"""Client-side operations over a unified encrypted channel (per local user id)."""

from __future__ import annotations

import base64
import json
import socket

import zkac
from zkac.tcp import FramedSession, client_handshake_anon

from . import pir, store


def _b64(data: bytes) -> str:
    return base64.b64encode(data).decode()


def _unb64(s: str) -> bytes:
    return base64.b64decode(s)


def _parse_server(server: str) -> tuple[str, int]:
    host, _, port = server.rpartition(":")
    return host or "127.0.0.1", int(port)


def parse_spec(spec: str) -> tuple[str, str, str]:
    """Parse 'host:port:registry_id:role' into (server, registry_id, role)."""
    parts = spec.rsplit(":", 2)
    if len(parts) != 3:
        raise ValueError(f"invalid spec {spec!r}, expected host:port:registry_id:role")
    return parts[0], parts[1], parts[2]


def _resolve_server_pk(userid: str, server: str) -> zkac.PublicKey:
    pin = store.load_server_pin(userid, server)
    if pin is None:
        raise RuntimeError(
            f"no pinned key for {server}; run: zkac-node server pin {userid} {server} --key <hex>"
        )
    return zkac.PublicKey.from_bytes(_unb64(pin["server_public_key_b64"]))


def _mgmt_connect(userid: str, server: str) -> tuple[socket.socket, FramedSession]:
    host, port = _parse_server(server)
    sock = socket.create_connection((host, port))
    server_pk = _resolve_server_pk(userid, server)
    node = zkac.Node(zkac.Keypair())
    session = client_handshake_anon(sock, node, server_pk)
    framed = FramedSession(sock, session)
    framed.send(json.dumps({"op": "mgmt"}).encode())
    return sock, framed


def _mgmt_cmd(framed: FramedSession, cmd: dict) -> dict:
    framed.send(json.dumps(cmd).encode())
    return json.loads(framed.recv())


def _mgmt_single(userid: str, server: str, cmd: dict) -> dict:
    sock, framed = _mgmt_connect(userid, server)
    try:
        return _ok(_mgmt_cmd(framed, cmd))
    finally:
        sock.close()


def _ok(resp: dict) -> dict:
    if resp.get("error"):
        raise RuntimeError(resp["error"])
    return resp


def create_registry(userid: str, server: str, role_names: list[str]) -> str:
    identity = store.load_identity(userid)
    admin_mat = store.new_admin_material()
    bbs_issuer, bbs_pk, admin_cred = store.reconstruct_admin(admin_mat)

    role_entries = [(zkac.role_id(name), bbs_pk, 1) for name in role_names]
    state = zkac.RegistryState.build(
        bbs_pk, identity["issuance_pk"], 1, b"\x00" * 32, role_entries,
    )
    state_bytes = state.serialize()
    state_cert = state.certify(admin_cred)
    registry_id = state.registry_id()

    resp = _mgmt_single(userid, server, {
        "cmd": "create_registry",
        "state_bytes_b64": _b64(state_bytes),
        "state_cert_b64": _b64(bytes(state_cert)),
    })

    rid_hex = resp["registry_id"]
    store.save_admin(userid, rid_hex, {
        "server": server,
        "roles": role_names,
        **admin_mat,
    })
    return rid_hex


def update_registry(userid: str, server: str, registry_id_hex: str, add_roles: list[str]):
    admin_data = store.load_admin(userid, registry_id_hex)
    bbs_issuer, bbs_pk, admin_cred = store.reconstruct_admin(admin_data)
    identity = store.load_identity(userid)

    cur = _mgmt_single(userid, server, {
        "cmd": "get_registry", "registry_id": registry_id_hex,
    })

    old_state = zkac.RegistryState.deserialize(_unb64(cur["state_bytes_b64"]))
    prev_hash = old_state.state_hash()
    new_version = old_state.version() + 1

    old_roles = admin_data.get("roles", [])
    all_roles = list(old_roles) + [r for r in add_roles if r not in old_roles]
    role_entries = [(zkac.role_id(name), bbs_pk, 1) for name in all_roles]

    new_state = zkac.RegistryState.build(
        bbs_pk, identity["issuance_pk"], new_version, bytes(prev_hash), role_entries,
    )
    new_cert = new_state.certify(admin_cred)

