#!/usr/bin/env python3
# -*- coding: utf-8 -*-

# Copyright (C) 2018 Andy Stewart
#
# Author:     Andy Stewart <lazycat.manatee@gmail.com>
# Maintainer: Andy Stewart <lazycat.manatee@gmail.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from PyQt5 import QtCore
from PyQt5.QtCore import Qt, QRect
from PyQt5.QtGui import QColor, QPixmap, QImage, QFont
from PyQt5.QtGui import QPainter
from PyQt5.QtWidgets import QWidget
from core.buffer import Buffer
import fitz
import time

class AppBuffer(Buffer):
    def __init__(self, buffer_id, url, arguments):
        Buffer.__init__(self, buffer_id, url, arguments, False, QColor(0, 0, 0, 255))

        self.add_widget(PdfViewerWidget(url, QColor(0, 0, 0, 255)))
        self.buffer_widget.send_input_message = self.send_input_message

    def handle_input_message(self, result_type, result_content):
        if result_type == "jump_page":
            self.buffer_widget.jump_to_page(int(result_content))
        elif result_type == "jump_percent":
            self.buffer_widget.jump_to_percent(int(result_content))

    def scroll(self, scroll_direction, scroll_type):
        if scroll_type == "page":
            if scroll_direction == "up":
                self.buffer_widget.scroll_up_page()
            else:
                self.buffer_widget.scroll_down_page()
        else:
            if scroll_direction == "up":
                self.buffer_widget.scroll_up()
            else:
                self.buffer_widget.scroll_down()

    def save_session_data(self):
        return "{0}:{1}:{2}".format(self.buffer_widget.scroll_offset, self.buffer_widget.scale, self.buffer_widget.read_mode)

    def restore_session_data(self, session_data):
        (scroll_offset, scale, read_mode) = session_data.split(":")
        self.buffer_widget.scroll_offset = float(scroll_offset)
        self.buffer_widget.scale = float(scale)
        self.buffer_widget.read_mode = read_mode
        self.buffer_widget.update()

    def scroll_up(self):
        self.buffer_widget.scroll_up()

    def scroll_down(self):
        self.buffer_widget.scroll_down()

    def scroll_up_page(self):
        self.buffer_widget.scroll_up_page()

    def scroll_down_page(self):
        self.buffer_widget.scroll_down_page()

    def swtich_to_read_mode(self):
        self.buffer_widget.switch_to_read_mode()

    def scroll_to_home(self):
        self.buffer_widget.scroll_to_home()

    def scroll_to_end(self):
        self.buffer_widget.scroll_to_end()

    def zoom_reset(self):
        self.buffer_widget.zoom_reset()

    def zoom_in(self):
        self.buffer_widget.zoom_in()

    def zoom_out(self):
        self.buffer_widget.zoom_out()

    def jump_to_page(self):
        self.buffer_widget.send_input_message("Jump to: ", "jump_page")

    def jump_to_percent(self):
        self.buffer_widget.send_input_message("Jump to percent: ", "jump_percent")

    def remember_current_position(self):
        self.buffer_widget.remember_current_position()

    def remeber_jump(self):
        self.buffer_widget.remeber_jump()

class PdfViewerWidget(QWidget):

    def __init__(self, url, background_color):
        super(PdfViewerWidget, self).__init__()

        self.url = url
        self.background_color = background_color

        # Load document first.
        self.document = fitz.open(url)

        # Get document's page information.
        self.first_pixmap = self.document.getPagePixmap(0)
        self.page_width = self.first_pixmap.width
        self.page_height = self.first_pixmap.height
        self.page_total_number = self.document.pageCount

        # Init scale and scale mode.
        self.scale = 1.0
        self.read_mode = "fit_to_width"

        # Init scroll attributes.
        self.scroll_step = 20
        self.scroll_offset = 0
        self.mouse_scroll_offset = 20

        # Padding between pages.
        self.page_padding = 10

        # Init font.
        self.page_annotate_height = 22
        self.page_annotate_padding_right = 10
        self.page_annotate_padding_bottom = 10
        self.page_annotate_color = QColor("#333333")
        self.font = QFont()
        self.font.setPointSize(12)

        # Page cache.
        self.page_cache_pixmap_dict = {}
        self.page_cache_scale = self.scale
        self.page_cache_trans = None
        self.page_cache_context_delay = 1000

        self.last_action_time = 0

        self.is_page_just_changed = False

        self.remember_offset = None

    def remember_current_position(self):
        self.remember_offset = self.scroll_offset
        self.message_to_emacs.emit("EAF pdf viewer: remember position.")

