"""Sondervertretungs-Faktoren: special_assignments Tabelle

Revision ID: 0029
Revises: 0028
Create Date: 2026-05-25

Neue Tabelle special_assignments:
  - user_id + company_id (ForeignKeys mit CASCADE)
  - date_from / date_to
  - factor NUMERIC(5,3)   – Multiplikator (z.B. 1.5)
  - mode ENUM(fza|payroll|both)
  - label / description (optional)
  - Overlap-Check per Constraint (date_from <= date_to) + App-seitige Prüfung
"""
import sqlalchemy as sa
from alembic import op
from sqlalchemy.dialects import postgresql

revision = "0029"
down_revision = "0028"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.execute("CREATE EXTENSION IF NOT EXISTS btree_gist")

    # Enum erzeugen
    op.execute("CREATE TYPE assignment_mode AS ENUM ('fza', 'payroll', 'both')")

    op.create_table(
        "special_assignments",
        sa.Column("id", postgresql.UUID(as_uuid=True), primary_key=True, server_default=sa.text("gen_random_uuid()")),
        sa.Column("user_id", postgresql.UUID(as_uuid=True), sa.ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True),
        sa.Column("company_id", postgresql.UUID(as_uuid=True), sa.ForeignKey("companies.id", ondelete="CASCADE"), nullable=False, index=True),
        sa.Column("date_from", sa.Date, nullable=False),
        sa.Column("date_to", sa.Date, nullable=False),
        sa.Column("factor", sa.Numeric(5, 3), nullable=False),
        sa.Column("mode", sa.Enum("fza", "payroll", "both", name="assignment_mode", create_type=False), nullable=False, server_default="both"),
        sa.Column("label", sa.String(100), nullable=True),
        sa.Column("description", sa.Text, nullable=True),
        sa.CheckConstraint("factor > 0 AND factor <= 10", name="ck_special_assignment_factor"),
        sa.CheckConstraint("date_from <= date_to", name="ck_special_assignment_dates"),
    )

    # Exclusion Constraint: kein überlappender Zeitraum pro User
    op.execute(
        """
        ALTER TABLE special_assignments
        ADD CONSTRAINT special_assignments_no_overlap
        EXCLUDE USING gist (
            user_id WITH =,
            daterange(date_from, date_to, '[]') WITH &&
        )
        """
    )


def downgrade() -> None:
    op.drop_table("special_assignments")
    op.execute("DROP TYPE IF EXISTS assignment_mode")