#
#  Copyright (C) 2018 Codethink Limited
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU Lesser General Public
#  License as published by the Free Software Foundation; either
#  version 2 of the License, or (at your option) any later version.
#
#  This library 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
#  Lesser General Public License for more details.
#
#  You should have received a copy of the GNU Lesser General Public
#  License along with this library. If not, see <http://www.gnu.org/licenses/>.
#
#  Authors:
#        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
import os
import sys
import curses
from collections import OrderedDict
import click

# Import a widget internal for formatting time codes
from .widget import TimeCode


# Status()
#
# A widget for formatting overall status.
#
# Note that the render() and clear() methods in this class are
# simply noops in the case that the application is not connected
# to a terminal, or if the terminal does not support ANSI escape codes.
#
# Args:
#    context (Context): The Context
#    state (State): The state data from the Core
#    content_profile (Profile): Formatting profile for content text
#    format_profile (Profile): Formatting profile for formatting text
#    success_profile (Profile): Formatting profile for success text
#    error_profile (Profile): Formatting profile for error text
#    stream (Stream): The Stream
#
class Status:

    # Table of the terminal capabilities we require and use
    _TERM_CAPABILITIES = {"move_up": "cuu1", "move_x": "hpa", "clear_eol": "el"}

    def __init__(self, context, state, content_profile, format_profile, success_profile, error_profile, stream):

        self._context = context
        self._state = state
        self._content_profile = content_profile
        self._format_profile = format_profile
        self._success_profile = success_profile
        self._error_profile = error_profile
        self._stream = stream
        self._jobs = OrderedDict()
        self._last_lines = 0  # Number of status lines we last printed to console
        self._spacing = 1
        self._header = _StatusHeader(
            context, state, content_profile, format_profile, success_profile, error_profile, stream
        )

        self._term_width, _ = click.get_terminal_size()
        self._alloc_lines = 0
        self._alloc_columns = None
        self._need_alloc = True
        self._term_caps = self._init_terminal()

        state.register_task_added_callback(self._add_job)
        state.register_task_removed_callback(self._remove_job)
        state.register_task_changed_callback(self._job_changed)

    # clear()
    #
    # Clear the status area, it is necessary to call
    # this before printing anything to the console if
    # a status area is in use.
    #
    # To print some logging to the output and then restore
    # the status, use the following:
    #
    #   status.clear()
    #   ... print something to console ...
    #   status.render()
    #
    def clear(self):

        if not self._term_caps:
            return

        for _ in range(self._last_lines):
            self._move_up()
            self._clear_line()
        self._last_lines = 0

    # render()
    #
    # Render the status area.
    #
    # If you are not printing a line in addition to rendering
    # the status area, for instance in a timeout, then it is
    # not necessary to call clear().
    def render(self):

        if not self._term_caps:
            return

        elapsed = self._stream.elapsed_time

        self.clear()
        self._check_term_width()
        self._allocate()

        # Nothing to render, early return
        if self._alloc_lines == 0:
            return

        # Before rendering the actual lines, we need to add some line
        # feeds for the amount of lines we intend to print first, and
        # move cursor position back to the first line
        for _ in range(self._alloc_lines + self._header.lines):
            click.echo("", err=True)
        for _ in range(self._alloc_lines + self._header.lines):
            self._move_up()

        # Render the one line header
        text = self._header.render(self._term_width, elapsed)
        click.echo(text, err=True)

        # Now we have the number of columns, and an allocation for
        # alignment of each column
        n_columns = len(self._alloc_columns)
        for line in self._job_lines(n_columns):
            text = ""
            for job in line:
                column = line.index(job)
                text += job.render(self._alloc_columns[column] - job.size, elapsed)

                # Add spacing between columns
                if column < (n_columns - 1):
                    text += " " * self._spacing

            # Print the line
            click.echo(text, err=True)

        # Track what we printed last, for the next clear
        self._last_lines = self._alloc_lines + self._header.lines

    ###################################################
    #                 Private Methods                 #
    ###################################################

