"""
HarshItPDF — HF Spaces Gradio deployment (Free Tier).
Build-time (packages.txt): installs Java 17 JDK, Tesseract, unzip, wget.
Runtime: downloads JAR, patches bytecode, starts mock license + Java backend.
Gradio UI: splash screen with JS auto-redirect to /proxy/{BACKEND_PORT}/
"""

import os
import sys
import time
import json
import shutil
import struct
import glob
import re
import threading
import subprocess
import urllib.request
import zipfile
import logging

logging.basicConfig(
    level=logging.INFO,
    format="[%(name)s] %(levelname)s %(message)s",
)
logger = logging.getLogger("harshitpdf")

# ═══════════════════════════════════════════════════════════════
# Configuration
# ═══════════════════════════════════════════════════════════════
PUBLIC_PORT = int(os.environ.get("PORT", "7860"))
BACKEND_PORT = int(os.environ.get("BACKEND_PORT", "7870"))
LICENCE_SERVER_PORT = int(os.environ.get("LICENCE_SERVER_PORT", "7871"))

RELEASE_TAG = "v2.11.0"
JAR_URL = (
    f"https://github.com/Stirling-Tools/Stirling-PDF/releases/download/"
    f"{RELEASE_TAG}/Stirling-PDF-with-login.jar"
)

JAR_PATH = "Stirling-PDF-with-login.jar"
EXTRACT_DIR = "jar-extracted"
STATIC_DIR = os.path.join(EXTRACT_DIR, "BOOT-INF", "classes", "static")
ASSETS_DIR = os.path.join(STATIC_DIR, "assets")
CLASSES_DIR = os.path.join(EXTRACT_DIR, "BOOT-INF", "classes")
LIB_DIR = os.path.join(EXTRACT_DIR, "BOOT-INF", "lib")
CONFIGS_DIR = "configs"
PATCHED_FLAG = os.path.join(EXTRACT_DIR, ".harshitpdf-patched-v9")

BRAND_REPLACEMENTS = [
    ("Stirling PDF", "HarshItPDF"),
    ("Stirling-PDF", "HarshItPDF"),
    ("StirlingPDF", "HarshItPDF"),
    ("stirling-pdf", "harshitpdf"),
    ("stirlingpdf", "harshitpdf"),
    ("Stirling Tools", "HarshIt"),
    ("Stirling-Tools", "HarshIt"),
    ("Stirling Tools ", "HarshIt "),
]

# ═══════════════════════════════════════════════════════════════
# Branding helper
# ═══════════════════════════════════════════════════════════════

def _brand(text):
    for old, new in BRAND_REPLACEMENTS:
        text = text.replace(old, new)
    return text

# ═══════════════════════════════════════════════════════════════
# Import mock license server
# ═══════════════════════════════════════════════════════════════

SELF_DIR = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, SELF_DIR)
from license_server import start_license_server

# ═══════════════════════════════════════════════════════════════
# JAR lifecycle
# ═══════════════════════════════════════════════════════════════

def _download_jar():
    if os.path.exists(JAR_PATH):
        return
    logger.info(f"Downloading {JAR_URL} ...")
    urllib.request.urlretrieve(JAR_URL, JAR_PATH)
    logger.info("Download complete.")


def _extract_jar():
    if os.path.exists(os.path.join(EXTRACT_DIR, "BOOT-INF")):
        if not os.path.exists(PATCHED_FLAG):
            logger.info("Patch version changed — re-extracting JAR...")
            shutil.rmtree(EXTRACT_DIR, ignore_errors=True)
        else:
            return
    logger.info("Extracting JAR...")
    try:
        subprocess.run(
            ["unzip", "-q", "-o", JAR_PATH, "-d", EXTRACT_DIR],
            check=True, timeout=120,
        )
    except (FileNotFoundError, subprocess.TimeoutExpired):
        with zipfile.ZipFile(JAR_PATH) as zf:
            zf.extractall(EXTRACT_DIR)
    logger.info("Extraction complete.")


def _get_main_class():
    with zipfile.ZipFile(JAR_PATH) as zf:
        manifest = zf.read("META-INF/MANIFEST.MF").decode()
        for line in manifest.split("\n"):
            s = line.strip()
            if s.startswith("Main-Class:"):
                return s.split(":", 1)[1].strip()
    return "org.springframework.boot.loader.launch.JarLauncher"


