#
#  Copyright (C) 2022 Codethink Limited
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.
#
#  Authors:
#        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
import datetime
import os
from collections import defaultdict, OrderedDict
from contextlib import ExitStack
from mmap import mmap
import re
import textwrap
from ruamel import yaml
import click

from .profile import Profile
from ..types import _Scope
from .. import __version__ as bst_version
from .. import FileType
from .._exceptions import BstError, ImplError
from .._message import MessageType
from .._artifactelement import ArtifactElement

# These messages are printed a bit differently
ERROR_MESSAGES = [MessageType.FAIL, MessageType.ERROR, MessageType.BUG]


# Widget()
#
# Args:
#    content_profile (Profile): The profile to use for rendering content
#    format_profile (Profile): The profile to use for rendering formatting
#
# An abstract class for printing output columns in our text UI.
#
class Widget:
    def __init__(self, context, content_profile, format_profile):

        # The context
        self.context = context

        # The content profile
        self.content_profile = content_profile

        # The formatting profile
        self.format_profile = format_profile

    # render()
    #
    # Renders a string to be printed in the UI
    #
    # Args:
    #    message (Message): A message to print
    #
    # Returns:
    #    (str): The string this widget prints for the given message
    #
    def render(self, message):
        raise ImplError("{} does not implement render()".format(type(self).__name__))


# Used to add fixed text between columns
class FixedText(Widget):
    def __init__(self, context, text, content_profile, format_profile):
        super().__init__(context, content_profile, format_profile)
        self.text = text

    def render(self, message):
        return self.format_profile.fmt(self.text)


# Used to add the wallclock time this message was created at
class WallclockTime(Widget):
    def __init__(self, context, content_profile, format_profile, output_format=False):
        self._output_format = output_format
        super().__init__(context, content_profile, format_profile)

    def render(self, message):

        fields = [
            self.content_profile.fmt("{:02d}".format(x))
            for x in [
                message.creation_time.hour,
                message.creation_time.minute,
                message.creation_time.second,
            ]
        ]
        text = self.format_profile.fmt(":").join(fields)

        if self._output_format == "us":
            text += self.content_profile.fmt(".{:06d}".format(message.creation_time.microsecond))

        return text


# A widget for rendering the debugging column
class Debug(Widget):
    def render(self, message):
        element_name = "n/a" if message.element_name is None else message.element_name

        text = self.format_profile.fmt("pid:")
        text += self.content_profile.fmt("{: <5}".format(message.pid))
        text += self.format_profile.fmt("element name:")
        text += self.content_profile.fmt("{: <30}".format(element_name))

        return text


# A widget for rendering the time codes
class TimeCode(Widget):
    def __init__(self, context, content_profile, format_profile, microseconds=False):
        self._microseconds = microseconds
        super().__init__(context, content_profile, format_profile)

    def render(self, message):
        return self.render_time(message.elapsed)

    def render_time(self, elapsed):
        if elapsed is None:
            fields = [self.content_profile.fmt("--") for i in range(3)]
        else:
            hours, remainder = divmod(int(elapsed.total_seconds()), 60 * 60)
            minutes, seconds = divmod(remainder, 60)
            fields = [self.content_profile.fmt("{0:02d}".format(field)) for field in [hours, minutes, seconds]]

        text = self.format_profile.fmt(":").join(fields)

        if self._microseconds:
            if elapsed is not None:
                text += self.content_profile.fmt(".{0:06d}".format(elapsed.microseconds))
            else:
                text += self.content_profile.fmt(".------")
        return text


# A widget for rendering the MessageType
class TypeName(Widget):

    _action_colors = {
        MessageType.DEBUG: "cyan",
        MessageType.STATUS: "cyan",
        MessageType.INFO: "magenta",
        MessageType.WARN: "yellow",
        MessageType.START: "blue",
        MessageType.SUCCESS: "green",
        MessageType.FAIL: "red",
        MessageType.SKIPPED: "yellow",
        MessageType.ERROR: "red",
        MessageType.BUG: "red",
    }

    def render(self, message):
        return self.content_profile.fmt(
            "{: <7}".format(message.message_type.upper()),
            bold=True,
            dim=True,
            fg=self._action_colors[message.message_type],
        )


