBase):
    PRIORITY = 2000

    def get_interfaces(self):
        return [
            "orientation_guesser",
            "syncable",  # actually satisfied by the plugin 'doctracker'
        ]

    def get_deps(self):
        return [
            {
                'interface': 'doc_tracking',
                'defaults': ['paperwork_backend.doctracker']
            },
            {
                'interface': 'ocr_settings',
                'defaults': ['paperwork_backend.pyocr'],
            },
            {
                'interface': 'page_tracking',
                'defaults': ['paperwork_backend.pagetracker'],
            },
            {
                'interface': 'pillow',
                'defaults': [
                    'paperwork_backend.pillow.img',
                    'paperwork_backend.pillow.pdf',
                ],
            },
        ]

    def init(self, core):
        super().init(core)
        self.core.call_all(
            "doc_tracker_register", ID,
            lambda sync, total_expected=-1: OrientationTransaction(
                self, sync, total_expected
            )
        )

    def guess_page_orientation_by_url(self, doc_url, page_idx):
        LOGGER.info(
            "Using OCR to guess orientation of page %d of %s",
            page_idx, doc_url
        )

        doc_id = self.core.call_success("doc_url_to_id", doc_url)

        if doc_id is not None:
            self.core.call_one(
                "mainloop_schedule", self.core.call_all,
                "on_page_modification_start", doc_id, page_idx
            )
        try:
            page_img_url = self.core.call_success(
                "page_get_img_url", doc_url, page_idx
            )

            for ocr_tool in pyocr.get_available_tools():
                LOGGER.info(
                    "Orientation guessing: Will use tool '%s'",
                    ocr_tool.get_name()
                )
                if ocr_tool.can_detect_orientation():
                    break
                LOGGER.warning(
                    "Orientation guessing: Tool '%s' cannot detect"
                    " orientation",
                    ocr_tool.get_name()
                )
            else:
                LOGGER.warning(
                    "Orientation guessing: No tool found able to detect"
                    " orientation"
                )
                return None

            ocr_langs = self.core.call_success("ocr_get_active_langs")

            img = self.core.call_success("url_to_pillow", page_img_url)

            try:
                r = ocr_tool.detect_orientation(img, lang="+".join(ocr_langs))
            except pyocr.PyocrException as exc:
                LOGGER.warning(
                    "Orientation guessing: Failed to guess orientation",
                    exc_info=exc
                )
                return None

            angle = r['angle']
            if angle == 0:
                return 0

            t_angle = {
                90: PIL.Image.ROTATE_90,
                180: PIL.Image.ROTATE_180,
                270: PIL.Image.ROTATE_270,
            }[angle]
            img = img.transpose(t_angle)

            page_img_url = self.core.call_success(
                "page_get_img_url", doc_url, page_idx, write=True
            )
            self.core.call_success("pillow_to_url", img, page_img_url)
        finally:
            if doc_id is not None:
                self.core.call_one(
                    "mainloop_schedule", self.core.call_all,
                    "on_page_modification_end", doc_id, page_idx
                )

        return angle
