"""Non-Owner Gitea machine capability and branch reconciliation boundary."""

from __future__ import annotations

from dataclasses import dataclass
from typing import Any, Mapping, Protocol


class MachineBrokerError(RuntimeError):
    pass


class GiteaTransport(Protocol):
    def compare_and_swap_branch(self, branch: str, expected_oid: str, new_oid: str) -> str: ...
    def create_or_update_pr(self, branch: str, target: str, title: str, body: str) -> Mapping[str, Any]: ...
    def publish_status(self, branch: str, state: str, description: str) -> Mapping[str, Any]: ...
    def protected_merge(self, pr_number: int) -> Mapping[str, Any]: ...
    def read_branch(self, branch: str) -> str | None: ...
    def whoami(self) -> Mapping[str, Any]: ...
    def repository(self, owner: str, name: str) -> Mapping[str, Any]: ...


@dataclass(frozen=True, slots=True)
class MachineCredentialProjection:
    """Opaque systemd credential reference; the credential value is never accepted."""

    reference: str
    account: str
    owner_account: str = "aiman"

    @classmethod
    def from_mapping(cls, value: Mapping[str, Any]) -> "MachineCredentialProjection":
        if set(value) != {"scheme", "name", "account"}:
            raise MachineBrokerError("CREDENTIAL_REFERENCE_INVALID")
        if value["scheme"] != "systemd-credential" or value["name"] != "gitea-machine-token":
            raise MachineBrokerError("CREDENTIAL_REFERENCE_INVALID")
        return cls(f"{value['scheme']}:{value['name']}", str(value["account"]))

    def __post_init__(self) -> None:
        if self.reference != "systemd-credential:gitea-machine-token":
            raise MachineBrokerError("CREDENTIAL_REFERENCE_INVALID")
        if not self.account or self.account == self.owner_account:
            raise MachineBrokerError("OWNER_MACHINE_IDENTITY_REJECTED")


@dataclass(frozen=True, slots=True)
class CampaignCapabilityReceipt:
    campaign_id: str
    task_id: str
    repository: str
    branch: str
    expected_oid: str
    capabilities: frozenset[str]
    denied: frozenset[str]

    def require(self, capability: str) -> None:
        if capability in self.denied or capability not in self.capabilities:
            raise MachineBrokerError("CAPABILITY_DENIED")
        if self.branch in {"main", "master"}:
            raise MachineBrokerError("PROTECTED_BRANCH_DENIED")


class GiteaMachineBroker:
    def __init__(self, transport: GiteaTransport, credential: MachineCredentialProjection, receipt: CampaignCapabilityReceipt) -> None:
        self.transport = transport
        self.credential = credential
        self.receipt = receipt

    def verify_identity(self) -> Mapping[str, Any]:
        identity = dict(self.transport.whoami())
        login = identity.get("login") or identity.get("username")
        if not isinstance(login, str) or not login or login == self.credential.owner_account or login != self.credential.account:
            raise MachineBrokerError("GITEA_MACHINE_IDENTITY_INVALID")
        owner, name = self.receipt.repository.split("/", 1)
        repo = dict(self.transport.repository(owner, name))
        if repo.get("full_name") != self.receipt.repository:
            raise MachineBrokerError("GITEA_REPOSITORY_MISMATCH")
        return {"login": login, "repository": self.receipt.repository, "owner_account": self.credential.owner_account}

    def push_branch(self, new_oid: str) -> str:
        self.receipt.require("exact_task_branch_push")
        return self.transport.compare_and_swap_branch(self.receipt.branch, self.receipt.expected_oid, new_oid)

    def create_pr(self, title: str, body: str) -> Mapping[str, Any]:
        self.receipt.require("pr_create_update")
        return self.transport.create_or_update_pr(self.receipt.branch, "main", title, body)

    def status(self, state: str, description: str, context: str = "aios/durable-release") -> Mapping[str, Any]:
        self.receipt.require("status_publish")
        return self.transport.publish_status(self.receipt.branch, state, description, context)

    def merge(self, pr_number: int) -> Mapping[str, Any]:
        self.receipt.require("protected_merge")
        return self.transport.protected_merge(pr_number)

    def readback(self) -> str | None:
        self.receipt.require("remote_readback")
        return self.transport.read_branch(self.receipt.branch)


def reconcile_exact_branch(authority_oid: str, gitea_oid: str | None, expected_oid: str) -> str:
    if authority_oid != expected_oid:
        return "AUTHORITY_EXPECTATION_MISMATCH"
    if gitea_oid is None:
        return "CREATE_REQUIRED"
    if gitea_oid == expected_oid:
        return "ALREADY_IN_SYNC"
    return "MANUAL_OWNER_REVIEW_REQUIRED"


def reconcile_fast_forward(
    remote_oid: str | None,
    expected_old_oid: str,
    new_oid: str,
    *,
    old_is_ancestor_of_new: bool,
) -> str:
    """Return a bounded action for an active Job/lease branch scope."""
    if remote_oid is None:
        return "CREATE_REQUIRED"
    if remote_oid == new_oid:
        return "ALREADY_IN_SYNC"
    if remote_oid == expected_old_oid and old_is_ancestor_of_new:
        return "FAST_FORWARD_REQUIRED"
    return "MANUAL_OWNER_REVIEW_REQUIRED"