# A widget for displaying the Element name
class ElementName(Widget):
    def render(self, message):
        action_name = message.action_name
        element_name = message.task_element_name or message.element_name

        if element_name is not None:
            name = "{: <30}".format(element_name)
        else:
            name = "core activity"
            name = "{: <30}".format(name)

        if not action_name:
            action_name = "Main"

        return (
            self.content_profile.fmt("{: >8}".format(action_name.lower()))
            + self.format_profile.fmt(":")
            + self.content_profile.fmt(name)
        )


# A widget for displaying the primary message text
class MessageText(Widget):
    def render(self, message):
        return message.message


# A widget for formatting the element cache key
class CacheKey(Widget):
    def __init__(self, context, content_profile, format_profile, err_profile):
        super().__init__(context, content_profile, format_profile)

        self._err_profile = err_profile
        self._key_length = context.log_key_length

    def render(self, message):

        if not self._key_length:
            return ""

        if message.element_name is None:
            return " " * self._key_length

        dim = False
        key = " " * self._key_length
        element_key = message.task_element_key or message.element_key
        if element_key:
            key = element_key.brief
            dim = not element_key.strict

        if message.message_type in ERROR_MESSAGES:
            text = self._err_profile.fmt(key)
        else:
            text = self.content_profile.fmt(key, dim=dim)

        return text


# A widget for formatting the log file
class LogFile(Widget):
    def __init__(self, context, content_profile, format_profile, err_profile):
        super().__init__(context, content_profile, format_profile)

        self._err_profile = err_profile
        self._logdir = context.logdir

    def render(self, message):
        return self.render_abbrev(message)

    def render_abbrev(self, message, abbrev=True):
        if message.logfile and message.scheduler:
            logfile = message.logfile

            if abbrev and self._logdir != "" and logfile.startswith(self._logdir):
                logfile = logfile[len(self._logdir) :]
                logfile = logfile.lstrip(os.sep)

            if message.message_type in ERROR_MESSAGES:
                text = self._err_profile.fmt(logfile)
            else:
                text = self.content_profile.fmt(logfile, dim=True)
        else:
            text = ""

        return text


# START and SUCCESS messages are expected to have no useful
# information in the message text, so we display the logfile name for
# these messages, and the message text for other types.
#
class MessageOrLogFile(Widget):
    def __init__(self, context, content_profile, format_profile, err_profile):
        super().__init__(context, content_profile, format_profile)
        self._message_widget = MessageText(context, content_profile, format_profile)
        self._logfile_widget = LogFile(context, content_profile, format_profile, err_profile)

    def render(self, message):
        # Show the log file only in the main start/success messages
        if message.logfile and message.scheduler and message.message_type in [MessageType.START, MessageType.SUCCESS]:
            text = self._logfile_widget.render(message)
        else:
            text = self._message_widget.render(message)
        return text


# LogLine
#
# A widget for formatting a log line
#
# 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
#    detail_profile (Profile): Formatting profile for detail text
#    indent (int): Number of spaces to use for general indentation
#
class LogLine(Widget):
    def __init__(
        self, context, state, content_profile, format_profile, success_profile, err_profile, detail_profile, indent=4
    ):
        super().__init__(context, content_profile, format_profile)

        self._columns = []
        self._failure_messages = defaultdict(list)
        self._success_profile = success_profile
        self._err_profile = err_profile
        self._detail_profile = detail_profile
        self._indent = " " * indent
        self._log_lines = context.log_error_lines
        self._message_lines = context.log_message_lines
        self._resolved_keys = None
        self._state = state

        self._logfile_widget = LogFile(context, content_profile, format_profile, err_profile)

        if context.log_debug:
            self._columns.extend([Debug(context, content_profile, format_profile)])

        self.logfile_variable_names = {
            "elapsed": TimeCode(context, content_profile, format_profile, microseconds=False),
            "elapsed-us": TimeCode(context, content_profile, format_profile, microseconds=True),
            "wallclock": WallclockTime(context, content_profile, format_profile),
            "wallclock-us": WallclockTime(context, content_profile, format_profile, output_format="us"),
            "key": CacheKey(context, content_profile, format_profile, err_profile),
            "element": ElementName(context, content_profile, format_profile),
            "action": TypeName(context, content_profile, format_profile),
            "message": MessageOrLogFile(context, content_profile, format_profile, err_profile),
        }
        logfile_tokens = self._parse_logfile_format(context.log_message_format, content_profile, format_profile)
        self._columns.extend(logfile_tokens)

