"""unique name constraints on musicians and sources

Revision ID: e5f6a2b3c4d1
Revises: d7e3b19f0a2c
Create Date: 2026-06-09
"""
from alembic import op
import sqlalchemy as sa
from sqlalchemy.sql import text

revision = "e5f6a2b3c4d1"
down_revision = "d7e3b19f0a2c"
branch_labels = None
depends_on = None


def _dedup_musicians(conn):
    """Keep the lowest-id musician for each name; re-point FKs and delete dupes."""
    rows = conn.execute(text(
        "SELECT MIN(id) AS keep_id, LOWER(name) AS lname "
        "FROM musicians GROUP BY LOWER(name) HAVING COUNT(*) > 1"
    )).fetchall()

    for row in rows:
        keep_id = row[0]
        lname   = row[1]
        dupe_ids = [r[0] for r in conn.execute(
            text("SELECT id FROM musicians WHERE LOWER(name) = :n AND id != :k"),
            {"n": lname, "k": keep_id}
        ).fetchall()]

        for dupe_id in dupe_ids:
            # Re-point learned_from_id in tune_by_instrument
            conn.execute(text(
                "UPDATE tune_by_instrument SET learned_from_id = :k "
                "WHERE learned_from_id = :d"
            ), {"k": keep_id, "d": dupe_id})
            # Re-point reference_musicians (skip if keep_id row already exists for that ref)
            conn.execute(text(
                "DELETE FROM reference_musicians WHERE musician_id = :d "
                "AND reference_id IN ("
                "  SELECT reference_id FROM reference_musicians WHERE musician_id = :k"
                ")"
            ), {"d": dupe_id, "k": keep_id})
            conn.execute(text(
                "UPDATE reference_musicians SET musician_id = :k WHERE musician_id = :d"
            ), {"k": keep_id, "d": dupe_id})
            conn.execute(text("DELETE FROM musicians WHERE id = :d"), {"d": dupe_id})


def _dedup_sources(conn):
    """Keep the lowest-id source for each name; re-point tunes.source_id and delete dupes."""
    rows = conn.execute(text(
        "SELECT MIN(id) AS keep_id, LOWER(name) AS lname "
        "FROM sources GROUP BY LOWER(name) HAVING COUNT(*) > 1"
    )).fetchall()

    for row in rows:
        keep_id = row[0]
        lname   = row[1]
        dupe_ids = [r[0] for r in conn.execute(
            text("SELECT id FROM sources WHERE LOWER(name) = :n AND id != :k"),
            {"n": lname, "k": keep_id}
        ).fetchall()]

        for dupe_id in dupe_ids:
            conn.execute(text(
                "UPDATE tunes SET source_id = :k WHERE source_id = :d"
            ), {"k": keep_id, "d": dupe_id})
            conn.execute(text("DELETE FROM sources WHERE id = :d"), {"d": dupe_id})


def upgrade() -> None:
    conn = op.get_bind()
    _dedup_musicians(conn)
    _dedup_sources(conn)
    op.create_unique_constraint("uq_musicians_name", "musicians", ["name"])
    op.create_unique_constraint("uq_sources_name",   "sources",   ["name"])


def downgrade() -> None:
    op.drop_constraint("uq_musicians_name", "musicians", type_="unique")
    op.drop_constraint("uq_sources_name",   "sources",   type_="unique")