import os
import re
from contextlib import contextmanager
from pathlib import Path
from typing import Optional, Iterator, Iterable


# So that httpie.cli.definition can provide man-page-specific output. Must be set before importing httpie.
os.environ['HTTPIE_BUILDING_MAN_PAGES'] = '1'

import httpie
from httpie.cli.definition import options as core_options, IS_MAN_PAGE
from httpie.cli.options import ParserSpec
from httpie.manager.cli import options as manager_options
from httpie.output.ui.rich_help import OptionsHighlighter, to_usage
from httpie.output.ui.rich_utils import render_as_string


assert IS_MAN_PAGE, 'CLI definition does not understand we’re building man pages'

# Escape certain characters, so they are rendered properly on all terminals.
# <https://man7.org/linux/man-pages/man7/groff_char.7.html>
ESCAPE_MAP = {
    '"': '\[dq]',
    "'": '\[aq]',
    '~': '\(ti',
    '’': "\(ga",
    '\\': '\e',
}
ESCAPE_MAP = {ord(key): value for key, value in ESCAPE_MAP.items()}

EXTRAS_DIR = Path(__file__).parent.parent
MAN_PAGE_PATH = EXTRAS_DIR / 'man'
PROJECT_ROOT = EXTRAS_DIR.parent

OPTION_HIGHLIGHT_RE = re.compile(
    OptionsHighlighter.highlights[0]
)


class ManPageBuilder:
    def __init__(self):
        self.source = []

    def title_line(
        self,
        full_name: str,
        program_name: str,
        program_version: str,
        last_edit_date: str,
    ) -> None:
        self.source.append(
            f'.TH {program_name} 1 "{last_edit_date}" '
            f'"{full_name} {program_version}" "{full_name} Manual"'
        )

    def set_name(self, program_name: str) -> None:
        with self.section('NAME'):
            self.write(program_name)

    def write(self, text: str, *, bold: bool = False) -> None:
        if bold:
            text = '.B ' + text
        self.source.append(text)

    def separate(self) -> None:
        self.source.append('.PP')

    def format_desc(self, desc: str) -> str:
        description = _escape_and_dedent(desc)
        description = OPTION_HIGHLIGHT_RE.sub(
            # Boldify the option part, but don't remove the prefix (start of the match).
            lambda match: match[1] + self.boldify(match['option']),
            description
        )
        return description

    def add_comment(self, comment: str) -> None:
        self.source.append(f'.\\" {comment}')

    def add_options(self, options: Iterable[str], *, metavar: Optional[str] = None) -> None:
        text = ", ".join(map(self.boldify, options))
        if metavar:
            text += f' {self.underline(metavar)}'
        self.write(f'.IP "{text}"')

    def build(self) -> str:
        return '\n'.join(self.source)

    @contextmanager
    def section(self, section_name: str) -> Iterator[None]:
        self.write(f'.SH {section_name}')
        self.in_section = True
        yield
        self.in_section = False

    def underline(self, text: str) -> str:
        return r'\fI\,{}\/\fR'.format(text)

    def boldify(self, text: str) -> str:
        return r'\fB\,{}\/\fR'.format(text)


def _escape_and_dedent(text: str) -> str:
    lines = []
    for should_act, line in enumerate(text.splitlines()):
        # Only dedent after the first line.
        if should_act:
            if line.startswith('    '):
                line = line[4:]

        lines.append(line)
    return '\n'.join(lines).translate(ESCAPE_MAP)


def to_man_page(program_name: str, spec: ParserSpec, *, is_top_level_cmd: bool = False) -> str:
    builder = ManPageBuilder()
    builder.add_comment(
        f"This file is auto-generated from the parser declaration "
        + (f"in {Path(spec.source_file).relative_to(PROJECT_ROOT)} " if spec.source_file else "")
        + f"by {Path(__file__).relative_to(PROJECT_ROOT)}."
    )

    builder.title_line(
        full_name='HTTPie',
        program_name=program_name,
        program_version=httpie.__version__,
        last_edit_date=httpie.__date__,
    )
    builder.set_name(program_name)

    with builder.section('SYNOPSIS'):
        # `http` and `https` are commands that can be directly used, so they can have
        # a valid usage. But `httpie` is a top-level command with multiple sub commands,
        # so for the synopsis we'll only reference the `httpie` name.
        if is_top_level_cmd:
            synopsis = program_name
        else:
            synopsis = render_as_string(to_usage(spec, program_name=program_name))
        builder.write(synopsis)

    with builder.section('DESCRIPTION'):
        builder.write(spec.description)
        if spec.man_page_hint:
            builder.write(spec.man_page_hint)

    for index, group in enumerate(spec.groups, 1):
        with builder.section(group.name):
            if group.description:
                builder.write(group.description)

            for argument in group.arguments:
                if argument.is_hidden:
                    continue

                raw_arg = argument.serialize(isolation_mode=True)

                metavar = raw_arg.get('metavar')
                if raw_arg.get('is_positional'):
                    # In case of positional arguments, metavar is always equal
                    # to the list of options (e.g `METHOD`).
                    metavar = None
                builder.add_options(raw_arg['options'], metavar=metavar)

                desc = builder.format_desc(raw_arg.get('description', ''))
                builder.write('\n' + desc + '\n')

            builder.separate()

    if spec.epilog:
        with builder.section('SEE ALSO'):
            builder.write(builder.format_desc(spec.epilog))

    return builder.build()


def main() -> None:
    for program_name, spec, config in [
        ('http', core_options, {}),
        ('https', core_options, {}),
        ('httpie', manager_options, {'is_top_level_cmd': True}),
    ]:
        with open((MAN_PAGE_PATH / program_name).with_suffix('.1'), 'w') as stream:
            stream.write(to_man_page(program_name, spec, **config))


if __name__ == '__main__':
    main()