# ═══════════════════════════════════════════════════════════════
# Constant-pool parser (robust)
# ═══════════════════════════════════════════════════════════════

CP_TAG_SIZES = {
    1: None, 2: None,
    3: 4, 4: 4, 5: 8, 6: 8,
    7: 2, 8: 2, 16: 2, 19: 2, 20: 2,
    9: 4, 10: 4, 11: 4, 12: 4, 17: 4, 18: 4,
    15: 3,
}


def _parse_constant_pool(class_data):
    if len(class_data) < 10:
        return [], 10
    cp_count = struct.unpack(">H", class_data[8:10])[0]
    idx = 10
    cp = [None]
    i = 1
    while i < cp_count:
        if idx >= len(class_data):
            break
        tag = class_data[idx]
        idx += 1
        if tag == 1 or tag == 2:
            if idx + 2 > len(class_data):
                break
            length = struct.unpack(">H", class_data[idx:idx+2])[0]
            if idx + 2 + length > len(class_data):
                break
            val = class_data[idx+2:idx+2+length].decode("utf-8", errors="replace")
            cp.append((tag, val))
            idx += 2 + length
            i += 1
        elif tag in (5, 6):
            if idx + 8 > len(class_data):
                break
            cp.append((tag, None))
            cp.append((tag, None))
            idx += 8
            i += 2
        elif tag in CP_TAG_SIZES and CP_TAG_SIZES[tag] is not None:
            size = CP_TAG_SIZES[tag]
            if idx + size > len(class_data):
                break
            if tag in (7, 8, 16, 19, 20):
                val = struct.unpack(">H", class_data[idx:idx+2])[0]
                cp.append((tag, val))
            elif tag in (9, 10, 11, 12, 17, 18):
                a = struct.unpack(">H", class_data[idx:idx+2])[0]
                b = struct.unpack(">H", class_data[idx+2:idx+4])[0]
                cp.append((tag, (a, b)))
            elif tag == 15:
                cp.append((tag, (class_data[idx], struct.unpack(">H", class_data[idx+1:idx+3])[0])))
            else:
                cp.append((tag, None))
            idx += size
            i += 1
        else:
            cp.append((tag, None))
            break
    return cp, idx


def _get_method_code_ranges(class_data):
    _, idx = _parse_constant_pool(class_data)
    if not idx:
        return []
    idx += 6
    if idx + 2 > len(class_data):
        return []
    interfaces_count = struct.unpack(">H", class_data[idx:idx+2])[0]
    idx += 2 + interfaces_count * 2
    if idx + 2 > len(class_data):
        return []
    fields_count = struct.unpack(">H", class_data[idx:idx+2])[0]
    idx += 2
    for _ in range(fields_count):
        if idx + 6 > len(class_data):
            return []
        idx += 6
        attr_count = struct.unpack(">H", class_data[idx:idx+2])[0]
        idx += 2
        for _ in range(attr_count):
            if idx + 6 > len(class_data):
                return []
            idx += 2
            attr_len = struct.unpack(">I", class_data[idx:idx+4])[0]
            idx += 4 + attr_len
    if idx + 2 > len(class_data):
        return []
    methods_count = struct.unpack(">H", class_data[idx:idx+2])[0]
    idx += 2
    code_ranges = []
    for _ in range(methods_count):
        if idx + 6 > len(class_data):
            break
        idx += 6
        attr_count = struct.unpack(">H", class_data[idx:idx+2])[0]
        idx += 2
        for _ in range(attr_count):
            if idx + 6 > len(class_data):
                break
            idx += 2
            attr_len = struct.unpack(">I", class_data[idx:idx+4])[0]
            idx += 4
            attr_start = idx
            attr_end = idx + attr_len
            if attr_end <= len(class_data) and attr_len >= 8:
                code_len = struct.unpack(">I", class_data[attr_start+4:attr_start+8])[0]
                code_start = attr_start + 8
                code_end = code_start + code_len
                if code_end <= attr_end:
                    code_ranges.append((code_start, code_end))
            idx = attr_end
    return code_ranges


