exports.up = async function (knex) {
  await knex.schema.createTable('approval_definitions', (table) => {
    table.string('id', 191).primary().defaultTo(knex.raw('(UUID())'));
    table.string('name', 191).notNullable();
    table.text('description');
    table.string('triggerType', 191).notNullable();
    table.string('targetObjectType', 191);
    table.json('entryCriteria');
    table.json('steps');
    table.json('votingPolicy');
    table.string('rejectionRule', 191);
    table.string('materialChangePolicy', 191);
    table.integer('version').notNullable().defaultTo(1);
    table.boolean('isActive').notNullable().defaultTo(true);
    table.timestamp('createdAt').notNullable().defaultTo(knex.fn.now());
    table.timestamp('updatedAt').notNullable().defaultTo(knex.fn.now());
  });

  await knex.schema.createTable('approval_requests', (table) => {
    table.string('id', 191).primary().defaultTo(knex.raw('(UUID())'));
    table.string('definitionId', 191).notNullable();
    table.string('status', 191).notNullable().defaultTo('pending');
    table.string('targetObjectType', 191).notNullable();
    table.string('targetObjectId', 191).notNullable();
    table.string('action', 191);
    table.string('stateFrom', 191);
    table.string('stateTo', 191);
    table.json('fieldChanges');
    table.json('snapshot');
    table.string('versionHash', 191);
    table.string('submittedById', 191);
    table.timestamp('submittedAt');
    table.string('currentStepKey', 191);
    table.timestamp('createdAt').notNullable().defaultTo(knex.fn.now());
    table.timestamp('updatedAt').notNullable().defaultTo(knex.fn.now());

    table.index(['definitionId']);
    table.index(['targetObjectType', 'targetObjectId']);
    table.index(['submittedById']);
    table
      .foreign('definitionId')
      .references('id')
      .inTable('approval_definitions')
      .onDelete('CASCADE')
      .onUpdate('CASCADE');
    table
      .foreign('submittedById')
      .references('id')
      .inTable('users')
      .onDelete('SET NULL')
      .onUpdate('CASCADE');
  });

  await knex.schema.createTable('approval_steps', (table) => {
    table.string('id', 191).primary().defaultTo(knex.raw('(UUID())'));
    table.string('requestId', 191).notNullable();
    table.string('stepKey', 191).notNullable();
    table.string('name', 191).notNullable();
    table.integer('stepOrder').notNullable();
    table.string('status', 191).notNullable().defaultTo('pending');
    table.json('routing');
    table.json('voting');
    table.timestamp('dueAt');
    table.timestamp('completedAt');
    table.timestamp('createdAt').notNullable().defaultTo(knex.fn.now());
    table.timestamp('updatedAt').notNullable().defaultTo(knex.fn.now());

    table.index(['requestId']);
    table.index(['status']);
    table
      .foreign('requestId')
      .references('id')
      .inTable('approval_requests')
      .onDelete('CASCADE')
      .onUpdate('CASCADE');
  });

  await knex.schema.createTable('approval_assignments', (table) => {
    table.string('id', 191).primary().defaultTo(knex.raw('(UUID())'));
    table.string('stepId', 191).notNullable();
    table.string('assigneeId', 191).notNullable();
    table.string('status', 191).notNullable().defaultTo('pending');
    table.text('response');
    table.timestamp('respondedAt');
    table.timestamp('dueAt');
    table.string('reassignedFromId', 191);
    table.string('delegatedById', 191);
    table.timestamp('createdAt').notNullable().defaultTo(knex.fn.now());
    table.timestamp('updatedAt').notNullable().defaultTo(knex.fn.now());

    table.index(['stepId']);
    table.index(['assigneeId']);
    table.index(['status']);
    table
      .foreign('stepId')
      .references('id')
      .inTable('approval_steps')
      .onDelete('CASCADE')
      .onUpdate('CASCADE');
    table
      .foreign('assigneeId')
      .references('id')
      .inTable('users')
      .onDelete('RESTRICT')
      .onUpdate('CASCADE');
    table
      .foreign('reassignedFromId')
      .references('id')
      .inTable('users')
      .onDelete('SET NULL')
      .onUpdate('CASCADE');
    table
      .foreign('delegatedById')
      .references('id')
      .inTable('users')
      .onDelete('SET NULL')
      .onUpdate('CASCADE');
  });

  await knex.schema.createTable('approval_effect_logs', (table) => {
    table.string('id', 191).primary().defaultTo(knex.raw('(UUID())'));
    table.string('requestId', 191).notNullable();
    table.string('effectKey', 191).notNullable();
    table.string('status', 191).notNullable().defaultTo('success');
    table.json('response');
    table.timestamp('executedAt').notNullable().defaultTo(knex.fn.now());

    table.unique(['requestId', 'effectKey']);
    table.index(['requestId']);
    table
      .foreign('requestId')
      .references('id')
      .inTable('approval_requests')
      .onDelete('CASCADE')
      .onUpdate('CASCADE');
  });

  await knex.schema.createTable('tasks', (table) => {
    table.string('id', 191).primary().defaultTo(knex.raw('(UUID())'));
    table.string('title', 191).notNullable();
    table.text('description');
    table.string('status', 191).notNullable().defaultTo('open');
    table.string('priority', 191);
    table.timestamp('dueAt');
    table.string('assignedToId', 191);
    table.string('relatedObjectType', 191);
    table.string('relatedObjectId', 191);
    table.timestamp('createdAt').notNullable().defaultTo(knex.fn.now());
    table.timestamp('updatedAt').notNullable().defaultTo(knex.fn.now());

    table.index(['assignedToId']);
    table.index(['relatedObjectType', 'relatedObjectId']);
    table
      .foreign('assignedToId')
      .references('id')
      .inTable('users')
      .onDelete('SET NULL')
      .onUpdate('CASCADE');
  });

  await knex.schema.createTable('activity_logs', (table) => {
    table.string('id', 191).primary().defaultTo(knex.raw('(UUID())'));
    table.string('action', 191).notNullable();
    table.string('subjectType', 191).notNullable();
    table.string('subjectId', 191).notNullable();
    table.text('description');
    table.json('properties');
    table.string('causerId', 191);
    table.timestamp('createdAt').notNullable().defaultTo(knex.fn.now());

    table.index(['subjectType', 'subjectId']);
    table.index(['causerId']);
    table
      .foreign('causerId')
      .references('id')
      .inTable('users')
      .onDelete('SET NULL')
      .onUpdate('CASCADE');
  });
};

exports.down = async function (knex) {
  await knex.schema.dropTableIfExists('activity_logs');
  await knex.schema.dropTableIfExists('tasks');
  await knex.schema.dropTableIfExists('approval_effect_logs');
  await knex.schema.dropTableIfExists('approval_assignments');
  await knex.schema.dropTableIfExists('approval_steps');
  await knex.schema.dropTableIfExists('approval_requests');
  await knex.schema.dropTableIfExists('approval_definitions');
};