""" Automatically update certain sections of README.md for osxphotos 
    Also updates osxphotos/phototemplate.md 
"""

# This is a pretty "dumb" script that searches the README.md for
# certain tags, expressed as HTML comments, and replaces text between
# those tags.  The following replacements are made:
# 1. the output of "osxphotos help export"
# 2. the template substitution table
# Running this script ensures the above sections of the README.md contain
# the most current information, updated directly from the code.

import re

from click.testing import CliRunner

from osxphotos.cli import cli_main
from osxphotos.phototemplate import get_template_field_table, get_template_help

TUTORIAL_HELP = "osxphotos/tutorial.md"

USAGE_START = (
    "<!-- OSXPHOTOS-EXPORT-USAGE:START - Do not remove or modify this section -->"
)
USAGE_STOP = "<!-- OSXPHOTOS-EXPORT-USAGE:END -->"

TEMPLATE_TABLE_START = (
    "<!-- OSXPHOTOS-TEMPLATE-TABLE:START - Do not remove or modify this section -->"
)
TEMPLATE_TABLE_STOP = "<!-- OSXPHOTOS-TEMPLATE-TABLE:END -->"

TEMPLATE_HELP_START = (
    "<!-- OSXPHOTOS-TEMPLATE-HELP:START - Do not remove or modify this section -->"
)
TEMPLATE_HELP_STOP = "<!-- OSXPHOTOS-TEMPLATE-HELP:END -->"

TUTORIAL_START = "<!-- OSXPHOTOS-TUTORIAL:START -->"
TUTORIAL_STOP = "<!-- OSXPHOTOS-TUTORIAL:END -->"

TUTORIAL_HEADER_START = "<!-- OSXPHOTOS-TUTORIAL-HEADER:START -->"
TUTORIAL_HEADER_STOP = "<!-- OSXPHOTOS-TUTORIAL-HEADER:END -->"

TEMPLATE_SYSTEM_LINK_START = "<!-- OSXPHOTOS-TEMPLATE-SYSTEM-LINK:START -->"
TEMPLATE_SYSTEM_LINK_STOP = "<!-- OSXPHOTOS-TEMPLATE-SYSTEM-LINK:END -->"

API_README = "API_README.md"


def generate_help_text(command):
    """generate output of `osxphotos help command`"""
    runner = CliRunner()

    # get current help text
    with runner.isolated_filesystem():
        result = runner.invoke(cli_main, ["help", command, "--width", 78])
        help_txt = result.output

    # running the help command above doesn't output the full "Usage" line
    help_txt = help_txt.replace("Usage: cli-main", "Usage: osxphotos")
    return help_txt


def replace_text(text, start_tag, stop_tag, replacement_text, prefix="", postfix=""):
    """replace text between start/stop tags with new text

    Args:
        text: str, original text
        start_tag: str, tag to find at beginning of replacement
        stop_tag: str, tag to find at end of replacement
        prefix: optional prefix that will go between start_tag and replacement_text
        postfix: optional postfix that will go between replacement_text and stop_tag
        replacement_text: str, new text to place between start_tag, stop_tag

    Returns:
        str
    """

    # sanity check to ensure tags are present
    if start_tag not in text:
        raise ValueError(f"start_tag {start_tag} not in text")
    if stop_tag not in text:
        raise ValueError(f"stop_tag {stop_tag} not in text")

    begin = end = ""
    try:
        begin = text.split(start_tag)[0]
        end = text.split(stop_tag)[1]
    except IndexError as e:
        # didn't find one of the delimiters
        raise ValueError(f"Unable to parse input: {e}") from e

    return begin + start_tag + prefix + replacement_text + postfix + stop_tag + end


def main():
    """update README.md"""

    # update the help text for `osxphotos help export`
    print("Updating help for `osxphotos help export`")
    with open("README.md", "r") as file:
        readme = file.read()
    help_txt = generate_help_text("export")
    new_readme = replace_text(
        readme, USAGE_START, USAGE_STOP, help_txt, prefix="\n```\n", postfix="\n```\n"
    )

    # update the template substitution table
    print("Updating template substitution table")
    template_table = get_template_field_table()
    new_readme = replace_text(
        new_readme,
        TEMPLATE_TABLE_START,
        TEMPLATE_TABLE_STOP,
        template_table,
        prefix="\n",
        postfix="\n",
    )

    # update the template system docs
    template_help = get_template_help()

    new_readme = replace_text(
        new_readme,
        TEMPLATE_HELP_START,
        TEMPLATE_HELP_STOP,
        template_help,
        prefix="\n",
        postfix="\n",
    )

    # update the tutorial
    print("Updating tutorial")
    with open(TUTORIAL_HELP) as fd:
        tutorial_help = fd.read()

    # indent all Markdown headers two more levels
    tutorial_help = re.sub(r"^([#]+)", r"\1##", tutorial_help, flags=re.MULTILINE)

    # insert link for Template System
    tutorial_help = replace_text(
        tutorial_help,
        TEMPLATE_SYSTEM_LINK_START,
        TEMPLATE_SYSTEM_LINK_STOP,
        "[Template System](#template-system)",
    )

    # remove Tutorial Header
    tutorial_help = replace_text(
        tutorial_help, TUTORIAL_HEADER_START, TUTORIAL_HEADER_STOP, ""
    )

    # insert tutorial text into readme
    new_readme = replace_text(new_readme, TUTORIAL_START, TUTORIAL_STOP, tutorial_help)

    print("Writing new README.md")
    with open("README.md", "w") as file:
        file.write(new_readme)


if __name__ == "__main__":
    main()