import os
import re
import hashlib
from html.parser import HTMLParser
from .security import get_safe_path, PROJECTS_DIR
from .state import load_ledger, update_failure_count

class TagBalanceParser(HTMLParser):
    def __init__(self):
        super().__init__()
        self.stack = []
        self.errors = []
        # Exclude 'p' and 'font' to avoid false positives on standard HTML5 tag-omissions
        self.tracked_tags = {'table', 'tr', 'td', 'div', 'nav', 'header', 'footer', 'main', 'section'}

    def handle_starttag(self, tag, attrs):
        if tag in self.tracked_tags: self.stack.append((tag, self.getpos()))

    def handle_endtag(self, tag):
        if tag in self.tracked_tags:
            if not self.stack:
                self.errors.append(f"Orphaned </{tag}> near line {self.getpos()[0]}")
            else:
                last_open, pos = self.stack.pop()
                if last_open != tag:
                    self.errors.append(f"Mismatched tag: <{last_open}> (L{pos[0]}) closed by </{tag}> (L{self.getpos()[0]})")

def run_audit(project_name, page_id):
    ledger = load_ledger(project_name)
    task = next((t for t in ledger.get("task_queue", []) if t["page_id"] == page_id), None)
    if not task: return {"status": "error", "reason": "Task not found."}

    dest_file = get_safe_path(PROJECTS_DIR, project_name, "dist", task["filename"])
    if not os.path.exists(dest_file):
        return {"status": "error", "reason": "Compiled file not found on disk."}

    # 1. Hash Freshness Check
    with open(dest_file, "r", encoding="utf-8") as f:
        disk_content = f.read()
        
    disk_hash = hashlib.sha256(disk_content.encode('utf-8')).hexdigest()
    ledger_hash = ledger.get("hashes", {}).get(page_id, "")
    if disk_hash != ledger_hash:
        return {"status": "error", "reason": "Security Fault: Disk hash does not match Ledger hash. Stale or tampered file."}

    errors = []
    
    # 2. Tag Balance Audit
    parser = TagBalanceParser()
    try:
        parser.feed(disk_content)
        errors.extend(parser.errors)
        if parser.stack:
            for unclosed, pos in parser.stack:
                errors.append(f"Unclosed <{unclosed}> near line {pos[0]}")
    except Exception as e:
        errors.append(f"Parser failure: {str(e)}")

    # 3. Link Matrix Audit
    allowed_files = {t["filename"] for t in ledger.get("task_queue", [])}
    links = re.findall(r'href=["\']([^"\']+)["\']', disk_content, re.IGNORECASE)
    for link in links:
        if not link.startswith(("http", "https", "mailto:", "#")) and link not in allowed_files:
            errors.append(f"Dead Link Found: '{link}' is not in the project task queue.")

    # 4. Three-Strike Circuit Breaker
    if errors:
        strikes = update_failure_count(project_name, page_id, increment=True)
        if strikes >= 3:
            return {
                "status": "circuit_breaker", 
                "reason": f"Page '{page_id}' failed structural audit 3 consecutive times. Escalating to human.",
                "errors": errors
            }
        return {"status": "error", "strikes": strikes, "errors": errors}
    
    # Reset strikes on success
    update_failure_count(project_name, page_id, increment=False)
    return {"status": "success", "message": "Audit passed. File is structurally sound."}