-- 040_job_post_department_id.sql
-- Move the department link from requisitions to job posts: many job posts -> one
-- department. Reverses 039 (requisitions.department_id) and adds
-- job_posts.department_id, the FK behind JobPosts.department_id /
-- JobPosts.department_ref and Department.job_posts.
--
-- job_posts.department (free text) stays: analytics, filters and the talent pool
-- key off it, and the app now writes the department's name there whenever
-- department_id is set.
--
-- Idempotent; applied at startup by alembic_setup.run_manual_sql() after 039.

-- =============================================================================
-- 1. requisitions: drop the 039 link, keeping the department name as text
-- =============================================================================
DO $$
BEGIN
    IF EXISTS (
        SELECT 1 FROM information_schema.columns
        WHERE table_schema = 'app' AND table_name = 'requisitions' AND column_name = 'department_id'
    ) THEN
        -- Rows created while the link existed wrote only department_id; carry the name back.
        UPDATE app.requisitions r
        SET department = d.name
        FROM app.departments d
        WHERE r.department_id = d.id
          AND (r.department IS NULL OR btrim(r.department) = '');

        ALTER TABLE app.requisitions
            DROP CONSTRAINT IF EXISTS fk_requisitions_department_id_departments;
        DROP INDEX IF EXISTS app.ix_requisitions_department_id;
        ALTER TABLE app.requisitions DROP COLUMN department_id;
    END IF;
END $$;

-- =============================================================================
-- 2. job_posts.department_id -> departments.id
-- =============================================================================
ALTER TABLE app.job_posts
    ADD COLUMN IF NOT EXISTS department_id uuid;

DO $$
BEGIN
    IF NOT EXISTS (
        SELECT 1 FROM pg_constraint
        WHERE conname = 'fk_job_posts_department_id_departments'
    ) THEN
        ALTER TABLE app.job_posts
            ADD CONSTRAINT fk_job_posts_department_id_departments
            FOREIGN KEY (department_id) REFERENCES app.departments (id);
    END IF;
END $$;

CREATE INDEX IF NOT EXISTS ix_job_posts_department_id
    ON app.job_posts (department_id);

-- Backfill: job posts whose text department equals a department's name or short
-- code (case-insensitive, trimmed). Unmatched rows stay NULL.
UPDATE app.job_posts j
SET department_id = d.id
FROM app.departments d
WHERE j.department_id IS NULL
  AND lower(btrim(j.department)) IN (lower(d.name), lower(d.short_code));