    # _job_changed()
    #
    # Reacts to a specified job being changed
    #
    # Args:
    #    action_name (str): The action name for this job
    #    full_name (str): The name of this specific job (e.g. element name)
    #
    def _job_changed(self, action_name, full_name):
        job_key = (action_name, full_name)
        task = self._state.tasks[job_key]
        job = self._jobs[job_key]
        if job.update(task):
            self._need_alloc = True

    # _init_terminal()
    #
    # Initialize the terminal and return the resolved terminal
    # capabilities dictionary.
    #
    # Returns:
    #    (dict|None): The resolved terminal capabilities dictionary,
    #                 or None if the terminal does not support all
    #                 of the required capabilities.
    #
    def _init_terminal(self):

        # We need both output streams to be connected to a terminal
        if not (sys.stdout.isatty() and sys.stderr.isatty()):
            return None

        # Initialized terminal, curses might decide it doesnt
        # support this terminal
        try:
            curses.setupterm(os.environ.get("TERM", "dumb"))
        except curses.error:
            return None

        term_caps = {}

        # Resolve the string capabilities we need for the capability
        # names we need.
        #
        for capname, capval in self._TERM_CAPABILITIES.items():
            code = curses.tigetstr(capval)

            # If any of the required capabilities resolve empty strings or None,
            # then we don't have the capabilities we need for a status bar on
            # this terminal.
            if not code:
                return None

            # Decode sequences as latin1, as they are always 8-bit bytes,
            # so when b'\xff' is returned, this must be decoded to u'\xff'.
            #
            # This technique is employed by the python blessings library
            # as well, and should provide better compatibility with most
            # terminals.
            #
            term_caps[capname] = code.decode("latin1")

        return term_caps

    def _check_term_width(self):
        term_width, _ = click.get_terminal_size()
        if self._term_width != term_width:
            self._term_width = term_width
            self._need_alloc = True

    def _move_up(self):
        assert self._term_caps is not None

        # Explicitly move to beginning of line, fixes things up
        # when there was a ^C or ^Z printed to the terminal.
        move_x = curses.tparm(self._term_caps["move_x"].encode("latin1"), 0)
        move_x = move_x.decode("latin1")

        move_up = curses.tparm(self._term_caps["move_up"].encode("latin1"))
        move_up = move_up.decode("latin1")

        click.echo(move_x + move_up, nl=False, err=True)

    def _clear_line(self):
        assert self._term_caps is not None

        clear_eol = curses.tparm(self._term_caps["clear_eol"].encode("latin1"))
        clear_eol = clear_eol.decode("latin1")
        click.echo(clear_eol, nl=False, err=True)

    def _allocate(self):
        if not self._need_alloc:
            return

        # State when there is no jobs to display
        alloc_lines = 0
        alloc_columns = []
        line_length = 0

        # Test for the widest width which fits columnized jobs
        for columns in reversed(range(len(self._jobs))):
            alloc_lines, alloc_columns = self._allocate_columns(columns + 1)

            # If the sum of column widths with spacing in between
            # fits into the terminal width, this is a good allocation.
            line_length = sum(alloc_columns) + (columns * self._spacing)
            if line_length < self._term_width:
                break

        self._alloc_lines = alloc_lines
        self._alloc_columns = alloc_columns
        self._need_alloc = False

    def _job_lines(self, columns):
        jobs_list = list(self._jobs.values())
        for i in range(0, len(self._jobs), columns):
            yield jobs_list[i : i + columns]

    # Returns an array of integers representing the maximum
    # length in characters for each column, given the current
    # list of jobs to render.
    #
    def _allocate_columns(self, columns):
        column_widths = [0 for _ in range(columns)]
        lines = 0
        for line in self._job_lines(columns):
            line_len = len(line)
            lines += 1
            for col in range(columns):
                if col < line_len:
                    job = line[col]
                    column_widths[col] = max(column_widths[col], job.size)

        return lines, column_widths

    # _add_job()
    #
    # Adds a job to track in the status area
    #
    # Args:
    #    action_name (str): The action name for this job
    #    full_name (str): The name of this specific job (e.g. element name)
    #
    def _add_job(self, action_name, full_name):
        task = self._state.tasks[(action_name, full_name)]
        elapsed = task.elapsed_offset
        job = _StatusJob(self._context, action_name, full_name, self._content_profile, self._format_profile, elapsed)
        self._jobs[(action_name, full_name)] = job
        self._need_alloc = True

