#!/usr/bin/env python3
"""
Prune communishift_projects under ansible/inventory/group_vars/all:

  - Keeps entries where do_not_delete is truthy (true / yes / 1 / on, case-insensitive strings).
  - Removes every other child mapping under communishift_projects.

Only the communishift_projects mapping (that key plus its body up to—but not including—the
next line at indentation 0) is rewritten. All other bytes in the file are preserved.

Default: dry-run (no writes). Print summary; use --diff for a unified file diff.

Dependencies: PyYAML (python3-pyyaml).

Examples:

  ansible/scripts/communishift_prune_projects
  ansible/scripts/communishift_prune_projects --diff
  ansible/scripts/communishift_prune_projects --write
"""

from __future__ import annotations

import argparse
import difflib
import os
import re
import sys
from pathlib import Path
from tempfile import NamedTemporaryFile
from typing import Any, Dict, List, Mapping, Sequence, Tuple

try:
    import yaml
except ImportError as exc:
    sys.stderr.write(
        "This script requires PyYAML (install python3-pyyaml on this host).\n"
    )
    raise SystemExit(1) from exc


_STANZA_START = re.compile(r"^([A-Za-z0-9_.-]+):\s*(?:\#.*)?\s*$")
_CHILD_INDENT = 2


def ansible_truthy(value: Any) -> bool:
    if isinstance(value, bool):
        return value
    if isinstance(value, str):
        return value.strip().lower() in {"true", "yes", "1", "on"}
    return False


def _expanded_indent(raw: str) -> int:
    return len(raw.expandtabs()) - len(raw.expandtabs().lstrip(" "))


def locate_communishift_block(lines: Sequence[str]) -> Tuple[int, int]:
    start = None
    for i, line in enumerate(lines):
        if line.lstrip("\ufeff").startswith("communishift_projects:"):
            start = i
            break
    if start is None:
        raise ValueError('No root key line starting with "communishift_projects:"')

    root_indent = _expanded_indent(lines[start])
    j = start + 1
    n_lines = len(lines)
    while j < n_lines:
        line = lines[j]
        if line.strip("\r\n") == "":
            j += 1
            continue
        if _expanded_indent(line) <= root_indent:
            break
        j += 1
    return start, j


def parse_stanza_blocks(
    section_body: Sequence[str],
) -> Tuple[List[str], Dict[str, List[str]]]:
    """
    Lines AFTER the communishift_projects: line. Preamble = comments/blanks/stanzas whose
    first line is not a two-space child key line.
    """
    preamble: List[str] = []
    blocks: Dict[str, List[str]] = {}

    idx = 0
    maximum = len(section_body)
    while idx < maximum:
        line = section_body[idx]
        stripped_for_match = line.rstrip("\r\n")
        indent = _expanded_indent(line)
        matched = indent == _CHILD_INDENT and bool(
            _STANZA_START.match(stripped_for_match.lstrip(" "))
        )
        if matched:
            key_match = _STANZA_START.match(stripped_for_match.lstrip(" "))
            assert key_match is not None
            key = key_match.group(1)
            if key in blocks:
                raise ValueError("Duplicate Communishift stanza key {0!r}".format(key))
            stanza_lines: List[str] = [line]
            idx += 1
            while idx < maximum:
                nxt = section_body[idx]
                n_indent = _expanded_indent(nxt)
                nn = _STANZA_START.match(nxt.rstrip("\r\n").lstrip(" "))
                if n_indent == _CHILD_INDENT and nn:
                    break
                stanza_lines.append(nxt)
                idx += 1
            blocks[key] = list(stanza_lines)
            continue

        preamble.append(line)
        idx += 1

    return preamble, blocks


def stanza_keeps(meta: Any) -> bool:
    return isinstance(meta, Mapping) and ansible_truthy(meta.get("do_not_delete"))


def load_projects_map(path: Path) -> Mapping[str, Any]:
    raw = yaml.safe_load(path.read_text(encoding="utf-8"))
    if not isinstance(raw, dict):
        raise ValueError("YAML root must be a mapping")
    proj = raw.get("communishift_projects")
    if proj is None:
        raise ValueError("communishift_projects missing from YAML")
    if not isinstance(proj, dict):
        raise ValueError("communishift_projects must be a mapping")

