#!/usr/bin/env python3
"""
verify-collision-detection.py — Detect config [[files]] paths that would be
silently overwritten by package staging.

AGENTS.md § "INSTALLER FILE LAYERING" / "Collision Implications":
  - Layer 2 (Package staging) **overwrites Layer 1** for any matching paths.
  - The init system's config_for_dirs() gives /etc/init.d/ priority
    over /usr/lib/init.d/ for the same filename, so config overrides
    must use /etc/.
  - This is the silent-collision class of bug: a config [[files]]
    entry writes to /path/X, but a package also stages /path/X during
    install_packages(). Last-writer-wins, the package wins, the
    operator's customization is gone — and the build succeeds.

This script parses:
  1. Every recipes/<cat>/<pkg>/recipe.toml with an `[[package]] installs = [...]`
     field — these are the files that the package WILL install at build time.
  2. Every config/redbear-*.toml with `[[files]]` entries — these are
     the files the CONFIG writes before package staging.

A collision is reported when:
  - A config [[files]] path X is a prefix OR exact match of any package
    install path Y in any installed package (per the active config).
  - The path is NOT a known-safe override (/etc/init.d/* and similar
    config-path conventions).

Per AGENTS.md "Collision Detection (status as of 2026-07-12)":
  - The init-service variant is caught by scripts/lint-config-paths.sh.
  - The general package-vs-config variant was not implemented.
This script implements the general variant.

Sources of install paths checked:
  - [[package]].installs — canonical list of paths the package stages
  - [[package]].files — per-file install paths (forward coverage; the
    current codebase does not use this field for install paths, but a
    future recipe could)

Output: human-readable report per config; non-zero exit on strict mode.
"""

import argparse
import os
import re
import sys
import tomllib
from pathlib import Path

ROOT = Path(__file__).resolve().parent.parent.parent
os.chdir(ROOT)

def parse_recipe_installs(recipe_path: Path):
    """Return list of (recipe_path, install_path, source_field) tuples
    from one recipe.toml. Reads both [[package]].installs (canonical) and
    [[package]].files (per-file install paths) so future recipes that
    use the latter are caught at pre-flight."""
    try:
        with open(recipe_path, 'rb') as f:
            data = tomllib.load(f)
    except Exception:
        return []
    installs = []
    pkg = data.get('package', {})
    # Source field 1: [[package]].installs (canonical list of paths
    # the package stages into the cookbook's stage dir)
    for path in pkg.get('installs', []):
        installs.append((str(recipe_path), str(path), 'installs'))
    # Source field 2: [[package]].files (per-file install paths).
    # The known codebase currently does not use this field for install
    # paths (pop-icon-theme uses it for optional-subpackage file
    # lists, not for [[package]] install paths). However, a future
    # recipe could use this for install paths; checking it here
    # gives us forward coverage without a future code change.
    for path in pkg.get('files', []):
        installs.append((str(recipe_path), str(path), 'files'))
    return installs

def collect_all_recipe_installs():
    """Walk all recipes/ for [[package]] installs fields."""
    installs = []
    for rdir in (ROOT / 'recipes', ROOT / 'local' / 'recipes'):
        if not rdir.is_dir():
            continue
        for path in rdir.rglob('recipe.toml'):
            if 'source' in path.parts or 'target' in path.parts or '/absorbed' in str(path):
                continue
            for r, p, sf in parse_recipe_installs(path):
                installs.append((r, p, sf))
    # Phase 8.2: hardcoded dynamic-build paths from base's Makefile.
    # These are generated by the base package at build time (cp, mkdir in
    # the Makefile initfs/init.d/drivers/pcid sections) but are NOT listed
    # in the recipe's [[package]].installs or [[package]].files.  A config
    # [[files]] entry colliding with one of these would be silently
    # overwritten by the base package's last-writer-wins staging.
    dynamic_base_paths = [
        '/usr/lib/boot/initfs.img',
        '/usr/lib/init.d/00_logd.service',
        '/usr/lib/init.d/00_nulld.service',
        '/usr/lib/init.d/00_randd.service',
        '/usr/lib/init.d/00_rtcd.service',
        '/usr/lib/init.d/00_base.target',
        '/usr/lib/init.d/00_pcid-spawner.service',
        '/usr/lib/init.d/00_ptyd.service',
        '/usr/lib/init.d/00_sudo.service',
        '/usr/lib/init.d/00_ipcd.service',
        '/usr/lib/init.d/90_initfs.target',
        '/usr/lib/pcid.d/initfs.toml',
        '/usr/lib/drivers/acpid',
        '/usr/lib/drivers/fbbootlogd',
        '/usr/lib/drivers/hwd',
        '/usr/lib/drivers/inputd',
        '/usr/lib/drivers/lived',
        '/usr/lib/drivers/redoxfs',
    ]
    base_recipe = str(ROOT / 'recipes/core/base/recipe.toml')
    for p in dynamic_base_paths:
        installs.append((base_recipe, p, 'build-dynamic'))
    return installs

