# flake8: noqa
from __future__ import absolute_import, division, unicode_literals
import sys
import re
from argparse import ArgumentParser
from functools import partial

from cola import app  # prints a message if Qt cannot be found
from qtpy import QtCore
from qtpy import QtGui
from qtpy import QtWidgets
from qtpy.QtCore import Qt
from qtpy.QtCore import Signal

# pylint: disable=ungrouped-imports
from cola import core
from cola import difftool
from cola import hotkeys
from cola import icons
from cola import observable
from cola import qtutils
from cola import utils
from cola.i18n import N_
from cola.models import dag
from cola.models import prefs
from cola.widgets import defs
from cola.widgets import filelist
from cola.widgets import diff
from cola.widgets import standard
from cola.widgets import text


PICK = 'pick'
REWORD = 'reword'
EDIT = 'edit'
FIXUP = 'fixup'
SQUASH = 'squash'
EXEC = 'exec'
COMMANDS = (
    PICK,
    REWORD,
    EDIT,
    FIXUP,
    SQUASH,
)
COMMAND_IDX = dict([(cmd_, idx_) for idx_, cmd_ in enumerate(COMMANDS)])
ABBREV = {
    'p': PICK,
    'r': REWORD,
    'e': EDIT,
    'f': FIXUP,
    's': SQUASH,
    'x': EXEC,
}


def main():
    """Start a git-cola-sequence-editor session"""
    args = parse_args()
    context = app.application_init(args)
    view = new_window(context, args.filename)
    app.application_run(context, view, start=view.start, stop=stop)
    return view.status


def winmain():
    """Windows git-cola-sequence-editor entrypoint"""
    return app.winmain(main)


def stop(_context, _view):
    """All done, cleanup"""
    QtCore.QThreadPool.globalInstance().waitForDone()


def parse_args():
    parser = ArgumentParser()
    parser.add_argument(
        'filename', metavar='<filename>', help='git-rebase-todo file to edit'
    )
    app.add_common_arguments(parser)
    return parser.parse_args()


def new_window(context, filename):
    window = MainWindow(context)
    editor = Editor(context, filename, parent=window)
    window.set_editor(editor)
    return window


def unabbrev(cmd):
    """Expand shorthand commands into their full name"""
    return ABBREV.get(cmd, cmd)


class MainWindow(standard.MainWindow):
    """The main git-cola application window"""

    def __init__(self, context, parent=None):
        super(MainWindow, self).__init__(parent)
        self.context = context
        self.status = 1
        self.editor = None
        default_title = '%s - git cola seqeuence editor' % core.getcwd()
        title = core.getenv('GIT_COLA_SEQ_EDITOR_TITLE', default_title)
        self.setWindowTitle(title)

        self.show_help_action = qtutils.add_action(
            self, N_('Show Help'), partial(show_help, context), hotkeys.QUESTION
        )

        self.menubar = QtWidgets.QMenuBar(self)
        self.help_menu = self.menubar.addMenu(N_('Help'))
        self.help_menu.addAction(self.show_help_action)
        self.setMenuBar(self.menubar)

        qtutils.add_close_action(self)
        self.init_state(context.settings, self.init_window_size)

    def init_window_size(self):
        """Set the window size on the first initial view"""
        context = self.context
        if utils.is_darwin():
            desktop = context.app.desktop()
            self.resize(desktop.width(), desktop.height())
        else:
            self.showMaximized()

    def set_editor(self, editor):
        self.editor = editor
        self.setCentralWidget(editor)
        editor.exit.connect(self.exit)
        editor.setFocus()

    def start(self, _context, _view):
        self.editor.start()

    def exit(self, status):
        self.status = status
        self.close()


class Editor(QtWidgets.QWidget):
    exit = Signal(int)

    def __init__(self, context, filename, parent=None):
        super(Editor, self).__init__(parent)

        self.widget_version = 1
        self.status = 1
        self.context = context
        self.filename = filename
        self.comment_char = comment_char = prefs.comment_char(context)
        self.cancel_action = core.getenv('GIT_COLA_SEQ_EDITOR_CANCEL_ACTION', 'abort')

