fieldwitness/frontends/web/app.py

"""
FieldWitness Web Frontend

Flask application factory that unifies Stego (steganography) and Attest
(provenance attestation) into a single web UI with fieldkit security features.

ARCHITECTURE
============

The stego web UI (3,600+ lines, 60 routes) is mounted wholesale via
_register_stego_routes() rather than being rewritten into a blueprint.
This preserves the battle-tested subprocess isolation, async job management,
and all existing route logic without modification.

FieldWitness-native features (attest, fieldkit, keys) are clean blueprints.

    Stego routes (mounted at root):
        /encode, /decode, /generate, /tools, /api/*

    FieldWitness blueprints:
        /attest, /verify         → attest blueprint
        /fieldkit/*              → fieldkit blueprint
        /keys/*                  → keys blueprint
        /admin/*                 → admin blueprint (extends stego's)
"""

import io
import os
import secrets
import sys
from pathlib import Path

from flask import (
    Flask,
    flash,
    jsonify,
    redirect,
    render_template,
    request,
    send_file,
    session,
    url_for,
)

import fieldwitness
from fieldwitness.config import FieldWitnessConfig
from fieldwitness.paths import INSTANCE_DIR, SECRET_KEY_FILE, TEMP_DIR, ensure_dirs

# Suppress numpy/scipy warnings in subprocesses
os.environ["NUMPY_MADVISE_HUGEPAGE"] = "0"
os.environ["OMP_NUM_THREADS"] = "1"


def create_app(config: FieldWitnessConfig | None = None) -> Flask:
    """Application factory."""
    config = config or FieldWitnessConfig.load()
    ensure_dirs()

    web_dir = Path(__file__).parent

    app = Flask(
        __name__,
        instance_path=str(INSTANCE_DIR),
        template_folder=str(web_dir / "templates"),
        static_folder=str(web_dir / "static"),
    )

    app.config["MAX_CONTENT_LENGTH"] = config.max_upload_mb * 1024 * 1024
    app.config["AUTH_ENABLED"] = config.auth_enabled
    app.config["HTTPS_ENABLED"] = config.https_enabled
    app.config["FIELDWITNESS_CONFIG"] = config

    # Session security: timeout + secure cookie flags
    from datetime import timedelta

    app.config["PERMANENT_SESSION_LIFETIME"] = timedelta(minutes=config.session_timeout_minutes)
    app.config["SESSION_COOKIE_HTTPONLY"] = True
    app.config["SESSION_COOKIE_SAMESITE"] = "Strict"
    if config.https_enabled:
        app.config["SESSION_COOKIE_SECURE"] = True

    # CSRF protection on all POST/PUT/DELETE routes
    from flask_wtf.csrf import CSRFProtect

    csrf = CSRFProtect(app)

    # Point temp_storage at ~/.fieldwitness/temp/ before any routes run, so all
    # uploaded files land where the killswitch's destroy_temp_files step
    # expects them.  Must happen after ensure_dirs() so the directory exists.
    import temp_storage as _ts

    _ts.init(TEMP_DIR)

    # Persist secret key so sessions survive restarts
    _load_secret_key(app)

    # ── Initialize auth ───────────────────────────────────────────
    # Add web dir to path so auth.py and support modules are importable
    sys.path.insert(0, str(web_dir))

    from auth import get_username, is_admin, is_authenticated
    from auth import init_app as init_auth

    init_auth(app)

    # ── Register stego routes ──────────────────────────────────
    _register_stego_routes(app)

    # ── Register FieldWitness-native blueprints ─────────────────────────
    from frontends.web.blueprints.attest import bp as attest_bp
    from frontends.web.blueprints.fieldkit import bp as fieldkit_bp
    from frontends.web.blueprints.keys import bp as keys_bp

    app.register_blueprint(attest_bp)
    app.register_blueprint(fieldkit_bp)
    app.register_blueprint(keys_bp)

    from frontends.web.blueprints.dropbox import bp as dropbox_bp
    from frontends.web.blueprints.federation import bp as federation_bp

    app.register_blueprint(dropbox_bp)
    app.register_blueprint(federation_bp)