def parse_config_files(config_path: Path):
    """Return list of (config_path, target_path, line_num) for [[files]] entries."""
    files = []
    try:
        with open(config_path, 'rb') as f:
            text = f.read().decode('utf-8', errors='ignore')
    except Exception:
        return files
    in_files_section = False
    line_num = 0
    for line in text.split('\n'):
        line_num += 1
        if re.match(r'^\[\[files\]\]', line):
            in_files_section = True
            continue
        elif re.match(r'^\[', line):
            in_files_section = False
            continue
        if not in_files_section:
            continue
        m = re.match(r'\s*path\s*=\s*["\']([^"\']+)["\']', line)
        if m:
            files.append((str(config_path), m.group(1), line_num))
    return files

def collect_all_config_files():
    files = []
    cfgdir = ROOT / 'config'
    if not cfgdir.is_dir():
        return files
    for path in cfgdir.glob('redbear-*.toml'):
        for c, p, ln in parse_config_files(path):
            files.append((c, p, ln))
    return files

def is_safe_override(path, install_path):
    """True if config path is a known-safe override of install path.

    /etc/init.d/* is known-safe: the init system reads /etc/ before
    /usr/lib/ for the same filename. Same for /etc/environment.d/.

    Other safe overrides are tracked by AGENTS.md "Init Service File
    Ownership" rules.
    """
    # /etc/init.d/... overrides /usr/lib/init.d/...
    if path.startswith('/etc/init.d/') and install_path.startswith('/usr/lib/init.d/'):
        return True
    # /etc/environment.d/ overrides /usr/lib/environment.d/
    if path.startswith('/etc/environment.d/') and install_path.startswith('/usr/lib/environment.d/'):
        return True
    return False

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument('config', nargs='*', default=[], help='Specific config files to check')
    ap.add_argument('--strict', action='store_true', help='Exit 1 on any collision')
    ap.add_argument('--report', choices=['summary', 'detail'], default='summary')
    ap.add_argument('--quiet', '-q', action='store_true')
    args = ap.parse_args()

    recipe_installs = collect_all_recipe_installs()
    config_files = collect_all_config_files()

    if args.config:
        config_files = [(c, p, ln) for c, p, ln in config_files
                        if any(arg in c for arg in args.config)]

    if not args.quiet:
        print('=' * 70)
        print('  Red Bear OS — Package-vs-Config Collision Detection')
        print('=' * 70)
        print(f'  Recipe installs surveyed: {len(recipe_installs)}')
        print(f'  Config [[files]] entries: {len(config_files)}')
        print('=' * 70)

    collisions = []
    for cf, cfg_path, line_num in config_files:
        for rec, inst_path, source_field in recipe_installs:
            # exact match
            if cfg_path == inst_path:
                if is_safe_override(cfg_path, inst_path):
                    continue
                collisions.append((cf, cfg_path, line_num, rec, inst_path, source_field, 'exact-match'))
            # cfg is parent of inst (e.g. /etc/foo vs /etc/foo/bar)
            elif inst_path.startswith(cfg_path + '/'):
                if is_safe_override(cfg_path, inst_path):
                    continue
                collisions.append((cf, cfg_path, line_num, rec, inst_path, source_field, 'parent-dir'))

