-- Migration 032: Progressionsgraph zwischen Übungen (Übung → Übung), getrennt von Varianten-Progression (014).
-- CURR-002 (1): gerichtete Kanten mit optionalem Graph-Kontainer; FK auf exercises; MVP edge_type erweiterbar.

CREATE TABLE IF NOT EXISTS exercise_progression_graphs (
    id SERIAL PRIMARY KEY,
    name VARCHAR(200) NOT NULL,
    description TEXT,
    visibility VARCHAR(50) NOT NULL DEFAULT 'private'
        CHECK (visibility IN ('private', 'club', 'official')),
    club_id INT REFERENCES clubs(id) ON DELETE SET NULL,
    created_by INT REFERENCES profiles(id) ON DELETE SET NULL,
    created_at TIMESTAMP DEFAULT NOW(),
    updated_at TIMESTAMP DEFAULT NOW()
);

CREATE INDEX IF NOT EXISTS idx_exercise_progression_graphs_club ON exercise_progression_graphs(club_id);
CREATE INDEX IF NOT EXISTS idx_exercise_progression_graphs_creator ON exercise_progression_graphs(created_by);
CREATE INDEX IF NOT EXISTS idx_exercise_progression_graphs_visibility ON exercise_progression_graphs(visibility);

DROP TRIGGER IF EXISTS exercise_progression_graphs_update ON exercise_progression_graphs;
CREATE TRIGGER exercise_progression_graphs_update
    BEFORE UPDATE ON exercise_progression_graphs
    FOR EACH ROW EXECUTE FUNCTION update_timestamp();

CREATE TABLE IF NOT EXISTS exercise_progression_edges (
    id SERIAL PRIMARY KEY,
    graph_id INT NOT NULL REFERENCES exercise_progression_graphs(id) ON DELETE CASCADE,
    from_exercise_id INT NOT NULL REFERENCES exercises(id) ON DELETE CASCADE,
    to_exercise_id INT NOT NULL REFERENCES exercises(id) ON DELETE CASCADE,
    edge_type VARCHAR(50) NOT NULL DEFAULT 'next_exercise',
    created_at TIMESTAMP DEFAULT NOW(),
    CHECK (from_exercise_id <> to_exercise_id),
    UNIQUE (graph_id, from_exercise_id, to_exercise_id, edge_type)
);

CREATE INDEX IF NOT EXISTS idx_progression_edges_graph ON exercise_progression_edges(graph_id);
CREATE INDEX IF NOT EXISTS idx_progression_edges_from ON exercise_progression_edges(from_exercise_id);
CREATE INDEX IF NOT EXISTS idx_progression_edges_to ON exercise_progression_edges(to_exercise_id);