/**
 * @param { import("knex").Knex } knex
 * @returns { Promise<void> }
 */
exports.up = async function (knex) {
  await knex.schema.createTable('comments', (table) => {
    table.uuid('id').primary().defaultTo(knex.raw('(UUID())'));
    table.string('parent_object_api_name').notNullable();
    table.uuid('parent_record_id').notNullable();
    table.uuid('author_user_id').notNullable();
    table.text('content').notNullable();
    table.timestamps(true, true);

    table.foreign('author_user_id').references('id').inTable('users').onDelete('CASCADE');
    table.index(['parent_object_api_name', 'parent_record_id'], 'comments_parent_idx');
    table.index(['author_user_id'], 'comments_author_idx');
  });

  await knex.schema.createTable('semantic_documents', (table) => {
    table.uuid('id').primary().defaultTo(knex.raw('(UUID())'));
    table.string('entity_type').notNullable();
    table.uuid('entity_id').notNullable();
    table.string('title').nullable();
    table.text('narrative').nullable();
    table.json('metadata').nullable();
    table.json('source_summary').nullable();
    table.timestamps(true, true);

    table.unique(['entity_type', 'entity_id'], {
      indexName: 'semantic_documents_entity_unique',
    });
    table.index(['entity_type'], 'semantic_documents_type_idx');
  });

  await knex.schema.createTable('semantic_chunks', (table) => {
    table.uuid('id').primary().defaultTo(knex.raw('(UUID())'));
    table.uuid('semantic_document_id').notNullable();
    table.integer('chunk_index').notNullable();
    table.string('source_kind').notNullable().defaultTo('base_record');
    table.uuid('source_ref_id').nullable();
    table.text('text').notNullable();
    table.json('metadata').nullable();
    table.timestamps(true, true);

    table.foreign('semantic_document_id').references('id').inTable('semantic_documents').onDelete('CASCADE');
    table.unique(['semantic_document_id', 'chunk_index'], {
      indexName: 'semantic_chunks_doc_index_unique',
    });
    table.index(['semantic_document_id'], 'semantic_chunks_document_idx');
    table.index(['source_kind'], 'semantic_chunks_source_kind_idx');
  });

  await knex.schema.createTable('semantic_links', (table) => {
    table.uuid('id').primary().defaultTo(knex.raw('(UUID())'));
    table.string('source_entity_type').notNullable();
    table.uuid('source_entity_id').notNullable();
    table.string('target_entity_type').notNullable();
    table.uuid('target_entity_id').notNullable();
    table.string('link_type').notNullable().defaultTo('related_to');
    table.string('status').notNullable().defaultTo('suggested');
    table.string('origin').notNullable().defaultTo('semantic');
    table.decimal('confidence', 5, 4).notNullable().defaultTo(0);
    table.text('reason').nullable();
    table.json('evidence').nullable();
    table.uuid('suggested_by_user_id').nullable();
    table.uuid('reviewed_by_user_id').nullable();
    table.timestamp('reviewed_at').nullable();
    table.timestamps(true, true);

    table.foreign('suggested_by_user_id').references('id').inTable('users').onDelete('SET NULL');
    table.foreign('reviewed_by_user_id').references('id').inTable('users').onDelete('SET NULL');

    table.unique(
      ['source_entity_type', 'source_entity_id', 'target_entity_type', 'target_entity_id', 'link_type'],
      { indexName: 'semantic_links_unique_pair_type' },
    );

    table.index(['source_entity_type', 'source_entity_id'], 'semantic_links_source_idx');
    table.index(['target_entity_type', 'target_entity_id'], 'semantic_links_target_idx');
    table.index(['status'], 'semantic_links_status_idx');
  });
};

/**
 * @param { import("knex").Knex } knex
 * @returns { Promise<void> }
 */
exports.down = async function (knex) {
  await knex.schema.dropTableIfExists('semantic_links');
  await knex.schema.dropTableIfExists('semantic_chunks');
  await knex.schema.dropTableIfExists('semantic_documents');
  await knex.schema.dropTableIfExists('comments');
};