import { describe, expect, test } from 'vitest';

import { analyzeDestructiveMigrations } from './destructiveMigrations.js';

describe('analyzeDestructiveMigrations', () => {
  test('returns empty when SQL has no destructive statements', () => {
    expect(
      analyzeDestructiveMigrations([
        {
          fileName: '0001_init.sql',
          sql: 'CREATE TABLE users (id uuid PRIMARY KEY);\nALTER TABLE users ADD COLUMN email text;'
        }
      ])
    ).toEqual([]);
  });

  test('flags DROP TABLE', () => {
    const findings = analyzeDestructiveMigrations([{ fileName: '0002_drop_users.sql', sql: 'DROP TABLE users;' }]);
    expect(findings).toEqual([
      {
        fileName: '0002_drop_users.sql',
        kind: 'drop_table',
        excerpt: expect.stringMatching(/DROP TABLE users/i)
      }
    ]);
  });

  test('flags DROP DATABASE, DROP SCHEMA, TRUNCATE, and DROP COLUMN', () => {
    const findings = analyzeDestructiveMigrations([
      {
        fileName: '0003_multi.sql',
        sql: `
DROP DATABASE IF EXISTS old_db;
DROP SCHEMA public CASCADE;
TRUNCATE TABLE events;
ALTER TABLE users DROP COLUMN email;
`
      }
    ]);
    expect(findings.map((f) => f.kind).sort()).toEqual(['drop_column', 'drop_database', 'drop_schema', 'truncate']);
  });

  test('flags ALTER TABLE … DROP col without the COLUMN keyword', () => {
    // Postgres treats COLUMN as optional: ALTER TABLE t DROP c;
    const findings = analyzeDestructiveMigrations([{ fileName: '0003b_drop_col_short.sql', sql: 'ALTER TABLE users DROP email;' }]);
    expect(findings).toHaveLength(1);
    expect(findings[0]?.kind).toBe('drop_column');
  });

  test('flags standalone DROP COLUMN without ALTER prefix', () => {
    const findings = analyzeDestructiveMigrations([{ fileName: '0004_drop_col.sql', sql: 'DROP COLUMN orphaned;' }]);
    expect(findings).toHaveLength(1);
    expect(findings[0]?.kind).toBe('drop_column');
  });

  test('ignores DROP INDEX, DROP VIEW, DROP CONSTRAINT, and non-column ALTER', () => {
    expect(
      analyzeDestructiveMigrations([
        {
          fileName: '0005_safe.sql',
          sql: `
DROP INDEX users_email_idx;
DROP VIEW user_summary;
ALTER TABLE users DROP CONSTRAINT users_email_key;
ALTER TABLE users DROP INDEX users_email_idx;
ALTER TABLE users ADD COLUMN name text;
`
        }
      ])
    ).toEqual([]);
  });

  test('ignores ALTER COLUMN DROP NOT NULL / DROP DEFAULT / DROP EXPRESSION (not column drops)', () => {
    expect(
      analyzeDestructiveMigrations([
        {
          fileName: '0005b_safe_alter.sql',
          sql: `
ALTER TABLE users ALTER COLUMN email DROP NOT NULL;
ALTER TABLE users ALTER COLUMN status DROP DEFAULT;
ALTER TABLE users ALTER COLUMN full_name DROP EXPRESSION;
`
        }
      ])
    ).toEqual([]);
  });

  test('does not flag DELETE FROM (data DML is out of the schema-destroying set)', () => {
    expect(analyzeDestructiveMigrations([{ fileName: '0005c_delete.sql', sql: 'DELETE FROM users WHERE id = 1;' }])).toEqual([]);
  });

  test('strips line and block comments before matching', () => {
    expect(
      analyzeDestructiveMigrations([
        {
          fileName: '0006_commented.sql',
          sql: `
-- DROP TABLE users;
/* DROP DATABASE doomed; */
CREATE TABLE users (id int);
`
        }
      ])
    ).toEqual([]);
  });

  test('is case-insensitive and finds multiple statements across files', () => {
    const findings = analyzeDestructiveMigrations([
      { fileName: 'a.sql', sql: 'drop table IF EXISTS foo;' },
      { fileName: 'b.sql', sql: 'Truncate events;' }
    ]);
    expect(findings).toHaveLength(2);
    expect(findings[0]).toMatchObject({ fileName: 'a.sql', kind: 'drop_table' });
    expect(findings[1]).toMatchObject({ fileName: 'b.sql', kind: 'truncate' });
  });
});