    # Exempt only the source-facing upload route from CSRF (sources don't have sessions).
    # The admin and verify-receipt routes in the dropbox blueprint retain CSRF protection.
    from frontends.web.blueprints.dropbox import upload as dropbox_upload

    csrf.exempt(dropbox_upload)

    # ── Context processor (injected into ALL templates) ───────────

    @app.context_processor
    def inject_globals():
        from fieldwitness.keystore import KeystoreManager

        ks = KeystoreManager()
        ks_status = ks.status()

        # Fieldkit alert level
        fieldkit_status = "ok"
        if config.deadman_enabled:
            from fieldwitness.fieldkit.deadman import DeadmanSwitch

            dm = DeadmanSwitch()
            if dm.should_fire():
                fieldkit_status = "alarm"
            elif dm.is_overdue():
                fieldkit_status = "warn"

        # Stego capabilities
        try:
            from fieldwitness.stego import HAS_AUDIO_SUPPORT, get_channel_status, has_dct_support
            from fieldwitness.stego.constants import (
                DEFAULT_PASSPHRASE_WORDS,
                MAX_FILE_PAYLOAD_SIZE,
                MAX_MESSAGE_CHARS,
                MAX_PIN_LENGTH,
                MAX_UPLOAD_SIZE,
                MIN_PASSPHRASE_WORDS,
                MIN_PIN_LENGTH,
                RECOMMENDED_PASSPHRASE_WORDS,
                TEMP_FILE_EXPIRY_MINUTES,
            )

            has_dct = has_dct_support()
            has_audio = HAS_AUDIO_SUPPORT
            channel_status = get_channel_status()

            # Stego-specific template vars (needed by stego templates)
            stego_vars = {
                "has_dct": has_dct,
                "has_audio": has_audio,
                "max_message_chars": MAX_MESSAGE_CHARS,
                "max_payload_kb": MAX_FILE_PAYLOAD_SIZE // 1024,
                "max_upload_mb": MAX_UPLOAD_SIZE // (1024 * 1024),
                "temp_file_expiry_minutes": TEMP_FILE_EXPIRY_MINUTES,
                "min_pin_length": MIN_PIN_LENGTH,
                "max_pin_length": MAX_PIN_LENGTH,
                "min_passphrase_words": MIN_PASSPHRASE_WORDS,
                "recommended_passphrase_words": RECOMMENDED_PASSPHRASE_WORDS,
                "default_passphrase_words": DEFAULT_PASSPHRASE_WORDS,
                "channel_mode": channel_status["mode"],
                "channel_source": channel_status.get("source"),
                "supported_audio_formats": "WAV, FLAC, MP3, OGG, AAC, M4A" if has_audio else "",
            }
        except ImportError:
            has_dct = False
            has_audio = False
            stego_vars = {}

        # Attest availability
        try:
            import fieldwitness.attest  # noqa: F401

            has_attest = True
        except ImportError:
            has_attest = False

        # Saved channel keys for authenticated users
        saved_channel_keys = []
        if is_authenticated():
            try:
                from auth import get_current_user, get_user_channel_keys

                current_user = get_current_user()
                if current_user:
                    saved_channel_keys = get_user_channel_keys(current_user.id)
            except Exception:
                pass

        base_vars = {
            "version": fieldwitness.__version__,
            "has_attest": has_attest,
            "has_fieldkit": config.killswitch_enabled or config.deadman_enabled,
            "fieldkit_status": fieldkit_status,
            "channel_configured": ks_status.has_channel_key,
            "channel_fingerprint": ks_status.channel_fingerprint or "",
            "identity_configured": ks_status.has_identity,
            "identity_fingerprint": ks_status.identity_fingerprint or "",
            "auth_enabled": app.config["AUTH_ENABLED"],
            "is_authenticated": is_authenticated(),
            "is_admin": is_admin(),
            "username": get_username() if is_authenticated() else None,
            "saved_channel_keys": saved_channel_keys,
            # QR support flags
            "has_qrcode": _HAS_QRCODE,
            "has_qrcode_read": _HAS_QRCODE_READ,
        }
        return {**base_vars, **stego_vars}

    # ── Root routes ───────────────────────────────────────────────

    @app.route("/")
    def index():
        return render_template("index.html")

    # ── Health check ─────────────────────────────────────────────

    @app.route("/health")
    def health():
        """System health and capability report.