        self.notifier = notifier = observable.Observable()
        self.diff = diff.DiffWidget(context, notifier, self)
        self.tree = RebaseTreeWidget(context, notifier, comment_char, self)
        self.filewidget = filelist.FileWidget(context, notifier, self)
        self.setFocusProxy(self.tree)

        self.rebase_button = qtutils.create_button(
            text=core.getenv('GIT_COLA_SEQ_EDITOR_ACTION', N_('Rebase')),
            tooltip=N_('Accept changes and rebase\n' 'Shortcut: Ctrl+Enter'),
            icon=icons.ok(),
            default=True,
        )

        self.extdiff_button = qtutils.create_button(
            text=N_('Launch Diff Tool'),
            tooltip=N_('Launch external diff tool\n' 'Shortcut: Ctrl+D'),
        )
        self.extdiff_button.setEnabled(False)

        self.help_button = qtutils.create_button(
            text=N_('Help'), tooltip=N_('Show help\nShortcut: ?'), icon=icons.question()
        )

        self.cancel_button = qtutils.create_button(
            text=N_('Cancel'),
            tooltip=N_('Cancel rebase\nShortcut: Ctrl+Q'),
            icon=icons.close(),
        )

        top = qtutils.splitter(Qt.Horizontal, self.tree, self.filewidget)
        top.setSizes([75, 25])

        main_split = qtutils.splitter(Qt.Vertical, top, self.diff)
        main_split.setSizes([25, 75])

        controls_layout = qtutils.hbox(
            defs.no_margin,
            defs.button_spacing,
            self.cancel_button,
            qtutils.STRETCH,
            self.help_button,
            self.extdiff_button,
            self.rebase_button,
        )
        layout = qtutils.vbox(defs.no_margin, defs.spacing, main_split, controls_layout)
        self.setLayout(layout)

        self.action_rebase = qtutils.add_action(
            self, N_('Rebase'), self.rebase, hotkeys.CTRL_RETURN, hotkeys.CTRL_ENTER
        )

        notifier.add_observer(diff.COMMITS_SELECTED, self.commits_selected)
        self.tree.external_diff.connect(self.external_diff)

        qtutils.connect_button(self.rebase_button, self.rebase)
        qtutils.connect_button(self.extdiff_button, self.external_diff)
        qtutils.connect_button(self.help_button, partial(show_help, context))
        qtutils.connect_button(self.cancel_button, self.cancel)

    def start(self):
        insns = core.read(self.filename)
        self.parse_sequencer_instructions(insns)

    # notifier callbacks
    def commits_selected(self, commits):
        self.extdiff_button.setEnabled(bool(commits))

    # helpers
    def parse_sequencer_instructions(self, insns):
        idx = 1
        re_comment_char = re.escape(self.comment_char)
        exec_rgx = re.compile(r'^\s*(%s)?\s*(x|exec)\s+(.+)$' % re_comment_char)
        # The upper bound of 40 below must match git.OID_LENGTH.
        # We'll have to update this to the new hash length when that happens.
        pick_rgx = re.compile(
            (
                r'^\s*(%s)?\s*'
                r'(p|pick|r|reword|e|edit|f|fixup|s|squash)'
                r'\s+([0-9a-f]{7,40})'
                r'\s+(.+)$'
            )
            % re_comment_char
        )
        for line in insns.splitlines():
            match = pick_rgx.match(line)
            if match:
                enabled = match.group(1) is None
                command = unabbrev(match.group(2))
                oid = match.group(3)
                summary = match.group(4)
                self.tree.add_item(idx, enabled, command, oid=oid, summary=summary)
                idx += 1
                continue
            match = exec_rgx.match(line)
            if match:
                enabled = match.group(1) is None
                command = unabbrev(match.group(2))
                cmdexec = match.group(3)
                self.tree.add_item(idx, enabled, command, cmdexec=cmdexec)
                idx += 1
                continue

        self.tree.decorate(self.tree.items())
        self.tree.refit()
        self.tree.select_first()

