package main

import (
	"bytes"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"sneak.berlin/go/webhooker/internal/config"
)

// dotEnvKey is a throwaway variable name these tests write and read,
// so they cannot disturb real configuration.
const dotEnvKey = "WEBHOOKER_TEST_DISPATCH_VALUE"

// writeDotEnvInWorkingDir puts contents in a .env file in a fresh
// temporary directory and moves the process there.
//
// The callers are deliberately not parallel and must stay that way:
// t.Chdir moves the whole process. Go releases parallel tests only
// after every sequential test in the package has finished, so nothing
// else runs while these do.
func writeDotEnvInWorkingDir(t *testing.T, contents string) {
	t.Helper()

	dir := t.TempDir()
	require.NoError(t, os.WriteFile(
		filepath.Join(dir, config.DotEnvPath),
		[]byte(contents), 0o600,
	))
	t.Chdir(dir)
}

// TestDispatch_MalformedDotEnvRefuses pins the second half of the
// defect. godotenv applies nothing at all when a file will not parse,
// so one mistyped line used to revert every variable in it to its
// default and start the server anyway, with no log line naming the
// file. The refusal has to arrive before any subcommand runs, which
// is why `help` — the one subcommand that touches nothing — is still
// refused here.
//
//nolint:paralleltest // t.Chdir moves the whole process.
func TestDispatch_MalformedDotEnvRefuses(t *testing.T) {
	writeDotEnvInWorkingDir(t, "PORT 19615\n")

	var stdout, stderr bytes.Buffer

	code := dispatch(
		[]string{helpCommand}, strings.NewReader(""), &stdout, &stderr,
	)

	require.Equal(t, 1, code, "a broken .env must exit non-zero")
	assert.Contains(
		t, stderr.String(), config.DotEnvPath,
		"the refusal must name the file",
	)
	assert.Empty(
		t, stdout.String(),
		"the subcommand must not have run",
	)
}

// TestDispatch_LoadsDotEnvBeforeSubcommands pins the ordering the
// godotenv/autoload import used to provide for free. It ran in an
// init(), so .env was in the environment before anything read it —
// including config.DataDir, which both the DATA_DIR lock and resetpw
// call outside the fx graph. Loading any later would let a .env that
// sets DATA_DIR lock one directory while the config opened databases
// in another.
func TestDispatch_LoadsDotEnvBeforeSubcommands(t *testing.T) {
	t.Setenv(dotEnvKey, "placeholder")
	require.NoError(t, os.Unsetenv(dotEnvKey))

	writeDotEnvInWorkingDir(t, dotEnvKey+"=from-dot-env\n")

	var stdout, stderr bytes.Buffer

	code := dispatch(
		[]string{helpCommand}, strings.NewReader(""), &stdout, &stderr,
	)

	require.Equal(t, 0, code)
	assert.Equal(
		t, "from-dot-env", os.Getenv(dotEnvKey),
		"the file must be applied before the subcommand runs",
	)
}

// TestDispatch_MissingDotEnvIsFine pins the case most deployments are
// in: no .env at all, which must stay a normal start.
//
//nolint:paralleltest // t.Chdir moves the whole process.
func TestDispatch_MissingDotEnvIsFine(t *testing.T) {
	t.Chdir(t.TempDir())

	var stdout, stderr bytes.Buffer

	code := dispatch(
		[]string{helpCommand}, strings.NewReader(""), &stdout, &stderr,
	)

	require.Equal(t, 0, code)
	assert.Empty(t, stderr.String())
}