def _get_method_code_info(class_data):
    cp, idx = _parse_constant_pool(class_data)
    if not idx:
        return []
    idx += 6
    if idx + 2 > len(class_data):
        return []
    interfaces_count = struct.unpack(">H", class_data[idx:idx+2])[0]
    idx += 2 + interfaces_count * 2
    if idx + 2 > len(class_data):
        return []
    fields_count = struct.unpack(">H", class_data[idx:idx+2])[0]
    idx += 2
    for _ in range(fields_count):
        if idx + 6 > len(class_data):
            return []
        idx += 6
        attr_count = struct.unpack(">H", class_data[idx:idx+2])[0]
        idx += 2
        for _ in range(attr_count):
            if idx + 6 > len(class_data):
                return []
            idx += 2
            attr_len = struct.unpack(">I", class_data[idx:idx+4])[0]
            idx += 4 + attr_len
    if idx + 2 > len(class_data):
        return []
    methods_count = struct.unpack(">H", class_data[idx:idx+2])[0]
    idx += 2
    methods = []
    for _ in range(methods_count):
        if idx + 6 > len(class_data):
            break
        name_idx = struct.unpack(">H", class_data[idx+2:idx+4])[0]
        idx += 6
        attr_count = struct.unpack(">H", class_data[idx:idx+2])[0]
        idx += 2
        name = ""
        if 0 < name_idx < len(cp) and cp[name_idx] and cp[name_idx][0] == 1:
            name = cp[name_idx][1]
        for _ in range(attr_count):
            if idx + 6 > len(class_data):
                break
            attr_name_idx = struct.unpack(">H", class_data[idx:idx+2])[0]
            attr_len = struct.unpack(">I", class_data[idx+2:idx+6])[0]
            idx += 6
            attr_start = idx
            attr_end = idx + attr_len
            if 0 < attr_name_idx < len(cp) and cp[attr_name_idx] and cp[attr_name_idx][0] == 1:
                attr_name = cp[attr_name_idx][1]
                if attr_name == "Code" and attr_len >= 8:
                    code_len = struct.unpack(">I", class_data[attr_start+4:attr_start+8])[0]
                    code_start = attr_start + 8
                    code_end = code_start + code_len
                    if code_end <= attr_end:
                        methods.append((name, code_start, code_end))
            idx = attr_end
    return methods


def _find_fieldref_index(class_data, class_name_substr, field_name):
    cp, _ = _parse_constant_pool(class_data)
    if not cp:
        return None
    field_name_idx = None
    for i, entry in enumerate(cp):
        if entry and entry[0] == 1 and entry[1] == field_name:
            field_name_idx = i
            break
    if not field_name_idx:
        return None
    nat_idx = None
    for i, entry in enumerate(cp):
        if entry and entry[0] == 12 and isinstance(entry[1], tuple) and entry[1][0] == field_name_idx:
            nat_idx = i
            break
    if not nat_idx:
        return None
    class_idx = None
    for i, entry in enumerate(cp):
        if entry and entry[0] == 7 and isinstance(entry[1], int):
            cn_entry = cp[entry[1]]
            if cn_entry and cn_entry[0] == 1 and class_name_substr in cn_entry[1]:
                class_idx = i
                break
    if not class_idx:
        return None
    for i, entry in enumerate(cp):
        if entry and entry[0] == 9 and isinstance(entry[1], tuple) and entry[1][0] == class_idx and entry[1][1] == nat_idx:
            return i
    return None


# ═══════════════════════════════════════════════════════════════
# Bytecode patching
# ═══════════════════════════════════════════════════════════════

def _patch_method_to_return_true(class_data, class_name=""):
    data = bytearray(class_data)
    ranges = _get_method_code_ranges(class_data)
    modified = False
    for start, end in ranges:
        i = start
        while i < end - 1:
            if data[i] == 0x03 and data[i + 1] == 0xac:
                data[i] = 0x04
                modified = True
                i += 2
                continue
            if data[i] == 0x04 and data[i + 1] == 0xac:
                i += 2
                continue
            i += 1
    return modified, bytes(data)


def _patch_class_file(path):
    with open(path, "rb") as fh:
        data = fh.read()
    modified, new_data = _patch_method_to_return_true(data, os.path.basename(path))
    if modified:
        with open(path, "wb") as fh:
            fh.write(new_data)
        return True
    return False


def _is_license_class(filename):
    name = filename.lower()
    return any(w in name for w in [
        "license", "licenseverifier", "licensechecker",
        "dynamiclicense", "premiumenabled",
    ])