        Anonymous callers get only {"status": "ok"} — no operational
        intelligence. Authenticated users get the full report.
        """
        # Anonymous callers get minimal response to prevent info leakage
        # (deadman status, key presence, memory, etc. are operational intel)
        if not is_authenticated():
            from flask import jsonify
            return jsonify({"status": "ok", "version": __import__("fieldwitness").__version__})

        import platform
        import sys

        from flask import jsonify

        from fieldwitness.keystore.manager import KeystoreManager

        ks = KeystoreManager()

        # Core modules
        modules = {}
        for name, import_path in [
            ("stego", "fieldwitness.stego"),
            ("attest", "fieldwitness.attest"),
        ]:
            try:
                mod = __import__(import_path, fromlist=["__version__"])
                modules[name] = {"status": "ok", "version": getattr(mod, "__version__", "unknown")}
            except ImportError as e:
                modules[name] = {"status": "missing", "error": str(e)}

        # Optional capabilities
        capabilities = {}

        # DCT steganography
        try:
            from fieldwitness.stego import has_dct_support
            capabilities["stego_dct"] = {
                "status": "ok" if has_dct_support() else "unavailable",
                "hint": None if has_dct_support() else "Install fieldwitness[stego-dct] (scipy, jpeglib, reedsolo)",
            }
        except ImportError:
            capabilities["stego_dct"] = {"status": "missing", "hint": "Install fieldwitness[stego-dct]"}

        # Audio steganography
        try:
            from fieldwitness.stego import HAS_AUDIO_SUPPORT
            capabilities["stego_audio"] = {
                "status": "ok" if HAS_AUDIO_SUPPORT else "unavailable",
                "hint": None if HAS_AUDIO_SUPPORT else "Install fieldwitness[stego-audio] (soundfile, numpy)",
            }
        except ImportError:
            capabilities["stego_audio"] = {"status": "missing", "hint": "Install fieldwitness[stego-audio]"}

        # Video steganography
        try:
            from fieldwitness.stego.constants import VIDEO_ENABLED
            capabilities["stego_video"] = {
                "status": "ok" if VIDEO_ENABLED else "unavailable",
                "hint": None if VIDEO_ENABLED else "Requires ffmpeg in PATH",
            }
        except (ImportError, AttributeError):
            capabilities["stego_video"] = {"status": "missing", "hint": "Requires ffmpeg"}

        # LMDB (attest storage)
        try:
            import lmdb  # noqa: F401
            capabilities["lmdb"] = {"status": "ok"}
        except ImportError:
            capabilities["lmdb"] = {"status": "missing", "hint": "Install fieldwitness[attest]"}

        # Perceptual hashing
        try:
            import imagehash  # noqa: F401
            capabilities["imagehash"] = {"status": "ok"}
        except ImportError:
            capabilities["imagehash"] = {"status": "missing", "hint": "Install fieldwitness[attest]"}

        # USB monitoring
        try:
            import pyudev  # noqa: F401
            capabilities["usb_monitor"] = {"status": "ok"}
        except ImportError:
            capabilities["usb_monitor"] = {"status": "unavailable", "hint": "Install fieldwitness[fieldkit] (Linux only)"}

        # GPIO (RPi killswitch)
        try:
            import gpiozero  # noqa: F401
            capabilities["gpio"] = {"status": "ok"}
        except ImportError:
            capabilities["gpio"] = {"status": "unavailable", "hint": "Install fieldwitness[rpi] (Raspberry Pi only)"}

        # Key status (existence only, no material)
        keys = {
            "identity": "ok" if ks.has_identity() else "missing",
            "channel_key": "ok" if ks.has_channel_key() else "missing",
            "trusted_keys": len(ks.get_trusted_keys()),
        }