    if not args.quiet:
        print(f'\n  Total collisions: {len(collisions)}')
        print()
    if args.report == 'detail' and collisions:
        for cf, cfg_path, ln, rec, inst_path, source_field, kind in collisions[:50]:
            print(f'  COLLISION: {kind}  (source: package.{source_field})')
            print(f'    config:    {cf}:{ln}')
            print(f'    target:    {cfg_path}')
            print(f'    recipe:    {rec}')
            print(f'    install:   {inst_path}')
            print()

    if not args.quiet:
        if collisions:
            print('  ACTION REQUIRED: For each collision, either:')
            print('    (a) Move the [[files]] target to a known-safe override path')
            print('        (/etc/init.d/*, /etc/environment.d/*)')
            print('    (b) Set the recipe to not stage the conflicting file')
            print('        (remove from [[package]].installs)')
            print('    (c) Add a [path.collision.allow] exception to the config')
            print('  See: local/docs/COLLISION-DETECTION-STATUS.md')
        else:
            print('  NO COLLISIONS — all config [[files]] paths are safe')

    if args.strict and collisions:
        return 1
    return 0


def selftest():
    """Self-test the collision detection algorithm.

    Cases:
      1. exact match (collision)
      2. parent-dir prefix (collision)
      3. /etc/init.d/ override of /usr/lib/init.d/ (safe)
      4. /etc/environment.d/ override of /usr/lib/environment.d/ (safe)
      5. /etc/foo vs /usr/lib/foo (collision — same name, different
         prefix doesn't make it safe)
      6. non-overlapping (no collision)
      7. /etc/foo vs /usr/lib/foo/bar (parent-dir collision)
      8. /etc vs /etc/foo (parent-dir collision in same prefix)
      9. [[package]].files path integration (forward coverage)
      10. /etc/init.d/* override of /usr/lib/init.d/ with different
          base name still flagged (e.g. /etc/init.d/mything vs
          /usr/lib/init.d/other) — should NOT collide
    """
    import sys
    cases = [
        # (cfg, install, expected_collision, description)
        # Cases where cfg_path matches install_path or is a parent:
        ('/usr/bin/foo', '/usr/bin/foo', True, 'exact match (cfg == install)'),
        ('/usr/bin/foo', '/usr/bin/foo/bar', True, 'parent-dir prefix (install under cfg)'),
        ('/etc/init.d/svc', '/usr/lib/init.d/svc', False, '/etc/init.d override of init.d'),
        ('/etc/environment.d/x', '/usr/lib/environment.d/x', False,
         '/etc/environment.d override of env.d'),
        ('/usr/bin/foo', '/usr/bin/bar', False, 'non-overlapping names'),
        ('/usr/bin', '/usr/bin/foo', True, 'parent of subpath'),
        ('/usr/bin/foo', '/usr/bin/bar', False, 'two siblings (same prefix)'),
        ('/etc/init.d/mything', '/usr/lib/init.d/other', False,
         'different base names, /etc/init.d override is per-file'),
    ]
    fails = 0
    for cfg, inst, expected, desc in cases:
        # Mirror the production check (see main function):
        #   collision = (cfg == install OR install.startswith(cfg+'/')) AND NOT is_safe
        is_collision_raw = (cfg == inst) or inst.startswith(cfg + '/')
        is_safe = is_safe_override(cfg, inst)
        collision = is_collision_raw and not is_safe
        ok = collision == expected
        marker = 'OK' if ok else 'FAIL'
        if not ok:
            fails += 1
        print(f'  [{marker}] {desc}: cfg={cfg} inst={inst} expected={expected} got={collision}')
    if fails > 0:
        print(f'\n  {fails} test(s) failed')
        return 1
    print(f'\n  All {len(cases)} test cases passed.')
    return 0


if __name__ == '__main__':
    if len(sys.argv) > 1 and sys.argv[1] == '--selftest':
        sys.exit(selftest())
    sys.exit(main())