import os
import re
import tempfile
import threading
import time
from typing import Optional, Callable

from PyQt6.QtCore import QRunnable, QThreadPool
from PyQt6.QtWidgets import QWidget, QVBoxLayout, QHBoxLayout, QLineEdit, QCheckBox, QPushButton

from bigtext import BigText
from logFileModel import LogFileModel
from ravenui import RavenUI


class FilterTask(QRunnable):
    aborted = False

    def __init__(
            self,
            source_model: LogFileModel,
            filter_model: LogFileModel,
            regex: re.Pattern,
            lock: threading.RLock,
            filter_match_found_listeners: Callable[[int], None],
            on_before: Callable[[], None],
            on_finish: Callable[[], None]
    ):
        super(FilterTask, self).__init__()
        self.source_model = source_model
        self.filter_model = filter_model
        self.regex = regex
        self.on_before = on_before
        self.on_finish = on_finish
        self.lock = lock
        self.filter_match_found_listeners = filter_match_found_listeners

    def run(self):
        # print("writing to tmp file", self.filter_model.get_file())

        # the lock ensures that we only start a new search when the previous search already ended
        with self.lock:
            # print("starting thread ", threading.currentThread())
            self.on_before()

            for listener in self.filter_match_found_listeners:
                listener(-1, -1)  # notify listeners that a new search started

            try:
                with open(self.source_model.get_file(), "rb") as source:
                    with open(self.filter_model.get_file(), "w+b") as target:
                        line_count = 0
                        lines_written = 0
                        while l := source.readline():
                            line_count = line_count + 1
                            line = l.decode("utf8", errors="ignore")

                            if self.regex.findall(line):
                                # time.sleep(0.5)
                                lines_written = lines_written + 1
                                source_line_offset = source.tell() - len(l)
                                target_line_offset = target.tell()
                                for listener in self.filter_match_found_listeners:
                                    listener(target_line_offset, source_line_offset)
                                target.write(l)

                            # sometime buffering can hide results for a while
                            # We force a flush periodically.
                            if line_count % 10000 == 0 and lines_written > 0:
                                target.flush()
                                lines_written = 0

                            if self.aborted:
                                # print("aborted ", time.time())
                                break
            finally:
                self.on_finish()
                #print("dome thread ", threading.currentThread())


class FilterWidget(QWidget):
    filter_model: LogFileModel
    filter_task: Optional[FilterTask] = None

    def __init__(self, source_model: LogFileModel):
        super(FilterWidget, self).__init__()
        self.source_model = source_model

        self._lock = threading.RLock()

        self.layout = QVBoxLayout(self)
        self.layout.setContentsMargins(0, 0, 0, 0)

        self.query_field = QLineEdit()
        self.query_field.textChanged.connect(self.filter_changed)

        self.btn_cancel_search = QPushButton(self.tr("Cancel"))
        self.btn_cancel_search.setVisible(False)
        self.btn_cancel_search.pressed.connect(self._cancel_search)

        self.ignore_case = QCheckBox(self.tr("ignore case"))
        self.ignore_case.setChecked(True)
        self.ignore_case.stateChanged.connect(self.filter_changed)

        self.is_regex = QCheckBox(self.tr("regex"))
        self.is_regex.setChecked(True)
        self.is_regex.stateChanged.connect(self.filter_changed)

        filter_bar = QWidget()
        filter_bar.layout = QHBoxLayout(filter_bar)
        filter_bar.layout.setContentsMargins(0, 0, 0, 0)
        filter_bar.layout.addWidget(self.query_field)
        filter_bar.layout.addWidget(self.btn_cancel_search)
        filter_bar.layout.addWidget(self.ignore_case)
        filter_bar.layout.addWidget(self.is_regex)

        (handle, self.tmpfilename) = tempfile.mkstemp()
        os.close(handle)
        self.filter_model = LogFileModel(self.tmpfilename, self.source_model.settings)
        self.hits_view = BigText(self.filter_model)

        self.layout.addWidget(filter_bar)
        self.layout.addWidget(self.hits_view)

        self.filter_match_found_listeners: [Callable[[int], None]] = []

    def add_line_click_listener(self, listener: Callable[[int], None]):
        self.hits_view.add_line_click_listener(listener)

    def add_filter_match_found_listener(self, listener: Callable[[int], None]):
        self.filter_match_found_listeners.append(listener)

    def destruct(self):
        # print("cleanup: ", self.tmpfilename)
        os.remove(self.tmpfilename)

    def _cancel_search(self):
        if self.filter_task:
            # print("cancel started ", time.time())
            self.filter_task.aborted = True

    def reset_filter(self):
        self.filter_model.truncate()
        self.source_model.clear_query_highlight()
        self.filter_model.clear_query_highlight()
        RavenUI.update_ui()

    def filter_changed(self):
        query = self.query_field.text()
        ignore_case = self.ignore_case.isChecked()
        is_regex = self.is_regex.isChecked()
        if len(query) == 0:
            self.reset_filter()
            return

        # cancel previous search
        self._cancel_search()

        try:
            flags = re.IGNORECASE if ignore_case else 0
            if is_regex:
                regex = re.compile(query, flags=flags)
            else:
                regex = re.compile(re.escape(query), flags=flags)
        except:
            # query was not a valid regex -> clear search hits, then abort
            self.filter_model.truncate()
            return

        self.source_model.set_query_highlight(query, ignore_case, is_regex)
        self.filter_model.set_query_highlight(query, ignore_case, is_regex)

        self.filter_task = FilterTask(
            self.source_model,
            self.filter_model,
            regex,
            self._lock,
            self.filter_match_found_listeners,
            lambda: self.btn_cancel_search.setVisible(True),
            lambda: self.btn_cancel_search.setVisible(False)
        )
        QThreadPool.globalInstance().start(self.filter_task)