    # show_pipeline()
    #
    # Display a list of elements in the specified format.
    #
    # The formatting string is the one currently documented in `bst show`, this
    # is used in pipeline session headings and also to implement `bst show`.
    #
    # Args:
    #    dependencies (list of Element): A list of Element objects
    #    format_: A formatting string, as specified by `bst show`
    #
    # Returns:
    #    (str): The formatted list of elements
    #
    def show_pipeline(self, dependencies, format_):
        report = ""
        p = Profile()

        for element in dependencies:
            line = format_

            key = element._get_display_key()
            dim_keys = not key.strict

            line = p.fmt_subst(line, "name", element._get_full_name(), fg="blue", bold=True)
            line = p.fmt_subst(line, "key", key.brief, fg="yellow", dim=dim_keys)
            line = p.fmt_subst(line, "full-key", key.full, fg="yellow", dim=dim_keys)

            try:
                if not element._has_all_sources_resolved():
                    line = p.fmt_subst(line, "state", "no reference", fg="red")
                else:
                    if element.get_kind() == "junction":
                        line = p.fmt_subst(line, "state", "junction", fg="magenta")
                    elif not element._can_query_cache():
                        line = p.fmt_subst(line, "state", "waiting", fg="blue")
                    elif element._cached_failure():
                        line = p.fmt_subst(line, "state", "failed", fg="red")
                    elif element._cached_success():
                        line = p.fmt_subst(line, "state", "cached", fg="magenta")
                    elif not element._can_query_source_cache():
                        line = p.fmt_subst(line, "state", "waiting", fg="blue")
                    elif element._fetch_needed():
                        line = p.fmt_subst(line, "state", "fetch needed", fg="red")
                    elif element._buildable():
                        line = p.fmt_subst(line, "state", "buildable", fg="green")
                    else:
                        line = p.fmt_subst(line, "state", "waiting", fg="blue")
            except BstError as e:
                # Provide context to plugin error
                e.args = ("Failed to determine state for {}: {}".format(element._get_full_name(), str(e)),)
                raise e

            # Element configuration
            if "%{config" in format_:
                line = p.fmt_subst(
                    line,
                    "config",
                    yaml.round_trip_dump(element._Element__config, default_flow_style=False, allow_unicode=True),
                )

            # Variables
            if "%{vars" in format_:
                variables = dict(element._Element__variables)
                line = p.fmt_subst(
                    line, "vars", yaml.round_trip_dump(variables, default_flow_style=False, allow_unicode=True)
                )

            # Environment
            if "%{env" in format_:
                environment = element._Element__environment
                line = p.fmt_subst(
                    line, "env", yaml.round_trip_dump(environment, default_flow_style=False, allow_unicode=True)
                )

            # Public
            if "%{public" in format_:
                environment = element._Element__public
                line = p.fmt_subst(
                    line, "public", yaml.round_trip_dump(environment, default_flow_style=False, allow_unicode=True)
                )

            # Workspaced
            if "%{workspaced" in format_:
                line = p.fmt_subst(line, "workspaced", "(workspaced)" if element._get_workspace() else "", fg="yellow")

            # Workspace-dirs
            if "%{workspace-dirs" in format_:
                workspace = element._get_workspace()
                if workspace is not None:
                    path = workspace.get_absolute_path()
                    if path.startswith("~/"):
                        path = os.path.join(os.getenv("HOME", "/root"), path[2:])
                    line = p.fmt_subst(line, "workspace-dirs", "Workspace: {}".format(path))
                else:
                    line = p.fmt_subst(line, "workspace-dirs", "")

