from datetime import datetime

from sqlalchemy import DateTime, Float, ForeignKey, Index, Integer, String, Text, text
from sqlalchemy.orm import Mapped, mapped_column

from app.models.base import Base, TimestampMixin, SoftDeleteMixin


class ChatGenerationTask(Base, TimestampMixin, SoftDeleteMixin):
    """Project-independent AI chat/image/video generation task.

    This table is intentionally NOT linked to projects.  It is used by the
    /generation-ai Celery pipeline so chat-style generation does not touch the
    legacy generation_records -> projects foreign-key chain.
    """

    __tablename__ = "chat_generation_tasks"
    __table_args__ = (
        # 防止前端按钮连点/网络重试时同一个 idempotency_key 并发创建多条任务。
        # nullable unique 兼容不传 idempotency_key 的普通请求。
        Index(
            "uq_chat_generation_tasks_user_mode_idempotency",
            "user_id",
            "generation_mode",
            "idempotency_key",
            unique=True,
            postgresql_where=text("deleted_at IS NULL AND idempotency_key IS NOT NULL"),
        ),
    )


    id: Mapped[str] = mapped_column(String(32), primary_key=True)
    user_id: Mapped[str] = mapped_column(
        String(32), ForeignKey("users.id", ondelete="CASCADE"), index=True, nullable=False
    )

    original_prompt: Mapped[str] = mapped_column(Text, nullable=False)
    optimized_prompt: Mapped[str | None] = mapped_column(Text, nullable=True)
    gen_type: Mapped[str] = mapped_column(String(16), default="video", index=True)

    duration: Mapped[int | None] = mapped_column(Integer, nullable=True)
    aspect_ratio: Mapped[str | None] = mapped_column(String(8), nullable=True)
    resolution: Mapped[str | None] = mapped_column(String(8), nullable=True)
    image_size: Mapped[str | None] = mapped_column(String(16), nullable=True)
    image_proportion: Mapped[str | None] = mapped_column(String(8), nullable=True)
    image_px: Mapped[str | None] = mapped_column(String(16), nullable=True)

    status: Mapped[str] = mapped_column(String(32), default="generating", index=True)
    pipeline_stage: Mapped[str | None] = mapped_column(String(32), nullable=True, index=True)
    generation_mode: Mapped[str] = mapped_column(String(32), default="chatapi_async", index=True)

    media_references: Mapped[str | None] = mapped_column(Text, nullable=True)
    provider_task_id: Mapped[str | None] = mapped_column(String(128), nullable=True, index=True)
    # Kept as alias-compatible storage for existing frontend/service naming.
    seedance_task_id: Mapped[str | None] = mapped_column(String(128), nullable=True, index=True)

    remote_result_url: Mapped[str | None] = mapped_column(Text, nullable=True)
    image_url: Mapped[str | None] = mapped_column(String(512), nullable=True)
    video_url: Mapped[str | None] = mapped_column(String(512), nullable=True)
    video_cover_url: Mapped[str | None] = mapped_column(String(512), nullable=True)

    engine_id: Mapped[str | None] = mapped_column(String(32), nullable=True, index=True)
    engine_snapshot_json: Mapped[str | None] = mapped_column(Text, nullable=True)
    provider_response_json: Mapped[str | None] = mapped_column(Text, nullable=True)

    credits_cost: Mapped[float] = mapped_column(Float, default=0.0)
    text_credits_cost: Mapped[float] = mapped_column(Float, default=0.0)
    text_tokens_used: Mapped[int] = mapped_column(Integer, default=0)
    video_tokens_used: Mapped[int] = mapped_column(Integer, default=0)
    image_tokens_used: Mapped[int] = mapped_column(Integer, default=0)

    retry_count: Mapped[int] = mapped_column(Integer, default=0)
    poll_count: Mapped[int] = mapped_column(Integer, default=0)
    last_poll_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    deadline_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    generated_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    error_message: Mapped[str | None] = mapped_column(Text, nullable=True)
    idempotency_key: Mapped[str | None] = mapped_column(String(64), nullable=True, index=True)

    # Celery 下载容灾字段。
    download_celery_task_id: Mapped[str | None] = mapped_column(String(160), nullable=True, index=True)
    download_enqueued_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    download_started_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    download_lease_until: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)
    download_next_retry_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True, index=True)
    download_attempt_count: Mapped[int] = mapped_column(Integer, default=0)
    download_last_error: Mapped[str | None] = mapped_column(Text, nullable=True)
    download_storage_date_dir: Mapped[str | None] = mapped_column(String(16), nullable=True)