    # actions
    def cancel(self):
        if self.cancel_action == 'save':
            status = self.save('')
        else:
            status = 1

        self.status = status
        self.exit.emit(status)

    def rebase(self):
        lines = [item.value() for item in self.tree.items()]
        sequencer_instructions = '\n'.join(lines) + '\n'
        status = self.save(sequencer_instructions)
        self.status = status
        self.exit.emit(status)

    def save(self, string):
        """Save the instruction sheet"""
        try:
            core.write(self.filename, string)
            status = 0
        except (OSError, IOError, ValueError) as e:
            msg, details = utils.format_exception(e)
            sys.stderr.write(msg + '\n\n' + details)
            status = 128
        return status

    def external_diff(self):
        items = self.tree.selected_items()
        if not items:
            return
        item = items[0]
        difftool.diff_expression(self.context, self, item.oid + '^!', hide_expr=True)


# pylint: disable=too-many-ancestors
class RebaseTreeWidget(standard.DraggableTreeWidget):
    external_diff = Signal()
    move_rows = Signal(object, object)

    def __init__(self, context, notifier, comment_char, parent=None):
        super(RebaseTreeWidget, self).__init__(parent=parent)
        self.context = context
        self.notifier = notifier
        self.comment_char = comment_char
        # header
        self.setHeaderLabels(
            [
                N_('#'),
                N_('Enabled'),
                N_('Command'),
                N_('SHA-1'),
                N_('Summary'),
            ]
        )
        self.header().setStretchLastSection(True)
        self.setColumnCount(5)

        # actions
        self.copy_oid_action = qtutils.add_action(
            self, N_('Copy SHA-1'), self.copy_oid, QtGui.QKeySequence.Copy
        )

        self.external_diff_action = qtutils.add_action(
            self, N_('Launch Diff Tool'), self.external_diff.emit, hotkeys.DIFF
        )

        self.toggle_enabled_action = qtutils.add_action(
            self, N_('Toggle Enabled'), self.toggle_enabled, hotkeys.PRIMARY_ACTION
        )

        self.action_pick = qtutils.add_action(
            self, N_('Pick'), lambda: self.set_selected_to(PICK), *hotkeys.REBASE_PICK
        )

        self.action_reword = qtutils.add_action(
            self,
            N_('Reword'),
            lambda: self.set_selected_to(REWORD),
            *hotkeys.REBASE_REWORD
        )

        self.action_edit = qtutils.add_action(
            self, N_('Edit'), lambda: self.set_selected_to(EDIT), *hotkeys.REBASE_EDIT
        )

        self.action_fixup = qtutils.add_action(
            self,
            N_('Fixup'),
            lambda: self.set_selected_to(FIXUP),
            *hotkeys.REBASE_FIXUP
        )

        self.action_squash = qtutils.add_action(
            self,
            N_('Squash'),
            lambda: self.set_selected_to(SQUASH),
            *hotkeys.REBASE_SQUASH
        )

        self.action_shift_down = qtutils.add_action(
            self, N_('Shift Down'), self.shift_down, hotkeys.MOVE_DOWN_TERTIARY
        )

        self.action_shift_up = qtutils.add_action(
            self, N_('Shift Up'), self.shift_up, hotkeys.MOVE_UP_TERTIARY
        )

        # pylint: disable=no-member
        self.itemChanged.connect(self.item_changed)
        self.itemSelectionChanged.connect(self.selection_changed)
        self.move_rows.connect(self.move)
        self.items_moved.connect(self.decorate)

    def add_item(self, idx, enabled, command, oid='', summary='', cmdexec=''):
        comment_char = self.comment_char
        item = RebaseTreeWidgetItem(
            idx,
            enabled,
            command,
            oid=oid,
            summary=summary,
            cmdexec=cmdexec,
            comment_char=comment_char,
        )
        self.invisibleRootItem().addChild(item)

    def decorate(self, items):
        for item in items:
            item.decorate(self)

    def refit(self):
        self.resizeColumnToContents(0)
        self.resizeColumnToContents(1)
        self.resizeColumnToContents(2)
        self.resizeColumnToContents(3)
        self.resizeColumnToContents(4)