            # Dependencies
            if "%{deps" in format_:
                deps = [e._get_full_name() for e in element._dependencies(_Scope.ALL, recurse=False)]
                line = p.fmt_subst(line, "deps", yaml.safe_dump(deps, default_style=None).rstrip("\n"))

            # Build Dependencies
            if "%{build-deps" in format_:
                build_deps = [e._get_full_name() for e in element._dependencies(_Scope.BUILD, recurse=False)]
                line = p.fmt_subst(line, "build-deps", yaml.safe_dump(build_deps, default_style=False).rstrip("\n"))

            # Runtime Dependencies
            if "%{runtime-deps" in format_:
                runtime_deps = [e._get_full_name() for e in element._dependencies(_Scope.RUN, recurse=False)]
                line = p.fmt_subst(
                    line, "runtime-deps", yaml.safe_dump(runtime_deps, default_style=False).rstrip("\n")
                )

            report += line + "\n"

        return report.rstrip("\n")

    # print_heading()
    #
    # A message to be printed at program startup, indicating
    # some things about user configuration and BuildStream version
    # and so on.
    #
    # Args:
    #    toplevel_project (Project): The toplevel project we were invoked from, or None
    #    stream (Stream): The stream
    #    log_file (file): An optional file handle for additional logging
    #
    def print_heading(self, toplevel_project, stream, *, log_file):
        context = self.context
        starttime = datetime.datetime.now()
        text = ""

        def format_spec(spec):
            if spec.instance_name:
                return "{} (instance: {})".format(spec.url, spec.instance_name)
            return spec.url

        self._resolved_keys = {element: element._get_cache_key() for element in stream.session_elements}

        # Main invocation context
        text += "\n"
        text += self.content_profile.fmt("BuildStream Version {}\n".format(bst_version), bold=True)
        values = OrderedDict()
        values["Session Start"] = starttime.strftime("%A, %d-%m-%Y at %H:%M:%S")
        if toplevel_project:
            values["Project"] = "{} ({})".format(toplevel_project.name, toplevel_project.directory)
        values["Targets"] = ", ".join([t.name for t in stream.targets])
        text += self._format_values(values)

        # User configurations
        text += "\n"
        text += self.content_profile.fmt("User Configuration\n", bold=True)
        values = OrderedDict()
        values["Configuration File"] = "Default Configuration" if not context.config_origin else context.config_origin
        values["Cache Directory"] = context.cachedir
        values["Log Files"] = context.logdir
        values["Source Mirrors"] = context.sourcedir
        values["Build Area"] = context.builddir
        values["Strict Build Plan"] = "Yes" if context.get_strict() else "No"
        values["Maximum Fetch Tasks"] = context.sched_fetchers
        values["Maximum Build Tasks"] = context.sched_builders
        values["Maximum Push Tasks"] = context.sched_pushers
        values["Maximum Network Retries"] = context.sched_network_retries

        if context.remote_cache_spec:
            values["Cache Storage Service"] = format_spec(context.remote_cache_spec)

        text += self._format_values(values)

        if context.remote_execution_specs:
            specs = context.remote_execution_specs

            text += "\n"
            text += self.content_profile.fmt("Remote Execution Configuration\n", bold=True)
            values = OrderedDict()
            values["Execution Service"] = format_spec(specs.exec_spec)
            re_storage_spec = specs.storage_spec or context.remote_cache_spec
            values["Storage Service"] = format_spec(re_storage_spec)
            if specs.action_spec:
                values["Action Cache Service"] = format_spec(specs.action_spec)
            text += self._format_values(values)

        # Print information about each loaded project
        #
        text += "\n"
        if toplevel_project:
            loaded_projects = toplevel_project.loaded_projects()
        else:
            loaded_projects = []

        for project_info in loaded_projects:
            project = project_info.project

            # Project title line
            text += (
                self.content_profile.fmt("Project", bold=True)
                + self.format_profile.fmt(": ", bold=True)
                + self.content_profile.fmt(project.name, bold=True)
            )
            text += "\n"

            # Details on how the project was loaded
            #
            values = OrderedDict()
            if project.junction:
                values["Junction path"] = project_info.project.junction._get_full_name()
            if project_info.provenance:
                values["Loaded by"] = str(project_info.provenance)
            text += self._format_values(values)

