"""M3 知识域：knowledge_doc + 扩宽 item.status（加知识四态）。

三个需要注意的点：

1. **item.status 的 CHECK 再扩一次**。0003 里是"任务 ∪ 工单"，知识的
   `draft/in_review/published/archived` 会被直接拦下。这里改为三者并集；
   "哪种 kind 只能用哪组状态"由 `app/domain/*.py` 的状态机保证，不靠数据库
   （CHECK 不能跨行判断 kind 与 status 的组合）。
2. **知识的来源写在数据库里**。`source_kind <> 'manual'` 时 `source_item_id` 必填。
   这条 CHECK 是 D3 的物理落点：LLM 自动归档出来的知识若没有来源，用户无法核对，
   等于往库里塞断言。
3. **downgrade 会删掉所有知识**（kind='knowledge' 的 item 及其扩展），原因与 0003 相同：
   旧约束容纳不下知识状态，不回删就回不到 0003。
"""

from __future__ import annotations

from collections.abc import Sequence

import sqlalchemy as sa
from alembic import op
from sqlalchemy.dialects import postgresql

revision: str = "0004"
down_revision: str | None = "0003"
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None

APP_ROLE = "dadao_app"

TENANT_TABLES_0004: tuple[str, ...] = ("knowledge_doc",)

TASK_STATUSES = ("inbox", "todo", "doing", "done", "blocked", "canceled")
TICKET_STATUSES = ("open", "accepted", "in_progress", "pending_verify", "done", "canceled")
KNOWLEDGE_STATUSES = ("draft", "in_review", "published", "archived")


def upgrade() -> None:
    # 1) item.status 放宽到 任务 ∪ 工单 ∪ 知识
    op.execute("ALTER TABLE item DROP CONSTRAINT IF EXISTS ck_item_status")
    statuses = ",".join(
        f"'{s}'" for s in (*TASK_STATUSES, *TICKET_STATUSES, *KNOWLEDGE_STATUSES)
    )
    op.execute(f"ALTER TABLE item ADD CONSTRAINT ck_item_status CHECK (status IN ({statuses}))")

    # 2) knowledge_doc
    op.create_table(
        "knowledge_doc",
        sa.Column(
            "item_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("item.id", ondelete="CASCADE"),
            primary_key=True,
        ),
        sa.Column(
            "workspace_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("workspace.id", ondelete="CASCADE"),
            nullable=False,
        ),
        sa.Column(
            "author_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("app_user.id", ondelete="RESTRICT"),
            nullable=False,
        ),
        sa.Column(
            "source_item_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("item.id", ondelete="SET NULL"),
            nullable=True,
        ),
        sa.Column("source_kind", sa.String(16), nullable=False, server_default="manual"),
        sa.Column("doc_type", sa.String(16), nullable=False, server_default="note"),
        sa.Column("status_hint", sa.String(16), nullable=False, server_default="draft"),
        sa.Column("summary", sa.Text(), nullable=False, server_default=""),
        sa.Column("generated_by", sa.String(16), nullable=False, server_default="human"),
        sa.Column("published_at", sa.DateTime(timezone=True), nullable=True),
        sa.Column("archived_at", sa.DateTime(timezone=True), nullable=True),
        sa.Column("chunk_count", sa.Integer(), nullable=False, server_default="0"),
        sa.Column(
            "created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False
        ),
        sa.Column(
            "updated_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False
        ),
        sa.Column("version", sa.Integer(), nullable=False, server_default="1"),
        sa.CheckConstraint(
            "source_kind = 'manual' OR source_item_id IS NOT NULL",
            name="ck_knowledge_source_required",
        ),
        sa.CheckConstraint("chunk_count >= 0", name="ck_knowledge_chunk_count"),
    )
    op.create_index("ix_knowledge_ws_status", "knowledge_doc", ["workspace_id", "status_hint"])
    op.create_index("ix_knowledge_ws_source", "knowledge_doc", ["workspace_id", "source_item_id"])

    # 3) RLS + 授权
    op.execute("ALTER TABLE knowledge_doc ENABLE ROW LEVEL SECURITY")
    op.execute(
        "CREATE POLICY knowledge_doc_isolation ON knowledge_doc "
        "USING (workspace_id = app_ws_id()) WITH CHECK (workspace_id = app_ws_id())"
    )
    op.execute(
        f"GRANT SELECT, INSERT, UPDATE, DELETE ON {', '.join(TENANT_TABLES_0004)} TO {APP_ROLE}"
    )


def downgrade() -> None:
    # 旧约束容纳不下知识状态：先清掉知识 item，才能回到 0003 的约束
    op.execute("DELETE FROM item WHERE kind = 'knowledge'")
    op.execute("DROP POLICY IF EXISTS knowledge_doc_isolation ON knowledge_doc")
    op.drop_index("ix_knowledge_ws_source", table_name="knowledge_doc")
    op.drop_index("ix_knowledge_ws_status", table_name="knowledge_doc")
    op.drop_table("knowledge_doc")

    op.execute("ALTER TABLE item DROP CONSTRAINT IF EXISTS ck_item_status")
    statuses = ",".join(f"'{s}'" for s in (*TASK_STATUSES, *TICKET_STATUSES))
    op.execute(f"ALTER TABLE item ADD CONSTRAINT ck_item_status CHECK (status IN ({statuses}))")