        # Backup status
        backup_info = ks.last_backup_info()
        keys["last_backup"] = backup_info["timestamp"] if backup_info else "never"
        keys["backup_overdue"] = ks.is_backup_overdue(config.backup_reminder_days)

        # Fieldkit status
        fieldkit = {
            "killswitch_enabled": config.killswitch_enabled,
            "deadman_enabled": config.deadman_enabled,
            "chain_enabled": config.chain_enabled,
        }
        if config.deadman_enabled:
            from fieldwitness.fieldkit.deadman import DeadmanSwitch
            dm = DeadmanSwitch()
            dm_status = dm.status()
            fieldkit["deadman_armed"] = dm_status["armed"]
            fieldkit["deadman_overdue"] = dm_status.get("overdue", False)

        # System info (no secrets)
        system = {
            "python": sys.version.split()[0],
            "platform": platform.machine(),
            "os": platform.system(),
        }

        # Memory (for Argon2 sizing awareness)
        try:
            import os as _os
            mem_bytes = _os.sysconf("SC_PAGE_SIZE") * _os.sysconf("SC_PHYS_PAGES")
            system["memory_mb"] = mem_bytes // (1024 * 1024)
        except (ValueError, OSError):
            pass

        # Overall status
        all_ok = (
            all(m["status"] == "ok" for m in modules.values())
            and keys["identity"] == "ok"
            and keys["channel_key"] == "ok"
        )

        return jsonify({
            "status": "ok" if all_ok else "degraded",
            "version": __import__("fieldwitness").__version__,
            "modules": modules,
            "capabilities": capabilities,
            "keys": keys,
            "fieldkit": fieldkit,
            "system": system,
        })

    return app


# ── QR support detection ─────────────────────────────────────────────

try:
    import qrcode  # noqa: F401

    _HAS_QRCODE = True
except ImportError:
    _HAS_QRCODE = False

try:
    from pyzbar.pyzbar import decode as pyzbar_decode  # noqa: F401

    _HAS_QRCODE_READ = True
except ImportError:
    _HAS_QRCODE_READ = False


# ── Stego route mounting ──────────────────────────────────────────


def _register_stego_routes(app: Flask) -> None:
    """
    Mount all stego web routes into the Flask app.

    Rather than rewriting 3,600 lines of battle-tested route logic,
    we import fieldwitness.stego's app.py and re-register its routes.
    The stego templates are in templates/stego/ and extend our base.html.
    """
    import temp_storage
    from auth import admin_required, login_required
    from fieldwitness.stego import (
        export_rsa_key_pem,
        generate_credentials,
        get_channel_status,
        load_rsa_key,
    )
    from fieldwitness.stego.constants import (
        DEFAULT_PASSPHRASE_WORDS,
        MAX_PIN_LENGTH,
        MIN_PASSPHRASE_WORDS,
        MIN_PIN_LENGTH,
        TEMP_FILE_EXPIRY,
        VALID_RSA_SIZES,
    )
    from fieldwitness.stego.qr_utils import (
        can_fit_in_qr,
        generate_qr_code,
    )
    from subprocess_stego import (
        SubprocessStego,
    )

    from fieldwitness.audit import log_action

    # Initialize subprocess wrapper
    subprocess_stego = SubprocessStego(timeout=180)

    # ── Auth routes (setup, login, logout, account) ────────────────

    from auth import (
        MAX_CHANNEL_KEYS,
        MAX_USERS,
        can_create_user,
        can_save_channel_key,
        change_password,
        create_admin_user,
        create_user,
        delete_user,
        generate_temp_password,
        get_all_users,
        get_current_user,
        get_recovery_key_hash,
        get_user_by_id,
        get_user_channel_keys,
        has_recovery_key,
        reset_user_password,
        verify_and_reset_admin_password,
        verify_user_password,
    )
    from auth import (
        is_authenticated as auth_is_authenticated,
    )
    from auth import (
        login_user as auth_login_user,
    )
    from auth import (
        logout_user as auth_logout_user,
    )
    from auth import (
        user_exists as auth_user_exists,
    )

