require('module-alias/register')

const { execFileSync } = require('child_process')
const fs = require('fs')
const path = require('path')

const REPO = path.join(__dirname, '..', '..', '..')

//
// These shell out to the Prisma CLI, which only exists inside nix-shell. Skip
// rather than fail when it is absent, so `npx jest` still works outside the
// shell -- but do NOT skip silently in a way that hides real drift when it IS
// available.
//
const hasPrisma = (() => {
	try {
		execFileSync('prisma', ['--version'], { stdio: 'ignore' })
		return true
	} catch (error) {
		return false
	}
})()

const describeWithPrisma = hasPrisma ? describe : describe.skip

if (!hasPrisma) {
	console.log('[schema tests] prisma not on PATH - skipping. Run inside nix-shell to exercise these.')
}

const prisma = (args) => execFileSync('prisma', args, {
	cwd: REPO,
	encoding: 'utf8',
	env: process.env,
})

describe('committed migration artifacts', () => {

	test('the baseline migration and lock file are present', () => {
		expect(fs.existsSync(path.join(REPO, 'prisma/schema.prisma'))).toBe(true)
		expect(fs.existsSync(path.join(REPO, 'prisma/migrations/0_init/migration.sql'))).toBe(true)
		expect(fs.existsSync(path.join(REPO, 'prisma/migrations/migration_lock.toml'))).toBe(true)
	})

	//
	// Prisma emits COLLATE utf8mb4_unicode_ci for MySQL, but every table in this
	// database is utf8mb4_general_ci, and `prisma migrate diff` does NOT report
	// the difference. So a regenerated migration would silently build a
	// differently-collated database. This asserts the hand-correction is intact.
	//
	test('no migration declares a collation other than utf8mb4_general_ci', () => {
		const dir = path.join(REPO, 'prisma/migrations')
		const files = fs.readdirSync(dir, { withFileTypes: true })
			.filter(entry => entry.isDirectory())
			.map(entry => path.join(dir, entry.name, 'migration.sql'))
			.filter(file => fs.existsSync(file))

		expect(files.length).toBeGreaterThan(0)

		files.forEach(file => {
			const ddl = fs.readFileSync(file, 'utf8')
				.split('\n')
				.filter(line => !line.trim().startsWith('--'))
				.join('\n')

			const collations = [...ddl.matchAll(/COLLATE\s+([A-Za-z0-9_]+)/gi)].map(match => match[1])
			collations.forEach(collation => {
				expect(collation).toBe('utf8mb4_general_ci')
			})
		})
	})

	test('the baseline creates the FULLTEXT index, not a plain one', () => {
		const sql = fs.readFileSync(path.join(REPO, 'prisma/migrations/0_init/migration.sql'), 'utf8')

		expect(sql).toMatch(/FULLTEXT INDEX `attachment_text_index`/)
		// A plain INDEX of that name would be the silent-failure mode.
		expect(sql).not.toMatch(/^\s*INDEX `attachment_text_index`/m)
	})

	//
	// @@fulltext is GA in Prisma 7 -- the `fullTextIndex` preview flag no longer
	// exists in the CLI at all (verified: zero occurrences in the 7.8.0 bundle).
	// It was silently ignored rather than rejected, which makes it exactly the
	// kind of dead config that misleads the next reader.
	//
	test('the schema declares @@fulltext and no longer carries the dead preview flag', () => {
		const schema = fs.readFileSync(path.join(REPO, 'prisma/schema.prisma'), 'utf8')

		expect(schema).toMatch(/@@fulltext\(\[text\]/)
		expect(schema).not.toMatch(/fullTextIndex/)
	})

	//
	// No generator block means `prisma generate` cannot produce a client into
	// this repo. That is the structural guarantee behind "migrations only" --
	// stronger than a convention, because it cannot be done by accident.
	//
	test('the schema declares no generator, so no client can be generated', () => {
		const schema = fs.readFileSync(path.join(REPO, 'prisma/schema.prisma'), 'utf8')

		expect(schema).not.toMatch(/generator\s+\w+\s*\{/)
		expect(schema).toMatch(/datasource\s+db\s*\{/)
	})

