"""
Render project files to pgfgantt plots.

Create a LaTeX representation of a project file.
"""

from pylatex.base_classes import command
from pylatex.base_classes import containers
from pylatex.utils import NoEscape
from project2latex import project as _project

def date_latex(date):
    """
    Convert a date object to a LaTeX representation.

    :param date: input date or datetime instance
    :return: LaTeX representation of the date
    """
    return NoEscape(date.strftime('%Y-%m-%d'))

def uid_latex(uid):
    """
    Convert a task UID to a LaTeX representation.

    :param uid: unique identifier to convert
    :return: LaTeX representation of the UID
    """
    return NoEscape("task" + str(uid))

class GanttNewLine(command.CommandBase):
    pass

class GanttTask(command.CommandBase):
    def __init__(self, task):
        self.task = task
        args = None

        if task.kind == _project.TaskKind.bar:
            # a normal task, lasting a given duration
            self._latex_name = 'ganttbar'
            args = command.Arguments(
                task.name,
                date_latex(task.start),
                date_latex(task.finish),
            )
        else:
            # a milestone at a fixed date with no duration
            self._latex_name = 'ganttmilestone'
            args = command.Arguments(
                task.name,
                date_latex(task.start),
            )

        super().__init__(
            # name tasks according to their unique id
            options=command.Options(
                name=uid_latex(task.uid),
            ),
            arguments=args
        )

class GanttLink(command.CommandBase):
    def __init__(self, from_uid, to_uid, kind):
        self.from_uid = from_uid
        self.to_uid = to_uid
        self.kind = kind

        link_type = ''
        if kind == _project.PredecessorKind.start_start:
            link_type = 's-s'
        elif kind == _project.PredecessorKind.start_finish:
            link_type = 's-f'
        elif kind == _project.PredecessorKind.finish_start:
            link_type = 'f-s'
        elif kind == _project.PredecessorKind.finish_finish:
            link_type = 'f-s'

        super().__init__(
            # options=NoEscape('link type=' + link_type),
            arguments=command.Arguments(
                uid_latex(from_uid),
                uid_latex(to_uid),
            )
        )

class GanttChart(containers.Environment):
    def __init__(self, project):
        self.project = project

        # initialize the chart environment with start and finish dates
        super().__init__(
            options='time slot format=isodate',
            arguments=command.Arguments(
                date_latex(project.start),
                date_latex(project.finish),
            )
        )

        # create task elements, one per line, in order
        for num, task in enumerate(project.tasks):
            self.append(GanttTask(task))
            if num < len(project.tasks) - 1:
                self.append(GanttNewLine())

        # create precedence links
        for task in project.tasks:
            if task.predecessor_kind != _project.PredecessorKind.none:
                self.append(GanttLink(
                    task.predecessor_uid,
                    task.uid,
                    task.predecessor_kind,
                ))