    # Login rate limiting: {username: [(timestamp, ...),]}
    _login_attempts: dict[str, list[float]] = {}

    @app.route("/login", methods=["GET", "POST"])
    def login():
        if not app.config.get("AUTH_ENABLED", True):
            return redirect(url_for("index"))
        if not auth_user_exists():
            return redirect(url_for("setup"))
        if auth_is_authenticated():
            return redirect(url_for("index"))
        if request.method == "POST":
            import time

            username = request.form.get("username", "")
            password = request.form.get("password", "")

            # Check lockout — read from app.config since _register_stego_routes
            # is a module-level function without access to create_app's config.
            _fw_config = app.config.get("FIELDWITNESS_CONFIG")
            max_attempts = _fw_config.login_lockout_attempts if _fw_config else 5
            lockout_mins = _fw_config.login_lockout_minutes if _fw_config else 15
            now = time.time()
            window = lockout_mins * 60
            attempts = _login_attempts.get(username, [])
            # Prune old attempts
            attempts = [t for t in attempts if now - t < window]
            _login_attempts[username] = attempts

            if len(attempts) >= max_attempts:
                from fieldwitness.audit import log_action

                log_action(
                    actor=username,
                    action="user.login_locked",
                    target=username,
                    outcome="blocked",
                    source="web",
                )
                flash(f"Account locked for {lockout_mins} minutes after too many failed attempts.", "error")
                return render_template("login.html")

            user = verify_user_password(username, password)
            if user:
                _login_attempts.pop(username, None)
                auth_login_user(user)
                session.permanent = True
                flash("Login successful", "success")
                return redirect(url_for("index"))
            else:
                attempts.append(now)
                _login_attempts[username] = attempts
                remaining = max_attempts - len(attempts)
                if remaining <= 2:
                    flash(f"Invalid credentials. {remaining} attempts remaining.", "error")
                else:
                    flash("Invalid username or password", "error")
        return render_template("login.html")

    @app.route("/logout", methods=["POST"])
    def logout():
        auth_logout_user()
        flash("Logged out successfully", "success")
        return redirect(url_for("index"))

    @app.route("/setup", methods=["GET", "POST"])
    def setup():
        if not app.config.get("AUTH_ENABLED", True):
            return redirect(url_for("index"))
        if auth_user_exists():
            return redirect(url_for("login"))
        if request.method == "POST":
            username = request.form.get("username", "admin")
            password = request.form.get("password", "")
            password_confirm = request.form.get("password_confirm", "")
            if password != password_confirm:
                flash("Passwords do not match", "error")
            else:
                success, message = create_admin_user(username, password)
                if success:
                    user = verify_user_password(username, password)
                    if user:
                        auth_login_user(user)
                        session.permanent = True
                    flash("Setup complete!", "success")
                    return redirect(url_for("index"))
                else:
                    flash(message, "error")
        return render_template("setup.html")

    @app.route("/recover", methods=["GET", "POST"])
    def recover():
        if not get_recovery_key_hash():
            flash("No recovery key configured", "error")
            return redirect(url_for("login"))
        if request.method == "POST":
            recovery_key = request.form.get("recovery_key", "").strip()
            new_password = request.form.get("new_password", "")
            new_password_confirm = request.form.get("new_password_confirm", "")
            if not recovery_key:
                flash("Please enter your recovery key", "error")
            elif new_password != new_password_confirm:
                flash("Passwords do not match", "error")
            elif len(new_password) < 8:
                flash("Password must be at least 8 characters", "error")
            else:
                success, message = verify_and_reset_admin_password(recovery_key, new_password)
                if success:
                    flash("Password reset. Please login.", "success")
                    return redirect(url_for("login"))
                else:
                    flash(message, "error")
        return render_template("recover.html")