	//
	// The running server must never depend on Prisma.
	//
	test('no application code imports prisma', () => {
		const { execFileSync } = require('child_process')
		let hits = ''
		try {
			hits = execFileSync('grep', [
				'-rn', '--include=*.js',
				'-E', "require\\(['\"]@?prisma", path.join(REPO, 'server'),
			], { encoding: 'utf8' })
		} catch (error) {
			hits = '' // grep exits 1 when nothing matches
		}
		expect(hits.trim()).toBe('')
	})

	test('no @relation is introduced - this database has no foreign keys', () => {
		// Adding relations would mean adding FK constraints to a live database,
		// which is a schema change well outside adopting a migration tool.
		const schema = fs.readFileSync(path.join(REPO, 'prisma/schema.prisma'), 'utf8')
		expect(schema).not.toMatch(/@relation/)
	})
})

describeWithPrisma('schema drift', () => {

	//
	// The check that keeps schema.prisma honest: if the live database and the
	// committed schema ever diverge, this fails.
	//
	test('schema.prisma matches the live database exactly', () => {
		const output = prisma([
			'migrate', 'diff',
			'--from-config-datasource',
			'--to-schema', 'prisma/schema.prisma',
			'--script',
		])

		expect(output).toMatch(/This is an empty migration/)
	})

	//
	// The load-bearing guarantee: the committed migrations, applied to an empty
	// database, reproduce the live schema exactly.
	//
	// Done by actually rebuilding into a scratch database and comparing
	// information_schema, rather than via `migrate diff --from-migrations`
	// (which requires a shadow database) -- and this is the stronger check
	// anyway, because it also catches collation drift, which Prisma's own diff
	// does NOT report.
	//
	test('the committed migrations rebuild the live schema exactly', () => {
		const db = require('@config/database')
		const SCRATCH = 'prisma_drift_check'

		const mysqlBin = (() => {
			try { execFileSync('mariadb', ['--version'], { stdio: 'ignore' }); return 'mariadb' }
			catch (error) { return 'mysql' }
		})()

		const adminArgs = ['-u', 'root']
		const socket = path.join(REPO, '.mysql', 'mysql.sock')
		if (fs.existsSync(socket)) { adminArgs.push(`--socket=${socket}`) }

		const admin = (sql, database) => execFileSync(
			mysqlBin,
			[...adminArgs, '-N', '-B', ...(database ? [database] : []), '-e', sql],
			{ encoding: 'utf8' }
		)

		try {
			admin(`DROP DATABASE IF EXISTS \`${SCRATCH}\`; CREATE DATABASE \`${SCRATCH}\`;`)

			execFileSync('prisma', ['migrate', 'deploy'], {
				cwd: REPO,
				encoding: 'utf8',
				env: { ...process.env, DATABASE_URL: `mysql://root@127.0.0.1:3306/${SCRATCH}` },
			})

			const snapshot = (schema) => ({
				columns: admin(
					`SELECT TABLE_NAME, COLUMN_NAME, COLUMN_TYPE, IS_NULLABLE, COLUMN_DEFAULT, EXTRA, COLLATION_NAME
					 FROM information_schema.COLUMNS
					 WHERE TABLE_SCHEMA='${schema}' AND TABLE_NAME <> '_prisma_migrations'
					 ORDER BY TABLE_NAME, COLUMN_NAME`
				),
				indexes: admin(
					`SELECT TABLE_NAME, INDEX_NAME, SEQ_IN_INDEX, COLUMN_NAME, NON_UNIQUE, INDEX_TYPE
					 FROM information_schema.STATISTICS
					 WHERE TABLE_SCHEMA='${schema}' AND TABLE_NAME <> '_prisma_migrations'
					 ORDER BY TABLE_NAME, INDEX_NAME, SEQ_IN_INDEX`
				),
				collations: admin(
					`SELECT TABLE_NAME, TABLE_COLLATION FROM information_schema.TABLES
					 WHERE TABLE_SCHEMA='${schema}' AND TABLE_NAME <> '_prisma_migrations'
					 ORDER BY TABLE_NAME`
				),
			})

			const live = snapshot('application')
			const rebuilt = snapshot(SCRATCH)

			expect(rebuilt.columns).toBe(live.columns)
			expect(rebuilt.indexes).toBe(live.indexes)
			expect(rebuilt.collations).toBe(live.collations)
		} finally {
			try { admin(`DROP DATABASE IF EXISTS \`${SCRATCH}\`;`) } catch (error) { /* best effort */ }
		}
	})

	test('migrate status reports no pending migrations', () => {
		const output = prisma(['migrate', 'status'])
		expect(output).toMatch(/Database schema is up to date/)
	})
})