const { pool } = require('../db');

const SAMPLE_LIMIT = 50;

const sampleSpecs = {
    catalog_categories: {
        columns: ['id', 'name', 'description', 'created_at', 'updated_at'],
        orderBy: ['updated_at', 'created_at', 'id']
    },
    catalog_products: {
        columns: ['id', 'type', 'sku', 'name', 'category_id', 'composition', 'gramature', 'material_yield', 'width_cm', 'color', 'subcategory', 'sizes', 'created_at', 'updated_at'],
        orderBy: ['updated_at', 'created_at', 'id']
    },
    consumption_references: {
        columns: ['id', 'product_id', 'material_product_id', 'color', 'general_yield', 'size_yields', 'size_areas', 'gramature', 'efficiency_percent', 'rib_g_per_piece', 'material_cost_per_kg', 'consumption_quantity', 'consumption_unit', 'source', 'last_production_order_id', 'created_at', 'updated_at'],
        orderBy: ['updated_at', 'created_at', 'id']
    },
    cutting_family_rules: {
        columns: ['family_key', 'units_per_roll', 'updated_at'],
        orderBy: ['family_key']
    },
    cutting_product_overrides: {
        columns: ['product_id', 'family_key', 'color', 'size', 'product_type', 'planning_notes', 'updated_at'],
        orderBy: ['updated_at', 'product_id']
    },
    orders: {
        columns: ['id', 'pedido_id', 'data_pedido', 'data_pedido_date', 'valor_pedido', 'produto_id', 'produto_descricao', 'quantidade', 'valor_unitario', 'id_vendedor', 'nome_vendedor', 'marketplace', 'canal_venda', 'numero_ecommerce', 'created_at'],
        orderBy: ['data_pedido_date', 'created_at', 'id']
    },
    production_order_markers: {
        columns: ['id', 'production_order_id', 'label', 'color', 'created_at'],
        orderBy: ['created_at', 'id']
    },
    production_order_components: {
        columns: ['id', 'production_order_id', 'component_tiny_id', 'component_sku', 'component_name', 'quantity_per_unit', 'total_quantity', 'unit', 'created_at', 'updated_at'],
        orderBy: ['updated_at', 'created_at', 'id']
    },
    production_order_steps: {
        columns: ['id', 'production_order_id', 'step_number', 'name', 'start_date', 'end_date', 'status', 'color', 'created_at', 'updated_at'],
        orderBy: ['updated_at', 'created_at', 'id']
    },
    production_orders: {
        columns: ['id', 'tiny_id', 'number', 'status', 'order_reference', 'issue_date', 'expected_date', 'product_sku', 'product_description', 'quantity', 'unit', 'integration_status', 'notes', 'supplier', 'lot_code', 'roll_quantity', 'fabric_kg', 'rib_kg', 'yield_pieces_per_kg', 'created_at', 'updated_at'],
        orderBy: ['updated_at', 'created_at', 'id']
    },
    stock: {
        columns: ['produto_id', 'nome', 'saldo', 'delta_estoque', 'updated_at'],
        orderBy: ['updated_at', 'produto_id']
    },
    stock_campaign_queue: {
        columns: ['id', 'base_product_name', 'produto_id', 'nome', 'saldo', 'delta_estoque', 'status', 'attempts', 'last_error', 'created_at', 'updated_at', 'sent_at'],
        orderBy: ['updated_at', 'created_at', 'id']
    },
    supply_fabric_plans: {
        columns: ['id', 'material', 'color', 'quantity_kg', 'supplier', 'priority', 'status', 'created_at', 'updated_at'],
        orderBy: ['updated_at', 'created_at', 'id']
    },
    supply_movements: {
        columns: ['id', 'receipt_id', 'lot_id', 'type', 'category', 'product', 'quantity', 'unit', 'reason', 'created_at'],
        orderBy: ['created_at', 'id']
    },
    supply_receipts: {
        columns: ['id', 'category', 'product', 'quantity', 'unit', 'supplier', 'invoice', 'notes', 'status', 'created_at', 'updated_at', 'approved_at'],
        orderBy: ['updated_at', 'created_at', 'id']
    },
    supply_stock_lots: {
        columns: ['id', 'receipt_id', 'category', 'product', 'quantity', 'unit', 'supplier', 'invoice', 'status', 'created_at', 'updated_at'],
        orderBy: ['updated_at', 'created_at', 'id']
    }
};