    @app.route("/account", methods=["GET", "POST"])
    @login_required
    def account():
        current_user = get_current_user()
        if request.method == "POST":
            current_password = request.form.get("current_password", "")
            new_password = request.form.get("new_password", "")
            confirm = request.form.get("confirm_password", "")
            if new_password != confirm:
                flash("Passwords do not match", "error")
            else:
                success, message = change_password(current_user.id, current_password, new_password)
                flash(message, "success" if success else "error")
        saved_keys = get_user_channel_keys(current_user.id) if current_user else []
        return render_template(
            "account.html",
            current_user=current_user,
            saved_channel_keys=saved_keys,
            max_channel_keys=MAX_CHANNEL_KEYS,
            can_save_keys=can_save_channel_key(current_user.id) if current_user else False,
            has_recovery=has_recovery_key(),
        )

    # ── Admin routes ─────────────────────────────────────────────

    @app.route("/admin/users")
    @admin_required
    def admin_users():
        users = get_all_users()
        return render_template(
            "admin/users.html",
            users=users,
            user_count=len(users),
            max_users=MAX_USERS,
            can_create=can_create_user(),
            current_user=get_current_user(),
        )

    @app.route("/admin/users/new", methods=["GET", "POST"])
    @admin_required
    def admin_new_user():
        if request.method == "POST":
            username = request.form.get("username", "")
            temp_password = generate_temp_password()
            success, message = create_user(username, temp_password)
            log_action(
                actor=get_username(),  # noqa: F821
                action="user.create",
                target=f"user:{username}",
                outcome="success" if success else "failure",
                source="web",
                detail=None if success else message,
            )
            if success:
                flash(
                    f"User '{username}' created with temporary password: {temp_password}", "success"
                )
            else:
                flash(message, "error")
            return redirect(url_for("admin_users"))
        return render_template("admin/user_new.html")

    @app.route("/admin/users/<int:user_id>/delete", methods=["POST"])
    @admin_required
    def admin_delete_user(user_id):
        target_user = get_user_by_id(user_id)
        target_name = target_user.username if target_user else str(user_id)
        success, message = delete_user(user_id, get_current_user().id)
        log_action(
            actor=get_username(),  # noqa: F821
            action="user.delete",
            target=f"user:{target_name}",
            outcome="success" if success else "failure",
            source="web",
            detail=None if success else message,
        )
        flash(message, "success" if success else "error")
        return redirect(url_for("admin_users"))

    @app.route("/admin/users/<int:user_id>/reset", methods=["POST"])
    @admin_required
    def admin_reset_password(user_id):
        temp_password = generate_temp_password()
        success, message = reset_user_password(user_id, temp_password)
        target_user = get_user_by_id(user_id)
        target_name = target_user.username if target_user else str(user_id)
        log_action(
            actor=get_username(),  # noqa: F821
            action="user.password_reset",
            target=f"user:{target_name}",
            outcome="success" if success else "failure",
            source="web",
            detail=None if success else message,
        )
        if success:
            flash(f"Password for '{target_name}' reset to: {temp_password}", "success")
        else:
            flash(message, "error")
        return redirect(url_for("admin_users"))

    # ── Generate routes ───────────────────────────────────────────

    @app.route("/generate", methods=["GET", "POST"])
    @login_required
    def generate():
        if request.method == "POST":
            words_per_passphrase = int(
                request.form.get("words_per_passphrase", DEFAULT_PASSPHRASE_WORDS)
            )
            use_pin = request.form.get("use_pin") == "on"
            use_rsa = request.form.get("use_rsa") == "on"

            if not use_pin and not use_rsa:
                flash("You must select at least one security factor (PIN or RSA Key)", "error")
                return render_template(
                    "stego/generate.html", generated=False, has_qrcode=_HAS_QRCODE
                )

            pin_length = int(request.form.get("pin_length", 6))
            rsa_bits = int(request.form.get("rsa_bits", 2048))
            words_per_passphrase = max(MIN_PASSPHRASE_WORDS, min(12, words_per_passphrase))
            pin_length = max(MIN_PIN_LENGTH, min(MAX_PIN_LENGTH, pin_length))
            if rsa_bits not in VALID_RSA_SIZES:
                rsa_bits = 2048