    # _remove_job()
    #
    # Removes a job currently being tracked in the status area
    #
    # Args:
    #    action_name (str): The action name for this job
    #    full_name (str): The name of this specific job (e.g. element name)
    #
    def _remove_job(self, action_name, full_name):
        del self._jobs[(action_name, full_name)]
        self._need_alloc = True


# _StatusHeader()
#
# A delegate object for rendering the header part of the Status() widget
#
# Args:
#    context (Context): The Context
#    content_profile (Profile): Formatting profile for content text
#    format_profile (Profile): Formatting profile for formatting text
#    success_profile (Profile): Formatting profile for success text
#    error_profile (Profile): Formatting profile for error text
#    stream (Stream): The Stream
#
class _StatusHeader:
    def __init__(self, context, state, content_profile, format_profile, success_profile, error_profile, stream):

        #
        # Public members
        #
        self.lines = 3

        #
        # Private members
        #
        self._content_profile = content_profile
        self._format_profile = format_profile
        self._success_profile = success_profile
        self._error_profile = error_profile
        self._stream = stream
        self._state = state
        self._time_code = TimeCode(context, content_profile, format_profile)
        self._context = context

    def render(self, line_length, elapsed):
        project = self._context.get_toplevel_project()
        line_length = max(line_length, 80)

        #
        # Line 1: Session time, project name, session / total elements
        #
        #  ========= 00:00:00 project-name (143/387) =========
        #
        session = str(len(self._stream.session_elements))
        total = str(len(self._stream.total_elements))

        size = 0
        text = ""
        size += len(total) + len(session) + 4  # Size for (N/N) with a leading space
        size += 8  # Size of time code
        size += len(project.name) + 1
        text += self._time_code.render_time(elapsed)
        text += " " + self._content_profile.fmt(project.name)
        text += (
            " "
            + self._format_profile.fmt("(")
            + self._content_profile.fmt(session)
            + self._format_profile.fmt("/")
            + self._content_profile.fmt(total)
            + self._format_profile.fmt(")")
        )

        line1 = self._centered(text, size, line_length, "=")

        #
        # Line 2: Dynamic list of queue status reports
        #
        #  (Sources Fetched:0 117 0)→ (Built:4 0 0)
        #
        size = 0
        text = ""

        # Format and calculate size for each queue progress
        for index, task_group in enumerate(self._state.task_groups.values()):

            # Add spacing
            if index > 0:
                size += 2
                text += self._format_profile.fmt("→ ")

            group_text, group_size = self._render_task_group(task_group)
            size += group_size
            text += group_text

        line2 = self._centered(text, size, line_length, " ")

        #
        # Line 3: Cache usage percentage report
        #
        #  ~~~~~~ cache: 44.2G / 64G (69%) ~~~~~~
        #
        cas = self._context.get_cascache()
        usage = cas.get_cache_usage()
        usage_string = str(usage)

        if usage.used_size is None:
            # Cache usage is unknown
            size = 0
            text = ""
        else:
            size = 21
            size += len(usage_string)
            if usage.used_percent >= 95:
                formatted_usage = self._error_profile.fmt(usage_string)
            elif usage.used_percent >= 80:
                formatted_usage = self._content_profile.fmt(usage_string)
            else:
                formatted_usage = self._success_profile.fmt(usage_string)

            text = (
                self._format_profile.fmt("~~~~~~ ")
                + self._content_profile.fmt("cache")
                + self._format_profile.fmt(": ")
                + formatted_usage
                + self._format_profile.fmt(" ~~~~~~")
            )

        line3 = self._centered(text, size, line_length, " ")

        return line1 + "\n" + line2 + "\n" + line3

    ###################################################
    #                 Private Methods                 #
    ###################################################
    def _render_task_group(self, group):
        processed = str(group.processed_tasks)
        skipped = str(group.skipped_tasks)
        failed = str(len(group.failed_tasks))