    def remember_jump(self):
        if self.remember_offset is None:
            self.message_to_emacs.emit("EAF pdf viewer: no position can jump.")
        else:
            current_scroll_offset = self.scroll_offset
            self.scroll_offset = self.remember_offset
            self.update()

            self.remember_offset = current_scroll_offset

    def get_page_pixmap(self, index, scale):
        # Just return cache pixmap when found match index and scale in cache dict.
        if self.page_cache_scale == scale:
            if index in self.page_cache_pixmap_dict.keys():
                return self.page_cache_pixmap_dict[index]
        # Clear dict if page scale changed.
        else:
            self.page_cache_pixmap_dict.clear()
            self.page_cache_scale = scale
            self.page_cache_trans = fitz.Matrix(scale, scale)

        page = self.document[index]
        trans = self.page_cache_trans if self.page_cache_trans is not None else fitz.Matrix(scale, scale)
        pixmap = page.getPixmap(matrix=trans, alpha=False)
        img = QImage(pixmap.samples, pixmap.width, pixmap.height, pixmap.stride, QImage.Format_RGB888)
        qpixmap = QPixmap.fromImage(img)

        self.page_cache_pixmap_dict[index] = qpixmap

        print("*** New page pixmap: %s %s" % (self.url, index))

        return qpixmap

    def clean_unused_page_cache_pixmap(self):
        # We need expand render index bound that avoid clean cache around current index.
        start_page_index = max(0, self.get_start_page_index() - 1)
        last_page_index = min(self.page_total_number, self.get_last_page_index() + 1)
        index_list = list(range(start_page_index, last_page_index))

        # Try to clean unused cache.
        cache_index_list = list(self.page_cache_pixmap_dict.keys())

        for cache_index in cache_index_list:
            if cache_index not in index_list:
                print("*** Clean unused page pixmap: %s %s" % (self.url, cache_index))
                self.page_cache_pixmap_dict.pop(cache_index)

    def resizeEvent(self, event):
        # Update scale attributes after widget resize.
        self.update_scale()

        QWidget.resizeEvent(self, event)

    def paintEvent(self, event):
        # Init painter.
        painter = QPainter(self)
        painter.save()

        # Draw background.
        painter.setBrush(self.background_color)
        painter.setPen(self.background_color)
        painter.drawRect(0, 0, self.rect().width(), self.rect().height())

        # Get start/last render index.
        start_page_index = self.get_start_page_index()
        last_page_index = self.get_last_page_index()

        # Translate painter at y coordinate.
        translate_y = (start_page_index * self.scale * self.page_height) - self.scroll_offset
        painter.translate(0, translate_y)

        # Render pages in visible area.
        for index in list(range(start_page_index, last_page_index)):
            if index < self.page_total_number:
                # Get page image.
                qpixmap = self.get_page_pixmap(index, self.scale)

                # Init render rect.
                render_width = self.page_width * self.scale
                render_height = self.page_height * self.scale
                render_x = (self.rect().width() - render_width) / 2
                render_y = (index - start_page_index) * self.scale * self.page_height

                # Add padding between pages.
                if (index - start_page_index) > 0:
                    painter.translate(0, self.page_padding)

                # Draw page image.
                painter.drawPixmap(QRect(render_x, render_y, render_width, render_height), qpixmap)

        # Clean unused pixmap cache that avoid use too much memory.
        self.clean_unused_page_cache_pixmap()

        painter.restore()

        # Render current page.
        painter.setFont(self.font)
        painter.setPen(self.page_annotate_color)
        painter.drawText(QRect(self.rect().x(),
                               self.rect().y() + self.rect().height() - self.page_annotate_height - self.page_annotate_padding_bottom,
                               self.rect().width() - self.page_annotate_padding_right,
                               self.page_annotate_height),
                         Qt.AlignRight,
                         "{0}% ({1}/{2})".format(int((start_page_index + 1) * 100 / self.page_total_number), start_page_index + 1, self.page_total_number))

    def build_context_wrap(f):
        def wrapper(*args):
            # Get self instance object.
            self_obj = args[0]

            # Record page before action.
            page_before_action = self_obj.get_start_page_index()

            # Do action.
            ret = f(*args)

            # Record page after action.
            page_after_action = self_obj.get_start_page_index()
            self_obj.is_page_just_changed = (page_before_action != page_after_action)

