-- Dual-path convergence (Gate B): apply the unified task system that
-- Alembic migrations 0124 (columns/indexes/FK) and 0127 (drop legacy FK)
-- create on the core path. Idempotent so both install paths converge to
-- the identical schema. The end state has NO foreign key on contact_id.
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS assignee_type VARCHAR(20) NOT NULL DEFAULT 'user';
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS assignee_id UUID;
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS entity_type VARCHAR(80);
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS entity_id UUID;
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS creator_type VARCHAR(20) NOT NULL DEFAULT 'user';
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS creator_id UUID;
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS parent_task_id UUID;
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS depends_on JSONB NOT NULL DEFAULT '[]'::jsonb;
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS task_type VARCHAR(30) NOT NULL DEFAULT 'todo';
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS success_criteria JSONB;
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS target_date TIMESTAMPTZ;
ALTER TABLE tasks ADD COLUMN IF NOT EXISTS progress INTEGER NOT NULL DEFAULT 0;

CREATE INDEX IF NOT EXISTS ix_tasks_tenant_entity ON tasks(tenant_id, entity_type, entity_id);
CREATE INDEX IF NOT EXISTS ix_tasks_tenant_assignee ON tasks(tenant_id, assignee_type, assignee_id);
CREATE INDEX IF NOT EXISTS ix_tasks_tenant_parent ON tasks(tenant_id, parent_task_id);
CREATE INDEX IF NOT EXISTS ix_tasks_tenant_type ON tasks(tenant_id, task_type);

DO $$
BEGIN
    IF NOT EXISTS (
        SELECT 1 FROM pg_constraint WHERE conname = 'fk_tasks_parent_task_id'
    ) THEN
        ALTER TABLE tasks ADD CONSTRAINT fk_tasks_parent_task_id
            FOREIGN KEY (parent_task_id) REFERENCES tasks(id) ON DELETE CASCADE;
    END IF;
END $$;