import hashlib
import json
import os
import subprocess
from functools import wraps
from pathlib import Path

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

app = Flask(__name__)

# Stable secret key: derive from username+password so it survives restarts
# but changes when credentials change
_username = os.environ.get("WEBUI_USERNAME", "admin")
_password = os.environ.get("WEBUI_PASSWORD", "admin123")
app.secret_key = hashlib.sha256(f"{_username}:{_password}:proxy-secret".encode()).hexdigest()

CONFIG_FILE = "/data/proxy_config.json"
NGINX_CONF_DIR = "/etc/nginx/conf.d"
NGINX_UPSTREAM_CONF = f"{NGINX_CONF_DIR}/proxy-targets.conf"
NGINX_ACCESS_LOG = "/var/log/nginx/access.log"
NGINX_ERROR_LOG = "/var/log/nginx/error.log"

USERNAME = os.environ.get("WEBUI_USERNAME", "admin")
PASSWORD = os.environ.get("WEBUI_PASSWORD", "admin123")


def load_config():
    if os.path.exists(CONFIG_FILE):
        with open(CONFIG_FILE) as f:
            return json.load(f)
    return {"targets": []}


def save_config(config):
    os.makedirs(os.path.dirname(CONFIG_FILE), exist_ok=True)
    with open(CONFIG_FILE, "w") as f:
        json.dump(config, f, indent=2)


def _proxy_location_block(target_scheme, upstream_name):
    """Generate proxy location block with all necessary directives."""
    return f"""    location / {{
        proxy_pass {target_scheme}://{upstream_name};

        # Headers
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header X-Forwarded-Port $server_port;

        # WebSocket support
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;

        # Timeouts
        proxy_connect_timeout 60s;
        proxy_send_timeout 120s;
        proxy_read_timeout 120s;

        # Buffers
        proxy_buffer_size 128k;
        proxy_buffers 4 256k;
        proxy_busy_buffers_size 256k;

        # Don't limit upload size
        client_max_body_size 0;

        # Pass redirects through
        proxy_redirect default;

        # Disable SSL verification for HTTPS targets
        proxy_ssl_verify off;
    }}"""


def generate_nginx_config(config):
    """Generate nginx upstream/server blocks from config."""
    lines = []

    # Connection upgrade map for WebSocket support
    lines.append("map $http_upgrade $connection_upgrade {")
    lines.append("    default upgrade;")
    lines.append("    '' close;")
    lines.append("}")
    lines.append("")

    for i, target in enumerate(config.get("targets", [])):
        name = target.get("name", f"target_{i}")
        target_host = target.get("target_host", "")
        target_port = target.get("target_port", 80)
        listen_port = target.get("listen_port", 0)
        domains = target.get("domains", [])
        target_scheme = target.get("target_scheme", "http")

        if not target_host or not target.get("enabled", True):
            continue

        upstream_name = f"upstream_{name}"
        lines.append(f"upstream {upstream_name} {{")
        lines.append(f"    server {target_host}:{target_port};")
        lines.append("}")
        lines.append("")

        location_block = _proxy_location_block(target_scheme, upstream_name)

        http_redirect = target.get("http_redirect", False)
        http_port = target.get("http_port", 0)

        # Domain-based routing
        if domains:
            for domain_entry in domains:
                domain = domain_entry.get("domain", "")
                domain_port = domain_entry.get("port", 443)
                if not domain:
                    continue
                lines.append("server {")
                lines.append(f"    listen {domain_port} ssl;")
                lines.append(f"    server_name {domain};")
                lines.append("")
                lines.append("    ssl_certificate /certs/server.crt;")
                lines.append("    ssl_certificate_key /certs/server.key;")
                lines.append("    ssl_protocols TLSv1.2 TLSv1.3;")
                lines.append("")
                lines.append(f"    access_log /var/log/nginx/access.log main;")
                lines.append(f"    error_log /var/log/nginx/error.log warn;")
                lines.append("")
                lines.append(location_block)
                lines.append("}")
                lines.append("")

                # HTTP -> HTTPS redirect for this domain
                if http_redirect and http_port:
                    lines.append("server {")
                    lines.append(f"    listen {http_port};")
                    lines.append(f"    server_name {domain};")
                    lines.append(f"    return 301 https://$host:{domain_port}$request_uri;")
                    lines.append("}")
                    lines.append("")