    return proj


def splice_communishift_projects(
    text: str,
    proj_data: Mapping[str, Any],
) -> Tuple[str, Dict[str, Any]]:
    lines = text.splitlines(keepends=True)
    start, end = locate_communishift_block(lines)
    header_line = lines[start]

    body = lines[start + 1 : end]
    preamble, blocks = parse_stanza_blocks(body)

    removed: List[str] = []
    skipped_non_mapping: List[str] = []
    kept_names: List[str] = []

    for key in sorted(blocks.keys()):
        meta = proj_data.get(key)
        if not stanza_keeps(meta):
            removed.append(key)
            if not isinstance(meta, dict):
                skipped_non_mapping.append(key)
            continue
        kept_names.append(str(meta.get("name", key)))

    sorted_kept = sorted(k for k in blocks if stanza_keeps(proj_data.get(k)))
    new_section: List[str] = [header_line]
    new_section.extend(preamble)
    for k in sorted_kept:
        new_section.extend(blocks[k])

    after = "".join(lines[:start] + new_section + lines[end:])
    stats = {
        "kept_count": len(sorted_kept),
        "kept_names": sorted(kept_names),
        "removed": removed,
        "skipped_non_mapping": skipped_non_mapping,
    }
    return after, stats


def main(argv: List[str]) -> int:
    ansible_root = Path(__file__).resolve().parent.parent
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument(
        "--group-vars",
        type=Path,
        default=ansible_root / "inventory" / "group_vars" / "all",
        help="YAML file defining communishift_projects",
    )
    parser.add_argument(
        "--diff",
        action="store_true",
        help="Print unified diff of the whole file",
    )
    parser.add_argument(
        "--write",
        action="store_true",
        help="Write the updated file",
    )
    args = parser.parse_args(argv)

    group_vars_path = Path(args.group_vars)
    original_text = group_vars_path.read_text(encoding="utf-8")

    try:
        proj_data = load_projects_map(group_vars_path)
    except ValueError as err:
        sys.stderr.write("{0}: {1}\n".format(group_vars_path, err))
        return 1

    try:
        after_text, stats = splice_communishift_projects(original_text, proj_data)
    except ValueError as err:
        sys.stderr.write("{0}: {1}\n".format(group_vars_path, err))
        return 1

    print("File: {0}".format(group_vars_path))
    extra = ""
    if stats["skipped_non_mapping"]:
        extra = " (+ {0} non-mapping skipped)".format(len(stats["skipped_non_mapping"]))

    print(
        "Keeping {0} project stanza(s){1}".format(stats["kept_count"], extra),
    )
    if stats["kept_names"]:
        print("  " + ", ".join(sorted(stats["kept_names"])))

    print("Removing {0} stanza key(s)".format(len(stats["removed"])))
    for name in sorted(stats["removed"], key=lambda s: str(s).lower()):
        print("  - {0}".format(name))

    if args.diff:
        sys.stdout.writelines(
            difflib.unified_diff(
                original_text.splitlines(True),
                after_text.splitlines(True),
                fromfile="{0} (before)".format(group_vars_path),
                tofile="{0} (after)".format(group_vars_path),
            )
        )

    if after_text == original_text:
        print("\nNo changes needed.")
        return 0

    if not args.write:
        print("\nDry-run only — no file modified. Pass --write to apply.")
        return 0

    fh = NamedTemporaryFile(
        mode="w",
        encoding="utf-8",
        suffix=".tmp",
        prefix="communishift-prune.",
        dir=str(group_vars_path.parent),
        delete=False,
    )
    tmp_path = fh.name
    try:
        fh.write(after_text)
        fh.flush()
        os.fsync(fh.fileno())
        fh.close()
        os.replace(tmp_path, group_vars_path)
    except OSError:
        fh.close()
        try:
            os.unlink(tmp_path)
        except OSError:
            pass
        raise
    print("\nUpdated {0}".format(group_vars_path))
    return 0


if __name__ == "__main__":
    raise SystemExit(main(sys.argv[1:]))