            # Print out duplicate declarations
            if project_info.duplicates:
                text += self.format_profile.fmt("{}Declared duplicate by:\n".format(self._indent))
                for duplicate in project_info.duplicates:
                    text += self.content_profile.fmt("{}{}\n".format(self._indent * 2, duplicate))

            # Print out internal declarations
            if project_info.internal:
                text += self.format_profile.fmt("{}Declared internal by:\n".format(self._indent))
                for internal in project_info.internal:
                    text += self.content_profile.fmt("{}{}\n".format(self._indent * 2, internal))

            text += "\n"

            # Project Options
            values = OrderedDict()
            project.options.printable_variables(values)
            if values:
                text += self.format_profile.fmt("{}Project Options\n".format(self._indent))
                text += self._format_values(values, indent=2)
                text += "\n"

            # Plugins
            text += self._format_plugins(
                {p: d for p, _, _, d in project.element_factory.list_plugins()},
                {p: d for p, _, _, d in project.source_factory.list_plugins()},
            )

            # Artifact cache servers
            specs = context.project_artifact_cache_specs.get(project.name)
            if specs:
                text += self.format_profile.fmt("{}Artifact cache servers\n".format(self._indent))
                text += self._format_list(specs, indent=2)
                text += "\n"

            # Source cache servers
            specs = context.project_source_cache_specs.get(project.name)
            if specs:
                text += self.format_profile.fmt("{}Source cache servers\n".format(self._indent))
                text += self._format_list(specs, indent=2)
                text += "\n"

        # Pipeline state
        text += self.content_profile.fmt("Pipeline\n", bold=True)
        text += self.show_pipeline(stream.total_elements, context.log_element_format)
        text += "\n"

        # Separator line before following output
        text += self.format_profile.fmt("=" * 79 + "\n")

        click.echo(text, nl=False, err=True)
        if log_file:
            click.echo(text, file=log_file, color=False, nl=False)

    # print_summary()
    #
    # Print a summary of activities at the end of a session
    #
    # Args:
    #    stream (Stream): The Stream
    #    log_file (file): An optional file handle for additional logging
    #
    def print_summary(self, stream, log_file):

        # Early silent return if there are no queues, can happen
        # only in the case that the stream early returned due to
        # an inconsistent pipeline state.
        if not self._state.task_groups:
            return

        text = ""

        assert self._resolved_keys is not None
        elements = sorted(e for (e, k) in self._resolved_keys.items() if k != e._get_cache_key())
        if elements:
            text += self.content_profile.fmt("Resolved key Summary\n", bold=True)
            text += self.show_pipeline(elements, self.context.log_element_format)
            text += "\n\n"

        if self._failure_messages:
            values = OrderedDict()

            for element_name, messages in sorted(self._failure_messages.items()):
                for group in self._state.task_groups.values():
                    # Exclude the failure messages if the job didn't ultimately fail
                    # (e.g. succeeded on retry)
                    if element_name in group.failed_tasks:
                        values[element_name] = "".join(self._render(v) for v in messages)

            if values:
                text += self.content_profile.fmt("Failure Summary\n", bold=True)
                text += self._format_values(values, style_value=False)

        text += self.content_profile.fmt("Pipeline Summary\n", bold=True)
        values = OrderedDict()

        values["Total"] = self.content_profile.fmt(str(len(stream.total_elements)))
        values["Session"] = self.content_profile.fmt(str(len(stream.session_elements)))

        processed_maxlen = 1
        skipped_maxlen = 1
        failed_maxlen = 1
        for group in self._state.task_groups.values():
            processed_maxlen = max(len(str(group.processed_tasks)), processed_maxlen)
            skipped_maxlen = max(len(str(group.skipped_tasks)), skipped_maxlen)
            failed_maxlen = max(len(str(len(group.failed_tasks))), failed_maxlen)

        for group in self._state.task_groups.values():
            processed = str(group.processed_tasks)
            skipped = str(group.skipped_tasks)
            failed = str(len(group.failed_tasks))

