-- Migración: Subpreguntas anidadas hasta 5 niveles
-- Fecha: 2025-11-25
-- Descripción: Agrega soporte y validación para subpreguntas anidadas hasta 5 niveles de profundidad

-- Agregar columna para tracking de nivel (opcional pero útil)
ALTER TABLE questions 
ADD COLUMN IF NOT EXISTS depth_level INTEGER DEFAULT 0;

-- Comentarios
COMMENT ON COLUMN questions.parent_question_id IS 'ID de la pregunta padre. NULL = pregunta principal. Soporta anidamiento hasta 5 niveles.';
COMMENT ON COLUMN questions.depth_level IS 'Nivel de profundidad: 0=principal, 1-5=subpreguntas anidadas';

-- Función para calcular profundidad de una pregunta
CREATE OR REPLACE FUNCTION calculate_question_depth(question_id INTEGER)
RETURNS INTEGER AS $$
DECLARE
    current_parent_id INTEGER;
    depth INTEGER := 0;
    max_iterations INTEGER := 10;  -- Protección contra loops infinitos
BEGIN
    -- Obtener el parent_id de la pregunta
    SELECT parent_question_id INTO current_parent_id
    FROM questions
    WHERE id = question_id;
    
    -- Si no tiene padre, es nivel 0
    IF current_parent_id IS NULL THEN
        RETURN 0;
    END IF;
    
    -- Subir por la jerarquía contando niveles
    WHILE current_parent_id IS NOT NULL AND depth < max_iterations LOOP
        depth := depth + 1;
        
        SELECT parent_question_id INTO current_parent_id
        FROM questions
        WHERE id = current_parent_id;
    END LOOP;
    
    RETURN depth;
END;
$$ LANGUAGE plpgsql;

-- Función trigger para validar profundidad máxima
CREATE OR REPLACE FUNCTION validate_question_depth()
RETURNS TRIGGER AS $$
DECLARE
    calculated_depth INTEGER;
    parent_depth INTEGER;
BEGIN
    -- Si no tiene padre, es nivel 0
    IF NEW.parent_question_id IS NULL THEN
        NEW.depth_level := 0;
        RETURN NEW;
    END IF;
    
    -- Validar que el padre existe y no es la misma pregunta
    IF NEW.parent_question_id = NEW.id THEN
        RAISE EXCEPTION 'Una pregunta no puede ser su propio padre';
    END IF;
    
    -- Calcular profundidad del padre
    SELECT depth_level INTO parent_depth
    FROM questions
    WHERE id = NEW.parent_question_id;
    
    IF parent_depth IS NULL THEN
        -- Si el padre no tiene depth_level, calcularlo
        parent_depth := calculate_question_depth(NEW.parent_question_id);
    END IF;
    
    -- La nueva pregunta es un nivel más profundo que su padre
    calculated_depth := parent_depth + 1;
    
    -- Validar que no excede 5 niveles
    IF calculated_depth > 5 THEN
        RAISE EXCEPTION 'No se permiten subpreguntas con profundidad mayor a 5. Esta pregunta tendría profundidad %, máximo permitido: 5', calculated_depth;
    END IF;
    
    -- Asignar el nivel calculado
    NEW.depth_level := calculated_depth;
    
    RETURN NEW;
END;
$$ LANGUAGE plpgsql;

-- Crear trigger para INSERT y UPDATE
DROP TRIGGER IF EXISTS validate_depth_trigger ON questions;
CREATE TRIGGER validate_depth_trigger
    BEFORE INSERT OR UPDATE OF parent_question_id ON questions
    FOR EACH ROW
    EXECUTE FUNCTION validate_question_depth();

-- Actualizar depth_level para preguntas existentes
UPDATE questions 
SET depth_level = calculate_question_depth(id);

-- Crear índice para mejorar queries de subpreguntas
CREATE INDEX IF NOT EXISTS idx_questions_parent ON questions(parent_question_id) WHERE parent_question_id IS NOT NULL;
CREATE INDEX IF NOT EXISTS idx_questions_depth ON questions(depth_level);

-- Función helper para obtener árbol de subpreguntas
CREATE OR REPLACE FUNCTION get_question_tree(root_question_id INTEGER)
RETURNS TABLE (
    id INTEGER,
    parent_question_id INTEGER,
    text TEXT,
    type VARCHAR(30),
    depth_level INTEGER,
    show_if_answer VARCHAR(50),
    path TEXT
) AS $$
BEGIN
    RETURN QUERY
    WITH RECURSIVE question_tree AS (
        -- Pregunta raíz
        SELECT 
            q.id,
            q.parent_question_id,
            q.text,
            q.type,
            q.depth_level,
            q.show_if_answer,
            q.id::TEXT as path
        FROM questions q
        WHERE q.id = root_question_id
        
        UNION ALL
        
        -- Subpreguntas recursivas
        SELECT 
            q.id,
            q.parent_question_id,
            q.text,
            q.type,
            q.depth_level,
            q.show_if_answer,
            qt.path || ' > ' || q.id::TEXT
        FROM questions q
        INNER JOIN question_tree qt ON q.parent_question_id = qt.id
        WHERE q.depth_level <= 5  -- Límite de seguridad
    )
    SELECT * FROM question_tree
    ORDER BY depth_level, id;
END;
$$ LANGUAGE plpgsql;

-- Verificar estructura actual
SELECT 
    COUNT(*) as total_preguntas,
    COUNT(CASE WHEN parent_question_id IS NULL THEN 1 END) as principales,
    COUNT(CASE WHEN parent_question_id IS NOT NULL THEN 1 END) as subpreguntas,
    MAX(depth_level) as max_profundidad
FROM questions;

-- Ver distribución por profundidad
SELECT 
    depth_level,
    COUNT(*) as cantidad,
    CASE 
        WHEN depth_level = 0 THEN 'Principales'
        WHEN depth_level = 1 THEN 'Nivel 1'
        WHEN depth_level = 2 THEN 'Nivel 2'
        WHEN depth_level = 3 THEN 'Nivel 3'
        WHEN depth_level = 4 THEN 'Nivel 4'
        WHEN depth_level = 5 THEN 'Nivel 5'
    END as descripcion
FROM questions
GROUP BY depth_level
ORDER BY depth_level;

SELECT '✓ Migración de subpreguntas anidadas completada' AS status;