        # IP/Port-based routing
        if listen_port:
            lines.append("server {")
            lines.append(f"    listen {listen_port} ssl;")
            lines.append(f"    server_name _;")
            lines.append("")
            lines.append("    ssl_certificate /certs/server.crt;")
            lines.append("    ssl_certificate_key /certs/server.key;")
            lines.append("    ssl_protocols TLSv1.2 TLSv1.3;")
            lines.append("")
            lines.append(f"    access_log /var/log/nginx/access.log main;")
            lines.append(f"    error_log /var/log/nginx/error.log warn;")
            lines.append("")
            lines.append(location_block)
            lines.append("}")
            lines.append("")

            # HTTP -> HTTPS redirect for this port
            if http_redirect and http_port:
                lines.append("server {")
                lines.append(f"    listen {http_port};")
                lines.append(f"    server_name _;")
                lines.append(f"    return 301 https://$host:{listen_port}$request_uri;")
                lines.append("}")
                lines.append("")

    conf_content = "\n".join(lines)
    os.makedirs(NGINX_CONF_DIR, exist_ok=True)
    with open(NGINX_UPSTREAM_CONF, "w") as f:
        f.write(conf_content)

    return conf_content


def reload_nginx():
    """Reload nginx configuration."""
    try:
        result = subprocess.run(
            ["nginx", "-t"],
            capture_output=True, text=True, timeout=10
        )
        if result.returncode != 0:
            return False, f"Nginx config test failed: {result.stderr}"

        result = subprocess.run(
            ["nginx", "-s", "reload"],
            capture_output=True, text=True, timeout=10
        )
        if result.returncode != 0:
            return False, f"Nginx reload failed: {result.stderr}"

        return True, "Nginx reloaded successfully"
    except Exception as e:
        return False, str(e)


def read_log_tail(filepath, lines=100):
    """Read the last N lines of a log file."""
    try:
        result = subprocess.run(
            ["tail", "-n", str(lines), filepath],
            capture_output=True, text=True, timeout=5
        )
        return result.stdout
    except Exception:
        return ""


def login_required(f):
    @wraps(f)
    def decorated(*args, **kwargs):
        if not session.get("logged_in"):
            # API requests get 401, browser requests get redirected
            if request.path.startswith("/api/"):
                auth = request.authorization
                if auth and auth.username == USERNAME and auth.password == PASSWORD:
                    return f(*args, **kwargs)
                return jsonify({"error": "Authentication required"}), 401
            return redirect(url_for("login"))
        return f(*args, **kwargs)
    return decorated


# ==================== Auth Routes ====================

@app.route("/login", methods=["GET", "POST"])
def login():
    error = None
    if request.method == "POST":
        if (request.form.get("username") == USERNAME and
                request.form.get("password") == PASSWORD):
            session["logged_in"] = True
            return redirect(url_for("index"))
        error = "Falscher Benutzername oder Passwort"
    return render_template("login.html", error=error)


@app.route("/logout")
def logout():
    session.clear()
    return redirect(url_for("login"))


# ==================== Public Routes ====================

@app.route("/ca.crt")
def download_ca():
    """Download CA certificate - no auth required so devices can easily fetch it."""
    ca_path = "/certs/ca.crt"
    if not os.path.exists(ca_path):
        return "CA certificate not found", 404
    return send_file(ca_path, as_attachment=True, download_name="ca.crt",
                     mimetype="application/x-x509-ca-cert")


# ==================== WebUI Routes ====================

@app.route("/")
@login_required
def index():
    config = load_config()
    return render_template("index.html", config=config)


@app.route("/logs")
@login_required
def logs():
    lines = int(request.args.get("lines", 100))
    log_type = request.args.get("type", "access")
    log_file = NGINX_ACCESS_LOG if log_type == "access" else NGINX_ERROR_LOG
    log_content = read_log_tail(log_file, lines)
    return render_template("logs.html", log_content=log_content, log_type=log_type, lines=lines)


@app.route("/target/add", methods=["POST"])
@login_required
def add_target():
    config = load_config()

    domains = []
    domain_names = request.form.getlist("domain_name[]")
    domain_ports = request.form.getlist("domain_port[]")
    for name, port in zip(domain_names, domain_ports):
        if name.strip():
            domains.append({"domain": name.strip(), "port": int(port) if port else 443})

    target = {
        "name": request.form.get("name", "").strip().replace(" ", "_"),
        "target_host": request.form.get("target_host", "").strip(),
        "target_port": int(request.form.get("target_port", 80)),
        "target_scheme": request.form.get("target_scheme", "http"),
        "listen_port": int(request.form.get("listen_port", 0) or 0),
        "http_redirect": request.form.get("http_redirect") == "on",
        "http_port": int(request.form.get("http_port", 0) or 0),
        "domains": domains,
        "enabled": True,
    }

    if not target["name"] or not target["target_host"]:
        return redirect(url_for("index"))

    config["targets"].append(target)
    save_config(config)
    generate_nginx_config(config)
    reload_nginx()

    return redirect(url_for("index"))