def _is_license_jar(filename):
    name = filename.lower()
    return "proprietary" in name or "license" in name or "ee" in name


def _patch_license_key_checker(path):
    """Patch getPremiumLicenseEnabledResult() → ENTERPRISE robustly."""
    with open(path, "rb") as fh:
        data = bytearray(fh.read())
    enterprise_idx = _find_fieldref_index(data, "License", "ENTERPRISE")
    if enterprise_idx:
        methods = _get_method_code_info(data)
        for name, cstart, cend in methods:
            if name == "getPremiumLicenseEnabledResult":
                for i in range(cstart, cend - 4):
                    if data[i] == 0x2a and data[i+1] == 0xb4 and data[i+4] == 0xb0:
                        data[i]   = 0xb2
                        data[i+1] = (enterprise_idx >> 8) & 0xff
                        data[i+2] = enterprise_idx & 0xff
                        data[i+3] = 0x00
                        data[i+4] = 0xb0
                        with open(path, "wb") as fh:
                            fh.write(bytes(data))
                        logger.info(f"Robust-patched {name} → ENTERPRISE (idx={enterprise_idx})")
                        return True
                logger.warning(f"Found {name} but no getfield+areturn pattern")
                return False
    logger.warning("ENTERPRISE not found in constant pool, trying hardcoded fallback...")
    if len(data) > 5643:
        expected = bytes([0xb4, 0x00, 0x0d, 0xb0])
        if data[5638:5642] == expected:
            data[5638:5643] = bytes([0xb2, 0x00, 0x4f, 0x00, 0xb0])
            with open(path, "wb") as fh:
                fh.write(bytes(data))
            logger.info("Patched LicenseKeyChecker using hardcoded offset fallback")
            return True
    logger.error("Could not patch LicenseKeyChecker")
    return False


def _extract_and_patch_license_classes_from_jar(jar_path):
    patched_files = []
    with zipfile.ZipFile(jar_path, "r") as zf:
        for name in zf.namelist():
            if not name.endswith(".class"):
                continue
            if not _is_license_class(os.path.basename(name)):
                continue
            data = zf.read(name)
            mod1, d1 = _patch_method_to_return_true(data, os.path.basename(name))
            if mod1:
                dest_path = os.path.join(CLASSES_DIR, name)
                os.makedirs(os.path.dirname(dest_path), exist_ok=True)
                with open(dest_path, "wb") as fh:
                    fh.write(d1)
                patched_files.append(name)
    if patched_files:
        logger.info(f"Extracted/patched from {os.path.basename(jar_path)}: {len(patched_files)} classes")
    return len(patched_files)


def _patch_license_classes():
    patched = 0
    if os.path.exists(CLASSES_DIR):
        for root, dirs, files in os.walk(CLASSES_DIR):
            for f in files:
                if not f.endswith(".class") or not _is_license_class(f):
                    continue
                path = os.path.join(root, f)
                try:
                    if _patch_class_file(path):
                        patched += 1
                        logger.info(f"Patched license class: {f}")
                except Exception as e:
                    logger.warning(f"Could not patch {f}: {e}")
    if os.path.exists(LIB_DIR):
        for f in os.listdir(LIB_DIR):
            if not f.endswith(".jar") or not _is_license_jar(f):
                continue
            try:
                patched += _extract_and_patch_license_classes_from_jar(os.path.join(LIB_DIR, f))
            except Exception as e:
                logger.warning(f"Could not process {f}: {e}")

    lck_path = os.path.join(
        CLASSES_DIR,
        "stirling/software/proprietary/security/configuration/ee/LicenseKeyChecker.class"
    )
    if not os.path.exists(lck_path) and os.path.exists(LIB_DIR):
        for jf in os.listdir(LIB_DIR):
            if "proprietary" not in jf.lower():
                continue
            with zipfile.ZipFile(os.path.join(LIB_DIR, jf)) as zf:
                cp = "stirling/software/proprietary/security/configuration/ee/LicenseKeyChecker.class"
                if cp in zf.namelist():
                    os.makedirs(os.path.dirname(lck_path), exist_ok=True)
                    with open(lck_path, "wb") as fh:
                        fh.write(zf.read(cp))
                    logger.info("Extracted LicenseKeyChecker.class for patching")
                    break
    if os.path.exists(lck_path):
        try:
            if _patch_license_key_checker(lck_path):
                patched += 1
        except Exception as e:
            logger.warning(f"Could not patch LicenseKeyChecker: {e}")
    else:
        logger.warning("LicenseKeyChecker.class not found")

    if patched:
        logger.info(f"Patched {patched} license verifier classes total.")


