import json
import os
import re
import sqlite3
import uuid
import datetime
from flask import Flask, render_template, request, jsonify, abort

# ── Load configuration ────────────────────────────────────────────────────────

_CONFIG_PATH = os.path.join(os.path.dirname(__file__), 'config.json')

def _load_config():
    with open(_CONFIG_PATH, 'r', encoding='utf-8') as f:
        return json.load(f)

try:
    CFG = _load_config()
except (FileNotFoundError, json.JSONDecodeError) as e:
    raise RuntimeError(f"Failed to load config.json: {e}") from e

_site   = CFG['site']
_server = CFG['server']
_db_cfg = CFG['database']
_pastes = CFG['pastes']
_theme  = CFG['theme']
_feat   = CFG['features']
_ui     = CFG['ui']

# ── Flask app setup ───────────────────────────────────────────────────────────

app = Flask(__name__)
app.config['SECRET_KEY'] = _server.get('secret_key', 'change-me')

DATABASE            = _db_cfg.get('path', 'bastebin.db')
MAX_ENCRYPTED_BYTES = _pastes.get('max_size_bytes', 2 * 1024 * 1024)
_ENCRYPTED_RE       = re.compile(r'^[A-Za-z0-9_-]+:[A-Za-z0-9_-]+$')

# ── Jinja helpers ─────────────────────────────────────────────────────────────

@app.context_processor
def inject_config():
    return {'cfg': CFG}

# ── Database ──────────────────────────────────────────────────────────────────

def get_db_connection():
    conn = sqlite3.connect(DATABASE, timeout=10)
    conn.row_factory = sqlite3.Row
    conn.execute('PRAGMA journal_mode=WAL')
    return conn

def init_db():
    conn   = sqlite3.connect(DATABASE)
    cursor = conn.cursor()
    cursor.execute("PRAGMA table_info(pastes)")
    columns = {row[1] for row in cursor.fetchall()}
    if columns and 'content' in columns and 'encrypted_data' not in columns:
        cursor.execute("DROP TABLE pastes")
    cursor.execute('''
        CREATE TABLE IF NOT EXISTS pastes (
            id             TEXT PRIMARY KEY,
            encrypted_data TEXT NOT NULL,
            created_at     TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
            expires_at     TIMESTAMP,
            views          INTEGER DEFAULT 0
        )
    ''')
    conn.commit()
    conn.close()

# ── Helpers ───────────────────────────────────────────────────────────────────

def generate_paste_id():
    length = _pastes.get('id_length', 8)
    return str(uuid.uuid4()).replace('-', '')[:length]

def validate_encrypted_data(value):
    if not isinstance(value, str):
        return False
    if len(value) > MAX_ENCRYPTED_BYTES:
        return False
    return bool(_ENCRYPTED_RE.match(value))

def _get_paste_or_abort(paste_id):
    conn  = get_db_connection()
    paste = conn.execute('SELECT * FROM pastes WHERE id = ?', (paste_id,)).fetchone()
    conn.close()
    if not paste:
        abort(404)
    if paste['expires_at']:
        expires_at = datetime.datetime.fromisoformat(paste['expires_at'])
        if expires_at < datetime.datetime.now():
            abort(410)
    return paste

# ── Routes ────────────────────────────────────────────────────────────────────

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

@app.route('/create', methods=['POST'])
def create_paste():
    data = request.get_json(silent=True)
    if not data:
        return jsonify({'error': 'JSON body required'}), 400

    if 'encrypted_data' in data:
        # Encrypted path — always accepted regardless of encrypt_pastes setting
        store_data = data.get('encrypted_data', '')
        if not validate_encrypted_data(store_data):
            return jsonify({'error': 'encrypted_data must be a valid iv:ciphertext string'}), 400
    elif 'content' in data:
        # Plaintext path — always accepted regardless of encrypt_pastes setting
        content  = data.get('content', '')
        title    = data.get('title', 'Untitled') or 'Untitled'
        language = data.get('language', _pastes.get('default_language', 'text'))
        if not content or not isinstance(content, str):
            return jsonify({'error': 'content must be a non-empty string'}), 400
        if len(content.encode('utf-8')) > MAX_ENCRYPTED_BYTES:
            return jsonify({'error': 'Paste too large'}), 413
        store_data = json.dumps({'title': title, 'content': content, 'language': language})
    else:
        return jsonify({'error': 'Provide either encrypted_data or content'}), 400

    allowed_expiry = set(_pastes.get('allow_expiry_options', ['never']))
    expires_in = data.get('expires_in', 'never')
    if expires_in not in allowed_expiry:
        expires_in = 'never'

    expires_at = None
    if expires_in != 'never':
        delta_map = {
            '1hour':  datetime.timedelta(hours=1),
            '1day':   datetime.timedelta(days=1),
            '1week':  datetime.timedelta(weeks=1),
            '1month': datetime.timedelta(days=30),
        }
        expires_at = datetime.datetime.now() + delta_map[expires_in]

    paste_id = generate_paste_id()
    conn = get_db_connection()
    conn.execute(
        'INSERT INTO pastes (id, encrypted_data, expires_at) VALUES (?, ?, ?)',
        (paste_id, store_data, expires_at)
    )
    conn.commit()
    conn.close()
    return jsonify({'paste_id': paste_id, 'url': f'/{paste_id}'})

@app.route('/<paste_id>')
def view_paste(paste_id):
    paste = _get_paste_or_abort(paste_id)
    conn  = get_db_connection()
    conn.execute('UPDATE pastes SET views = views + 1 WHERE id = ?', (paste_id,))
    conn.commit()
    paste = conn.execute('SELECT * FROM pastes WHERE id = ?', (paste_id,)).fetchone()
    conn.close()
    return render_template('view.html', paste=paste)

@app.route('/<paste_id>/raw')
def view_paste_raw(paste_id):
    paste = _get_paste_or_abort(paste_id)
    return jsonify({
        'id':             paste['id'],
        'encrypted_data': paste['encrypted_data'],
        'created_at':     paste['created_at'],
        'expires_at':     paste['expires_at'],
        'views':          paste['views'],
    })

@app.route('/api/languages')
def get_languages():
    return jsonify(CFG.get('languages', []))

@app.route('/api/config')
def get_client_config():
    """Expose the browser-safe portion of config to JavaScript."""
    return jsonify({
        'site':     _site,
        'theme':    _theme,
        'features': _feat,
        'ui':       _ui,
        'pastes': {
            'default_language':     _pastes.get('default_language', 'text'),
            'default_expiry':       _pastes.get('default_expiry', 'never'),
            'allow_expiry_options': _pastes.get('allow_expiry_options', []),
            'expiry_labels':        _pastes.get('expiry_labels', {}),
        }
    })

# ── Error handlers ────────────────────────────────────────────────────────────

@app.errorhandler(404)
def not_found(error):
    return render_template('404.html'), 404

@app.errorhandler(410)
def gone(error):
    return render_template('410.html'), 410

# ── Entry point ───────────────────────────────────────────────────────────────

if __name__ == '__main__':
    init_db()
    app.run(
        debug=_server.get('debug', False),
        host=_server.get('host', '0.0.0.0'),
        port=_server.get('port', 5000)
    )