@app.route("/target/<int:idx>/delete", methods=["POST"])
@login_required
def delete_target(idx):
    config = load_config()
    if 0 <= idx < len(config["targets"]):
        config["targets"].pop(idx)
        save_config(config)
        generate_nginx_config(config)
        reload_nginx()
    return redirect(url_for("index"))


@app.route("/target/<int:idx>/toggle", methods=["POST"])
@login_required
def toggle_target(idx):
    config = load_config()
    if 0 <= idx < len(config["targets"]):
        config["targets"][idx]["enabled"] = not config["targets"][idx].get("enabled", True)
        save_config(config)
        generate_nginx_config(config)
        reload_nginx()
    return redirect(url_for("index"))


@app.route("/target/<int:idx>/edit", methods=["POST"])
@login_required
def edit_target(idx):
    config = load_config()
    if 0 <= idx < len(config["targets"]):
        domains = []
        domain_names = request.form.getlist("domain_name[]")
        domain_ports = request.form.getlist("domain_port[]")
        for name, port in zip(domain_names, domain_ports):
            if name.strip():
                domains.append({"domain": name.strip(), "port": int(port) if port else 443})

        config["targets"][idx] = {
            "name": request.form.get("name", "").strip().replace(" ", "_"),
            "target_host": request.form.get("target_host", "").strip(),
            "target_port": int(request.form.get("target_port", 80)),
            "target_scheme": request.form.get("target_scheme", "http"),
            "listen_port": int(request.form.get("listen_port", 0) or 0),
            "http_redirect": request.form.get("http_redirect") == "on",
            "http_port": int(request.form.get("http_port", 0) or 0),
            "domains": domains,
            "enabled": config["targets"][idx].get("enabled", True),
        }
        save_config(config)
        generate_nginx_config(config)
        reload_nginx()
    return redirect(url_for("index"))


# ==================== API Routes ====================

@app.route("/api/targets", methods=["GET"])
@login_required
def api_list_targets():
    config = load_config()
    return jsonify(config)


@app.route("/api/targets", methods=["POST"])
@login_required
def api_add_target():
    config = load_config()
    target = request.get_json()
    if not target:
        return jsonify({"error": "Invalid JSON"}), 400
    if not target.get("name") or not target.get("target_host"):
        return jsonify({"error": "name and target_host are required"}), 400

    target.setdefault("target_port", 80)
    target.setdefault("target_scheme", "http")
    target.setdefault("listen_port", 0)
    target.setdefault("domains", [])
    target.setdefault("enabled", True)

    config["targets"].append(target)
    save_config(config)
    generate_nginx_config(config)
    success, msg = reload_nginx()

    return jsonify({"status": "ok" if success else "warning", "message": msg, "target": target}), 201


@app.route("/api/targets/<int:idx>", methods=["PUT"])
@login_required
def api_update_target(idx):
    config = load_config()
    if idx < 0 or idx >= len(config["targets"]):
        return jsonify({"error": "Target not found"}), 404

    target = request.get_json()
    if not target:
        return jsonify({"error": "Invalid JSON"}), 400

    config["targets"][idx] = target
    save_config(config)
    generate_nginx_config(config)
    success, msg = reload_nginx()

    return jsonify({"status": "ok" if success else "warning", "message": msg})


@app.route("/api/targets/<int:idx>", methods=["DELETE"])
@login_required
def api_delete_target(idx):
    config = load_config()
    if idx < 0 or idx >= len(config["targets"]):
        return jsonify({"error": "Target not found"}), 404

    removed = config["targets"].pop(idx)
    save_config(config)
    generate_nginx_config(config)
    success, msg = reload_nginx()

    return jsonify({"status": "ok" if success else "warning", "message": msg, "removed": removed})


@app.route("/api/reload", methods=["POST"])
@login_required
def api_reload():
    config = load_config()
    generate_nginx_config(config)
    success, msg = reload_nginx()
    return jsonify({"status": "ok" if success else "error", "message": msg})


@app.route("/api/logs", methods=["GET"])
@login_required
def api_logs():
    lines = int(request.args.get("lines", 100))
    log_type = request.args.get("type", "access")
    log_file = NGINX_ACCESS_LOG if log_type == "access" else NGINX_ERROR_LOG
    return jsonify({"type": log_type, "content": read_log_tail(log_file, lines)})


if __name__ == "__main__":
    app.run(host="0.0.0.0", port=5000, debug=True)