        size = 5  # Space for the formatting '[', ':', ' ', ' ' and ']'
        size += len(group.complete_name)
        size += len(processed) + len(skipped) + len(failed)
        text = (
            self._format_profile.fmt("(")
            + self._content_profile.fmt(group.complete_name)
            + self._format_profile.fmt(":")
            + self._success_profile.fmt(processed)
            + " "
            + self._content_profile.fmt(skipped)
            + " "
            + self._error_profile.fmt(failed)
            + self._format_profile.fmt(")")
        )

        return (text, size)

    def _centered(self, text, size, line_length, fill):
        remaining = line_length - size
        remaining -= 2

        final_text = self._format_profile.fmt(fill * (remaining // 2)) + " "
        final_text += text
        final_text += " " + self._format_profile.fmt(fill * (remaining // 2))

        return final_text


# _StatusJob()
#
# A delegate object for rendering a job in the status area
#
# Args:
#    context (Context): The Context
#    action_name (str): The action performed
#    full_name (str): The name of the job
#    content_profile (Profile): Formatting profile for content text
#    format_profile (Profile): Formatting profile for formatting text
#    elapsed (datetime): The offset into the session when this job is created
#
class _StatusJob:
    def __init__(self, context, action_name, full_name, content_profile, format_profile, elapsed):
        #
        # Public members
        #
        self.action_name = action_name  # The action name
        self.size = None  # The number of characters required to render
        self.full_name = full_name

        #
        # Private members
        #
        self._offset = elapsed
        self._content_profile = content_profile
        self._format_profile = format_profile
        self._time_code = TimeCode(context, content_profile, format_profile)
        self._current_progress = None  # Progress tally to render
        self._maximum_progress = None  # Progress tally to render

        self.size = self.calculate_size()

    # calculate_size()
    #
    # Calculates the amount of space the job takes up when rendered
    #
    # Returns:
    #    int: The size of the job when rendered
    #
    def calculate_size(self):
        # Calculate the size needed to display
        size = 10  # Size of time code with brackets
        size += len(self.action_name)
        size += len(self.full_name)
        size += 3  # '[' + ':' + ']'
        if self._current_progress is not None:
            size += len(str(self._current_progress))
            size += 1  # ':'
            if self._maximum_progress is not None:
                size += len(str(self._maximum_progress))
                size += 1  # '/'
        return size

    # update()
    #
    # Synchronises its internal data with the provided Task,
    # and returns whether its size has changed
    #
    # Args:
    #    task (Task): The task associated with this job
    #
    # Returns:
    #    bool: Whether the size of the job has changed
    #
    def update(self, task):
        changed = False
        size_changed = False
        if task.current_progress != self._current_progress:
            changed = True
            self._current_progress = task.current_progress
        if task.maximum_progress != self._maximum_progress:
            changed = True
            self._maximum_progress = task.maximum_progress
        if changed:
            old_size = self.size
            self.size = self.calculate_size()
            if self.size != old_size:
                size_changed = True

        return size_changed

    # render()
    #
    # Render the Job, return a rendered string
    #
    # Args:
    #    padding (int): Amount of padding to print in order to align with columns
    #    elapsed (datetime): The session elapsed time offset
    #
    def render(self, padding, elapsed):
        text = (
            self._format_profile.fmt("[")
            + self._time_code.render_time(elapsed - self._offset)
            + self._format_profile.fmt("]")
        )

        text += (
            self._format_profile.fmt("[")
            + self._content_profile.fmt(self.action_name)
            + self._format_profile.fmt(":")
            + self._content_profile.fmt(self.full_name)
        )

        if self._current_progress is not None:
            text += self._format_profile.fmt(":") + self._content_profile.fmt(str(self._current_progress))
            if self._maximum_progress is not None:
                text += self._format_profile.fmt("/") + self._content_profile.fmt(str(self._maximum_progress))

        # Add padding before terminating ']'
        terminator = (" " * padding) + "]"
        text += self._format_profile.fmt(terminator)

        return text