import os
import shutil
import subprocess
import tempfile
import unittest
from pathlib import Path


class EngineBuildTests(unittest.TestCase):
    def setUp(self):
        self.temporary = tempfile.TemporaryDirectory()
        self.root = Path(self.temporary.name)
        engine = Path(__file__).resolve().parents[1]
        for name in ['engine-fingerprint.sh', 'ensure-engine.sh']:
            shutil.copyfile(engine / name, self.root / name)
        for name in ['engine.py', 'exports.py', 'requirements.txt', 'requirements.lock.txt',
                     'personal-expense-template.xlsx', 'helper.entitlements']:
            (self.root / name).write_text('fixture\n')
        self.binary = self.root / 'dist/receipt-engine-helper.app/Contents/MacOS/receipt-engine-helper'
        (self.root / 'build-engine.sh').write_text('''#!/bin/bash
set -euo pipefail
cd "$(dirname "$0")"
echo build >> builds.log
mkdir -p dist/receipt-engine-helper.app/Contents/MacOS
printf 'fixture engine\\n' > dist/receipt-engine-helper.app/Contents/MacOS/receipt-engine-helper
chmod +x dist/receipt-engine-helper.app/Contents/MacOS/receipt-engine-helper
SOURCE_HASH="$(bash engine-fingerprint.sh)"
BINARY_HASH="$(shasum -a 256 dist/receipt-engine-helper.app/Contents/MacOS/receipt-engine-helper | cut -d ' ' -f 1)"
printf '%s\\n%s\\n' "$SOURCE_HASH" "$BINARY_HASH" > dist/receipt-engine-helper.source.sha256
''')

    def tearDown(self):
        self.temporary.cleanup()

    def ensure(self):
        return subprocess.run(['bash', str(self.root / 'ensure-engine.sh')],
                              capture_output=True, text=True, timeout=20)

    def build_count(self):
        return len((self.root / 'builds.log').read_text().splitlines())

    def test_missing_engine_builds_and_unchanged_engine_is_reused(self):
        self.assertEqual(self.ensure().returncode, 0)
        self.assertEqual(self.build_count(), 1)
        self.assertEqual(self.ensure().returncode, 0)
        self.assertEqual(self.build_count(), 1)

    def test_changed_sources_rebuild_even_when_timestamp_is_unchanged(self):
        self.assertEqual(self.ensure().returncode, 0)
        source = self.root / 'exports.py'
        original = source.stat()
        source.write_text('new grouping implementation\n')
        os.utime(source, ns=(original.st_atime_ns, original.st_mtime_ns))
        self.assertEqual(self.ensure().returncode, 0)
        self.assertEqual(self.build_count(), 2)

    def test_replaced_binary_rebuilds(self):
        self.assertEqual(self.ensure().returncode, 0)
        self.binary.write_text('old engine\n')
        self.assertEqual(self.ensure().returncode, 0)
        self.assertEqual(self.build_count(), 2)

    def test_missing_stamp_rebuilds(self):
        self.assertEqual(self.ensure().returncode, 0)
        (self.root / 'dist/receipt-engine-helper.source.sha256').unlink()
        self.assertEqual(self.ensure().returncode, 0)
        self.assertEqual(self.build_count(), 2)

    def test_failed_rebuild_does_not_accept_old_engine(self):
        self.assertEqual(self.ensure().returncode, 0)
        (self.root / 'build-engine.sh').write_text('exit 17\n')
        self.assertEqual(self.ensure().returncode, 17)


if __name__ == '__main__':
    unittest.main()