            try:
                creds = generate_credentials(
                    use_pin=use_pin,
                    use_rsa=use_rsa,
                    pin_length=pin_length,
                    rsa_bits=rsa_bits,
                    passphrase_words=words_per_passphrase,
                )

                qr_token = None
                qr_needs_compression = False
                qr_too_large = False

                if creds.rsa_key_pem and _HAS_QRCODE:
                    if can_fit_in_qr(creds.rsa_key_pem, compress=True):
                        qr_needs_compression = True
                    else:
                        qr_too_large = True

                    if not qr_too_large:
                        qr_token = secrets.token_urlsafe(16)
                        temp_storage.cleanup_expired(TEMP_FILE_EXPIRY)
                        temp_storage.save_temp_file(
                            qr_token,
                            creds.rsa_key_pem.encode(),
                            {
                                "filename": "rsa_key.pem",
                                "type": "rsa_key",
                                "compress": qr_needs_compression,
                            },
                        )

                return render_template(
                    "stego/generate.html",
                    passphrase=creds.passphrase,
                    pin=creds.pin,
                    generated=True,
                    words_per_passphrase=words_per_passphrase,
                    pin_length=pin_length if use_pin else None,
                    use_pin=use_pin,
                    use_rsa=use_rsa,
                    rsa_bits=rsa_bits,
                    rsa_key_pem=creds.rsa_key_pem,
                    passphrase_entropy=creds.passphrase_entropy,
                    pin_entropy=creds.pin_entropy,
                    rsa_entropy=creds.rsa_entropy,
                    total_entropy=creds.total_entropy,
                    has_qrcode=_HAS_QRCODE,
                    qr_token=qr_token,
                    qr_needs_compression=qr_needs_compression,
                    qr_too_large=qr_too_large,
                )
            except Exception as e:
                flash(f"Error generating credentials: {e}", "error")
                return render_template(
                    "stego/generate.html", generated=False, has_qrcode=_HAS_QRCODE
                )

        return render_template("stego/generate.html", generated=False, has_qrcode=_HAS_QRCODE)

    # ── Generate QR + Key download routes ───────────────────────

    @app.route("/generate/qr/<token>")
    @login_required
    def generate_qr(token):
        if not _HAS_QRCODE:
            return "QR code support not available", 501
        file_info = temp_storage.get_temp_file(token)
        if not file_info:
            return "Token expired or invalid", 404
        if file_info.get("type") != "rsa_key":
            return "Invalid token type", 400
        try:
            key_pem = file_info["data"].decode("utf-8")
            compress = file_info.get("compress", False)
            qr_png = generate_qr_code(key_pem, compress=compress)
            return send_file(io.BytesIO(qr_png), mimetype="image/png", as_attachment=False)
        except Exception as e:
            return f"Error generating QR code: {e}", 500

    @app.route("/generate/qr-download/<token>")
    @login_required
    def generate_qr_download(token):
        if not _HAS_QRCODE:
            return "QR code support not available", 501
        file_info = temp_storage.get_temp_file(token)
        if not file_info:
            return "Token expired or invalid", 404
        if file_info.get("type") != "rsa_key":
            return "Invalid token type", 400
        try:
            key_pem = file_info["data"].decode("utf-8")
            compress = file_info.get("compress", False)
            qr_png = generate_qr_code(key_pem, compress=compress)
            return send_file(
                io.BytesIO(qr_png),
                mimetype="image/png",
                as_attachment=True,
                download_name="fieldwitness_rsa_key_qr.png",
            )
        except Exception as e:
            return f"Error generating QR code: {e}", 500

    @app.route("/generate/download-key", methods=["POST"])
    @login_required
    def download_key():
        key_pem = request.form.get("key_pem", "")
        password = request.form.get("key_password", "")
        if not key_pem:
            flash("No key to download", "error")
            return redirect(url_for("generate"))
        if not password or len(password) < 8:
            flash("Password must be at least 8 characters", "error")
            return redirect(url_for("generate"))
        try:
            private_key = load_rsa_key(key_pem.encode("utf-8"))
            encrypted_pem = export_rsa_key_pem(private_key, password=password)
            key_id = secrets.token_hex(4)
            filename = f"fieldwitness_key_{private_key.key_size}_{key_id}.pem"
            return send_file(
                io.BytesIO(encrypted_pem),
                mimetype="application/x-pem-file",
                as_attachment=True,
                download_name=filename,
            )
        except Exception as e:
            flash(f"Error creating key file: {e}", "error")
            return redirect(url_for("generate"))