            # Start build context timer.
            self_obj.last_action_time = time.time()
            QtCore.QTimer().singleShot(self_obj.page_cache_context_delay, self_obj.build_context_cache)

            return ret

        return wrapper

    @build_context_wrap
    def wheelEvent(self, event):
        self.update_scroll_offset(max(min(self.scroll_offset - self.scale * event.angleDelta().y() / 120 * self.mouse_scroll_offset, self.max_scroll_offset()), 0))

    def get_start_page_index(self):
        return int(self.scroll_offset * 1.0 / self.scale / self.page_height)

    def get_last_page_index(self):
        return int((self.scroll_offset + self.rect().height()) * 1.0 / self.scale / self.page_height) + 1

    def build_context_cache(self):
        # Just build context cache when action duration longer than delay
        # Don't build contexnt cache when is_page_just_changed is True, avoid flickr when user change page.
        last_action_duration = (time.time() - self.last_action_time) * 1000
        if last_action_duration > self.page_cache_context_delay and not self.is_page_just_changed:
            start_page_index = max(0, self.get_start_page_index() - 1)
            last_page_index = min(self.page_total_number, self.get_last_page_index() + 1)

            print("*** Try build %s context cache pixmap from %s to %s" % (self.url, start_page_index, last_page_index - 1))
            for index in list(range(start_page_index, last_page_index)):
                self.get_page_pixmap(index, self.scale)

    def scale_to(self, new_scale):
        self.scroll_offset = new_scale * 1.0 / self.scale * self.scroll_offset
        self.scale = new_scale

    def scale_to_width(self):
        self.scale_to(self.rect().width() * 1.0 / self.page_width)

    def scale_to_height(self):
        self.scale_to(self.rect().size().height() * 1.0 / self.page_height)

    def update_scale(self):
        if self.read_mode == "fit_to_width":
            self.scale_to_width()
        elif self.read_mode == "fit_to_height":
            self.scale_to_height()

    def max_scroll_offset(self):
        return self.scale * self.page_height * self.page_total_number - self.rect().height()

    def switch_to_read_mode(self):
        if self.read_mode == "fit_to_customize":
            self.read_mode = "fit_to_width"
        elif self.read_mode == "fit_to_width":
            self.read_mode = "fit_to_height"
        elif self.read_mode == "fit_to_height":
            self.read_mode = "fit_to_width"

        self.update_scale()
        self.update()

    def scroll_up(self):
        self.update_scroll_offset(min(self.scroll_offset + self.scale * self.scroll_step, self.max_scroll_offset()))

    def scroll_down(self):
        self.update_scroll_offset(max(self.scroll_offset - self.scale * self.scroll_step, 0))

    def scroll_up_page(self):
        # Adjust scroll step to make users continue reading fluently.
        self.update_scroll_offset(min(self.scroll_offset + self.rect().height() - self.scroll_step, self.max_scroll_offset()))

    def scroll_down_page(self):
        # Adjust scroll step to make users continue reading fluently.
        self.update_scroll_offset(max(self.scroll_offset - self.rect().height() + self.scroll_step, 0))

    def scroll_to_home(self):
        self.update_scroll_offset(0)

    def scroll_to_end(self):
        self.update_scroll_offset(self.max_scroll_offset())

    def zoom_in(self):
        self.read_mode = "fit_to_customize"
        self.scale_to(min(10, self.scale + 0.2))
        self.update()

    def zoom_out(self):
        self.read_mode = "fit_to_customize"
        self.scale_to(max(1, self.scale - 0.2))
        self.update()

    def zoom_reset(self):
        self.read_mode = "fit_to_width"
        self.update_scale()
        self.update()

    def jump_to_page(self, page_num):
        self.update_scroll_offset(min(max(self.scale * (int(page_num) - 1) * self.page_height, 0), self.max_scroll_offset()))

    def jump_to_percent(self, percent):
        self.update_scroll_offset(min(max(self.scale * (self.page_total_number * self.page_height * percent / 100.0), 0), self.max_scroll_offset()))

    def update_scroll_offset(self, new_offset):
        if self.scroll_offset != new_offset:
            self.scroll_offset = new_offset
            self.update()
        else:
            print("Scroll offset is not change, don't redraw.")

if __name__ == '__main__':
    import sys
    from PyQt5.QtWidgets import QApplication

    app = QApplication(sys.argv)

    w = PdfViewerWidget(sys.argv[1], QColor(0, 0, 0, 255))
    w.resize(1920, 1080)
    w.show()

    sys.exit(app.exec_())