const quoteIdentifier = (identifier) => {
    if (!/^[a-z_][a-z0-9_]*$/.test(identifier)) {
        throw new Error(`Unsafe database identifier: ${identifier}`);
    }

    return `"${identifier}"`;
};

const listPublicTables = async () => {
    const result = await pool.query(`
        SELECT table_name
        FROM information_schema.tables
        WHERE table_schema = 'public'
          AND table_type = 'BASE TABLE'
        ORDER BY table_name
    `);

    return result.rows.map(row => row.table_name);
};

const listPublicColumns = async () => {
    const result = await pool.query(`
        SELECT table_name, column_name
        FROM information_schema.columns
        WHERE table_schema = 'public'
        ORDER BY table_name, ordinal_position
    `);

    return result.rows.reduce((columnsByTable, row) => {
        if (!columnsByTable[row.table_name]) columnsByTable[row.table_name] = [];
        columnsByTable[row.table_name].push(row.column_name);
        return columnsByTable;
    }, {});
};

const countTableRows = async (tableName) => {
    const result = await pool.query(`SELECT COUNT(*)::int AS count FROM ${quoteIdentifier(tableName)}`);
    return result.rows[0]?.count || 0;
};

const buildOrderClause = (spec, availableColumns) => {
    const orderColumns = spec.orderBy.filter(column => availableColumns.includes(column));
    if (!orderColumns.length) return '';

    const clauses = orderColumns.map(column => {
        const direction = column === 'family_key' || column === 'product_id' || column === 'produto_id' ? 'ASC' : 'DESC';
        return `${quoteIdentifier(column)} ${direction}`;
    });

    return ` ORDER BY ${clauses.join(', ')}`;
};

const sampleTableRows = async (tableName, availableColumns) => {
    const spec = sampleSpecs[tableName];
    if (!spec) return null;

    const selectedColumns = spec.columns.filter(column => availableColumns.includes(column));
    if (!selectedColumns.length) return null;

    const selectClause = selectedColumns.map(quoteIdentifier).join(', ');
    const orderClause = buildOrderClause(spec, availableColumns);
    const result = await pool.query(
        `SELECT ${selectClause} FROM ${quoteIdentifier(tableName)}${orderClause} LIMIT $1`,
        [SAMPLE_LIMIT]
    );

    return result.rows;
};

const buildDatabaseDiagnostic = async (user) => {
    const [tables, columnsByTable] = await Promise.all([
        listPublicTables(),
        listPublicColumns()
    ]);

    const counts = {};
    const samples = {};

    for (const tableName of tables) {
        counts[tableName] = await countTableRows(tableName);

        const sampleRows = await sampleTableRows(tableName, columnsByTable[tableName] || []);
        if (sampleRows) samples[tableName] = sampleRows;
    }

    return {
        generatedAt: new Date().toISOString(),
        generatedBy: {
            role: user?.role || null,
            userId: user?.userId || null
        },
        sampleLimit: SAMPLE_LIMIT,
        privacy: {
            countsIncludeAllPublicTables: true,
            samplesExcludeTables: ['app_users', 'client_identity_tokens'],
            ordersSampleExcludesCustomerNameAndPhone: true,
            productionOrdersSampleExcludesTinyPayload: true
        },
        counts,
        samples
    };
};

module.exports = {
    buildDatabaseDiagnostic
};