# ═══════════════════════════════════════════════════════════════
# HTML / JS / SVG / CSS patching
# ═══════════════════════════════════════════════════════════════

def _patch_html():
    count = 0
    if not os.path.exists(STATIC_DIR):
        return
    for root, dirs, files in os.walk(STATIC_DIR):
        for f in files:
            if not f.endswith(".html"):
                continue
            path = os.path.join(root, f)
            with open(path, "r", encoding="utf-8", errors="replace") as fh:
                content = fh.read()
            content = _brand(content)
            content = content.replace(
                "The Free Adobe Acrobat alternative (10M+ Downloads)",
                "Your private PDF powerhouse by HarshIt",
            )
            css_link = '<link rel="stylesheet" href="/harshitpdf-liquidglass.css">'
            if "harshitpdf-liquidglass.css" not in content:
                content = content.replace("</head>", css_link + "</head>")
            with open(path, "w", encoding="utf-8") as fh:
                fh.write(content)
            count += 1
    logger.info(f"Patched {count} HTML files.")


def _patch_js():
    count = 0
    if not os.path.exists(ASSETS_DIR):
        return
    for f in os.listdir(ASSETS_DIR):
        if not f.endswith(".js"):
            continue
        path = os.path.join(ASSETS_DIR, f)
        with open(path, "r", encoding="utf-8", errors="replace") as fh:
            content = fh.read()
        orig = content
        content = _brand(content)
        content = re.sub(
            r'requiresPremium\s*[=:]=?\s*(?:!0|!1|true|false|null)',
            'requiresPremium=!1',
            content,
        )
        content = re.sub(
            r'["\'](?:Premium feature[:\s].*?|Enterprise only[:\s].*?|Enterprise Seats|Upgrade to Server Plan)["\']',
            '""', content,
        )
        content = re.sub(
            r'premiumEnabled\s*[=:]=?\s*[se][?\w]+\.premiumEnabled\?\??[!\d]+',
            'premiumEnabled:!0', content,
        )
        if content != orig:
            with open(path, "w", encoding="utf-8") as fh:
                fh.write(content)
            count += 1
    logger.info(f"Patched {count} JS files.")


def _write_svgs():
    LOGO_SVGS = [
        (
            "StirlingPDFLogoBlackText.svg",
            '<svg width="140" height="26" viewBox="0 0 140 26" fill="none" '
            'xmlns="http://www.w3.org/2000/svg">'
            '<path d="M3 2h12l4 4v18a2 2 0 0 1-2 2H3a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2z" '
            'fill="#6366f1" opacity="0.9"/>'
            '<path d="M15 2l4 4h-4V2z" fill="#818cf8"/>'
            '<text x="6" y="17" font-family="system-ui,sans-serif" font-size="7" '
            'font-weight="700" fill="#fff">PDF</text>'
            '<text x="24" y="18" font-family="system-ui,-apple-system,sans-serif" '
            'font-size="14" font-weight="700" fill="#1a1a2e" letter-spacing="-0.3">'
            'HarshIt<tspan fill="#6366f1">PDF</tspan></text></svg>',
        ),
        (
            "favicon.svg",
            '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512">'
            '<defs><linearGradient id="g" x1="0" y1="0" x2="1" y2="1">'
            '<stop offset="0" stop-color="#6366f1"/>'
            '<stop offset="1" stop-color="#a855f7"/>'
            "</linearGradient></defs>"
            '<rect width="512" height="512" rx="100" fill="url(#g)"/>'
            '<path d="M140 120h160l60 60v200a20 20 0 0 1-20 20H140a20 20 0 0 1-20-20'
            'V140a20 20 0 0 1 20-20z" fill="#fff" opacity="0.95"/>'
            '<path d="M300 120l60 60h-60V120z" fill="#ddd" opacity="0.8"/>'
            '<text x="170" y="280" font-family="system-ui,sans-serif" font-size="80" '
            'font-weight="800" fill="#6366f1">PDF</text></svg>',
        ),
    ]
    logo_dir = os.path.join(STATIC_DIR, "modern-logo")
    os.makedirs(logo_dir, exist_ok=True)
    for name, svg in LOGO_SVGS:
        with open(os.path.join(logo_dir, name), "w") as fh:
            fh.write(svg)
    logger.info("Wrote SVGs.")


