import hashlib
import hmac
import os
import binascii

# ═══════════════════════════════════════════
# NOSTR SOVEREIGN IDENTITY (NIP-01)
# ═══════════════════════════════════════════
# Pure Python implementation of Schnorr signatures for Nostr.
# No dependencies required.

def sha256(data):
    return hashlib.sha256(data).digest()

def hmac_sha256(key, data):
    return hmac.new(key, data, hashlib.sha256).digest()

# Secp256k1 Constants
P = 2**256 - 2**32 - 977
N = 115792089237316195423570985008687907852837564279074904382605163141518161494337
G = (0x79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798,
     0x483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8)

def inverse(a, n):
    return pow(a, n - 2, n)

def point_add(p1, p2):
    if p1 is None: return p2
    if p2 is None: return p1
    (x1, y1), (x2, y2) = p1, p2
    if x1 == x2 and y1 != y2: return None
    if x1 == x2:
        m = (3 * x1 * x1 * inverse(2 * y1, P)) % P
    else:
        m = ((y2 - y1) * inverse(x2 - x1, P)) % P
    x3 = (m * m - x1 - x2) % P
    y3 = (m * (x1 - x3) - y1) % P
    return (x3, y3)

def point_mul(p, n):
    r = None
    for i in range(256):
        if (n >> i) & 1:
            r = point_add(r, p)
        p = point_add(p, p)
    return r

def get_pubkey(privkey):
    p = point_mul(G, privkey)
    return binascii.hexlify(p[0].to_bytes(32, 'big')).decode()

# Schnorr Signature (BIP340)
def sign_schnorr(msg_hash, privkey):
    k = int.from_bytes(sha256(privkey.to_bytes(32, 'big') + msg_hash), 'big') % N
    R = point_mul(G, k)
    if R[1] % 2 != 0:
        k = N - k
    r = R[0].to_bytes(32, 'big')
    e = int.from_bytes(sha256(r + binascii.unhexlify(get_pubkey(privkey)) + msg_hash), 'big') % N
    s = (k + e * privkey) % N
    return binascii.hexlify(r + s.to_bytes(32, 'big')).decode()

class NostrIdentity:
    def __init__(self, privkey_hex=None):
        if privkey_hex:
            self.privkey = int(privkey_hex, 16)
        else:
            self.privkey = int.from_bytes(os.urandom(32), 'big') % N
        self.pubkey = get_pubkey(self.privkey)

    def sign_event(self, event):
        # NIP-01 Event Signing
        import json
        event_data = [
            0,
            event['pubkey'],
            event['created_at'],
            event['kind'],
            event['tags'],
            event['content']
        ]
        serialized = json.dumps(event_data, separators=(',', ':'))
        msg_hash = sha256(serialized.encode())
        event['id'] = binascii.hexlify(msg_hash).decode()
        event['sig'] = sign_schnorr(msg_hash, self.privkey)
        return event

if __name__ == "__main__":
    # Test Identity
    identity = NostrIdentity()
    print(f"Nostr Pubkey: {identity.pubkey}")
    
    event = {
        "pubkey": identity.pubkey,
        "created_at": 1677628800,
        "kind": 1,
        "tags": [],
        "content": "Sovereignty and service always. #Timmy"
    }
    signed_event = identity.sign_event(event)
    print(f"Signed Event: {signed_event}")