import uuid
from datetime import datetime
from typing import Any

from sqlalchemy import JSON, DateTime, ForeignKey, Integer, String, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column, relationship
from sqlalchemy.sql import func

from app.core.database import Base
from app.core.sql_types import GUID as Uuid


class ApprovalRequest(Base):
    __tablename__ = "approval_requests"
    __mapper_args__ = {"eager_defaults": True}

    id: Mapped[uuid.UUID] = mapped_column(
        Uuid,
        primary_key=True,
        default=uuid.uuid4,
    )
    external_id: Mapped[str] = mapped_column(String(128), nullable=False, unique=True)
    approval_type: Mapped[str] = mapped_column(String(64), nullable=False)
    applicant_id: Mapped[uuid.UUID | None] = mapped_column(
        Uuid,
        ForeignKey("identity_persons.id"),
    )
    status: Mapped[str] = mapped_column(String(32), nullable=False)
    source_payload: Mapped[Any | None] = mapped_column(JSON)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        nullable=False,
        server_default=func.now(),
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        nullable=False,
        server_default=func.now(),
        onupdate=func.now(),
    )

    steps: Mapped[list["ApprovalStep"]] = relationship(back_populates="approval")


class ApprovalSubmissionIntent(Base):
    """Durable intent for one Feishu approval-instance submission.

    The provider UUID is persisted before the outbound POST.  It is Feishu's
    native idempotency key and is therefore the recovery anchor when a timeout
    leaves the create result unknown.
    """

    __tablename__ = "approval_submission_intents"
    __table_args__ = (
        UniqueConstraint(
            "scope", "applicant_id", "idempotency_key",
            name="uq_approval_submission_intent_key",
        ),
        UniqueConstraint(
            "provider_request_uuid",
            name="uq_approval_submission_intent_provider_uuid",
        ),
    )
    __mapper_args__ = {"eager_defaults": True}

    id: Mapped[uuid.UUID] = mapped_column(
        Uuid, primary_key=True, default=uuid.uuid4,
    )
    scope: Mapped[str] = mapped_column(String(64), nullable=False)
    applicant_id: Mapped[uuid.UUID] = mapped_column(
        Uuid, ForeignKey("identity_persons.id"), nullable=False,
    )
    idempotency_key: Mapped[str] = mapped_column(String(128), nullable=False)
    payload_fingerprint: Mapped[str] = mapped_column(String(64), nullable=False)
    provider_request_uuid: Mapped[str] = mapped_column(String(64), nullable=False)
    state: Mapped[str] = mapped_column(
        String(32), nullable=False, default="prepared",
    )
    payload: Mapped[Any] = mapped_column(JSON, nullable=False)
    external_id: Mapped[str | None] = mapped_column(
        String(128), nullable=True, unique=True,
    )
    employee_request_id: Mapped[uuid.UUID | None] = mapped_column(
        Uuid, ForeignKey("employee_requests.id"), nullable=True,
    )
    approval_request_id: Mapped[uuid.UUID | None] = mapped_column(
        Uuid, ForeignKey("approval_requests.id"), nullable=True,
    )
    attempt_count: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
    last_error: Mapped[str | None] = mapped_column(String(512), nullable=True)
    next_attempt_at: Mapped[datetime | None] = mapped_column(
        DateTime(timezone=True), nullable=True, index=True,
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
        onupdate=func.now(),
    )
    completed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))


class ApprovalStep(Base):
    __tablename__ = "approval_steps"

    id: Mapped[uuid.UUID] = mapped_column(
        Uuid,
        primary_key=True,
        default=uuid.uuid4,
    )
    approval_id: Mapped[uuid.UUID] = mapped_column(
        Uuid,
        ForeignKey("approval_requests.id"),
        nullable=False,
    )
    step_name: Mapped[str] = mapped_column(String(128), nullable=False)
    approver_id: Mapped[uuid.UUID | None] = mapped_column(
        Uuid,
        ForeignKey("identity_persons.id"),
    )
    status: Mapped[str] = mapped_column(String(32), nullable=False)
    acted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
    detail: Mapped[Any | None] = mapped_column(JSON)

    approval: Mapped["ApprovalRequest"] = relationship(back_populates="steps")