"""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
"""
from alembic import op

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 (nur falls nicht vorhanden – CREATE TYPE IF NOT EXISTS nicht überall unterstützt)
    op.execute("""
        DO $$
        BEGIN
            IF NOT EXISTS (SELECT 1 FROM pg_type WHERE typname = 'assignment_mode') THEN
                CREATE TYPE assignment_mode AS ENUM ('fza', 'payroll', 'both');
            END IF;
        END $$
    """)

    # Tabelle nur anlegen falls noch nicht vorhanden (idempotent)
    op.execute("""
        CREATE TABLE IF NOT EXISTS special_assignments (
            id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
            user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
            company_id UUID NOT NULL REFERENCES companies(id) ON DELETE CASCADE,
            date_from DATE NOT NULL,
            date_to DATE NOT NULL,
            factor NUMERIC(5,3) NOT NULL,
            mode assignment_mode NOT NULL DEFAULT 'both',
            label VARCHAR(100),
            description TEXT,
            CONSTRAINT ck_special_assignment_factor CHECK (factor > 0 AND factor <= 10),
            CONSTRAINT ck_special_assignment_dates CHECK (date_from <= date_to)
        )
    """)
    op.execute("CREATE INDEX IF NOT EXISTS ix_special_assignments_user_id ON special_assignments(user_id)")
    op.execute("CREATE INDEX IF NOT EXISTS ix_special_assignments_company_id ON special_assignments(company_id)")

    # Exclusion Constraint (nur falls noch nicht vorhanden)
    op.execute("""
        DO $$
        BEGIN
            IF NOT EXISTS (
                SELECT 1 FROM pg_constraint WHERE conname = 'special_assignments_no_overlap'
            ) THEN
                ALTER TABLE special_assignments
                ADD CONSTRAINT special_assignments_no_overlap
                EXCLUDE USING gist (
                    user_id WITH =,
                    daterange(date_from, date_to, '[]') WITH &&
                );
            END IF;
        END $$
    """)


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