    # actions
    def item_changed(self, item, column):
        if column == item.ENABLED_COLUMN:
            self.validate()

    def validate(self):
        invalid_first_choice = set([FIXUP, SQUASH])
        for item in self.items():
            if item.is_enabled() and item.is_commit():
                if item.command in invalid_first_choice:
                    item.reset_command(PICK)
                break

    def set_selected_to(self, command):
        for i in self.selected_items():
            i.reset_command(command)
        self.validate()

    def set_command(self, item, command):
        item.reset_command(command)
        self.validate()

    def copy_oid(self):
        item = self.selected_item()
        if item is None:
            return
        clipboard = item.oid or item.cmdexec
        qtutils.set_clipboard(clipboard)

    def selection_changed(self):
        item = self.selected_item()
        if item is None or not item.is_commit():
            return
        context = self.context
        oid = item.oid
        params = dag.DAG(oid, 2)
        repo = dag.RepoReader(context, params)
        commits = []
        for c in repo.get():
            commits.append(c)
        if commits:
            commits = commits[-1:]
        self.notifier.notify_observers(diff.COMMITS_SELECTED, commits)

    def toggle_enabled(self):
        item = self.selected_item()
        if item is None:
            return
        item.toggle_enabled()

    def select_first(self):
        items = self.items()
        if not items:
            return
        idx = self.model().index(0, 0)
        if idx.isValid():
            self.setCurrentIndex(idx)

    def shift_down(self):
        item = self.selected_item()
        if item is None:
            return
        items = self.items()
        idx = items.index(item)
        if idx < len(items) - 1:
            self.move_rows.emit([idx], idx + 1)

    def shift_up(self):
        item = self.selected_item()
        if item is None:
            return
        items = self.items()
        idx = items.index(item)
        if idx > 0:
            self.move_rows.emit([idx], idx - 1)

    def move(self, src_idxs, dst_idx):
        new_items = []
        items = self.items()
        for idx in reversed(sorted(src_idxs)):
            item = items[idx].copy()
            self.invisibleRootItem().takeChild(idx)
            new_items.insert(0, item)

        if new_items:
            self.invisibleRootItem().insertChildren(dst_idx, new_items)
            self.setCurrentItem(new_items[0])
            # If we've moved to the top then we need to re-decorate all items.
            # Otherwise, we can decorate just the new items.
            if dst_idx == 0:
                self.decorate(self.items())
            else:
                self.decorate(new_items)
        self.validate()

    # Qt events

    def dropEvent(self, event):
        super(RebaseTreeWidget, self).dropEvent(event)
        self.validate()

    def contextMenuEvent(self, event):
        menu = qtutils.create_menu(N_('Actions'), self)
        menu.addAction(self.action_pick)
        menu.addAction(self.action_reword)
        menu.addAction(self.action_edit)
        menu.addAction(self.action_fixup)
        menu.addAction(self.action_squash)
        menu.addSeparator()
        menu.addAction(self.toggle_enabled_action)
        menu.addSeparator()
        menu.addAction(self.copy_oid_action)
        menu.addAction(self.external_diff_action)
        menu.exec_(self.mapToGlobal(event.pos()))


class ComboBox(QtWidgets.QComboBox):
    validate = Signal()


class RebaseTreeWidgetItem(QtWidgets.QTreeWidgetItem):

    ENABLED_COLUMN = 1
    COMMAND_COLUMN = 2
    OID_LENGTH = 7

    def __init__(
        self,
        idx,
        enabled,
        command,
        oid='',
        summary='',
        cmdexec='',
        comment_char='#',
        parent=None,
    ):
        QtWidgets.QTreeWidgetItem.__init__(self, parent)
        self.combo = None
        self.command = command
        self.idx = idx
        self.oid = oid
        self.summary = summary
        self.cmdexec = cmdexec
        self.comment_char = comment_char

