#!/usr/bin/env python3
import urllib.request
import urllib.parse
import json
import subprocess
import os
import re
import tempfile
import sys
import shutil

def run_cmd(cmd, cwd=None):
    return subprocess.run(cmd, cwd=cwd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)

def get_local_foreign_packages():
    res = run_cmd(['pacman', '-Qm'])
    if res.returncode != 0:
        return {}
    pkgs = {}
    for line in res.stdout.strip().split('\n'):
        if line:
            parts = line.split()
            if len(parts) == 2:
                pkgs[parts[0]] = parts[1]
    return pkgs

def get_aur_info(pkgnames):
    if not pkgnames:
        return {}
    results = {}
    chunk_size = 100
    pkgs = list(pkgnames)
    for i in range(0, len(pkgs), chunk_size):
        chunk = pkgs[i:i+chunk_size]
        url = "https://aur.archlinux.org/rpc/v5/info?" + "&".join([f"arg[]={urllib.parse.quote(p)}" for p in chunk])
        try:
            req = urllib.request.urlopen(url, timeout=10)
            data = json.loads(req.read().decode('utf-8'))
            if data.get('type') == 'multiinfo':
                for item in data.get('results', []):
                    results[item['Name']] = item
        except Exception:
            pass
    return results

def needs_upgrade(local_ver, aur_ver):
    res = run_cmd(['vercmp', local_ver, aur_ver])
    try:
        return int(res.stdout.strip()) < 0
    except Exception:
        return False

def extract_ver(content):
    pkgver, pkgrel = None, None
    for line in content.split('\n'):
        line = line.strip()
        if line.startswith('pkgver='):
            pkgver = line.split('=', 1)[1].strip('"\'')
        elif line.startswith('pkgrel='):
            pkgrel = line.split('=', 1)[1].strip('"\'')
    return pkgver, pkgrel

def strip_volatile_fields(content):
    content = re.sub(r'^pkgver=.*$', '', content, flags=re.MULTILINE)
    content = re.sub(r'^pkgrel=.*$', '', content, flags=re.MULTILINE)
    sum_patterns = [
        r'md5sums', r'sha1sums', r'sha224sums', r'sha256sums', 
        r'sha384sums', r'sha512sums', r'b2sums', r'cksums'
    ]
    for sp in sum_patterns:
        pattern = r'^' + sp + r'(?:_[a-zA-Z0-9_]+)?=\(.*?\)'
        content = re.sub(pattern, '', content, flags=re.MULTILINE | re.DOTALL)
    
    lines = [line.rstrip() for line in content.split('\n') if line.strip()]
    return '\n'.join(lines)

def main():
    local_pkgs = get_local_foreign_packages()
    if not local_pkgs:
        sys.exit(0)

    aur_info = get_aur_info(list(local_pkgs.keys()))
    
    upgrades = []
    for pkg, local_ver in local_pkgs.items():
        if pkg in aur_info:
            aur_ver = aur_info[pkg]['Version']
            if needs_upgrade(local_ver, aur_ver):
                upgrades.append((pkg, local_ver, aur_ver))
                
    if not upgrades:
        sys.exit(0)
        
    print(f"Checking PKGBUILD diffs for {len(upgrades)} upgrades...")
    
    temp_dir = tempfile.mkdtemp()
    try:
        for pkg, local_ver, aur_ver in upgrades:
            print(f"Checking {pkg} ({local_ver} -> {aur_ver})")
            repo_dir = os.path.join(temp_dir, pkg)
            res = run_cmd(['git', 'clone', '--quiet', f'https://aur.archlinux.org/{pkg}.git', repo_dir])
            if res.returncode != 0:
                print(f"Failed to clone {pkg}", file=sys.stderr)
                sys.exit(1)
            
            res = run_cmd(['git', 'log', '--pretty=format:%H'], cwd=repo_dir)
            commits = res.stdout.strip().split('\n')
            
            old_pkgbuild_content = None
            new_pkgbuild_content = None
            
            with open(os.path.join(repo_dir, 'PKGBUILD'), 'r', encoding='utf-8', errors='ignore') as f:
                new_pkgbuild_content = f.read()
                
            local_ver_no_epoch = local_ver.split(':', 1)[-1]
            parts = local_ver_no_epoch.rsplit('-', 1)
            expected_ver, expected_rel = parts if len(parts) == 2 else (parts[0], "")
            
            for commit in commits:
                res = run_cmd(['git', 'show', f"{commit}:PKGBUILD"], cwd=repo_dir)
                if res.returncode == 0:
                    content = res.stdout
                    p_ver, p_rel = extract_ver(content)
                    if p_ver == expected_ver and p_rel == expected_rel:
                        old_pkgbuild_content = content
                        break
            
            if old_pkgbuild_content is None:
                print(f"ERROR: Could not find old PKGBUILD for {pkg} version {local_ver}. Cannot safely verify diff.", file=sys.stderr)
                sys.exit(1)
            
            old_stripped = strip_volatile_fields(old_pkgbuild_content)
            new_stripped = strip_volatile_fields(new_pkgbuild_content)
            
            if old_stripped != new_stripped:
                print(f"ERROR: Unsafe changes detected in PKGBUILD for {pkg}!", file=sys.stderr)
                with open(os.path.join(temp_dir, 'old'), 'w') as f:
                    f.write(old_stripped)
                with open(os.path.join(temp_dir, 'new'), 'w') as f:
                    f.write(new_stripped)
                subprocess.run(['diff', '-u', os.path.join(temp_dir, 'old'), os.path.join(temp_dir, 'new')])
                sys.exit(1)
                
    finally:
        shutil.rmtree(temp_dir)

if __name__ == '__main__':
    main()