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
	}{
		{
			name: "unknown field",
			text: `{"endpont": "api"}`,
		},
		{
			name: "unknown nested field",
			text: `{"compactor": {"modle": "x"}}`,
		},
		{
			name: "endpoint URL",
			text: `{"endpoint": "https://example.com/v1/responses"}`,
		},
		{
			name: "empty model",
			text: `{"compactor": {"model": ""}}`,
		},
		{
			name: "second object",
			text: `{} {}`,
		},
		{
			name: "broken JSON",
			text: `{"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
	}{
		{
			name: "ONECHAT_DIR first",
			dir:  filepath.Join(root, "a"),
			xdg:  filepath.Join(root, "xdg"),
			home: root,
			want: filepath.Join(root, "a"),
		},
		{
			name: "absolute XDG_DATA_HOME",
			dir:  "",
			xdg:  filepath.Join(root, "xdg"),
			home: root,
			want: filepath.Join(root, "xdg", "onechat"),
		},
		{
			name: "relative XDG_DATA_HOME ignored",
			dir:  "",
			xdg:  "xdg",
			home: root,
			want: filepath.Join(root, ".local", "share", "onechat"),
		},
		{
			name: "home directory last",
			dir:  "",
			xdg:  "",
			home: root,
			want: 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)
}