        # if core.abbrev is set to a higher value then we will notice by
        # simply tracking the longest oid we've seen
        oid_len = self.__class__.OID_LENGTH
        self.__class__.OID_LENGTH = max(len(oid), oid_len)

        self.setText(0, '%02d' % idx)
        self.set_enabled(enabled)
        # checkbox on 1
        # combo box on 2
        if self.is_exec():
            self.setText(3, '')
            self.setText(4, cmdexec)
        else:
            self.setText(3, oid)
            self.setText(4, summary)

        flags = self.flags() | Qt.ItemIsUserCheckable
        flags = flags | Qt.ItemIsDragEnabled
        flags = flags & ~Qt.ItemIsDropEnabled
        self.setFlags(flags)

    def __eq__(self, other):
        return self is other

    def __hash__(self):
        return self.oid

    def copy(self):
        return self.__class__(
            self.idx,
            self.is_enabled(),
            self.command,
            oid=self.oid,
            summary=self.summary,
            cmdexec=self.cmdexec,
        )

    def decorate(self, parent):
        if self.is_exec():
            items = [EXEC]
            idx = 0
        else:
            items = COMMANDS
            idx = COMMAND_IDX[self.command]
        combo = self.combo = ComboBox()
        combo.setEditable(False)
        combo.addItems(items)
        combo.setCurrentIndex(idx)
        combo.setEnabled(self.is_commit())

        signal = combo.currentIndexChanged
        # pylint: disable=no-member
        signal.connect(lambda x: self.set_command_and_validate(combo))
        combo.validate.connect(parent.validate)

        parent.setItemWidget(self, self.COMMAND_COLUMN, combo)

    def is_exec(self):
        return self.command == EXEC

    def is_commit(self):
        return bool(self.command != EXEC and self.oid and self.summary)

    def value(self):
        """Return the serialized representation of an item"""
        if self.is_enabled():
            comment = ''
        else:
            comment = self.comment_char + ' '
        if self.is_exec():
            return '%s%s %s' % (comment, self.command, self.cmdexec)
        return '%s%s %s %s' % (comment, self.command, self.oid, self.summary)

    def is_enabled(self):
        return self.checkState(self.ENABLED_COLUMN) == Qt.Checked

    def set_enabled(self, enabled):
        self.setCheckState(self.ENABLED_COLUMN, enabled and Qt.Checked or Qt.Unchecked)

    def toggle_enabled(self):
        self.set_enabled(not self.is_enabled())

    def set_command(self, command):
        """Set the item to a different command, no-op for exec items"""
        if self.is_exec():
            return
        self.command = command

    def refresh(self):
        """Update the view to match the updated state"""
        if self.is_commit():
            command = self.command
            self.combo.setCurrentIndex(COMMAND_IDX[command])

    def reset_command(self, command):
        """Set and refresh the item in one shot"""
        self.set_command(command)
        self.refresh()

    def set_command_and_validate(self, combo):
        command = COMMANDS[combo.currentIndex()]
        self.set_command(command)
        self.combo.validate.emit()


def show_help(context):
    help_text = N_(
        """
Commands
--------
pick = use commit
reword = use commit, but edit the commit message
edit = use commit, but stop for amending
squash = use commit, but meld into previous commit
fixup = like "squash", but discard this commit's log message
exec = run command (the rest of the line) using shell

These lines can be re-ordered; they are executed from top to bottom.

If you disable a line here THAT COMMIT WILL BE LOST.

However, if you disable everything, the rebase will be aborted.

Keyboard Shortcuts
------------------
? = show help
j = move down
k = move up
J = shift row down
K = shift row up

1, p = pick
2, r = reword
3, e = edit
4, f = fixup
5, s = squash
spacebar = toggle enabled

ctrl+enter = accept changes and rebase
ctrl+q     = cancel and abort the rebase
ctrl+d     = launch difftool
"""
    )
    title = N_('Help - git-cola-sequence-editor')
    return text.text_dialog(context, help_text, title)
