"""Add p60_reference table for HMRC annual ground-truth reconciliation.

P60 is the authoritative end-of-year certificate HMRC issues; its figures
match what HMRC has on file. Storing one row per (tax_year, employer) lets
the dashboard compare `SUM(payslip)` against the P60 totals and surface
missing-month gaps or parser drift.

Columns mirror what the P60 explicitly prints; everything derived (effective
rate, deltas) stays in the dashboard SQL. `paperless_doc_id` is unique so
re-uploading the same PDF is idempotent. `raw_extraction` keeps the full
parsed dict for debugging parser regressions.
"""
import sqlalchemy as sa
from sqlalchemy.dialects import postgresql

from alembic import op

revision = "0005"
down_revision = "0004"
branch_labels = None
depends_on = None

SCHEMA = "payslip_ingest"


def upgrade() -> None:
    op.create_table(
        "p60_reference",
        sa.Column("id", sa.Integer(), primary_key=True, autoincrement=True),
        sa.Column("tax_year", sa.String(), nullable=False),
        sa.Column("employer", sa.String(), nullable=False),
        sa.Column("employer_paye_ref", sa.String(), nullable=True),
        sa.Column("gross_pay", sa.Numeric(12, 2), nullable=False),
        sa.Column("income_tax", sa.Numeric(12, 2), nullable=False),
        sa.Column("national_insurance", sa.Numeric(12, 2), nullable=False),
        sa.Column("student_loan", sa.Numeric(12, 2), nullable=True),
        sa.Column("tax_code", sa.String(), nullable=True),
        sa.Column("paperless_doc_id", sa.Integer(), nullable=False, unique=True),
        sa.Column(
            "raw_extraction",
            postgresql.JSONB().with_variant(sa.JSON(), "sqlite"),
            nullable=False,
        ),
        sa.Column(
            "created_at",
            sa.TIMESTAMP(timezone=True),
            nullable=False,
            server_default=sa.text("now()"),
        ),
        sa.UniqueConstraint("tax_year", "employer", name="uq_p60_tax_year_employer"),
        schema=SCHEMA,
    )
    op.create_index(
        "ix_p60_reference_tax_year",
        "p60_reference",
        ["tax_year"],
        schema=SCHEMA,
    )


def downgrade() -> None:
    op.drop_index("ix_p60_reference_tax_year", table_name="p60_reference", schema=SCHEMA)
    op.drop_table("p60_reference", schema=SCHEMA)