            processed_align = " " * (processed_maxlen - len(processed))
            skipped_align = " " * (skipped_maxlen - len(skipped))
            failed_align = " " * (failed_maxlen - len(failed))

            status_text = (
                self.content_profile.fmt("processed ")
                + self._success_profile.fmt(processed)
                + self.format_profile.fmt(", ")
                + processed_align
            )

            status_text += (
                self.content_profile.fmt("skipped ")
                + self.content_profile.fmt(skipped)
                + self.format_profile.fmt(", ")
                + skipped_align
            )

            status_text += self.content_profile.fmt("failed ") + self._err_profile.fmt(failed) + " " + failed_align
            values["{} Queue".format(group.name)] = status_text

        text += self._format_values(values, style_value=False)

        click.echo(text, nl=False, err=True)
        if log_file:
            click.echo(text, file=log_file, color=False, nl=False)

    ###################################################
    #             Widget Abstract Methods             #
    ###################################################

    def render(self, message):

        # Track logfiles for later use
        element_name = message.element_name
        if message.message_type in ERROR_MESSAGES and element_name is not None:
            self._failure_messages[element_name].append(message)

        return self._render(message)

    ###################################################
    #                 Private Methods                 #
    ###################################################
    def _parse_logfile_format(self, format_string, content_profile, format_profile):
        logfile_tokens = []
        while format_string:
            if format_string.startswith("%%"):
                logfile_tokens.append(FixedText(self.context, "%", content_profile, format_profile))
                format_string = format_string[2:]
                continue
            m = re.search(r"^%\{([^\}]+)\}", format_string)
            if m is not None:
                variable = m.group(1)
                format_string = format_string[m.end(0) :]
                if variable not in self.logfile_variable_names:
                    raise Exception("'{0}' is not a valid log variable name.".format(variable))
                logfile_tokens.append(self.logfile_variable_names[variable])
            else:
                m = re.search("^[^%]+", format_string)
                if m is not None:
                    text = FixedText(self.context, m.group(0), content_profile, format_profile)
                    format_string = format_string[m.end(0) :]
                    logfile_tokens.append(text)
                else:
                    # No idea what to do now
                    raise Exception("'{0}' could not be parsed into a valid logging format.".format(format_string))
        return logfile_tokens

    def _render(self, message):

        # Render the column widgets first
        text = ""
        for widget in self._columns:
            text += widget.render(message)

        text += "\n"

        extra_nl = False

        # Now add some custom things
        if message.detail:

            # Identify frontend messages, we never abbreviate these
            frontend_message = not message.element_name

            # Split and truncate message detail down to message_lines lines
            lines = message.detail.splitlines(True)

            n_lines = len(lines)
            abbrev = False
            if message.message_type not in ERROR_MESSAGES and not frontend_message and n_lines > self._message_lines:
                lines = lines[0 : self._message_lines]
                if self._message_lines > 0:
                    abbrev = True
            else:
                lines[n_lines - 1] = lines[n_lines - 1].rstrip("\n")

            detail = self._indent + self._indent.join(lines)

            text += "\n"
            if message.message_type in ERROR_MESSAGES:
                text += self._err_profile.fmt(detail, bold=True)
            else:
                text += self._detail_profile.fmt(detail)

            if abbrev:
                text += self._indent + self.content_profile.fmt(
                    "Message contains {} additional lines".format(n_lines - self._message_lines), dim=True
                )
            text += "\n"

            extra_nl = True

        if message.scheduler and message.message_type == MessageType.FAIL:
            text += "\n"

            if self.context is not None and not self.context.log_verbose:
                text += self._indent + self._err_profile.fmt("Log file: ")
                text += self._indent + self._logfile_widget.render(message) + "\n"
            elif self._log_lines > 0:
                text += (
                    self._indent
                    + self._err_profile.fmt("Printing the last {} lines from log file:".format(self._log_lines))
                    + "\n"
                )
                text += self._indent + self._logfile_widget.render_abbrev(message, abbrev=False) + "\n"
                text += self._indent + self._err_profile.fmt("=" * 70) + "\n"

