#!/usr/bin/env python3

import argparse
import sys
from typing import Tuple, Union

try:
    from sweagent import TOOLS_DIR
except ImportError:
    pass
else:
    default_lib = TOOLS_DIR / "windowed" / "lib"
    assert default_lib.is_dir()
    sys.path.append(str(default_lib))
    sys.path.append(str(TOOLS_DIR / "registry" / "lib"))

from windowed_file import FileNotOpened, WindowedFile  # type: ignore
from flake8_utils import flake8, format_flake8_output  # type: ignore

_USAGE_MSG = """Usage: edit <start_line>:<end_line>
<replacement_text>
end_of_edit"""

_EDIT_SUCCESS_MSG = """File updated. Please review the changes and make sure they are correct
(correct indentation, no duplicate lines, etc). Edit the file again if necessary."""

_LINT_ERROR_TEMPLATE = """Your proposed edit has introduced new syntax error(s). Please read this error message carefully and then retry editing the file.

ERRORS:
{errors}

This is how your edit would have looked if applied
------------------------------------------------
{window_applied}
------------------------------------------------

This is the original code before your edit
------------------------------------------------
{window_original}
------------------------------------------------

Your changes have NOT been applied. Please fix your edit command and try again.
DO NOT re-run the same failed edit command. Running it again will lead to the same error."""


def get_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser()
    parser.add_argument("line_range", help="Line range in format start:end")
    parser.add_argument("replacement_text", help="Text to insert", nargs="?")
    return parser


def parse_line_range(line_range: str) -> Tuple[int, int]:
    try:
        start, end = map(int, line_range.split(":"))
        return start - 1, end - 1
    except ValueError:
        print(_USAGE_MSG)
        exit(1)


def main(line_range: str, replacement_text: Union[str, None] = None):
    # Handle file opening
    try:
        wf = WindowedFile(exit_on_exception=False)
    except FileNotOpened:
        print("No file opened. Use the `open` command first.")
        exit(1)

    # Parse line range
    start_line, end_line = parse_line_range(line_range)

    if replacement_text is None:
        # Read replacement text from stdin (e.g., when sent via bash heredoc)
        # if not provided as argument
        replacement_lines = []
        while True:
            try:
                line = input()
                if line == "end_of_edit":
                    break
                replacement_lines.append(line)
            except EOFError:
                break
        replacement_text = "\n".join(replacement_lines)
    else:
        if replacement_text.endswith("\n"):
            replacement_text = replacement_text[:-1]

    if replacement_text is None:
        print(_USAGE_MSG)
        exit(1)

    # Get pre-edit linting errors
    pre_edit_lint = flake8(wf.path)

    # Perform the edit
    wf.set_window_text(replacement_text, line_range=(start_line, end_line))

    # Check for new linting errors
    post_edit_lint = flake8(wf.path)
    new_flake8_output = format_flake8_output(
        post_edit_lint,
        previous_errors_string=pre_edit_lint,
        replacement_window=(start_line, end_line),
        replacement_n_lines=len(replacement_text.splitlines()),
    )

    if new_flake8_output:
        # Show error and revert changes
        with_edits = wf.get_window_text(line_numbers=True, status_line=True, pre_post_line=True)
        wf.undo_edit()
        without_edits = wf.get_window_text(line_numbers=True, status_line=True, pre_post_line=True)
        print(
            _LINT_ERROR_TEMPLATE.format(
                errors=new_flake8_output, window_applied=with_edits, window_original=without_edits
            )
        )
        exit(1)

    # Success - update window position and show result
    wf.goto(start_line, mode="top")
    print(_EDIT_SUCCESS_MSG)
    wf.print_window()


if __name__ == "__main__":
    main(**vars(get_parser().parse_args()))