    # ── Encode/Decode/Tools routes (from stego_routes.py) ────────

    from stego_routes import register_stego_routes

    register_stego_routes(
        app,
        **{
            "login_required": login_required,
            "subprocess_stego": subprocess_stego,
            "temp_storage": temp_storage,
            "has_qrcode_read": _HAS_QRCODE_READ,
        },
    )

    # /about route is in stego_routes.py

    # ── API routes (capacity, channel, download) ──────────────────

    @app.route("/api/channel/status")
    @login_required
    def api_channel_status():
        result = subprocess_stego.get_channel_status(reveal=False)
        if result.success:
            return jsonify(
                {
                    "success": True,
                    "mode": result.mode,
                    "configured": result.configured,
                    "fingerprint": result.fingerprint,
                    "source": result.source,
                }
            )
        else:
            status = get_channel_status()
            return jsonify(
                {
                    "success": True,
                    "mode": status["mode"],
                    "configured": status["configured"],
                    "fingerprint": status.get("fingerprint"),
                    "source": status.get("source"),
                }
            )

    @app.route("/api/compare-capacity", methods=["POST"])
    @login_required
    def api_compare_capacity():
        carrier = request.files.get("carrier")
        if not carrier:
            return jsonify({"error": "No carrier image provided"}), 400
        try:
            carrier_data = carrier.read()
            result = subprocess_stego.compare_modes(carrier_data)
            if not result.success:
                return jsonify({"error": result.error or "Comparison failed"}), 500
            return jsonify(
                {
                    "success": True,
                    "width": result.width,
                    "height": result.height,
                    "lsb": {
                        "capacity_bytes": result.lsb["capacity_bytes"],
                        "capacity_kb": round(result.lsb["capacity_kb"], 1),
                        "output": result.lsb.get("output", "PNG"),
                    },
                    "dct": {
                        "capacity_bytes": result.dct["capacity_bytes"],
                        "capacity_kb": round(result.dct["capacity_kb"], 1),
                        "output": result.dct.get("output", "JPEG"),
                        "available": result.dct.get("available", True),
                        "ratio": round(result.dct.get("ratio_vs_lsb", 0), 1),
                    },
                }
            )
        except Exception as e:
            return jsonify({"error": str(e)}), 500

    @app.route("/api/download/<file_id>")
    @login_required
    def api_download(file_id):
        file_info = temp_storage.get_temp_file(file_id)
        if not file_info:
            return jsonify({"error": "File not found or expired"}), 404
        filename = file_info.get("filename", "download")
        mime_type = file_info.get("mime_type", "application/octet-stream")
        return send_file(
            io.BytesIO(file_info["data"]),
            mimetype=mime_type,
            as_attachment=True,
            download_name=filename,
        )

    @app.route("/api/generate/credentials", methods=["POST"])
    @login_required
    def api_generate_credentials():
        try:
            creds = generate_credentials(use_pin=True, use_rsa=False)
            return jsonify(
                {
                    "success": True,
                    "passphrase": creds.passphrase,
                    "pin": creds.pin,
                }
            )
        except Exception as e:
            return jsonify({"error": str(e)}), 500


def _load_secret_key(app: Flask) -> None:
    """Load or generate persistent secret key for Flask sessions."""
    SECRET_KEY_FILE.parent.mkdir(parents=True, exist_ok=True)
    if SECRET_KEY_FILE.exists():
        app.secret_key = SECRET_KEY_FILE.read_bytes()
    else:
        key = secrets.token_bytes(32)
        SECRET_KEY_FILE.write_bytes(key)
        SECRET_KEY_FILE.chmod(0o600)
        app.secret_key = key