def _write_manifests():
    manifest = {
        "short_name": "HarshItPDF",
        "name": "HarshItPDF",
        "icons": [],
        "start_url": ".",
        "display": "standalone",
        "theme_color": "#0a0a1a",
        "background_color": "#0a0a1a",
    }
    for name in ("manifest.json", "manifest-classic.json"):
        path = os.path.join(STATIC_DIR, name)
        os.makedirs(os.path.dirname(path), exist_ok=True)
        with open(path, "w") as fh:
            json.dump(manifest, fh, indent=2)


def _write_css():
    candidates = glob.glob(os.path.join(SELF_DIR, "liquidglass*.css"))
    css_src = candidates[0] if candidates else None
    css_dst = os.path.join(STATIC_DIR, "harshitpdf-liquidglass.css")
    if css_src and os.path.exists(css_src):
        shutil.copy(css_src, css_dst)
        logger.info(f"Copied CSS: {css_src} -> {css_dst}")
    else:
        with open(css_dst, "w") as fh:
            fh.write("/* HarshItPDF Liquid Glass fallback */\n")


def _patch_settings_template():
    template_path = os.path.join(CLASSES_DIR, "settings.yml.template")
    if not os.path.exists(template_path):
        logger.warning("settings.yml.template not found.")
        return
    with open(template_path, "r") as fh:
        content = fh.read()
    content = _brand(content)
    with open(template_path, "w") as fh:
        fh.write(content)
    logger.info("Patched settings.yml.template.")


def _write_settings_yml():
    os.makedirs(CONFIGS_DIR, exist_ok=True)
    settings_path = os.path.join(CONFIGS_DIR, "settings.yml")
    template_path = os.path.join(CLASSES_DIR, "settings.yml.template")
    if os.path.exists(template_path):
        with open(template_path, "r") as fh:
            content = fh.read()
    else:
        content = """# HarshItPDF Settings
security:
  enableLogin: true
  initialLogin:
    username: admin
    password: changeme123
ui:
  appName: HarshItPDF
  appNavbarName: HarshItPDF
  homeDescription: Your private PDF powerhouse by HarshIt
system:
  showUpdate: false
  rootUriPath: ""
  defaultLocale: en-US
premium:
  enabled: false
enterpriseEdition:
  enabled: true
  maxUsers: 999
endpoints:
  groupsToRemove: []
"""
    content = _brand(content)
    with open(settings_path, "w") as fh:
        fh.write(content)
    logger.info(f"Wrote settings.yml ({len(content)} chars).")


def _patch_banner():
    banner_path = os.path.join(CLASSES_DIR, "banner.txt")
    os.makedirs(os.path.dirname(banner_path), exist_ok=True)
    with open(banner_path, "w") as fh:
        fh.write(r"""  _  __           _     _ ___ ___  ___  ___
 | |/ /__ _ _ __| |_  |_ _| _ \ _ _| __| _ \
 | ' // _` | '_ \ ' \  | ||  _/| || _||   /
 | . \ (_| | | | | || | | || | | |_| |_| _|
 |_|\_\__,_|_| |_|
                  |__/
Powered by Spring Boot ${spring-boot.version}
""")


def _patch_meta():
    for name in ("og-metadata.json",):
        path = os.path.join(STATIC_DIR, name)
        if os.path.exists(path):
            with open(path, "r") as fh:
                content = fh.read()
            with open(path, "w") as fh:
                fh.write(_brand(content))


def _fix_python_path():
    venv_dir = "/opt/venv"
    venv_bin = os.path.join(venv_dir, "bin")
    venv_python = os.path.join(venv_bin, "python3")
    if not os.path.exists(venv_dir):
        os.makedirs(venv_bin, exist_ok=True)
    system_python = shutil.which("python3")
    if system_python and not os.path.exists(venv_python):
        try:
            os.symlink(system_python, venv_python)
        except Exception as e:
            logger.warning(f"Could not create python3 symlink: {e}")


