Migration sql changes (#199)

* safe migration script changes

* lamassu migration script fixes

migrations/db.js

@@ -1,7 +1,22 @@
+const _ = require('lodash/fp')
 const db = require('../lib/db')
 const sequential = require('promise-sequential')
 
-module.exports = {multi}
+module.exports = {
+  multi,
+  defineEnum,
+  dropEnum,
+  renameEnum,
+  alterColumn,
+  addColumn,
+  dropColumn,
+  renameColumn,
+  dropConstraint,
+  addConstraint,
+  addSequence,
+  alterSequence,
+  ifColumn
+}
 
 function multi (sqls, cb) {
   const doQuery = s => {
@@ -21,3 +36,139 @@ function multi (sqls, cb) {
       cb(err)
     })
 }
+
+function beginEnd (statement) {
+  return `
+  DO $$
+  BEGIN
+    ${statement};
+  END $$
+`
+}
+
+function defineEnum (name, values) {
+  return beginEnd(`
+    IF NOT EXISTS (
+      SELECT 1 FROM pg_type WHERE typname = '${name}'
+    ) THEN
+      CREATE TYPE ${name} AS ENUM (${values});
+    END IF
+  `)
+}
+
+function dropEnum (name) {
+  return beginEnd(`
+    IF EXISTS (
+      SELECT 1 FROM pg_type WHERE typname = '${name}'
+    ) THEN
+      DROP TYPE ${name};
+    END IF
+  `)
+}
+
+function renameEnum (name, newName) {
+  return beginEnd(`
+    IF EXISTS (
+      SELECT 1 FROM pg_type WHERE typname = '${name}'
+    ) THEN
+      IF NOT EXISTS (
+        SELECT 1 FROM pg_type WHERE typname = '${newName}'
+      ) THEN
+        ALTER TYPE ${name} RENAME TO ${newName};
+      END IF;
+    END IF
+  `)
+}
+
+function ifColumn (table, column, statement, not, skipBeginEnd) {
+  statement = `
+    IF EXISTS (
+      SELECT NULL
+      FROM INFORMATION_SCHEMA.TABLEs
+      WHERE table_name = '${table}'
+    ) THEN
+      IF ${not ? 'NOT' : ''} EXISTS (
+        SELECT NULL
+        FROM INFORMATION_SCHEMA.COLUMNS
+        WHERE table_name = '${table}'
+          AND column_name = '${column}'
+      ) THEN
+        ${statement};
+      END IF;
+    END IF
+  `
+  return skipBeginEnd ? statement : beginEnd(statement)
+}
+
+function alterColumn (table, column, change) {
+  return ifColumn(table, column, `
+  ALTER TABLE ${table} 
+    ALTER ${column} ${change}`)
+}
+
+function addColumn (table, column, change) {
+  return ifColumn(table, column, `
+  ALTER TABLE ${table} 
+    ADD ${column} ${change}`, true)
+}
+
+function dropColumn (table, column) {
+  return ifColumn(table, column, `
+  ALTER TABLE ${table} 
+    DROP ${column}`)
+}
+
+function renameColumn (table, column, newName) {
+  return ifColumn(table, column,
+    ifColumn(table, column, `
+      ALTER TABLE ${table} 
+        RENAME ${column} to ${newName}`, true, true))
+}
+
+function dropConstraint (table, column) {
+  return beginEnd(`
+    IF EXISTS( 
+      SELECT NULL
+        FROM INFORMATION_SCHEMA.constraint_column_usage
+        WHERE constraint_name = '${column}'
+      ) THEN
+        ALTER TABLE ${table} DROP CONSTRAINT ${column};
+    END IF
+  `)
+}
+
+function addConstraint (table, column, change, refTable, refColumn) {
+  return ifColumn(refTable, refColumn, `
+    IF NOT EXISTS(
+      SELECT NULL
+        FROM INFORMATION_SCHEMA.constraint_column_usage
+        WHERE constraint_name = '${column}'
+      ) THEN
+        ALTER TABLE ${table} ADD CONSTRAINT ${column} ${change};
+    END IF
+  `, false)
+}
+
+function addSequence (name, change) {
+  return beginEnd(`
+    IF NOT EXISTS(
+      SELECT NULL
+        FROM INFORMATION_SCHEMA.sequences
+        WHERE sequence_name = '${name}'
+      ) THEN
+        CREATE SEQUENCE ${name} ${change};
+    END IF
+  `)
+}
+
+function alterSequence (name, change) {
+  return beginEnd(`
+    IF EXISTS(
+        SELECT NULL
+          FROM INFORMATION_SCHEMA.sequences
+          WHERE sequence_name = '${name}'
+      ) THEN
+        ALTER SEQUENCE ${name} ${change};
+    END IF
+  `)
+}