    _mgmt_single(userid, server, {
        "cmd": "update_registry",
        "registry_id": registry_id_hex,
        "state_bytes_b64": _b64(new_state.serialize()),
        "state_cert_b64": _b64(bytes(new_cert)),
    })

    admin_data["roles"] = all_roles
    store.save_admin(userid, registry_id_hex, admin_data)


def get_registry(userid: str, server: str, registry_id_hex: str) -> dict:
    return _mgmt_single(userid, server, {
        "cmd": "get_registry", "registry_id": registry_id_hex,
    })


def list_own_registries(userid: str) -> list[dict]:
    result = []
    for rid in store.list_admin_registries(userid):
        data = store.load_admin(userid, rid)
        result.append({
            "registry_id": rid,
            "server": data.get("server", "?"),
            "roles": data.get("roles", []),
        })
    return result


def grant(userid: str, server: str, registry_id_hex: str, role_name: str,
          recipient_pk_hex: str) -> tuple[str, int]:
    admin_data = store.load_admin(userid, registry_id_hex)
    roles = admin_data.get("roles", [])
    if role_name not in roles:
        raise RuntimeError(f"role {role_name!r} not in registry (have: {roles})")

    bbs_issuer, bbs_pk, admin_cred = store.reconstruct_admin(admin_data)
    role_rid = zkac.role_id(role_name)
    epoch = 1

    req = zkac.prepare_blind_request()
    blind_sig = bbs_issuer.issue_blind(req.commitment_with_proof(), role_rid, epoch)

    payload = json.dumps({
        "registry_id": registry_id_hex,
        "role_name": role_name,
        "epoch": epoch,
        "issuer_pk_b64": _b64(bbs_pk.to_bytes()),
        "blind_sig_b64": _b64(blind_sig),
        "member_secret_b64": _b64(req.member_secret()),
        "prover_blind_b64": _b64(req.prover_blind()),
    }).encode()

    recipient_pk = bytes.fromhex(recipient_pk_hex)
    eph_kp = zkac.IssuanceKeypair()
    ciphertext = eph_kp.encrypt(recipient_pk, payload)

    sock, framed = _mgmt_connect(userid, server)
    try:
        transcript_hash = bytes(framed.session.transcript_hash())
        admin_proof = admin_cred.present(transcript_hash)
        resp = _ok(_mgmt_cmd(framed, {
            "cmd": "post_grant",
            "registry_id": registry_id_hex,
            "eph_pk_b64": _b64(eph_kp.public_key_bytes()),
            "ciphertext_b64": _b64(ciphertext),
            "admin_proof_b64": _b64(admin_proof),
        }))
    finally:
        sock.close()

    return resp["grant_id"], resp.get("pool_index", -1)


def _pir_recover_row(
    framed_a: FramedSession,
    framed_b: FramedSession,
    n: int,
    pool_index: int,
) -> dict:
    idx_a, idx_b = pir.pir_query_indices(n, pool_index)
    xa = _ok(_mgmt_cmd(framed_a, {"cmd": "pir_fold", "indices": idx_a}))
    xb = _ok(_mgmt_cmd(framed_b, {"cmd": "pir_fold", "indices": idx_b}))
    raw = pir.pir_recover(_unb64(xa["xor_b64"]), _unb64(xb["xor_b64"]))
    return pir.unpad_grant_record(raw)


def _fetch_grant_entry_pir(
    userid: str, server_a: str, server_b: str, pool_index: int,
) -> dict:
    sock_a, fa = _mgmt_connect(userid, server_a)
    sock_b, fb = _mgmt_connect(userid, server_b)
    try:
        a = _ok(_mgmt_cmd(fa, {"cmd": "mail_pool_len"}))
        b = _ok(_mgmt_cmd(fb, {"cmd": "mail_pool_len"}))
        if a["n"] != b["n"] or a["record_bytes"] != b["record_bytes"]:
            raise RuntimeError("PIR peers disagree on pool length or record size")
        n = a["n"]
        if not (0 <= pool_index < n):
            raise RuntimeError("pool_index out of range for current pool")
        return _pir_recover_row(fa, fb, n, pool_index)
    finally:
        sock_a.close()
        sock_b.close()


def list_pending(userid: str, server: str, pir_peer: str) -> list[dict]:
    """Scan the grant pool via two-server XOR PIR (one Chor query per row)."""
    identity = store.load_identity(userid)
    receiver_kp = zkac.IssuanceKeypair.from_secret(identity["issuance_sk"])

    info = _mgmt_single(userid, server, {"cmd": "server_info"})
    store.pin_server(userid, server, info["server_public_key_b64"])
    info_b = _mgmt_single(userid, pir_peer, {"cmd": "server_info"})
    store.pin_server(userid, pir_peer, info_b["server_public_key_b64"])