                log_content = self._read_last_lines(message.logfile)
                log_content = textwrap.indent(log_content, self._indent)
                text += self._detail_profile.fmt(log_content)
                text += "\n"
                text += self._indent + self._err_profile.fmt("=" * 70) + "\n"
            extra_nl = True

        if extra_nl:
            text += "\n"

        return text

    def _read_last_lines(self, logfile):
        with ExitStack() as stack:
            # mmap handles low-level memory details, allowing for
            # faster searches
            f = stack.enter_context(open(logfile, "r+", encoding="utf-8"))
            log = stack.enter_context(mmap(f.fileno(), os.path.getsize(f.name)))

            count = 0
            end = log.size() - 1

            while count < self._log_lines and end >= 0:
                location = log.rfind(b"\n", 0, end)
                count += 1

                # If location is -1 (none found), this will print the
                # first character because of the later +1
                end = location

            # end+1 is correct whether or not a newline was found at
            # that location. If end is -1 (seek before beginning of file)
            # then we get the first characther. If end is a newline position,
            # we discard it and only want to print the beginning of the next
            # line.
            lines = log[(end + 1) :].splitlines()
            return "\n".join([line.decode("utf-8") for line in lines]).rstrip()

    # _format_plugins()
    #
    # Formats the plugins loaded by a project
    #
    # Args:
    #    element_plugins (dict): Dict of element plugin kind and display string tuples
    #    source_plugins (dict): Dict of source plugin kind and display string tuples
    #
    # Returns:
    #    (str): The formatted text
    #
    def _format_plugins(self, element_plugins, source_plugins):
        text = ""
        if element_plugins:
            text += self.format_profile.fmt("{}Element Plugins\n".format(self._indent))
            text += self._format_values(element_plugins, style_key=True, indent=2)
            text += "\n"
        if source_plugins:
            text += self.format_profile.fmt("{}Source Plugins\n".format(self._indent))
            text += self._format_values(source_plugins, style_key=True, indent=2)
            text += "\n"

        return text

    # _format_values()
    #
    # Formats an indented dictionary of titles / values, ensuring
    # the values are aligned.
    #
    # Args:
    #    values (dict): A dictionary, usually an OrderedDict()
    #    style_key (bool): Whether to use the content profile for the keys
    #    style_value (bool): Whether to use the content profile for the values
    #    indent (number): Number of initial indentation levels
    #
    # Returns:
    #    (str): The formatted values
    #
    def _format_values(self, values, *, style_key=False, style_value=True, indent=1):
        text = ""
        max_key_len = 0
        for key, value in values.items():
            max_key_len = max(len(key), max_key_len)

        for key, value in values.items():

            key = str(key)
            text += self._indent * indent
            if style_key:
                text += self.content_profile.fmt(key)
            else:
                text += self.format_profile.fmt(key)
            text += self.format_profile.fmt(":")

            # Special case for values containing newlines
            if isinstance(value, str) and "\n" in value:
                text += "\n"
                text += textwrap.indent(value, self._indent * indent)
                continue

            # Alignment spacing
            text += " {}".format(" " * (max_key_len - len(key)))

            # Print the value
            if style_value:
                text += self.content_profile.fmt(str(value))
            else:
                text += str(value)
            text += "\n"

        return text

    # _format_list()
    #
    # Formats an indented list of values, ensuring the values have bullets.
    #
    # Args:
    #    values (list): A list of values to format as strings (or strings)
    #    indent (number): Number of initial indentation levels (must be >= 1)
    #
    # Returns:
    #    (str): The formatted values
    #
    def _format_list(self, values, *, indent=1):
        text = ""

        # We need at least 2 leading spaces inside the indentation in order
        # to print bullets.
        assert indent >= 1

        # Indent string in case of multiline values
        indent_string = self._indent * indent

        # Prepare the indented bullet right away
        indent_bullet = self.format_profile.fmt(indent_string[:-2] + "* ")

        for value in values:
            value = str(value)

            # In case of newlines, replace each newline in the value with a trailing
            # indent and strip the result.
            value = value.replace("\n", "\n" + indent_string)
            value = value.strip()

