import Database from 'better-sqlite3';
import { afterEach, beforeEach, expect, it, vi } from 'vitest';
import { runMigrations, type Migration } from '../../src/lib/server/db/migration-runner.js';

let handle: Database.Database;
beforeEach(() => {
    handle = new Database(':memory:');
    handle.pragma('foreign_keys = ON');
});
afterEach(() => {
    vi.restoreAllMocks();
    handle.close();
});

it('applies ordered upgrades once and appends only pending versions', () => {
    const first = vi.fn((db: Database.Database) =>
        db.exec("CREATE TABLE records(value TEXT); INSERT INTO records VALUES('original')")
    );
    const migrations: Migration[] = [{ version: 1, name: 'records', run: first }];
    runMigrations(handle, migrations);
    handle.exec("UPDATE records SET value='edited'");
    const next = vi.fn((db: Database.Database) => {
        expect(db.pragma('user_version', { simple: true })).toBe(1);
        db.exec('ALTER TABLE records ADD COLUMN added INTEGER DEFAULT 7');
    });
    migrations.push({ version: 2, name: 'additional field', run: next });
    runMigrations(handle, migrations);
    runMigrations(handle, migrations);
    expect(first).toHaveBeenCalledTimes(1);
    expect(next).toHaveBeenCalledTimes(1);
    expect(handle.prepare('SELECT * FROM records').get()).toEqual({ value: 'edited', added: 7 });
    expect(handle.pragma('user_version', { simple: true })).toBe(2);
});

it('rolls back schema, data and version on failure, then retries only the failed step', () => {
    let fail = true;
    const migrations: Migration[] = [
        {
            version: 1,
            name: 'records',
            run: (db) =>
                db.exec("CREATE TABLE records(value TEXT); INSERT INTO records VALUES('old')")
        },
        {
            version: 2,
            name: 'backfill',
            run: (db) => {
                db.exec(
                    "ALTER TABLE records ADD COLUMN extra TEXT; UPDATE records SET value='new'"
                );
                if (fail) throw new Error('interrupted');
            }
        },
        {
            version: 3,
            name: 'index',
            run: (db) => db.exec('CREATE INDEX records_value ON records(value)')
        }
    ];
    expect(() => runMigrations(handle, migrations)).toThrow('interrupted');
    expect(handle.pragma('user_version', { simple: true })).toBe(1);
    expect(handle.prepare('SELECT * FROM records').get()).toEqual({ value: 'old' });
    expect(handle.pragma('index_list(records)')).toEqual([]);
    fail = false;
    runMigrations(handle, migrations);
    expect(handle.prepare('SELECT * FROM records').get()).toEqual({ value: 'new', extra: null });
    expect(handle.pragma('user_version', { simple: true })).toBe(3);
});

it('does not commit a migration if recording its version fails', () => {
    const pragma = handle.pragma.bind(handle);
    vi.spyOn(handle, 'pragma').mockImplementation((sql, options) => {
        if (sql === 'user_version = 1') throw new Error('version write failed');
        return pragma(sql, options);
    });
    expect(() =>
        runMigrations(handle, [
            {
                version: 1,
                name: 'records',
                run: (db) => db.exec('CREATE TABLE records(value TEXT)')
            }
        ])
    ).toThrow('version write failed');
    expect(pragma('user_version', { simple: true })).toBe(0);
    expect(
        handle.prepare("SELECT 1 FROM sqlite_master WHERE name='records'").get()
    ).toBeUndefined();
});

it('rebuilds a referenced table without cascading and restores foreign key enforcement', () => {
    handle.exec(`CREATE TABLE parent(id INTEGER PRIMARY KEY);
        CREATE TABLE child(parent_id INTEGER REFERENCES parent(id) ON DELETE CASCADE);
        INSERT INTO parent VALUES(1); INSERT INTO child VALUES(1);`);
    runMigrations(handle, [
        {
            version: 1,
            name: 'rebuild',
            mode: 'foreign-keys-off',
            run: (db) =>
                db.exec(`CREATE TABLE replacement(id INTEGER PRIMARY KEY, label TEXT);
            INSERT INTO replacement(id) SELECT id FROM parent;
            DROP TABLE parent; ALTER TABLE replacement RENAME TO parent;`)
        }
    ]);
    expect(handle.prepare('SELECT * FROM child').all()).toEqual([{ parent_id: 1 }]);
    expect(handle.pragma('foreign_keys', { simple: true })).toBe(1);
    expect(handle.pragma('foreign_key_check')).toEqual([]);
});

it('rolls back broken references and restores foreign keys on failure', () => {
    handle.exec(`CREATE TABLE parent(id INTEGER PRIMARY KEY);
        CREATE TABLE child(parent_id INTEGER REFERENCES parent(id));`);
    expect(() =>
        runMigrations(handle, [
            {
                version: 1,
                name: 'broken reference',
                mode: 'foreign-keys-off',
                run: (db) => db.exec('INSERT INTO child VALUES(99)')
            }
        ])
    ).toThrow('broken references');
    expect(handle.prepare('SELECT * FROM child').all()).toEqual([]);
    expect(handle.pragma('foreign_keys', { simple: true })).toBe(1);
    expect(handle.pragma('user_version', { simple: true })).toBe(0);
});

it('leaves interrupted autocommit work pending for a resumable retry', () => {
    let fail = true;
    const migrations: Migration[] = [
        {
            version: 1,
            name: 'vacuum',
            mode: 'autocommit',
            run: (db) => {
                expect(db.inTransaction).toBe(false);
                db.exec('CREATE TABLE IF NOT EXISTS records(value TEXT); VACUUM');
                if (fail) throw new Error('interrupted after vacuum');
            }
        }
    ];
    expect(() => runMigrations(handle, migrations)).toThrow('interrupted after vacuum');
    expect(handle.pragma('user_version', { simple: true })).toBe(0);
    fail = false;
    runMigrations(handle, migrations);
    expect(handle.pragma('user_version', { simple: true })).toBe(1);
});

it('rejects newer databases and invalid migration sequences before running work', () => {
    const run = vi.fn();
    handle.pragma('user_version = 2');
    expect(() => runMigrations(handle, [{ version: 1, name: 'older app', run }])).toThrow(
        'Database version 2 is not supported'
    );
    handle.pragma('user_version = 0');
    expect(() => runMigrations(handle, [{ version: 2, name: 'gap', run }])).toThrow('consecutive');
    expect(run).not.toHaveBeenCalled();
});