package main

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

	"github.com/stretchr/testify/require"
)

func TestLoadConfigGivesDefaultsWithoutAFile(t *testing.T) {
	dir := t.TempDir()
	config, err := loadConfig(dir)
	require.NoError(t, err)
	require.Equal(t, defaultConfig(), config)
	require.NoFileExists(t, filepath.Join(dir, "config.json"))
}

func TestLoadConfigKeepsDefaultsForMissingFields(t *testing.T) {
	dir := t.TempDir()
	writeConfig(t, dir, `{"endpoint": "api", "compactor": {"effort": "xhigh"}}`)

	config, err := loadConfig(dir)
	require.NoError(t, err)
	require.Equal(t, Config{
		Endpoint: endpointAPI,
		Compactor: ModelConfig{
			Model:  "gpt-6-luna",
			Effort: "xhigh",
		},
	}, config)
}

func TestLoadConfigRejectsInvalidFiles(t *testing.T) {
	testCases := []struct {
		name string
		text string
	}{
		{"unknown field", `{"endpont": "api"}`},
		{"unknown nested field", `{"compactor": {"modle": "x"}}`},
		{"endpoint URL", `{"endpoint": "https://example.com/v1/responses"}`},
		{"empty model", `{"compactor": {"model": ""}}`},
		{"second object", `{} {}`},
		{"broken JSON", `{"endpoint": `},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			dir := t.TempDir()
			writeConfig(t, dir, tc.text)

			_, err := loadConfig(dir)
			require.Error(t, err)
		})
	}
}

func TestDataDirFollowsTheOrder(t *testing.T) {
	root := t.TempDir()
	testCases := []struct {
		name string
		dir  string
		xdg  string
		home string
		want string
	}{
		{"ONECHAT_DIR first", filepath.Join(root, "a"), filepath.Join(root, "xdg"), root, filepath.Join(root, "a")},
		{"absolute XDG_DATA_HOME", "", filepath.Join(root, "xdg"), root, filepath.Join(root, "xdg", "onechat")},
		{"relative XDG_DATA_HOME ignored", "", "xdg", root, filepath.Join(root, ".local", "share", "onechat")},
		{"home directory last", "", "", root, filepath.Join(root, ".local", "share", "onechat")},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			t.Setenv("ONECHAT_DIR", tc.dir)
			t.Setenv("XDG_DATA_HOME", tc.xdg)
			t.Setenv("HOME", tc.home)

			dir, err := dataDir()
			require.NoError(t, err)
			require.Equal(t, tc.want, dir)

			info, err := os.Stat(dir)
			require.NoError(t, err)
			require.Equal(t, os.FileMode(0o700), info.Mode().Perm())
		})
	}
}

func TestDataDirFailsWithoutAHome(t *testing.T) {
	t.Setenv("ONECHAT_DIR", "")
	t.Setenv("XDG_DATA_HOME", "")
	t.Setenv("HOME", "")

	_, err := dataDir()
	require.ErrorContains(t, err, "ONECHAT_DIR")
}

func writeConfig(t *testing.T, dir, text string) {
	t.Helper()

	err := os.WriteFile(filepath.Join(dir, "config.json"), []byte(text), 0o600)
	require.NoError(t, err)
}