def _install_opencv():
    try:
        import cv2
        logger.info(f"OpenCV available: {cv2.__version__}")
    except ImportError:
        logger.info("OpenCV not found, installing...")
        try:
            subprocess.run(
                [sys.executable, "-m", "pip", "install", "--quiet", "opencv-python-headless"],
                check=False, timeout=60,
            )
            import cv2
            logger.info(f"OpenCV installed: {cv2.__version__}")
        except Exception as e:
            logger.warning(f"Could not install OpenCV: {e}")


def _compile_license_override():
    java_src = """package stirling.software.SPDF.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;

@Configuration
public class HarshItLicenseOverride {
    @Bean
    @ConditionalOnMissingBean(name = "runningProOrHigher")
    @Qualifier("runningProOrHigher")
    public boolean runningProOrHigher() {
        return true;
    }
}
"""
    src_path = os.path.join(EXTRACT_DIR, "HarshItLicenseOverride.java")
    with open(src_path, "w") as fh:
        fh.write(java_src)
    lib_dir = os.path.join(EXTRACT_DIR, "BOOT-INF", "lib")
    if not os.path.exists(lib_dir):
        logger.warning("BOOT-INF/lib not found, skipping license override compile")
        return False
    jars = [os.path.join(lib_dir, j) for j in os.listdir(lib_dir) if j.endswith(".jar")]
    classpath = ":".join(jars)
    dest_dir = os.path.join(EXTRACT_DIR, "BOOT-INF", "classes")
    try:
        result = subprocess.run(
            ["javac", "-cp", classpath, "-d", dest_dir, src_path],
            capture_output=True, text=True, timeout=60
        )
        if result.returncode == 0:
            logger.info("Compiled HarshItLicenseOverride.class")
            return True
        else:
            logger.warning(f"javac failed: {result.stderr[:200]}")
            return False
    except Exception as e:
        logger.warning(f"Could not compile override: {e}")
        return False


def _patch_files():
    if os.path.exists(PATCHED_FLAG):
        return
    logger.info("Applying HarshItPDF patches...")
    _patch_html()
    _patch_js()
    _write_svgs()
    _write_manifests()
    _write_css()
    _patch_settings_template()
    _write_settings_yml()
    _patch_banner()
    _patch_meta()
    _fix_python_path()
    _install_opencv()
    _patch_license_classes()
    _compile_license_override()
    with open(PATCHED_FLAG, "w") as fh:
        fh.write(str(time.time()))
    logger.info("All patches applied.")


# ═══════════════════════════════════════════════════════════════
# Backend lifecycle
# ═══════════════════════════════════════════════════════════════

_backend_process = None
_backend_ready = threading.Event()


def _stream_output(pipe):
    try:
        for line in pipe:
            print(line, end="")
            if "Started SPDFApplication" in line:
                _backend_ready.set()
    except Exception as e:
        logger.warning(f"Backend stream error: {e}")


def _find_tessdata():
    candidates = [
        "/usr/share/tesseract-ocr/5/tessdata/",
        "/usr/share/tesseract-ocr/4.00/tessdata/",
        "/usr/share/tesseract-ocr/4/tessdata/",
        "/usr/share/tessdata/",
    ]
    for c in candidates:
        if os.path.exists(c):
            return c
    return ""


def start_backend():
    logger.info("Launching HarshItPDF...")
    main_class = _get_main_class()

    env = os.environ.copy()
    env["SERVER_PORT"] = str(BACKEND_PORT)
    env["SYSTEM_ROOTURIPATH"] = ""
    env["SECURITY_ENABLELOGIN"] = "true"
    env["SECURITY_INITIALLOGIN_USERNAME"] = "admin"
    env["SECURITY_INITIALLOGIN_PASSWORD"] = "changeme123"
    env["UI_APPNAME"] = "HarshItPDF"
    env["UI_APPNAVBARNAME"] = "HarshItPDF"
    env["UI_HOMEDESCRIPTION"] = "Your private PDF powerhouse by HarshIt"
    env["SYSTEM_SHOWUPDATE"] = "false"
    env["PREMIUM_ENABLED"] = "true"
    env["PREMIUM_KEY"] = "harshitpdf-unlocked-0000-0000-0000-000000000001"
    env["DISABLE_ADDITIONAL_FEATURES"] = "false"
    env["PYTHON_PATH"] = shutil.which("python3") or "/usr/bin/python3"
    tessdata = _find_tessdata()
    if tessdata:
        env["TESSDATA_PREFIX"] = tessdata

    logger.info(f"Launching Java backend on internal port {BACKEND_PORT}...")