    sock_a, fa = _mgmt_connect(userid, server)
    sock_b, fb = _mgmt_connect(userid, pir_peer)
    try:
        a = _ok(_mgmt_cmd(fa, {"cmd": "mail_pool_len"}))
        b = _ok(_mgmt_cmd(fb, {"cmd": "mail_pool_len"}))
        if a["n"] != b["n"] or a["record_bytes"] != b["record_bytes"]:
            raise RuntimeError("PIR peers disagree on pool length or record size")
        n = a["n"]
        results = []
        for i in range(n):
            row = _pir_recover_row(fa, fb, n, i)
            if row.get("claimed"):
                continue
            try:
                eph_pk = _unb64(row["eph_pk_b64"])
                ct = _unb64(row["ciphertext_b64"])
                plaintext = json.loads(receiver_kp.decrypt(eph_pk, ct))
                results.append({
                    "grant_id": row["grant_id"],
                    "pool_index": i,
                    "registry_id": plaintext.get("registry_id", "?"),
                    "role_name": plaintext.get("role_name", "?"),
                })
            except Exception:
                results.append({
                    "grant_id": row.get("grant_id", "?"),
                    "pool_index": i,
                    "registry_id": "?",
                    "role_name": "(undecryptable)",
                })
        return results
    finally:
        sock_a.close()
        sock_b.close()


def collect(
    userid: str,
    spec: str,
    *,
    pir_peer: str,
    pool_index: int,
) -> dict:
    server, registry_id_hex, role_name = parse_spec(spec)
    identity = store.load_identity(userid)
    receiver_kp = zkac.IssuanceKeypair.from_secret(identity["issuance_sk"])

    info = _mgmt_single(userid, server, {"cmd": "server_info"})
    store.pin_server(userid, server, info["server_public_key_b64"])
    info_b = _mgmt_single(userid, pir_peer, {"cmd": "server_info"})
    store.pin_server(userid, pir_peer, info_b["server_public_key_b64"])

    row = _fetch_grant_entry_pir(userid, server, pir_peer, pool_index)
    if row.get("claimed"):
        raise RuntimeError("grant row is already claimed")
    try:
        eph_pk = _unb64(row["eph_pk_b64"])
        ct = _unb64(row["ciphertext_b64"])
        plaintext = json.loads(receiver_kp.decrypt(eph_pk, ct))
    except Exception as exc:
        raise RuntimeError(
            "PIR row did not decrypt for this user (wrong pool_index or desynced peers)"
        ) from exc
    if (plaintext.get("registry_id") != registry_id_hex or
            plaintext.get("role_name") != role_name):
        raise RuntimeError(
            "PIR row does not match this collect spec (check pool_index and peers)"
        )
    target_grant_id = row["grant_id"]
    target_payload = plaintext

    _mgmt_single(userid, server, {
        "cmd": "claim_grant",
        "grant_id": target_grant_id,
    })

    _ = _mgmt_single(userid, server, {
        "cmd": "get_registry", "registry_id": registry_id_hex,
    })

    cred_data = {
        "blind_sig_b64": target_payload["blind_sig_b64"],
        "member_secret_b64": target_payload["member_secret_b64"],
        "prover_blind_b64": target_payload["prover_blind_b64"],
        "role_name": role_name,
        "epoch": target_payload["epoch"],
        "issuer_pk_b64": target_payload["issuer_pk_b64"],
    }
    cred = store.reconstruct_credential(cred_data)
    cred.present(b"self-test")

    store.save_credential(userid, registry_id_hex, role_name, cred_data)

    return {"registry_id": registry_id_hex, "role": role_name, "server": server}


def authenticate(userid: str, registry_id_hex: str, role_name: str,
                 server: str | None = None) -> dict:
    admin_data = None
    try:
        admin_data = store.load_admin(userid, registry_id_hex)
    except FileNotFoundError:
        pass

    if server is None:
        if admin_data and admin_data.get("server"):
            server = admin_data["server"]
        else:
            raise RuntimeError("server address required (--server host:port)")

    cred_data = store.load_credential_data(userid, registry_id_hex, role_name)
    cred = store.reconstruct_credential(cred_data)

    server_pk = _resolve_server_pk(userid, server)
    node = zkac.Node(zkac.Keypair())
    host, port = _parse_server(server)

    sock = socket.create_connection((host, port))
    try:
        session = client_handshake_anon(sock, node, server_pk)
        framed = FramedSession(sock, session)

        transcript_hash = bytes(session.transcript_hash())
        auth_proof = cred.present(transcript_hash)
        role_rid = zkac.role_id(role_name)

        framed.send(json.dumps({
            "op": "auth",
            "registry_id": registry_id_hex,
            "role_id": role_rid.hex(),
            "bbs_auth_b64": _b64(auth_proof),
        }).encode())

        return json.loads(framed.recv())
    finally:
        sock.close()