            # Append the bullet
            text += indent_bullet

            # Append the value
            text += self.content_profile.fmt(value)
            text += "\n"

        return text

    # pretty_print_element_contents()
    #
    # Formats a dictionary of elements and their contents in a human readable way
    #
    # Args:
    #    values (Dict[str, Directory]): A dictionary
    #    style_value (bool): Whether to use the content profile for the values
    #    list_long (bool): whether to display verbose information about files
    #
    # Returns:
    #    (str): The formatted element contents
    #
    def pretty_print_element_contents(self, values, long_=False, style_value=True):
        text = ""

        for element_name, directory in values.items():

            text += self.format_profile.fmt("  {}:".format(element_name))

            rendered_files = []
            for filename in directory.list_relative_paths():
                filestat = directory.stat(filename)
                rendered_files.append(self._get_filestats(directory, filename, filestat, list_long=long_))

            value_list = "\n\t" + "\n\t".join(rendered_files)

            if not rendered_files:
                message = "\n\tThis element has no associated artifacts"
                if style_value:
                    text += self.content_profile.fmt(message)
                else:
                    text += message
            elif style_value:
                text += self.content_profile.fmt(value_list)
            else:
                text += value_list
            text += "\n"

        return text

    # show_state_of_artifacts()
    #
    # Show the cached status of artifacts
    #
    # Example output:
    #
    #    "cached      foo.bst"      <- If cached locally
    #    "failed      foo.bst"      <- If cached locally as a failure
    #    "available   foo.bst"      <- If available to download from a remote
    #    "not cached  foo.bst"      <- If not cached/available remotely.
    #
    # Note that artifact names may also be displayed here.
    #
    # Args:
    #    targets (list [Element]): Elements (or ArtifactElements) we wish to show the
    #                              cached status of
    #
    def show_state_of_artifacts(self, targets):
        report = ""
        p = Profile()
        for element in targets:

            #
            # Here we selectively show the element name or artifact name
            # depending on whether we were asked about an artifact or an element.
            #
            if isinstance(element, ArtifactElement):
                element_name = element.get_artifact_name()
            else:
                element_name = element._get_full_name()

            line = "%{state: >12} %{name}"
            line = p.fmt_subst(line, "name", element_name, fg="yellow")

            if element._cached_success():
                line = p.fmt_subst(line, "state", "cached", fg="magenta")
            elif element._cached():
                line = p.fmt_subst(line, "state", "failed", fg="red")
            elif element._cached_remotely():
                line = p.fmt_subst(line, "state", "available", fg="green")
            else:
                line = p.fmt_subst(line, "state", "not cached", fg="bright_red")

            report += line + "\n"

        return report

    # _get_filestats()
    #
    # Gets the necessary information from a dictionary
    #
    # Args:
    #    directory (Directory): The base directory
    #    filename (str): A filename inside the directory
    #    filestat (FileStat): A FileStat for the filename
    #    list_long (Bool): whether to display verbose information about artifacts
    #
    # Returns:
    #    (str): The information about the element
    #
    def _get_filestats(self, directory, filename, filestat, list_long=False):
        if list_long:
            size = str(filestat.size)
            # Support files up to 99G, meaning maximum characters is 11
            max_v_len = 11
            if filestat.file_type == FileType.DIRECTORY:
                return (
                    "drwxr-xr-x  dir    {}".format(size)
                    + "{} ".format(" " * (max_v_len - len(size)))
                    + "{}".format(filename)
                )
            elif filestat.file_type == FileType.SYMLINK:
                target = directory.readlink(*filename.split(os.path.sep))
                return (
                    "lrwxrwxrwx  link   {}".format(size)
                    + "{} ".format(" " * (max_v_len - len(size)))
                    + "{} -> {}".format(filename, target)
                )
            elif filestat.executable:
                return (
                    "-rwxr-xr-x  exe    {}".format(size)
                    + "{} ".format(" " * (max_v_len - len(size)))
                    + "{}".format(filename)
                )
            else:
                return (
                    "-rw-r--r--  reg    {}".format(size)
                    + "{} ".format(" " * (max_v_len - len(size)))
                    + "{}".format(filename)
                )
        return filename