    global _backend_process
    _backend_process = subprocess.Popen(
        [
            "java",
            "-Xmx2G",
            "-XX:+UseSerialGC",
            "-XX:MaxRAMPercentage=60.0",
            "-cp", EXTRACT_DIR,
            main_class,
        ],
        env=env,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        text=True,
    )
    threading.Thread(target=_stream_output, args=(_backend_process.stdout,), daemon=True).start()
    time.sleep(2)


def check_backend():
    try:
        resp = urllib.request.urlopen(f"http://127.0.0.1:{BACKEND_PORT}/login", timeout=3)
        return resp.status == 200
    except Exception:
        return False


# ═══════════════════════════════════════════════════════════════
# Service orchestrator  (runs at module import on HF Spaces)
# ═══════════════════════════════════════════════════════════════

def _start_services():
    logger.info("=" * 60)
    logger.info("HarshItPDF Starting...")
    logger.info("=" * 60)

    _download_jar()
    _extract_jar()
    _patch_files()

    logger.info(f"Starting mock license server on port {LICENCE_SERVER_PORT}...")
    lic_thread = threading.Thread(target=start_license_server, daemon=True)
    lic_thread.start()
    time.sleep(0.5)

    start_backend()

    logger.info("Waiting for backend to be ready...")
    _backend_ready.wait(timeout=120)

    if check_backend():
        logger.info(f"HarshItPDF backend is live on port {BACKEND_PORT}")
    else:
        logger.warning("Backend health check failed — app may still be starting")

    # Keep-alive monitor
    while True:
        if _backend_process and _backend_process.poll() is not None:
            logger.error("Java backend exited! Restarting...")
            _backend_ready.clear()
            start_backend()
            _backend_ready.wait(timeout=120)
        time.sleep(10)


# ═══════════════════════════════════════════════════════════════
# Gradio UI
# ═══════════════════════════════════════════════════════════════
import gradio as gr

# ZeroGPU guard (required on GPU-backed spaces, harmless on CPU)
try:
    import spaces
    @spaces.GPU(duration=1)
    def _gpuguard():
        pass
except ImportError:
    pass


def build_gradio_ui():
    proxy_url = f"/proxy/{BACKEND_PORT}/"
    with gr.Blocks(title="HarshItPDF", theme=gr.themes.Base()) as demo:
        gr.HTML(f"""
        <script>
            (function(){{
                const check = () => {{
                    fetch("{proxy_url}login", {{mode: "no-cors"}})
                        .then(() => window.location.href = "{proxy_url}")
                        .catch(() => setTimeout(check, 3000));
                }};
                setTimeout(check, 2000);
            }})();
        </script>
        <div style="text-align:center;padding-top:20vh;color:#e0e0ff;background:#0f0f23;min-height:100vh;font-family:sans-serif;">
            <h1 style="font-size:2.5rem;background:linear-gradient(135deg,#6366f1,#a855f7);-webkit-background-clip:text;-webkit-text-fill-color:transparent;">HarshItPDF</h1>
            <p style="opacity:0.7;">Your private PDF powerhouse</p>
            <div style="width:40px;height:40px;border:3px solid rgba(99,102,241,0.3);border-top-color:#6366f1;border-radius:50%;animation:spin 1s linear infinite;margin:1rem auto;"></div>
            <p style="font-family:monospace;font-size:0.9rem;opacity:0.6;margin-top:1rem;">Starting backend... This may take 1–2 min on cold start.</p>
            <p style="font-size:0.85rem;opacity:0.5;margin-top:0.5rem;">Default login: admin / changeme123</p>
            <style>@keyframes spin{{to{{transform:rotate(360deg)}}}}</style>
        </div>
        """)
    return demo


# Start services in background thread when module is imported
_svc_thread = threading.Thread(target=_start_services, daemon=True)
_svc_thread.start()

# HF Spaces Gradio SDK requires `demo` at module scope
demo = build_gradio_ui()